Acid/Base Balance

In the U.S. calcium intake is one of the highest in the world, yet paradoxically we also have one of the highest rates of bone demineralization (osteoporosis).  Bone mineral content is dependent not just upon calcium intake but upon net calcium balance (calcium intake minus calcium excretion).  Most nutritionists focus upon the calcium intake side of the calcium balance equation, however few realize that the calcium excretion side of the equation is just as important.

Bone health is substantially dependent on dietary acid/base balance.  All foods upon digestion ultimately must report to the kidney as either acid or base.  When the diet yields a net acid load (such as low-carb fad diets that restrict consumption of fruits and vegetables), the acid must be buffered by the alkaline stores of base in the body.  Calcium salts in the bones represent the largest store of alkaline base in the body and are depleted and eliminated in the urine when the diet produces a net acid load.  The highest acid-producing foods are hard cheeses, cereal grains, salted foods, meats, and legumes, whereas the only alkaline, base-producing foods are fruits and vegetables.  Because the average American diet is overloaded with grains, cheeses, salted processed foods, and fatty meats at the expense of fruits and vegetables, it produces a net acid load and promotes bone demineralization.  By replacing hard cheeses, cereal grains, and processed foods with plenty of green vegetables and fruits, the body comes back into acid/base balance which brings us also back into calcium balance.  The goal is to avoid a net acid load on your kidneys.

The Paleo Diet recommends an appropriate balance of acidic and basic (alkaline) foods (i.e., lean meats, fish and seafood, fruits, and vegetables) and will not cause osteoporosis in otherwise healthy individuals.  Indeed, The Paleo Diet promotes bone health.

In addition to promoting bone demineralization, a net acid-producing diet also contributes to the following maladies and illnesses: calcium kidney stones, age-related muscle wasting, hypertension, stroke, asthma and exercise-induced asthma.

The following table lists the acid, base values for 114 common foods.  Base-producing foods are fruits and vegetables, whereas grains, meats, fish, cheese and salted processed foods are acid-producing.

PRAL (Potential Renal Acid Load per 100 grams)

(Negative numbers indicate base or alkaline-producing foods and positive numbers are acid-producing foods)

This table adapted from:
Remer T, Manz F.  Potential renal acid load of foods and its influence on urine pH. J Am Diet Assoc 1995;95:791-797.