My question is regarding the consumption of milk. There are a great number of coaches around the country who advocate at least moderate, if not generous, amounts of milk in their athletes’ diets. Does it not provide a good source of protein and carbohydrate balance, not to mention the calcium content? What is the paleo stance on milk and why?
Dr. Cordain’s Response:
There are several reasons why not to consume dairy products:
Hominids evolved during 2.6 million years behaving as hunter-gatherers.
Although there wasn’t a single diet, and diet rather varied by latitude, season, climate, culture, etc., all ancestral diets shared key characteristics. Food sources were limited to unprocessed foraged plants, and unprocessed land and marine animals hunted from the proximate environment. As such, human diets consisted of combinations of wild animal carcasses (including brains, bone marrow, and organs), shellfish, fish, fruits, leafy vegetables, mushrooms, insects, larvae, nuts, seasonal honey, and eggs.
Ten thousand years ago, major changes in the environment happened, including the human diet. New foods, such as cereal grains, legumes, dairy, vegetable oils, refined sugars, fatty domesticated meats and salt, were introduced.
Since that time, there is strong evidence that our genome has remained essentially unchanged over the past 10,000 years. Evolutionary medicine predicts that these environmental changes may have caused adverse effects.
Indeed, it is believed that this mismatch between our ancient genome and the modern environment (including our modern diet) is at the root of the so-called diseases of western civilization, such as type 2 diabetes, obesity, dislipidemia, hypertension, certain types of cancer, acne, autoimmune diseases, myopia, polycystic ovary syndrome and more.
Regarding dairy, we know that this food group was not available for human intake prior to the onset of animal husbandry–roughly 9,000 years ago in the Middle East, and 7,000 years ago in Northern Europe. So dairy is a relatively new food on an evolutionary time scale, which explains why it may produce the following adverse effects, through different mechanisms:
- Milk is a source of estrogens and dihydrotestosterone precursors, which can increase the risk of certain cancers and acne.
- Milk increases IGF-1, and the IGF-1/IGFBP-3 ratio, and this increases the risk of certain cancers and acne–among other diseases–as explained by Dr. Cordain in his paper “Hyperinsulinemic diseases of civilization: more than just syndrome X”
- Milk contains insulin, and bovine insulin differs in only 3 amino acids from human insulin. This feature can increase the risk of Type 1 diabetes in genetically susceptible persons.
- Betacellulin: is a hormone belonging to the EGF family of hormones. If it is confirmed that Betacellulin is able to enter circulation, then there is a very good possibility that it may increase the susceptibility of certain epithelial cancers.
- Milk elevates insulin as much as white bread. Constantly elevating plasma insulin levels may lead to insulin resistance, which is at the root of several metabolic diseases such as obesity, type 2 diabetes or hypertension.
- High calcium intake adversely affects zinc absorption, a key mineral in more than 300 enzymatic reactions.
- Milk contains several allergenic proteins.
- Dairy products, especially hard cheeses, yield a very high net acidic load which might lead to calcium and muscle loss and decrease growth hormone.
In sports nutrition BCAA intake is crucial for muscle recovery. Lean meat is the biggest sources of BCAA (33 grs/1000Kcal). Dairy contains much less BCAA (12 grs/1000Kcal), so if you replace grass produced or free ranging meats with dairy you are taking much less BCAA which is crucial in muscle recovery.
Loren Cordain, Ph.D., Professor Emeritus