Most studies in humans have shown that whereas certain, though limited, conversion of high doses of ALA to EPA occurs; conversion to DHA is severely restricted. It has been suggested that only about 15 percent of ALA converts to EPA and 5 percent to DHA. ( H. Gerster. Conversion of ALA and DHA. Internat. J Vit. Nutr. Res 68 (1998)-Cunnane , 1995, Nutrition Advisory Panel, 1995).
The most important interference is an excess of Omega-6 fatty acids in the bloodstream competing for the same enzymes as Omega-3s for a similar type of metabolism that could inhibit conversion by as much as 40%!
This explains why a high intake of Omega-6 fats in the diet, mainly coming from vegetable oils, prevents the metabolism of ALA to DHA. Other problems might also inhibit the conversion process, such as a deficiency in certain vitamin and mineral co-factors (vitamin B3, B6, B12, C, Zinc and Magnesium), aging or disease. Studies have suggested that certain populations, such as North American natives, Inuit, Orientals, Norwegians, and Welsh-Irish may not effectively convert ALA to EPA in the body.
Flax oil must be refrigerated and will only last two to three months once opened. However it can be stored in the freezer to increase its shelf life. Also, flax oil is very sensitive to oxidation and becomes rancid very easily. Therefore it is preferable to use freshly ground flax seeds instead of the oil.
Also, according to deceased health guru, Dr. Bernard Jensen (Vibrant Health From Your Kitchen), flax oil can weaken the lining of the gut, and can therefore be used for only about three weeks at a time and then be interrupted for at least two months.
And in their book called Protein Power: Michael and Mary Eades state: ” . . . But taking flax seed oil is kind of like buying crude oil and running it through your home distillery to make gasoline for your car. If that’s the only way you can get gasoline, then that’s what you have to do. If you can buy the gasoline already distilled, however, it is much more efficient to do that and avoid the hassle of the home distillation process.”