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THEORY #4: COOKING DESTROYS ENZYMES IN FOOD.

The food-enzyme theory purports that heating food at temperatures reaching 118 degrees F (48 degrees C) or higher denatures food enzymes. All cooking temperatures exceed this limit. Even steaming or boiling a food will produce temperatures up to 212 degrees F (100 degrees C).

SCIENTIFIC FINDINGS

There is no question that heat denatures enzymes. It appears as though optimal food enzyme action (maximum reaction rate) occurs at around 104 degrees F (40 degrees C). However, even slightly higher temperatures can negatively affect enzyme activity. At first, the enzyme begins to unfold and the shape of the active site changes. The substrate may still attach, but not as strongly as it otherwise would. This slows down the reaction time. When the temperature reaches about 113 degrees F (45 degrees C), enzyme function can be more seriously compromised. By the time the temperature reaches 135–140 degrees F (57–60 degrees C), food enzymes are generally completely denatured. The longer the heat is maintained above 113 degrees F (45 degrees C), the more enzyme activity is lost. The whole process is quite gradual, and at certain stages, it is even reversible. However, once the enzyme is completely denatured, the process is usually irreversible. The magic number (118 degrees F/48 degrees C) offered by proponents of the food-enzyme theory is certainly consistent with scientific findings. However, while some imagine enzyme activity as going from 100 percent at temperatures under 118 degrees F (48 degrees C) to 0 percent over this temperature, the process is in fact very gradual.26, 27

THEORY #5: FOOD ENZYMES ARE VITAL FOR OPTIMAL HUMAN DIGESTION.

Proponents of the food-enzyme theory contend that food enzymes are not only vital to optimal human digestion, but also that enzymes in raw food actually take priority over digestive enzymes secreted by the body. Howell’s explanation of the role of food enzymes in human digestion is as follows: Food enzymes become active the moment the plant cell wall is ruptured by chewing. As the food goes down the esophagus, it drops into the upper part of the stomach. The lower part of the stomach remains flat and closed while food sits in the upper part for thirty to forty-five minutes. During this phase of predigestion, minimal acid and enzymes are secreted by the body, and food enzymes continue to work on the food ingested. The greater the amount of food enzymes present during the predigestion phase, the less work the body has to do later. When the bottom section of the stomach opens up and this mass of food moves down, the body starts secreting acid and protein enzymes called pepsin. (Howell believed these enzymes could survive the acid of the stomach.) Even at this point, food enzymes continue to work unless they are either denatured or temporarily inactivated by the acid of the stomach. According to Howell, some enzymes survive to the small intestine; some can be reactivated and continue to assist with digestion in the small intestine.28

Many advocates also believe that food enzymes can then get through the small intestine to the bloodstream in their intact form and have healing effects on the body. Some advocates suggest that inhibition or destruction of food enzymes significantly decreases or even eliminates the total nutritive value of foods consumed. They add that food enzymes prime the digestive process so that the digestive enzymes can more effectively do their jobs. According to the food-enzyme concept, it is best to eat at least 75 percent of our food raw, and that if we eat cooked food, oral enzymes should be taken along with them.

SCIENTIFIC FINDINGS

The fundamental issue is whether or not food enzymes are vital for human digestion and health. In our effort to address all of the previous points, we will answer five critical questions.

Question 1: Is Dr. Howell’s description of digestion correct?

Howell was quite accurate in his description of the physiology of the stomach. The stomach is divided into two compartments—the proximal stomach (upper part) and the distal stomach (lower part). The upper part of the stomach acts as a reservoir for food. Contractions in this part of the stomach are rare.29 The time that solid food is held in this part of the stomach (lag time) ranges from twenty to sixty minutes, averaging about forty minutes.30–32 The function of the distal stomach is to mix and grind food, turning it into a paste called chyme. Chyme is then dispensed into the small intestine at a very controlled rate of 1–5 milliliters (5 milliliters equals 1 teaspoon) about twice a minute. Food particles generally must be less than 3 millimeters in diameter to pass into the small intestine. If they’re larger, they are generally returned to the stomach for further mastication.

Question 2: Can food enzymes survive the harsh pH of the stomach or be reactivated once they arrive?

Mainstream medical thinking on food enzymes is that they are completely broken down in the acidic environment of the stomach and therefore have no activity in the small intestine, where most digestive enzyme action occurs. This makes perfect sense. The pH of the empty stomach is generally between 1.3 and 2.5. After we eat, the stomach becomes less acidic, and the pH can rise to between 4.5 and 5.8. Within an hour after we eat, the pH falls to less than 3.1.29 Food enzymes are largely denatured at a pH of less than 3.133, 34 so the logical assumption is that food enzymes could not survive past the stomach. Some people argue that food enzymes can survive acid with a pH as low as 2; however, there is only one study we could find that supported this claim. This study looked at a highly stable cysteine protease isolated from the latex of Ervatamia coronaria, a medicinal flowering plant that is native to India. The authors of this study stated that the cysteine protease from Ervatamia coronaria survives within a very broad pH range of 2–12, which, to their knowledge, is unique.35

While the mainstream view of food enzymes is theoretically accurate, there are many factors that could alter the typical scenario. For example, if hydrochloric acid secretion is low, antacids are consumed, food particles are not sufficiently reduced in size, or the stomach empties more quickly than usual, food enzymes could potentially survive into the small intestine. In some cases, food enzymes may begin to unravel somewhat but not become completely denatured, and they may become reactivated in the small intestine. Research has demonstrated some survival of salivary amylase into the small intestine. Salivary amylase, like food enzymes, is easily degraded at a pH of less than 4.34, 36

Based on the knowledge that the pH of a full stomach can rise to 4.5–5.8 for up to an hour after we have eaten, that food stays in the upper portion of the stomach for an average of forty minutes, and that the main function of this part of the stomach is as a reservoir, we can expect that the enzymes naturally present in raw food would survive and be active during this time. In addition, food preparation techniques (such as chopping, blending, and puréeing) and chewing release or activate some of the enzymes present within the plant cell walls. When food is pushed down to the lower part of the stomach, where the pH is below 3.1, and is ground into small particles, we can expect that most food enzymes will be deactivated or completely denatured by stomach acid. To summarize, food enzymes have some action before food is ingested (for example, when food is cut, blended, or processed) and in the upper part of the stomach after ingestion. However, they appear to have limited activity by the time they reach the small intestine. The more pressing question is: what is the significance of this predigestive action to the entire digestive process?

Question 3: Are there enough enzymes in raw plant foods to contribute significantly to human digestion and human health?

As we stated earlier, enzymes in plants are specifically designed to protect and propagate the plant. Digestive enzymes produced in the human body are designed specifically to break down the foods that we consume. While food enzymes can provide some of the initial digestion of protein, fat, and carbohydrate, the quantity of enzymes in food is small relative to the enzyme production that takes place in the pancreas and gastrointestinal tract. For this reason, most experts contend that food enzymes play a relatively minor role in human digestion. Unfortunately, research assessing the enzyme content of plant foods is scarce. Hallelujah Acres’ researcher Michael Donaldson measured the amylase in carrot juice.37 Amylase activity was only 20–30 units per liter of juice. Salivary amylase excretions have about 200 units of amylase per milliliter unstimulated (that is, without our having eaten beforehand).38 Donaldson concludes:

Overall, I think the quantity of digestive enzymes present in raw fruits and vegetables is going to be found to be rather small, especially when compared to the amount secreted by the pancreas.

According to enzyme researcher Stephen Rothman:

I am unaware of any evidence that suggests that enzymes in raw vegetables or fruits, at quantities normally eaten, can substitute for our digestive enzymes or provide substantial assistance in the digestive process. Nor am I aware of any evidence that they pass safely through the acid environment of the stomach or are not rapidly degraded when they reach the intestines. Unless we eat large quantities of raw pancreas, the food we eat does not contain substantial quantities of enzymes to digest it, and those that it does contain are mostly denatured in the stomach before digestion occurs in the intestines.

One study reported that the effects of predigestion were minimal, even with oral enzymes, which are much more concentrated than enzymes in food.39 Patients with cystic fibrosis (a disease that includes pancreatic insufficiency and minimal pancreatic enzyme secretion) were given either enterically coated enzymes (that is, enzymes in a capsule with a coating that protects the enzymes from stomach acid so they can survive into the small intestine) or enterically coated enzymes plus uncoated enzymes. All of these enzymes were derived from animal tissues. The patients receiving both forms of enzymes did not have a significant improvement in their digestion of food compared to the patients taking only the coated enzymes. This would suggest that predigestion had minimal effect on overall digestion and absorption. Some may argue that the animal enzymes function over a much narrower pH and that plant enzymes would have had a greater impact. While this may be a valid criticism, we would still expect significant action in the upper part of the stomach if this stage of digestion were as critical as some purport it to be.

It is important to note that there are enzymes in plants—apart from those that break down protein, carbohydrate, and fat—that are of value to human health in a very different way. These enzymes, myrosinase and alliinase, help to change phytochemicals in plants to active metabolites with anticancer properties (see page 51 for more information).

Question 4. Do live food enzymes get absorbed into the bloodstream and have a healing effect on the body?

Proponents of the food-enzyme theory believe that live enzymes in raw plant foods are able to cross the gastrointestinal tract intact and have a healing effect on the body. The most important scientific evidence for this, they say, comes from a research paper by Michael Gardner at the school of Biomedical Sciences in England titled “Gastrointestinal Absorption of Intact Proteins.”40 In this paper, Gardner concludes: “The concordance between results obtained by independent workers using different experimental approaches is now so strong that we cannot fail to accept that intact proteins and high-molecular fragments thereof do cross the gastrointestinal tract in humans and animals (both neonates and adults).”

We asked Michael Gardner if his research provides evidence of the value of food enzymes to human health. We also asked him if his research proves that enzymes in food pass through the stomach intact and provide subsequent health benefits. He replied as follows:

There is plenty of sound evidence that small quantities of intact proteins, including enzymes, can be absorbed in their intact form across the gastrointestinal tract. However, this must not be interpreted as showing that absorbed enzymes have medicinal benefits. The evidence for this is weak and inconclusive. It is plausible that, in some individuals, some enzymes are absorbed in great enough quantity to have a systemic effect, but I am not aware of good proof of this—certainly not proof that would meet scientific rigor or the various regulatory bodies if such enzymes were being regarded as medicinal products. It is possible or plausible that some food enzymes might have benefit, but proof is lacking.

Even if they do have benefit (I have not studied these claims, which would need to be supported by rigorous objective measurements), any benefit might arise from other constituents. My research has never measured any effects of absorbed enzymes on health. Some of my research, with collaborators, did show a strong indication that absorbed peptides from certain proteins (especially gluten and casein) were likely to have adverse effects on mental health, especially autism and probably schizophrenia. My research and my analysis of a wide range of literature from other scientists does not prove or disprove whether intact proteins in general can pass down through the stomach and into the small intestine in their intact form; further, the extent of this will depend on the protein, the state of the person’s gastric acidity, and the speed of gastric emptying. It would be most foolish to try to generalize on this. Certainly, if it is desired to administer small proteins, such as insulin, orally, protection from gastric digestion (mainly by pepsins) is essential. While I am sure that the food-enzyme claims are made in a bona fide way, objective evidence to support the powerful assertion that live foods are incredible life-giving and healing foods is not produced.

Question 5: Are food enzymes necessary for optimal digestion?

Many raw-food proponents believe that food enzymes survive the acid environment of the stomach, make it into the small intestine, and play a key role in digestion at this stage. Two reports that specifically address this issue were based on a medical hypothesis written by American biochemists L. J. Prochaska and W. V. Piekutowski in 1994 and 2000.41, 42 Their enzyme-synergy hypothesis promotes the idea of a synergistic effect of enzymes in food with enzymes in the human body. It is important to recognize that a medical hypothesis does not prove cause and effect, but rather it is an idea that has yet to be conclusively proved.

The basis of the Prochaska and Piekutowski enzyme-synergy hypothesis is as follows: “Enzymes that occur naturally in foodstuffs can act synergistically with those in the human digestive tract to release the maximum amount of thermodynamic free energy from the food. This hypothesis predicts, and in fact, requires that endogenous enzymes in foodstuffs survive digestion until the bolus of food reaches the small intestine. The surviving enzyme molecules in foodstuffs are thought to be required for maximum thermodynamic energy release from consumed foods and that processes such as heating, hydrogenation, and the addition of preservatives into food may denature or inhibit the endogenous enzymes’ activities. In this hypothesis, inhibition or destruction of these enzymes is thought to decrease or eliminate the total nutritive value of the ingested foodstuffs. These endogenous enzymes in food then play a central role in the digestion of foodstuffs and are thought to prime the digestive process so that the digestive enzymes can maximally release the thermodynamic energy of ingested food.”41, 42

The contention that digestion absolutely requires that food enzymes survive the acid of the stomach to the small intestine is not one that is widely held. In fact, if this were true, cooked food would be very poorly digested. Numerous studies have shown that not only is cooked food digestible, sometimes it is more digestible than uncooked food.

The suggestion that cooking completely eliminates the nutritive value of ingested foods is also contentious, as carbohydrates, proteins, fats, vitamins, and minerals are well absorbed from foods whether they are cooked or not. If we could not digest and absorb nutrients from cooked food, people consuming primarily cooked food (which is virtually everyone eating the standard Western diet) would be underweight (due to a lack of available calories from food) and would suffer from multiple vitamin and mineral deficiencies. With over 65 percent of the American population being overweight or obese, we can safely surmise that most people have no problem digesting and absorbing carbohydrates, protein, and fat from cooked food.

However, Prochaska and Piekutowski’s hypothesis puts forth some compelling evidence regarding the survival of food enzymes into the small intestine. The authors suggest that enzymes in dairy products, whole grains, and legumes can survive into the small intestine and enhance the digestibility of food. Here is a brief summary of the evidence they provide:

Dairy products. According to the enzyme-synergy hypothesis, dairy yogurt provides the most salient example of enzyme survival through the stomach. Yogurt contains about the same amount of a milk sugar called lactose as fluid milk. In order to digest this sugar, it must be split into glucose and galactose by an enzyme called beta-galactosidase. Yogurt has been shown to be more digestible for people with lactase deficiency (lactase is one member of the family of beta-galactosidases) than other dairy products. This is because the friendly bacteria in yogurt contain beta-galactosidase, which breaks down the lactose (milk sugar) in the small intestine.43, 44 Beta-galactosidase survives the acid pH of the stomach because these enzymes are packaged within living microorganisms that are able to withstand the acid pH of the stomach to a much greater extent than they could otherwise.45 These conclusions have been corroborated by other researchers44, 46 and provide evidence that fermented foods, or foods containing viable microorganisms, improve the survival of enzymes within living microorganisms through the acidity of the stomach.

A similar phenomenon has been reported with fungal enzymes. An interesting report comes from the National Enzyme Company (NEC) of Forsyth, Missouri, an enzyme-manufacturing company, and TNO Nutrition and Food Research in Zeist, Netherlands.47 The objective of their research was to determine the efficacy of an NEC fungal digestive-enzyme supplement on the digestibility of proteins and carbohydrates. A controlled dynamic gastrointestinal model was used to test the supplements, simulating both healthy human digestion and impaired digestion. The researchers conclude that “NEC fungal enzymes not only survive the acidity of the stomach, but also are active in that harsh environment where most other types of enzymes are inactivated.” They add that NEC fungal enzymes should not be enterically coated to protect against stomach acid, because that would serve only to prevent them from working in the stomach. It appears as though these fungal enzymes are afforded protection that is similar to that of beta-galactosidase in yogurt and are better able to withstand stomach acid than food enzymes that are not associated with living microorganisms.

Grains. Prochaska and Piekutowski suggest that cooking impairs the digestibility of phytate (the storage form of phosphorus in plants) because phytase enzymes (the enzymes that break down phytate) are destroyed by the heat. They cite findings from a Swedish research team led by Ann-Sofie Sandberg on phytase activity in ileostomy patients (people who have had surgery to remove the large intestine, with digestion ending at the terminal part of their small intestine).48 This research demonstrated that phytates are not digestible when heat-treated cereals are consumed but are quite digestible from unheated cereals. The authors of this study suggested that phytase activity may have been lost in the cooked product but not in the raw product. A 1987 study on ileostomy patients by the same team was also cited.49 In this study, raw wheat bran was compared to heat-treated wheat bran. The authors reported that 95 percent of the phytate in the heat-treated bran was retained compared to only 40 percent in the raw-bran group. The conclusion in this study was also that dietary phytase was likely responsible. While Prochaska and Piekutowski suggest that these studies prove that phytase survives through the stomach, it may be that the phytase activity occurred in the upper part of the stomach. A 1996 study by the same group of Swedish researchers reported that the optimum pH for wheat phytase has been shown to be 5.15, and that wheat phytase activity decreases rapidly when the pH varies from this optimal level.50 They add that plant phytase is inactivated when the pH is reduced to 2–3. We asked Ann-Sofie Sandberg whether she thought that the phytase survived to the small intestine, and she replied that on the basis of other work their team has completed, phytate is primarily degraded in the stomach, which offers the best conditions for phytate solubility and phytase activity (besides being degraded by enzymes secreted from the microorganisms of the large colon). Recall that the pH of the stomach after we eat can rise to between 4.5 and 5.8. (The optimal pH for phytase activity falls perfectly within this range.) Sandberg adds that phytases are generally poorly active at the intestinal pH, which is too alkaline for phytase activity. On the other hand, microbial phytases are active over a much wider pH range than plant phytases and have been shown to survive at pH levels as low as 1–3 (similar to the pH level of the stomach one hour after we have eaten). This may help to explain why studies using supplemental microbial phytases show their survival into the small intestine.51 It is important to remember that the most effective way to reduce phytates in grains is to ferment them with phytase-producing microorganisms or to soak and sprout them so that naturally occurring phytases will break down the phytates.50 For recipe examples, see Herbed Almond Cheese, page 270, and Sprouted Whole-Grain Cereal, page 261.

Legumes. According to the enzyme-synergy hypothesis, legumes provide the strongest evidence that endogenous proteins in food survive the digestive process in humans. Prochaska and Piekutowski contend that beans contain antinutrient proteins, such as protease inhibitors (compounds that block the action of protease enzymes), and lectins that survive stomach acid, so we can expect that the enzymes in beans will also survive. The authors overlook research showing that enzyme inhibitors have a more stable structure than enzymes and are often able to survive the acid pH of the stomach.52

The whole question of legumes being a source of enzymes is only relevant for raw or sprouted products, as cooking can deactivate both enzymes and enzyme inhibitors. For the majority of the world’s population, legumes are consumed cooked. Sprouting would seem to be an excellent alternative to cooking, as it can deactivate enzyme inhibitors while significantly increasing enzymes. These enzymes degrade enzyme inhibitors and also may be useful for predigestion in the upper part of the stomach, although it is unlikely that most enzymes would survive the acid pH of the stomach after being mixed with gastric juices. However, the use of sprouted legumes is often limited among raw-food practitioners. Some people find sprouted legumes unpalatable or difficult to digest, with the possible exceptions of lentils, chickpeas, mung beans, and peas. In addition, certain legumes, such as soybeans and chickpeas, are relatively high in enzyme inhibitors, even after sprouting (see pages 227–231).

What We Know about Food Enzymes

1. Food enzymes are released when food is chewed or otherwise ground up. The activity of these enzymes is greatest in three locations: before we actually begin eating (for example, while a fruit smoothie is still in the blender or glass), in the mouth, and in the upper part of the stomach.

2. Food is held in the upper part of the stomach for twenty to sixty minutes, averaging about forty minutes. This part of the stomach serves primarily as a reservoir, without the release of hydrochloric acid and with little churning taking place during this time. We do not know precisely how significant this stage of predigestion is to the entire digestive process. However, we do know that the chemical breakdown of food occurs mainly in the small intestine. This leads us to the conclusion that food enzymes play a relatively minor role in human digestion.

3. Once food descends to the lower part of the stomach, the pH of the stomach drops from as much as 4.5–5.8 down to 1.3–2.5 and food enzymes are largely denatured or inactivated. Consequently, few food enzymes survive into the small intestine, although this is variable, depending on many circumstances.

4. Food enzymes that are found within viable organisms, such as friendly bacteria in yogurt and microbial or fungal enzymes, appear to have a much greater chance of surviving the acid of the stomach and functioning within the small intestine.

5. Some enzymes, such as myrosinase and alliinase, help to convert phytochemicals into their active metabolites. These enzymes are degraded by cooking, so selecting raw sources of these enzymes (for example, cruciferous and Allium vegetables) may provide a health advantage (see page 51).

In short, the medical hypothesis offered by Prochaska and Piekutowski provides strong evidence that beta-galactosidase enzymes in cultured dairy products survive stomach acid. The arguments for grains and legumes are less convincing. It would appear as though enzyme action from these foods likely occurs in the upper part of the stomach. Some studies have used supplemental microbial enzymes, and these have been shown to survive over a much broader pH range.

CONCLUSION: Edward Howell was a health pioneer who had tremendous insights about digestion in the early 1900s, when many vitamins had not yet even been discovered and phytochemicals were unheard of. Some of his theories have stood the test of time; others have long since been disproved. Raw food offers many advantages, and food enzymes are among them. There is good evidence that food enzymes play a positive role in health and digestion, although the role appears somewhat different, and less critical, than what proponents of the food-enzyme theory have suggested.


CHAPTER 11

Food Safety: Raw Case Files

 

You might imagine that edible plants are completely safe. Nature is rarely that simple. While the effects of plants on human health are overwhelmingly positive, there are three things that can turn plants from health heroes into potential villains:

1. Plants often have complex defense systems designed to protect them from predators, and these systems can include toxic chemicals. The same chemicals can be harmful to people too.

2. Whether they grow in the ocean or land, plants can be contaminated with environmental pollutants, such as heavy metals, dioxins, or PCBs.

3. Disease-causing bacteria that originate in the intestines of humans or animals can make their way onto plants.

This chapter provides a glimpse into the world of food safety, selecting six controversial issues of special interest to raw foodists. You will notice the framework for this chapter is based on criminal rap sheets. For each suspect, a charge is laid, evidence is summarized, and a verdict read. Please note that the charges are not statements of fact but rather common accusations made against that suspect food—you will discover whether the accusations are true or false after examining the evidence.

Suspect 001: Buckwheat Greens

Charge: Buckwheat greens (mature shoots with green leaves) contain a toxic compound called fagopyrin and should generally be minimized or avoided in the diet.

Evidence: Fagopyrism is a condition triggered in cattle and sheep by the ingestion of buckwheat greens. It creates a sensitivity to light that causes swelling and irritation of the skin. While fagopyrism has long been recognized in animals, it’s a rather recent phenomenon in humans. With it, people (especially those with light-colored skin) experience extreme sensitivity to sunlight, skin irritation, and itching. Affected individuals also report tingling in the hands and face and an increased sensitivity to cold. While buckwheat greens are not traditionally consumed by humans, they have gained popularity as juicing greens by some health advocates.

The most comprehensive examination of fagopyrism in humans was published online by Gilles Arbour, a Canadian man who was affected by the condition after consuming raw juices containing buckwheat greens for an extended period of time.1 The condition was said to be common among the staff and guests at Ann Wigmore’s retreat where buckwheat greens were juiced.1 Fagopyrin is a red fluorescent pigment in buckwheat. It is most concentrated in the buckwheat flowers, followed by the leaves. Little or no fagopyrin is present in other parts of the plant.2

Among the most pressing questions for raw-food adherents is whether fagopyrin is present in significant quantities in buckwheat sprouts (very young shoots before green leaves have developed). This gluten-free food is a popular base for crackers and cereals and is used extensively in raw vegan cuisine. One Korean study reported almost no fagopyrin present in buckwheat sprouts with up to eight days of sprouting.3 In Korea, where buckwheat sprouts are commonly consumed, it is well known that buckwheat should only be sprouted in the dark. This is because exposure to light causes greening of the plant and an increase in the fagopyrin content. It is said that fagopyrin can be minimized by rinsing the buckwheat three to four times a day, as the fagopyrin will be lost in the pinkish rinse liquid. As buckwheat is normally soaked for twenty minutes, then sprouted for about a day (with regular rinsing), we would expect the fagopyrin to be negligible. Physician and raw-food advocate Gabriel Cousens described two individuals who developed symptoms after eating large quantities of buckwheat sprouts (an amount equal to 20 percent of their total food intake) for six months. No symptoms appeared with lesser intakes by these individuals.4

Verdict: Guilty as charged.

Although occasionally consuming fresh juices that include buckwheat greens is unlikely to produce adverse effects, regular consumption of buckwheat greens is ill advised. Buckwheat groats and seeds contain only trace amounts of fagopyrin and don’t generally pose a risk. Buckwheat is often sprouted for only a day, but even with longer sprouting times, fagopyrin content appears minimal. However, eating very large amounts of sprouted buckwheat over a long period of time may produce symptoms in some individuals.

Suspect 002: Alfalfa Sprouts

Charge: Alfalfa sprouts contain a toxic compound called L-canavanine (LCN) and should be completely avoided.

Evidence: L-canavanine is a nonprotein amino acid that is structurally similar to the amino acid L-arginine. With regular, high consumption of alfalfa sprouts, L-canavanine can be inadvertently used in place of L-arginine to manufacture proteins in the body. Proteins containing L-canavanine instead of L-arginine cannot perform their usual assigned tasks in the body. These structurally aberrant molecules can disrupt both enzyme activity and metabolism.5

There is some evidence that L-canavanine can stimulate or exacerbate symptoms of systemic lupus erythematosus (SLE) and possibly other inflammatory diseases.5 In 1981, a clinical trial using alfalfa seeds for cholesterol reduction resulted in enlargement of the spleen and reductions in various blood cells in one of the study participants.6 In 1983, two lupus patients in remission experienced reactivation of their symptoms while taking alfalfa tablets.7 Four healthy individuals were reported to have developed lupuslike symptoms while consuming twelve to twenty-four alfalfa tablets per day for three weeks to seven months.8 In the Baltimore Lupus Environmental Study, a significant association between alfalfa consumption and the development of lupus was reported.9 However, no such association was found in a Swedish study that reported similar alfalfa-sprout intakes in cases and controls.10

While it was once thought that germination reduces the content of Lcanavanine in alfalfa sprouts, it is now known that L-canavinine increases slightly during germination, regardless of whether it is grown in a dark or light environment.11

Verdict: Guilty on a lesser charge.

L-canavanine is a toxic compound and can be dangerous when consumed in high amounts. However, the L-canavanine content of alfalfa sprouts is low and will not generally trigger negative health consequences in healthy individuals. Nevertheless, eating large portions (several cups) of alfalfa sprouts on a daily basis or juicing similar amounts of alfalfa sprouts is not advised. In addition, L-canavanine may be problematic for people with systemic lupus erythematosus, and until evidence to the contrary is available, it would be best for those individuals to minimize or avoid its consumption.

Suspect 003: Sprouted Legumes

Charge: Legumes are high in antinutrients (substances that block the absorption of nutrients), such as hemagglutinins and trypsin inhibitors. Cooking is the only preparation method that breaks down these compounds, so legumes should be avoided in raw vegan diets.

Evidence: To understand antinutrients in legumes and other seeds, it is helpful to explore the seed itself. A legume is the seed or small embryo of a plant, surrounded by a protective covering called a seed coat. Inside the seed coat is stored food (protein, carbohydrates, fat, vitamins, and minerals) along with substances that protect the seed from predators, such as microorganisms, insects, birds, and animals. Not surprisingly, many of these substances work as antinutrients in human nutrition. These antinutrients include hemagglutinins as well as compounds that inhibit the action of enzymes such as amylase (which breaks down starches) and trypsin (which breaks down protein). When a legume is germinated, enzymes are released to break down these antinutrients so that the stored starch and protein become available for plant growth. When animals eat ungerminated legumes, these antinutritional factors can adversely affect the digestibility of the nutrients that are present. Some of these compounds are actually toxic. For this reason, there has been considerable research examining how best to rid plants of these compounds before they are consumed. Most of this research has been conducted on animals and in test tubes.

Hemagglutinins are proteins that bind to sugar molecules. In excess, they cause red blood cells to clump together, increase cell division, and interfere with the transport of nutrients across intestinal-cell membranes. Hemagglutinins are present in many foods but are most concentrated in legumes, particularly red kidney beans and small red beans. Approximately one to three hours after a person consumes raw or undercooked red kidney beans, three to four hours of debilitating nausea, vomiting, and diarrhea ensue. Hemagglutinins are completely destroyed by conventional cooking practices. Boiling presoaked beans for thirty minutes or simmering them at 176 degrees F (80 degrees C) for two hours completely destroys this toxin, as does pressure cooking unsoaked beans at 250 degrees F (121 degrees C) for fifteen minutes.12 Germination can reduce hemagglutinin by 75–100 percent,13–16 although some studies have shown even smaller reductions.17 Despite the fact that the types of hemagglutinins in beans are toxic, there is some evidence that those in lentils and peas are not.18

Trypsin is an enzyme that breaks protein into its component parts (amino acids) so they can be absorbed into the bloodstream. Trypsin inhibitors are proteins that block the action of trypsin, thereby reducing protein digestibility from the food. There are two main families of trypsin inhibitors in legumes: the Bowman-Birk type (found in most legume species, including soybeans) and the Kunitz type (found mainly in soybeans). Soybeans are the most concentrated sources of trypsin inhibitors; amounts in other legumes average only 15–40 percent of the quantity in soybeans.19 Peas are low in trypsin inhibitors (less than 2–13 percent), while chickpeas and lima beans contain more than most other legumes, about 66 and 77 percent of the levels found in soy, respectively.20 Studies have shown that in soybeans, the Kunitz-type inhibitors are completely inactivated by the human gastric juices of the stomach, while the Bowman-Birk-type inhibitors are impervious to these acidic conditions. As a result, Bowman-Birk-type inhibitors generally arrive undamaged in the small intestine, decreasing the digestibility of the protein in the food eaten.18 When trypsin inhibitors block the action of trypsin, the pancreas is stimulated to produce more of this enzyme. This can drain the body’s supply of sulfur-containing amino acids that are used in making trypsin.21–23 Legumes are already low in sulfur-containing amino acids, so when beans high in trypsin inhibitors are consumed, protein nutrition could be compromised, especially when protein intakes are marginal.

In some small animals, particularly those fed an experimental diet of raw soybeans or that are injected with pure trypsin inhibitor, this continued stress damages the pancreas, causing the cells that produce digestive enzymes to increase in both size and number.21, 24 It has been suggested by some raw foodists that trypsin inhibitors would cause similar damage to the pancreas in humans; however, evidence does not support this theory. In larger animals, such as pigs, dogs, cows, and monkeys, the pancreas appears completely unaffected by trypsin inhibitors.24 Whether or not trypsin inhibitors cause damage to the pancreas seems to depend on the size of the pancreas relative to the total body weight of the animal. Therefore, scientists believe that it is highly unlikely that trypsin inhibitors would cause pancreatic damage in humans.20 Numerous studies, as shown in table 11.1, below, demonstrate how different food-preparation methods reduce the amount of trypsin inhibitors in various legumes.

Generally, the quantity of trypsin inhibitors in germinated legumes decreases the longer the legumes are sprouted, as the seed slowly releases its store of nutrients until the plant is viable on its own. One study found that inhibitors in lentils were reduced by only 18 percent after six days but were reduced by 45 percent after ten days.19 Another found that the trypsin inhibitors in soy continued to decline during germination until they were completely gone after thirteen days.25

Fermentation appears to produce even greater reductions in trypsin inhibitors than germination. One study tested six different legumes and found 38–47 percent reductions with fermentation.26 A second study subjected lentils to natural fermentation for four days at 86 degrees F (30 degrees C) and reported a 50–82 percent drop in trypsin-inhibitor activity.27 Another research team found that fermentation by fungi or bacteria eliminated 97–100 percent of the trypsin inhibitors in cowpeas within thirty-six hours.28

Most experts agree that the quantity of trypsin inhibitors that remains when using standard cooking methods does not present a risk to human health.20, 23 There’s evidence that Bowman-Birk inhibitors have both anticancer and anti-inflammatory actions,23, 29 so eating small amounts of this inhibitor over time could offer some protection. However, considerably more trypsin inhibitor remains after germination than after cooking, so its potential negative effect on the digestion of protein may be of greater concern in raw vegan diets compared to mixed vegan diets containing both raw and cooked foods. Test-tube studies examining protein digestibility and protein quality have reported mixed results, with most studies finding little difference in the digestibility of boiled and germinated legumes.13, 30 This may be because germination reduces phytates (which inhibit protein metabolism) even more than cooking does. At this point, we are uncertain about the health consequences of the increased intakes of trypsin inhibitors associated with raw vegan diets that include sprouted legumes.

TABLE 11.1 A comparison of preparation methods that reduce trypsin inhibitors in legumes

 

Preparation method

Percentage of reduction

Boiling13, 14, 23, 26, 28, 32

80%–100%

Soaking (at least 16 hours)14, 27, 28, 33

10%–20%

Soaking plus dissolved baking soda28

24%

Germination13, 19, 27, 28, 32–40

15%–65% (average of 30%)*

*The more commonly consumed sprouted legumes tended to fall at the lower end of this range (chickpeas, 34%;13 mung beans, 22%;14 and lentils 18–28%19, 27).

Evidence suggests that the total trypsin produced by the average person in a day would be completely inhibited by the trypsin inhibitors contained in 100 grams of raw soybeans (just over one-half cup (125 milliliters).18 We know that chickpeas contain about 66 percent of the trypsin inhibitors found in soy, while mung beans have about 37 percent and lentils about 25 percent. Using these figures, we can calculate the reduction in trypsin activity that would be experienced by an individual consuming one cup (250 milliliters) of sprouted mung beans, lentils, or chickpeas, as shown in table 11.2, below.

While the significance of these figures is uncertain, the reduction in trypsin caused by eating mung bean or lentil sprouts is not significantly different from what would be produced by eating lightly boiled soybeans. (Approximately 14 percent of trypsin inhibitors remain after soaking and then boiling soybeans for twenty minutes.)31 Using this very conservative estimate (longer cooking periods would result in greater reduction), if you eat one cup of these lightly cooked soybeans, the trypsin activity in your body would be reduced by approximately 9 percent. This decrease has not been shown to have negative consequences for human health. The much higher levels of inhibitors expected from sprouted chickpeas (compared with sprouted lentils or mung beans) may be more of a concern, particularly if raw sprouted chickpeas are dietary staples and intakes of the sulfur-containing amino acids are borderline.1

TABLE 11.2 Estimated reduction in trypsin activity with the consumption of sprouted legumes

 

Legume

Reduction in trypsin activity*

1 cup sprouted chickpeas

21%

1 cup sprouted lentils

6%

1 cup sprouted mung beans**

5%

*The reduction in trypsin activity is the amount of trypsin that would essentially be disabled by the trypsin inhibitors contained in the sprouted legumes.

**While mung beans have higher trypsin inhibitors than lentils per 100 grams of unsprouted seed, the effect of one cup of sprouts is lower because mung beans produce a greater volume of sprouts.

Verdict: Mixed.

Many legumes are high in antinutritional factors, such as hemagglutinins and trypsin inhibitors, and these factors are most effectively reduced by cooking. While soaking and sprouting also reduce these factors significantly, about 70 percent of the trypsin inhibitors and up to 25 percent of the hemagglutinins remain. The significance of these findings for human health is not known. It would seem reasonable to limit sprouted legumes that provide high amounts of trypsin inhibitors, such as chickpeas. If using sprouted legumes, lentils and mung beans would appear to be better choices. It is worth noting that when consumed in small quantities as part of a health-promoting diet, many so-called antinutrients have been shown to provide health benefits.

Suspect 004: Mushrooms

Charge: Common edible mushrooms, such as button, crimini (brown), portobello, and shiitake, contain compounds called hydrazines, which are toxic to the liver and are carcinogenic. Shiitake mushrooms contain varying amounts of formaldehyde. Ingestion of shiitake mushrooms may cause dermatitis and photosensitivity in some people. They have also been linked to abdominal distress and abnormal blood counts in some individuals. Cooking mushrooms reduces or eliminates these toxic compounds, whereas raw mushrooms generally contain significant amounts. For this reason, raw mushrooms are best avoided.

Evidence: Common cultivated mushrooms, including button, crimini (brown), and portobello, contain hydrazines, which have been shown to be both carcinogenic and mutagenic in animals and in laboratory tests.41, 42 Although they are suspected to be human carcinogens, more evidence would be required for definitive proof.43–45 A Swedish research group estimated the carcinogenicity of a hydrazine in mushrooms called agaritine by figuring that the consumption of an average of 4 grams (1 tablespoon) of mushrooms per day would contribute to a lifetime cumulative cancer risk of about two cases per 100,000 lives.46 It’s important to recognize that while hydrazines appear carcinogenic, there are also studies suggesting that extracts of cooked white button mushrooms could be protective against breast cancer and prostate cancer.47–49 These studies suggest that certain fatty acids and phytochemicals in mushrooms depress the activity of the enzyme aromatase, which is required for estrogen synthesis. A study following over 2,000 Chinese women reported a 64 percent reduction of breast cancer risk in those women who ate one-third of an ounce or more of mushrooms every day compared to those who did not eat mushrooms.50

Most methods of food preparation decrease the content of agaritine in mushrooms. Simply storing mushrooms in the refrigerator reduced agaritine by 25 percent in six days and 50 percent in fourteen days. Boiling mushrooms reduced agaritine up to 88 percent, one minute of microwaving decreased agaritine by about 65 percent, and frying resulted in about a 50 percent reduction. Dry baking was not as effective, with only a 23 percent reduction in ten minutes of baking time.42 Canned mushrooms retain little agaritine, about 90 percent less than fresh mushrooms.41 Dehydrating mushrooms at 77 degrees F (25 degrees C) for twenty-four hours resulted in an 18 percent reduction, while dehydrating them at 122 degrees C (50 degrees C) for seven to eight hours resulted in a 24 percent reduction.42

To our knowledge, no studies have examined whether marinating mushrooms affects their agaritine content. However, one study found that when agaritine (isolated from mushrooms) was kept in an open container with tap water, it was completely degraded within 48 hours. In closed containers, just under 50 percent of the agaritine remained after 120 hours. These findings show that agaritine breakdown is accelerated with exposure to oxygen. Temperatures ranging from 40 to 72 degrees F (4 to 22 degrees C) did not significantly affect agaritine levels, while a more acid pH resulted in significantly greater reductions than a more neutral pH.51 It’s possible that marinating mushrooms in lemon juice or vinegar for several hours may produce significant reductions in agaritine but, unfortunately, no studies have yet been done to confirm this hypothesis.

Fruits and vegetables, along with other living organisms, contain naturally occurring formaldehyde in the range of 2–60 milligrams per kilogram. While these levels are thought to pose little threat to health, higher amounts (100–406 milligrams per kilogram) have been reported in dried shiitake mushrooms.52 One study suggests that the levels of formaldehyde detected in shiitake mushrooms exceeds safe limits.31 Another study found that cooking shiitake mushrooms for six minutes produces significant reduction in formaldehyde levels, whereas storage for up to ten days had no effect on formaldehyde levels. (Interestingly, the authors of this study did not agree that the usual levels of formaldehyde in shiitake mushrooms were likely to pose an appreciable health risk.)53

Studies have also noted that shiitake mushrooms can cause dermatitis and photosensitivity in some individuals;54, 55 however, this effect is not seen when the mushrooms are thoroughly cooked.55 Finally, daily consumption of 4 grams (1 tablespoon) of shiitake mushroom powder (sixteen capsules, or the equivalent of four medium-sized dried mushrooms) for up to ten weeks resulted in abdominal discomfort and abnormal blood counts in seventeen of forty-nine patients in a cholesterol-lowering study and five out of ten patients in a study designed to investigate these effects.56 Some experts suggest that shiitake mushrooms should be thoroughly cooked prior to consumption.57–59 On the other hand, one of the key active compounds in shiitake mushrooms, lentinan, has been shown to have immune-regulating, antiviral, and anticancer activities.60–62 Lentinan has been approved for use as a drug in Japan (generally as an adjunct to chemotherapy).63

Verdict: Mixed.

Hydrazines, such as agaritine, are considered probable human carcinogens. However, there is insufficient evidence to demonstrate beyond a reasonable doubt that human consumption of button, crimini (brown), and portobello mushrooms poses a serious threat to health. Conversely, while eating raw mushrooms is a common practice, it may not be risk free. It’s worth noting that most of the favorable reports on mushrooms have been based on the cooked product. It seems reasonable to limit our exposure to hydrazines when possible, so limiting the amount of raw mushrooms we eat seems well advised. We know that dehydrating mushrooms results in small reductions in agaritine; however, reductions are less than what is achieved in cooking. There is a possibility that marinating mushrooms, particularly using an acidic medium, such as lemon juice or vinegar, is as effective at reducing agaritine as cooking, although further research is needed before we can be assured of this. Raw foodists who wish to eat raw mushrooms may be wise to marinate them overnight prior to their use. It is advisable to cook shiitake mushrooms prior to consumption. Finally, it’s common knowledge that collecting wild mushrooms is risky business and is best done only by those who have the necessary expertise. (Most wild edible mushrooms are also safer when cooked.)

Suspect 005: Sea Vegetables

Charge: Sea vegetables are sources of heavy metals, particularly arsenic. Hijiki contains unsafe levels of inorganic arsenic and should be avoided.

Evidence: Sea vegetables have long been prized for their ability to behave like sponges, accumulating a rich supply of the ocean’s minerals. Unfortunately, these nutritionally unique plants are also notorious for soaking up heavy metals, especially arsenic, from polluted waters. Generally, the type of arsenic that accumulates in sea vegetables is the less toxic form called organic arsenic. Exposure to organic arsenic has not been associated with adverse health consequences. However, inorganic arsenic is toxic. According to a 1981 World Health Organization (WHO) report, an ingested dose of 70–180 milligrams (70,000–180,000 micrograms) of arsenic (III) oxide (an inorganic form of arsenic) can prove fatal in humans.64 Acute toxicity causes fever, vomiting, and diarrhea, and in severe cases, multiorgan failure. Chronic toxicity has been linked to nerve damage, respiratory disorders, skin lesions, and cancer. The Joint FAO/WHO Expert Committee on Food Additives set a provisional tolerable weekly intake for inorganic arsenic at 15 micrograms per kilogram of body weight.65 For a person weighing 150 pounds (70 kilograms), this would amount to an upper limit of approximately 1 milligram (1,000 micrograms) per week.

Analyses done by governments in Canada, the United Kingdom, Hong Kong, and New Zealand have found high levels of inorganic arsenic in hijiki. In 2001, the Canadian Food Inspection Agency (CFIA) put out an advisory for consumers to avoid consuming hijiki. By 2005, health protection agencies in the United Kingdom, Hong Kong, Australia, and New Zealand had followed suit.66–69 Government findings were later confirmed by independent research teams, as shown in table 11.3, page 234.

TABLE 11.3 Arsenic amounts in hijiki and other sea vegetables per kilogram (2.2 pounds) dry weight

 

 

Given the ranges of inorganic arsenic reported in hijiki (an average of 83 milligrams per kilogram/2.2 pounds), consumption of 7–15 grams (0.25–0.50 ounces) dry weight of hijiki could exceed the recommended upper limit of 1 milligram (1,000 micrograms) per week. (One-half cup/125 milliliters of dried hijiki weighs about 10 grams, or one-third ounce.) It’s important to note that these figures are for dried sea vegetables, and most people soak and drain sea vegetables prior to consumption. Studies suggest that approximately 50 percent of the arsenic is lost with recommended soaking procedures. Cooking further reduces the initial concentrations to about 10 percent of the original levels.70 There is some suggestion that the alginates in sea vegetables actually bind with heavy metals, rendering them indigestible and causing them to be quickly eliminated from the body. However, most of the evidence for this has been based on animal studies. In order to clarify the metabolism of arsenic from hijiki in humans, a research team from Japan investigated the fate of arsenic in a healthy volunteer who consumed 330 grams of a processed hijiki food (hijiki-bean combination) containing 0.869 milligrams (869 micrograms) of inorganic arsenic and 1.253 milligrams (1,253 micrograms) total arsenic, which is approximately the recommended upper limit. The researchers noted that the volunteer’s urinary excretion of arsenic was comparable to that of someone with arsenic poisoning.71

A report of arsenic toxicity from kelp supplements led to an evaluation of arsenic in commercial kelp supplements. Of nine samples tested, eight showed levels higher than that deemed acceptable by the U.S. Food and Drug Administration.72

Verdict: Guilty on a lesser charge.

Although eating an occasional small serving of hijiki at your favorite restaurant may not be harmful, regular consumption of larger quantities seems ill advised, at least until evidence suggests otherwise. Intakes of inorganic arsenic from hijiki are generally overestimated, as losses of approximately 50 percent are incurred with soaking. However, the risk is greater for consumers of raw hijiki, as they don’t benefit from the reductions in arsenic that occur with heating. If you use kelp supplements, be sure that they’re tested for heavy metals, and don’t exceed intakes suggested on the label. While other sea vegetables have not been found to have high levels of inorganic arsenic, sea vegetables are known to absorb other heavy metals, such as cadmium and lead, and should be consumed in moderation.73

Suspect 006: Sprouts

Charge: Raw sprouts are a potential source of pathogenic bacteria and are best avoided.

Evidence: The three most prominent outbreaks of foodborne illness in the United States in 2008 were traced to hot peppers (chiles) and tomatoes (imported from Mexico), cantaloupes (imported from Honduras), and domestic peanuts. While most people associate food pathogens with animal products, such as fish, raw eggs, and undercooked hamburger or chicken, becoming a raw-food vegan is no guarantee you’ll avoid food poisoning.

Food pathogens include a variety of organisms that contaminate food and make people sick. Symptoms of infection range from diarrhea, fever, vomiting, abdominal cramps, and dehydration to multiple organ failure and death.75 The vast majority of cases go unreported, although the U.S. Centers for Disease Control and Prevention estimates that every year approximately 76 million people are infected and 5,000 die.76, 77

Most pathogenic bacteria originate in the intestines of animals or people. They usually make their way from animal or human intestines to our produce through the “back door.” Fruits and vegetables may be grown in fresh manure and irrigated or washed with water that is contaminated by manure. Pathogens can be introduced from infected workers who handle the food in the field, in packing houses, or at the point of purchase. They can be transferred from a contaminated food to a clean food by a knife or other utensil, or through contact with a contaminated cutting board. Improper storage or holding conditions can also support bacterial growth. In the majority of cases, the original source of contamination can be traced back to concentrated animal-feeding operations (also known as factory farms). Livestock in the United States produce more than thirteen times the excrement of the entire American population, and unlike human waste, it goes largely untreated. Man-made lagoons on factory farms hold millions of gallons of pathogen-laden waste, which commonly seeps into waterways. This water may then be used for crop irrigation, resulting in pathogens being sprayed directly on our food.78 This applies both to conventional and organic crops.

Heating food to an internal temperature above 160 degrees F (78 degrees C) effectively wipes out most pathogenic bacteria.79 Animal products, such as meat, poultry, fish, and eggs, are almost always cooked prior to consumption. Food safety guidelines suggest very specific internal temperatures should be reached to ensure that pathogenic bacteria is destroyed. Dairy products are generally pasteurized to eliminate dangerous bacteria. Fruits, vegetables, and sprouts are less frequently cooked, and in raw diets they are rarely, if ever, cooked. Storing perishable foods at 40 degrees F (4.5 degrees C) helps to reduce the growth of bacteria. Washing produce can reduce contamination, but it does not always eliminate it.80

Alfalfa sprouts and other raw sprouts pose a unique challenge, as pathogens lurk in the tiny cracks and crevices of seeds. Even miniscule numbers of pathogens can multiply to millions during the sprouting process. This is because the best condition for growing sprouts is also the ideal medium for breeding bacteria. The pathogens most commonly associated with sprouts are Salmonella and Escherichia coli O157:H7, or E. coli (the leading cause of kidney failure in children). From 1990 to 2005, sprouts caused thirty-three outbreaks in North America: twenty-eight from alfalfa sprouts, four from mung bean sprouts, and one from clover sprouts. In a 2007 public meeting conducted by the FDA, an official of the Centers for Disease Control (CDC) reported that sprouts were implicated in 20 out of 168 outbreaks of all produce-related single food outbreaks between 1998 and 2004.81 As a result, health authorities in the United States and Canada have issued warnings about the consumption of raw sprouts and advise high-risk groups (the elderly, young children, pregnant women, and people with weakened immune systems) to avoid eating raw sprouts altogether.82, 83

While the evidence against sprouts looks rather incriminating, it’s important to remember that it’s not sprouts or sprout seeds that are at the root of the problem; rather, it is manure from the concentrated livestock operations on factory farms. The first critical step to ensuring sprout safety is to begin with clean seeds. There is considerable debate as to how to best accomplish this task. For commercial sprouting, the U.S. Food and Drug Administration (FDA) currently recommends that seeds be treated with 20,000 ppm calcium hypochlorite (bleaching powder) prior to germination, and that sprouts and spent irrigation water samples be periodically tested for pathogens;84, 85 however, organic sprout growers would lose their organic status if they used this method.86 One solution would be for the FDA to endorse a more eco-friendly method for disinfecting sprouts. A simple alternative would be the use of dry heat. A study out of Cornell University in New York found that exposing mung beans and alfalfa seeds to 131 degrees F (55 degrees C) in an incubator for at least four days effectively eliminated E. coli and Salmonella pathogens without affecting germination rate.87

For home sprouting, consumers need to acquire sprouting seeds from a reputable dealer and disinfect them at home prior to sprouting. A researcher from Japan subjected seeds to a ninety-second hot-water bath (194 degrees F/90 degrees C), followed by immersion in chilled water for thirty seconds. No viable pathogens remained in the seeds, none were detected during the sprouting process, and germination was not significantly affected.88 The findings of a microbiologist from Norringham University in the UK show exceptional results using hot water alone.89 Finally, the University of California at Davis provides a handout on safe sprouting at home. They suggest heating the seeds on a stovetop for five minutes in a 3 percent hydrogen peroxide solution preheated to 140 degrees F (60 degrees C), followed by a cold rinse.90

Verdict: Not guilty.

While there is no doubt that sprouts can be contaminat

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