n-3 Fatty acids: Comparison of plant and seafood sources in human nutrition.
n-3 Fatty acids: Comparison of plant and seafood sources in human nutrition.
Year: 1991
Authors: J A Nettleson.
Publication Name: J. Amer. Diet. Assoc.
Publication Details: Volume 91; Page 331.
Abstract:
This article reviews dietary sources of n-3 fatty acids, specifically ALA from plant oils such as flaxseed oil and EPA and DHA from fish and fish oils. Principle food sources of ALA in the typical North American diet are salad and cooking oil, salad dressing, shortening, margarine, and food-service fat and oil products made from canola oil (CO) and soybean oil. ALA is present in the highest level in dietary supplements of flaxseed and flaxseed oil and only in minimal amounts (0.5 to 2.3 g/100 g) in animal fats. Animal feeding trials have shown that ALA levels can be increased in poultry products and eggs through the inclusion of flax and canola oils and meal in rations. The ALA content of typical foods is presented in a number of tables in this paper. ALA content in plants is very small. Breast milk contains ALA, EPA as well as DHA identifying an importance for these EFA in prenatal and natal nutrition. In this paper, the author reviews the metabolism of ALA including its incorporation into tissues which may be low due to competition with LA as well as the finding that ALA is preferentially oxidized for energy. ALA conversion to EPA is reviewed and the importance of the ratio of dietary LA:ALA is emphasized as these EFA compete with one another for enzymes responsible for their metabolism into longer chain PUFA. A review of the health effects of ALA is presented. The importance of long-term consumption of ALA has been demonstrated in terms of reducing both platelet aggregation and blood pressure in humans. The author indicates that by selecting oils and margarines containing ALA, EPA levels can be modestly increased in tissues. Dietary supplements of flaxseed and flaxseed oil can also enhance tissue levels of EPA.
