Some 6,000 to 10,000 years ago, our ancestors relied on a pre-agricultural, hunter-gatherer diet. Since then, with the invention of agriculture and industrial-scale food production, our diet has become rich in saturated fat, simple sugars, sodium and chloride, while nutrients such as fiber, magnesium and potassium are lacking. These dietary changes are thought to be risk factors to a number of diseases, including atherosclerosis, hypertension, type 2 diabetes, osteoporosis and some cancers.

The contemporary human diet results in the body’s net production of noncarbonic acid, which ranges from 10 to 150 mEq/d among diets today. Although the body has mechanisms to compensate for deviations in systemic acid-base equilibrium, blood acidity tends to be increased and plasma bicarbonate concentrations tend to be decreased due to the present day net acid load. This condition, known as low-grade acidosis, may result in the dissolution of bone, muscle wasting, kidney stone formation, and damage to the kidney.

A recent report estimated the net endogenous acid production (NEAP), or total acid load of the diet, for 159 prehistoric, pre-agricultural Homo sapien diets. The prehistoric diets were found to be net base-producing, while the contemporary diet tends to be net acid-producing.

According to researchers, this switch from net base to net acid production was due to a reduction in endogenous bicarbonate production rates. This reduction is attributed to the replacement of base-rich plant foods, such as roots, leafy green vegetables and fruit, with cereal grains and EDNP foods such as refined sugars and separated fats. The latter foods are not net-base producing, and therefore do not compensate for the net acid-producing portions of today’s diet, namely animal foods such as meat, cheese, milk, yogurt and eggs.

Cereal grains, which are net acid-producing, account for 38 percent of the acid load in the present day diet. According to the recent report, when plant foods in two pre-agricultural-type diets (made up of varying animal and plant food ratios) were replaced by cereal grains, the result was a switch from a net base-producing diet to a net acid-producing one. However, when cereal grains were removed from the contemporary diet (using a computational model), NEAP decreased from 48 to -4 mEq/d, which is close to the neutral point between acid and base-producing diets.

However, eliminating cereal grains and increasing plant foods could not convert the contemporary diet to a net base-producing one. Researchers say that this shows that it is the combined effect of substituting cereal grains and EDNP foods for non-grain plant foods in the contemporary diet that accounts for the transition from a net base-producing diet to a net acid-producing one. Replacing both cereal grains and EDNP foods with non-grain plant foods had the effect of switching the net acid-producing diet to a net base-producing one.

Researchers say that potential benefits of a chronic net base-producing diet that could be explored include preventing and treating osteoporosis, age-related muscle wasting, calcium nephrolithiasis and sensitive hypertension. Improving exercise performance, treating infertility and slowing the progression of age- and disease-related chronic renal insufficiency are also mentioned. The report notes that study findings suggest a mild systemic metabolic alkalosis, which results from a chronic net base-producing diet, is the natural and optimal state of humans.

American Journal Clinical Nutrition December 2002 76: 1308-1316

Dr. Mercola's Comments:

This is an important addition to the increasing body of evidence suggesting that we are naturally designed to have a diet that is more basic than acidic. This makes perfect sense; if you look at your blood pH you will find that it is slightly basic. 7.0 is neutral, and a typical blood pH is 7.40 -- slightly basic. So if you are eating grains regularly your net acid load will push your body toward acidity, and your body will have to compensate for this acidity to maintain balance. One of the most common complications of this compensation is osteoporosis; your body will pluck out the calcium and magnesium ions stored in your bone to neutralize the excess acidity in your diet. As this article suggests, most of the excess acidity is the result of our replacing the vegetables that Paleolithic man ate with modern day grains. So we have further scientific support for the recommendation that a low- or no-grain diet coupled with a high intake of vegetables, clinically and anecdotally, seems to bring most people to higher levels of health. If you haven’t read the updated nutrition plan, I would encourage you to do so -- it has been simplified and is now made up of easy-to-follow, graduated steps. One of its major focal points is to help you exchange grains in your diet with vegetables. Does that mean you should never eat grains? Absolutely not, but most of us would have dramatically improved health if we radically reduced our grain intake. Grains do provide some benefit, and it is becoming very clear to me that the phytic acid content of grains, which has long been considered to be an anti-nutrient, may in fact be one of the major benefits of grains. Phtyic acid is only in whole grains; it is virtually stripped out of refined grains. Phytic acid is likely beneficial as it reduces iron levels. As I have been mentioning recently, increased iron levels is one of the most significant health threats to which many of us are exposed.