Enhancing the 3 Content of Animal Products to Benefit the Health of Consumers

During human evolution, our metabolism became adapted to a hunter-gatherer diet that provided a balanced intake of o6 and o3 fatty acids in a ratio of about 1:1. In the Western world, this ratio may currently be as high as 20:1.[5] Livestock raised on grain display much higher «6:«3 ratios in their tissues compared with meat from animals in the wild.[5] In the case of monogastric livestock, the «3 status of their tissues is easily improved by providing a source of these fatty acids in their diets. Thus, dietary supplementation of pigs and poultry with fish oil, fish meal, flaxseed, or certain algae readily enhances the concentration of «3 fatty acids in the lipids of pork, chicken meat, and eggs.[5]

Modulation of the fatty acid composition of ruminant meat and milk is restricted by the extensive biohydroge-nation of polyunsaturates that occurs in the rumen. This problem can be partially circumvented by encapsulation of oil supplements in a protective coating to prevent access by rumen microbes.[6] Also, there is some evidence that 20:5«3 and 22:6«3 are less susceptible to biohy-drogenation in comparison with 18:2o6 and 18:3o3. Although supplementation of dairy cows with fish oil (nonencapsulated) increases the proportions of «3 fatty acids in milk lipid, it is difficult to achieve concentrations of 22:6o3 greater than 0.1% of milk fatty acids due to the low efficiency (3%) of transfer of this fatty acid from diet to milk.[7] Fish oil supplements result in increased concentrations of trans-fatty acids and conjugated linoleic acid in milk and also depress milk fat content.[7] Intake of linseed or fish oil by cattle produced significant increases in the concentrations of «3 fatty acids in muscle phospholipid.1-6-1 Cattle fed on grass have higher concentrations of «3 fatty acids in muscle lipids compared with cattle raised on concentrates.

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