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Acid-Base Balance, Bones, and Minerals

 

Minerals are elements that come from the earth or the sea. They enter the body through plant foods (even the minerals in animal products can be traced back to plant sources or drinking water), and once inside, they stay until they are excreted (for example, in urine, feces, or perspiration). A mineral can perform one role in the body and then another, yet it remains the same mineral. Iron is iron, though it becomes part of various compounds, like a magician wearing a series of cloaks or assuming different characters. Minerals are part of dynamic systems in our bones, fluids, and nerves. While reading this and later when you sleep, you are remodeling bones and creating new red blood cells. For these purposes, you need a steady supply of building materials.

Though they also can settle out in hard little crystals, minerals are water-soluble and some (calcium, magnesium, and sodium) are found in drinking water, depending on the geographic locale. Filtration systems remove minerals, along with unwanted chemicals. Due to the solubility of minerals, when foods are boiled, these elements are leached into the cooking water, which is generally disposed of. Steaming leads to fewer losses; of course, retention is greatest in foods that remain raw. When nuts, seeds, and other raw foods are soaked and the soaking water is discarded, a small proportion of minerals is lost, though big gains are made in terms of how well the body can absorb the minerals that remain. The availability of minerals is increased immensely by preparation practices that have been recognized for decades in raw-food communities. At long last, the wisdom behind soaking, sprouting, blending, and juicing is being recognized and given credit by scientific research.

In this chapter, you will learn how to create a mineral-rich diet (including tips about mineral absorption), discover how diet can help to maintain the precise pH balance between acid and base in body fluids that is necessary to sustain life, and see how this balance affects bone health. For the essential minerals, you will find the functions of each and a wide range of delicious raw foods that can be your sources.

Acid-Base Balance and Bones

ACID-BASE BALANCE

One task of our hard-working kidneys, in partnership with our lungs, is to maintain the acidity, or pH, of our body fluids within a very narrow range (7.35 to 7.45). A pH between 0 and 7 is acidic (with the lowest numbers being more acidic); values above 7 indicate pH levels that are increasingly alkaline. Diet has a powerful influence on this system. Meat and other flesh foods, milk and dairy products, and grains are acid-forming, meaning that they influence body fluids and the urine to be acidic after these foods are consumed, digested, and metabolized. This effect is related to the amounts of phosphorus, sulfur, and protein in these foods. In contrast, vegetables and fruits tend to be alkali-forming, or base-forming, counterbalancing the effects of animal products and grains. Though many sour tasting fruits such as citrus fruits are acidic, this acidity is quickly disposed of during digestion. The end result on the body of the breakdown of both fruits and vegetables is linked to the presence of calcium, magnesium, and potassium, and the alkaline effect of these minerals. When we look at family meals, restaurant menus, and shopping-cart contents, it is easy to see why the standard Western diet tips the scales in an acid-forming direction.1–4

Though Paleolithic diets included wild game, it is estimated that two-thirds or more of the calories in these diets came from leafy greens, fruits, nuts, seeds, and other parts of uncultivated plants. (Naturally, diets varied greatly from one region to another.) The wild fruits eaten by early humans (and by primates) were higher in minerals and protein and were lower in sugars than the cultivated fruits we find in supermarkets today.5, 6 In a few situations, as with the the !Kung tribe of the African Kalahari Desert and the Hazda of Australian Tanzania, as much as 95 percent of their calories came from plant parts that they gathered. Grains and dairy products were not part of the diet. The traditional Hopi diet was centered on plant foods, such as purslane and other wild greens, corn, a mineral-rich plant-ash preparation, beans, and dried melon and peaches.7 Along with greens, gourds, and other plant foods, nuts and seeds were an important part of the earliest crops in eastern North America.8 Humans evolved on a diet that was much more alkali-forming than the diets eaten today. When humans switched from hunter-gatherer diets to diets containing grains plus large quantities of animal products, they greatly increased the amount of acid-forming foods that must be processed by the kidneys and other organs of the body.5, 6, 9–14

Table 9.1, page 177, shows an approximate prediction of the effect of various food groups on the acidity of the urine, called the potential renal acid load (PRAL). It is important to note that PRAL values are based on the quantities in 100 grams of food of four key nutrients that affect renal acid load—protein, potassium, magnesium, and phosphorus—rather than on measured metabolic responses in human subjects. The positive numbers above zero indicate foods that acidify our bodies and place a greater load on our kidneys. The negative numbers make our system more alkaline and decrease the amount of acid that our kidneys need to excrete. As you can see, a diet providing plenty of vegetables and fruits is highly important in maintaining the slightly alkaline pH that is essential to life and health.3, 4, 13, 15

TABLE 9.1 Estimated potential renal acid load (PRAL) of food groups

 

 

A few fruits—cranberries, plums, prunes, rhubarb, and sour cherries—are acid-forming because they contain organic acids (oxalic or benzoic acid), which are not completely broken down to bicarbonate in the body. Though the body’s required pH range of 7.35 to 7.45 is just slightly more alkaline than the neutral point of 7, this does not mean that acidic foods must be entirely avoided. The general idea is to get an assortment of foods, ending up with an overall mix that is just slightly alkaline. The body manages best when it has plenty of vegetables and fruits with a negative PRAL to offset the acid-forming foods with a positive PRAL that are used in smaller amounts, such as nuts and seeds and perhaps some legumes and grains. Buckwheat and quinoa, which are pseudo cereal grains, are less acid-forming than true grains.3, 16

Contemporary Western diets are off balance in that they contain an excess of acid-forming foods (over alkali-forming foods). The consequences of this excess acid load on the kidneys, and of keeping our cells in an environment that is a little too acidic, include the wasting of muscles, the formation of kidney stones, kidney damage, and the dissolution of bone. As we age, such diets lead to a mild but slowly increasing metabolic acidosis.9, 13, 14, 16, 17

Последнее изменение этой страницы: 2016-08-11

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