Whereas major changes have taken place in our diet over the past 10,000 years since the beginning of the Agricultural Revolution, our genes have not changed. The spontaneous mutation rate for nuclear DNA is estimated at 0.5% per million years. Therefore, over the past 10,000 years there has been time for very little change in our genes, perhaps 0.005%. In fact, our genes today are very similar to the genes of our ancestors during the Paleolithic period 40,000 years ago, at which time our genetic profile was established. Humans today live in a nutritional environment that differs from that for which our genetic constitution was selected. Studies on the evolutionary aspects of diet indicate that major changes have taken place in our diet, particularly in the type and amount of essential fatty acids (EFA) and in the antioxidant content of foods.

Today, industrialized societies are characterized by (1) an increase in energy intake
and decrease in energy expenditure; (2) an increase in saturated fat, omega–6 fatty
acids and trans fatty acids, and a decrease in omega–3 fatty acid intake; (3) a decrease
in complex carbohydrates and fiber; (4) an increase in cereal grains and a decrease in
fruits and vegetables, and (5) a decrease in protein, antioxidants and calcium intake
[7, 9, 12–16] (tables 1 and 2). The increase in trans fatty acids is detrimental to health
as shown in table 3 [17]. In addition, trans fatty acids interfere with the desaturation
and elongation of both omega–6 and omega–3 fatty acids, thus further decreasing the
amount of arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic
acid (DHA) availability for human metabolism [18].
The beneficial health effects of omega–3 fatty acids, EPA and DHA were described
first in the Greenland Eskimos who consumed a high seafood diet and had low rates
of coronary heart disease, asthma, type 1 diabetes mellitus, and multiple sclerosis.
Since that observation, the beneficial health effects of omega–3 fatty acids have been
extended to include benefits related to cancer, inflammatory bowel disease, rheumatoid
arthritis, and psoriasis [19].

Whereas evolutionary maladaptation leads to reproductive restriction (or differential
fertility), the rapid changes in our diet, particularly the last 150 years, are potent
promoters of chronic diseases such as atherosclerosis, essential hypertension, obesity,
diabetes, arthritis and other autoimmune diseases, and many cancers, especially
cancer of the breast [20], colon [21], and prostate [22]. In addition to diet, sedentary
lifestyles and exposure to noxious substances interact with genetically controlled biochemical
processes leading to chronic diseases.
In this review, I discuss the importance of the balance of omega–6 and omega–3
EFA, their physiologic function and mechanisms involved in the reduction of inflammatory
processes and gene expression. Inflammation is at the base of many chronic
diseases. A balanced omega–6:omega–3 fatty acid ratio is essential in the prevention
and treatment of coronary artery disease, hypertension, diabetes, arthritis, osteoporosis,
other inflammatory and autoimmune disorders, cancer and mental health.