Dr. Loren Cordain. is a professor of exercise physiology at Colorado State University in Ft. Collins, Colorado, and an expert in the area of Paleolithic nutrition

What are we really "designed" to eat?

Professor Loren Cordain, Ph.D.

Cereal grains are virtually indigestible by the human gastrointestinal tract without milling (grinding) and cooking.

The fossil record indicates that early farmers, compared to their hunter-gatherer predecessors had a characteristic reduction in stature, an increase in infant mortality, a reduction in life span, an increased incidence of infectious diseases, an increase in iron deficiency anemia, an increased incidence of osteomalacia, porotic hyperostosis and other bone mineral disorders and an increase in the number of dental caries and enamel defects.

I do know that all human beings don't do very well when the total caloric intake of cereal grains approaches 70%

The high phytate content of whole grain cereals can impair mineral metabolism i.e. iron, calcium, and other anti-nutrients have the potential to interact with the gastrointestinal tract and perhaps the immune system as well. The high lectin content of whole grain cereals can bind enterocytes in the small intestine and cause villous atrophy in addition to changing tight junction characteristics thereby allowing intestinal antigens (both dietary and pathogenic) access to the peripheral circulation.

Whole grain cereals are devoid of vitamin C and beta carotene (except for yellow maize). They have poorly absorbable vitamin B6, and the phytate levels in grains impairs the absorption of most of the divalent minerals.

Additionally, they contain low levels of essential fats and have quite high omega 6/omega 3 fatty acid ratios. Excessive consumption of cereal grains are associated with a wide variety of health problems. In animal models, rickets are routinely induced by feeding them high levels of cereal grains.

It is thought that the high levels of phytate in unleavened whole grain breads cause a zinc deficiency which in turn is responsible for hypogonadal dwarfism, along with other health problems associated with zinc deficiencies.

Cereal grains seem to have a simultaneous influence on vitamin D and Ca metabolism.
Epidemiological studies of populations consuming high levels of unleavened whole grain breads show vitamin D deficiency to be widespread. A study of radio-labelled 25 hydroxyvitamin D3 (25(OH)D3) in humans consuming 60g of wheat bran daily for 30 days clearly demonstrated an enhanced elimination of 25(OH)D3 in the intestinal lumen.
The mechanism by which cereal grain consumption influences vitamin D is unclear. Some investigators have suggested that cereal grains may interfere with the enterohepatic circulation of vitamin D or its metabolites, whereas others have shown that calcium deficiency increases that rate of inactivation of vitamin D in the liver.
This effect is mediated by 1,25 dihydroxyvitamin D (1,25(OH)2D) produced in response to secondary hyperparathyroidism, which promotes hepatic conversion of vitamin D to polar inactivation products which are excreted in bile. Consequently, the low Ca/P ratio of cereal grains has the ability to elevate PTH which in turn stimulates increased production of (1,25(OH)2D) which causes an accelerated loss of 25 hydroxy vitamin D.
So it doesn't get activated by the kidneys if there are a lot of cereal grains in the diet. The hormone version of vitamin D doesn't come into existence if people are eating 70-80% of their diets as cereal grains?
(1. Batchelor AJ, Compston JE: Reduced plasma half-life of radio-labelled 25 hydroxyvitamin D3 in subjects receiving a high fiber diet. Brit J Nutr 1983; 49:213-16. 2. Clements MR, Johnson L., Fraser DR:
A new mechanism for induced vitamin deficiency in calcium deprivation. Nature 1987; 325: 62-65. 3. Dagnelie PC et al. High prevalence of rickets in infants on macrobiotic diets. Am J Clin Nutr 1990; 51: 202-8.)

Wheat, rye, barley, and perhaps oats are problematical for individuals with celiac disease. Wheat seems to be associated with many auto-immune diseases.
Ironically, whole grain cereals (which are thought to be more healthful than refined cereals because of their greater nutrient and fiber content) have a greater potential to disrupt mineral metabolism because of their higher phytate and anti-nutrient content.

Although high grain cereals intrinsically contain higher nutrient levels than do refined cereal grains, the biological availability of nutrients in whole grain cereals remains paradoxically low because of their high anti-nutrient content. On the plus side, whole grain cereals, because of their high fiber content tend to have superior glycemic indices than do their refined counterparts.
Obviously, low to moderate amounts of cereal grains in the diet presents little or no health problems to most people. The majority of the grain products consumed in this country are refined, and consequently many of the anti-nutrients are milled out.

The critical dietary factor influencing bone metabolism and hence osteoporosis is not calcium intake, nor calcium excretion, but rather calcium balance.
The acid base status of the total diet rather than calcium intake or excretion determines calcium balance (Barzel US. The skeleton as an ion exchange: implications for the role of acid-base imbalance in the genesis of osteoporosis. J Bone Miner Res. 1995; 10: 1431-36).

Foods which yield a net acidic load mainly as sulfates and phosphates cause the kidneys to respond to this dietary acid challenge with net acid excretion, as well as ammonium and titratable acid excretion. Concurrently, the skeleton supplies buffer by active resorption of bone. Consequently, calciuria is directly related to net acid excretion (Barzel US, Massey LK Excess dietary protein can adversely affect bone. J Nutr 1998; 128:1051-53).

Foods which cause a net acid excretion include meat, fish, cheeses and grains (Remer T, et al. Potential renal acid loads of foods and its influence on urine pH. J Am Diet Assoc. 1995 Jul; 95: 791-97). Fruits and vegetables have a net alkaline value and consequently reduce acid excretion and hence reduce calciuria thereby halting bone resorption and actually allowing bone accretion to occur.

Large amount of fruits and vegetables (35% of total energy) included in the diet would produce a net dietary acid-base status which would have favored bone accretion even in the face of enormous protein intakes.
Similarly, nephro and urolithiiasis would be reduced from the high levels of fruit and vegetable consumption via their ability to reduce the potential renal acid load.

Many populations around the world consume low fat, high carbohydrate diets with little or no animal protein, yet paradoxically suffer high rates of diseases of insulin resistance and high levels of cardiovascular disease.

Further, cereal grains tend to have a high Omega-6/Omega-3 ratio because they are high in linoleic acid and low in linolenic. The oxidizability of the LDL molecule increases when it's loaded up with Omega-6 fats (linoleic acid primarily).
The types of fats that you eat influence the type of fats that are incorporated in the cell membrane. They can also influence hormonal profiles, and eicosanoid function. We tend to see a more inflammatory eicosanoid profile with elevated levels of Omega-6 fats.

Arachidonic acid is an essential fatty acid in virtually every cell of the body, and it is an important precursor for prostanoid synthesis and tissue function.
More recent data suggests that the balance of arachidonic acid to long chain Omega-3 fatty acid may be more important in influencing health than absolute dietary intakes of arachidonic acid.

Macronutrient and trace nutrient levels should be emulated in the design of healthful diets

Humanity is totally dependent now upon cereal grains for survival.
Cereal grains provide 56% of the food energy and 50% of the protein consumed by all of the world's peoples.
Without them, there would be worldwide starvation of an unprecedented proportion. we have wandered down a path of absolute dependence upon cereal grains, a path from which there is no return.
Clearly, it is not practical nor economically possible for all of the world's people to eat wild game, fruits and vegetables.

Experimentally, we know that the expression of certain auto-immune diseases (e.g. insulin dependent diabetes mellitus IDDM) increases in animal models when they are fed high cereal grain diets.
We believe that cereal grains may influence immune function by the ability of their lectins (specifically wheat germ agglutinin-WGA) to allow passage of undegraded dietary antigens and antigens derived from intestinal pathogens (viruses and bacteria) to peripheral tissue.
Through a process called molecular mimicry, in which there are structural similarities between the body's own tissue and that of the dietary antigen and/or the intestinal pathogen antigen, the immune system loses the ability to distinguish self tissue from non-self tissue and mounts an immune attack upon the body's own tissue. Many of these structural similarities between cereal grain peptides and the body's own tissues seem to involve collagenous tissues.
The literature suggests that the alcohol soluble portion of wheat contains peptide sequences that may mimic peptide sequences in the body.

Robert Crayhon: The upshot of all this is that it couldn't hurt if you've got an auto-immune disease to try a grain-free diet?

Well, it's more than grain-free. Dairy, legumes, and yeast contain peptides with amino acid sequence that are homologous to amino acid sequences in a variety of human tissues as well.

I think we need to have clinical trails obviously eliminating these kinds of foods: cereal grains, dairy products, legumes, and yeast. This would be difficult for people who have been weaned on a Western diet, but humans throughout most of the course of our stay on this planet did not eat those foods or rarely ate those foods.
These proteins are alien to our immune system. We would hope that clinical trails involving elimination of these suspect peptides will be done in the future and hopefully may be of benefit to people with auto-immune problems.

Animals are fed grains just like us. So there omega 6 to omega 3 ratios are terrible. Even if the meat were organic the ratio is about 20:1 not the ideal 2-3:1.

GRASS FED beef that has the ideal ratio.

Robert Crayhon, M.S. is a clinician, researcher and educator who was called "one of the top ten nutritionists in the country" by Self magazine (August 1993). An associate editor of Total Health magazine, he is the author of best-seller Robert Crayhon's Nutrition Made Simple and the just published The Carnitine Miracle (M. Evans and Company).

Excerpt’s from The Paleolithic Diet and Its Modern Implications