Increasing the amount of omega-3s in your diet, whether from fish or flax, will likely decrease your risk of getting heart disease, according to Penn State nutritionists.
Brenna et al (ISSFAL) 2009 - Alpha-Linolenic acid supplementation and conversion to omega-3 long-chain PUFA in humans.
The evidence reviewed in the Brenna et al., 2009 paper shows that humans cannot effectively convert ALA (an omega-3 from plant sources) into DHA (a longer-chain omega-3 found in fish and seafood).
This is an extremely important finding, because the health benefits associated with consuming 'omega-3' fatty acids relate only to EPA and DHA - not to ALA.
This paper represents the official position of ISSFAL (the International Society for the Study of Fatty Acids and Lipids) - an independent organisation that includes most of the world's leading scientists in this area.
For additional information on this subject, please see:
Omega-3 fatty acids for vegetarians
Brenna 2002 - Efficiency of conversion of alpha-linolenic acid to long chain n-3 fatty acids in man.
Francois et al 2003 - Supplementing lactating women with flaxseed oil does not increase DHA in their milk.
Davis & Kris-Etherton 2003 - Achieving optimal essential fatty acid status in vegetarians: current knowledge and practical implications.
Rosell et al 2005 - Long-chain n-3 PUFA in plasma in British meat-eating, vegetarian, and vegan men
Mangat 2009 - Do vegetarians have to eat fish for optimal cardiovascular protection?
Enos et al 2014 - Reducing the Dietary Omega-6:Omega-3 Utilizing α-Linolenic Acid; Not a Sufficient Therapy
A substantial amount of evidence exists supporting the heart-health benefits of eicosapentaenoic acid and docosahexaenoic acid (EPA and DHA), marine-derived omega-3 fatty acids. However, much less evidence exists to demonstrate the positive effects of alpha-linolenic acid (ALA), a plant-based omega-3 fatty acid.
"The benefits reported for EPA and DHA are stronger because supplements of EPA and DHA were tested, and EPA and DHA was the only difference between the treatment and control groups," said Jennifer Fleming, instructor and clinical research coordinator in nutritional sciences. "In contrast, in the ALA studies, there were diet differences beyond ALA between the treatment and control groups."
EPA and DHA can be found in seafood and fish oil, and are often consumed in the form of dietary supplements. ALA is found in flaxseed and its oil, vegetable oils, and some nuts, and is now available in supplement form. EPA and DHA have been available for much longer. Other sources of ALA, EPA and DHA are fortified foods such as orange juice, eggs, peanut butter, margarine and bread, among others. While there are many other omega-3 fortified foods in the market place, most are relatively low in omega-3 fatty acids.
Omega-3 fatty acids are considered essential for human health, but the body does not produce them -- therefore they must be consumed in order to maintain appropriate levels.
In reviewing existing literature on the subject, the researchers have come to the conclusion that ALA is likely just as effective in preventing cardiovascular disease as EPA and DHA have proven to be, as they report on the current issue of Advances in Nutrition.