Sunday, July 6, 2008

The Acid / Alkaline Diet

The basic chemistry of pH balance

Back in high school chemistry, we learned about pH: acids had low numbers, alkalines had high numbers, and a pH of 7.0 was neutral. And it all meant absolutely nothing in terms of day-to-day life.

It now turns out that we have a better shot at long-term health if our body's pH is neutral or slightly alkaline. When we tilt toward greater acidity, we have a greater risk of developing osteoporosis, weak muscles, heart disease, diabetes, kidney disease, and a host of other health problems.

The solution, according to scientists who have researched "chronic low-grade metabolic acidosis," is eating a diet that yields more alkaline and less acid. Just what kind of diet is that? One that's high in fruits and vegetables. That might not seem like a big surprise, except for a few unexpected twists and turns.

Acid-yielding foods deplete minerals

If the idea of balancing acid and alkaline foods seems a bit off the wall, it does have a somewhat checkered past. Most people, including physicians, aren't familiar with the dangers of acidosis, except in the most extreme situations. Those include lactic acidosis, from overexercise; ketoacidosis, when diabetes start burning their own fat; and renal acidosis, which can be a sign of kidney failure.

The original scientific research on acid-yielding and alkaline-yielding foods dates back to 1914 and was remarkably accurate. But the problem with acid-producing eating habits is very real, after digestion, all foods report to the kidneys as being either acidic or alkaline. The kidneys are responsible for fluid balance and maintaining a relatively neutral pH in the body. That's where things get interesting. When acid-yielding foods lower the body's pH, the kidneys coordinate efforts to buffer that acidity. Bones release calcium and magnesium to reestablish alkalinity, and muscles are broken down to produce ammonia, which is strongly alkaline. By the time the response is all over, your bone minerals and broken down muscle get excreted in urine.


The four cases of dietary acidosis

Some of the science, at first glance, appears counter-intuitive. For example, acidic and alkaline foods don't usually translate into acid- and alkaline-yielding foods. The distinction is subtle but significant. An acid-yielding food is one that creates a lower, or more acidic, pH. Citrus fruits and tomatoes are acidic, but they have a net alkaline yield once their constituents get to the kidneys.

So if acid foods don't necessarily make for an acid pH, what then happens? There are four big issues.

• First, fruits and vegetables are rich in potassium salts, a natural buffer. Eating few of these foods deprives us of potassium, a mineral that protects against hypertension and stroke. According to research in Paleo-Diet, humans evolved eating a 10:1 ratio of potassium to sodium, and he regards this ratio as our biological baseline. Today, because of heavily salted processed and fast foods, combined with a low intake of fruits and vegetables, the ratio is now 3:1 in favor of sodium. That reversal, wreaks havoc with pH and our dependency on potassium.

• Second, there has also been a similar reversal in the consumption of naturally occurring bicarbonate (such as potassium bicarbonate) in foods and added chloride (mostly in the form of sodium chloride, or table salt). Bicarbonate is alkaline, where as chloride is acid-yielding. Chloride also constricts blood vessels, and narrows blood vessels reduce circulation. Because the whole body depends on healthy circulation, vasoconstriction contributes to heart disease, stroke, dementia, and probably every other degenerative disease.

• Third, eating large amounts of animal protein (including meat, fowl, and seafood) releases sulfuric acid though the metabolism of sulfur-containing amino acids, also contributing to greater acidity. This acidic shift can be offset with greater consumption of fruits and vegetables (rich in potassium bicarbonate).

• Fourth, grains, such as wheat, rye, and corn, have a net acid-yielding effect, regardless of whether they are in the form of white bread, breakfast cereal, pasta or whole grains. Grains are the most frequently consumed plant food. In addition to their acid yield, grains displace more nutritious fruits and vegetables. The real problem is one of alkaline deficiency, more than one of too much acid. People eat plenty of acid-yielding animal protein, dairy products, and grains. The missing piece is an appreciate amount of fruits and vegetables, to produce an alkaline yield. Study after study has shown that most people don't eat the five recommended daily servings of fruits and vegetables.

pH, acidosis and diseases

The strongest evidence in support of maintaining an acid-alkaline balance relates to osteoporosis. Dairy may be rich in calcium, but most dairy foods also produce an acid yield. The acid-alkaline issue as one of mineral adequacy and depletion. It's a little like over-farming and depleting mineral levels in soil. If we eat foods that create an acidic pH in the body, we will deplete our bones of minerals and our muscles of protein.

Low-grade acidosis increases insulin resistance, the hallmark of both pre-diabetes and full-blown type-2 diabetes. It increases the risk of kidney stones and kidney failure. And one study suggests that it might even alter gene activity and raise the risk of breast cancer. No one yet knows all the consequences of a fundamental shift in the body's acid-alkaline balance, but it's far reaching.

The pH of common substances

Acid-Yielding Foods
Spaghetti, Corn flakes, While rice, Rye bread, White bread, Milk, Lentils, Beef, Pork
Parmesan cheese, Processed (soft) cheeses, Hard cheeses, Gouda cheese, Cottage cheese, Peanuts, Chicken, Cod, Eggs

Alkaline-Yielding Foods
Apricots, Kiwifruit, Cherries, Bananas, Strawberries, Peaches, Oranges, Lemon juice, Pears, Pineapple, Peaches, Apples, Watermelon, Celery, Carrots, Zucchini, Cauliflower, Broccoli, Green peppers, Cucumber, Tomatoes, Eggplant/ Brinjal, Lettuce, Green beans, Onions, Mushrooms

Very Alkaline-Yielding Foods
Spinach and other green leafy vegetables, Raisins, Dates

Note: All fruits and vegetables are alkaline yielding, unless they have been pickled or marinated.

Scientific Citations
. Rylander R, Remer T, Berkemeyer S, et al. Acid-base status affects renal magnesium losses in healthy, elderly persons. Journal of Nutrition, 2006;136:2374-2377.
. Frassetto L, Morris RC, Sellmeyer DE, et al. Diet, evolution and aging. The pathophysiologic effects of the post-agricultural inversion of the potassium-to-sodium and base-to-chloride ratios in the human diet. European Journal of Nutrition, 2001;40:200-213.
. Sebastian A, Frassetto LA, Morris RC. The acid-base effects of the contemporary Western diet: an evolutionary perspective. Eds: Alpern RJ and Heber SC, in The Kidney: Physiology and Pathophysiology, 9th edition.
. Patterson BH, Block G, Rosenberger WF, et al. Fruit and vegetables in the American diet: data from the NHANES II survey. American Journal of Public Health, 1990;80:1443-9.
. Li R, Serdula M, Bland S, et al. Trends in fruit and vegetable consumption among adults in 16 US states: behavioral risk factor surveillance system, 1990-1996.
. Menendez JA, Decker JP, Lupu R. In support of fatty acid synthase (FAS) as a metabolic oncogene: extracellular acidosis acts in an epigenetic fashion activating FAS gene expression in cancer cells. Journal of Cell Biochemistry, 2005;94:1-4.
. Macdonald HM, New SA, Fraser WD, et al. Low dietary potassium intakes and high dietary estimates of net endogenous acid production are associated with low bone mineral density in premenopausal women and increased markers of bone resorption in post menopausal women. American Journal of Clinical Nutrition, 2005;81:923-933.
. Sebastian A, Harris ST, Ottaway JH, et al. Improved mineral balance and skeletal metabolism in postmenopausal women treated with potassium bicarbonate. New England Journal of Medicine, 1994;330:1776-1781.
. Sellmeyer DE, Schloetter M, Sebastian A. Potassium citrate prevents increased urine calcium excretion and bone resorption induced by a high sodium chloride diet. Journal of Clinical Endocrinology & Metabolism, 2002;87:2008-2012.
*A NaturalNews Special Report by Jack Challem
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