the inclusion of high fiber vegetables, such as a large salad, can help with regularity in addition to
the nutrients they provide.
Essential fatty acids (EFAs)
As stated in chapter 9, EFAs are a special class of fatty acids which cannot be
synthesized in the human body and must be obtained from the diet. The two EFAs are linoleic
acid (LA) and alpha-linolenic acid (ALA). Both LA and ALA are found only in foods of plant origin
such as nuts, seeds, and some vegetables. Since a great deal of the fat intake on an average SKD
is from animal sources, a source of EFAs is needed.
One possible source is through supplementation. EFAs are found in varying degrees in
most vegetable oils. In general, LA is more abundant than ALA as it occurs in a wide variety of
vegetable oils. ALA occurs in high amounts in flax and pumpkin seeds oil as well as in soybean
oil. Many individuals have also used flax seeds or flax meal as a source of both EFAs and fiber. It
is difficult to determine EFA requirements for all individuals but many ketogenic dieters seem to
do well consuming 1-3 TBSP of a concentrated EFA source, such as flax oil, per day.
Omega-3 and omega-6 fatty acids
Another class of fats which may have health benefits are the omega-3 and omega-6 fatty
acids, also known as docosahexanoic acid (DHA) and eicosapentanoic acid (EPA) (5,6,7). Both
occur naturally in fatty fish such as salmon, sardines, mackerel, and trout. and may provide
cardioprotective effects. Since fatty fish can easily be consumed on a ketogenic diet,
supplementation of these oils is probably unnecessary.
Olive oil
Although not an essential fatty acid, oleic acid, which is found in high concentrations in
olive oil has been shown to have additional health effects, especially in terms of blood lipid levels.
Studies have shown that consumption of oleic acid lowers blood cholesterol (8). Therefore,
substituting olive oil for some of the saturated fats normally consumed on a ketogenic diet may
be useful for those individuals who show a negative blood cholesterol response.
References cited
- Stock A and Yudkin J. Nutrient intake of subjects on low carbohydrate diet used in treatment
of obesity. Am J Clin Nutr (1970) 23: 948-952. - Diplock AT. Antioxidant nutrients and disease prevention: An overview. Am J Clin Nutr (1991)
53: 189s-193s. - Rock CL et. al. Update on the biological characteristics of the antioxidant micronutrients: