A lower ratio of omega-6/omega-3 fatty acids (n−6/n−3) is recommended
to reduce the risk of many highly prevalent chronic diseases in
Western societies (ratio of n−6/n−3 in Western diets is 15/1–16.7/1
Mammalian cells cannot convert omega-6 to
omega-3 fatty acids because they lack the converting enzyme, omega-
3 desaturase. These two classes of essential fatty acids (EFAs) are not
interconvertible, are metabolically and functionally distinct and have
opposing physiological functions. Therefore, too much omega-6 may
be detrimental for cells. Corn oil is not a good source for EFAs because
the ratio of omega-6/omega-3 fatty acids from corn oil is 83, which is
much higher than the recommended ratio (1/1 to 4/1). However, the present study and other studies show that high
corn oil intake improves health and longevity in mice and rats
(10 mg/kg/d by oral gavage) (NTP, 1994). One explanation is that majority
of omega-6 PUFA from corn oil is used for energy, and is not
used to produce thrombi and atheromas, which are required for cardiovascular
disease development.Moreover, high levels of vitamin E (majorly
γ-tocopherol) (Elmadfa and Park, 1999) and plant sterols (0.77% by
weight) may counter the bad effects of omega-6
PUFA of corn oil. For example, γ-tocopherol, the major form of vitamin
E in the corn oil, and its metabolite have more anti-inflammatory properties
than α-tocopherol, the predominant form of vitamin E in the tissues
and most supplements