The three different types
Omega-3
Definitions
ALA (sometimes LNA): alpha-linolenic acid
EPA: eicosapentaenoic acid
DHA: docosahexaenoic acid
http://en.wikipedia.org/wiki/Omega-3
Omega-3 fatty acids which are important in human nutrition are: alpha-linolenic acid (18:3, ALA), eicosapentaenoic acid (20:5, EPA), and docosahexaenoic acid (22:6, DHA). These three polyunsaturates have either 3, 5 or 6 double bonds in a carbon chain of 18, 20 or 22 carbon atoms, respectively. All double bonds are in the cis-configuration, i.e. the two hydrogen atoms are on the same side of the double bond.
What are the general findings?
- Natural (human evolution) diet ratio of omega-3 to omega-6 fatty acids (omega3:omega6) was about 1:1 but present American diet is around 1:20 [4,5]
A diet rich in omega 3 fatty acids (such as the LNA from flax oil or the EPA and DHA from fish oils) not only provides the body with healthy fats, but it also lowers the blood level of potentially harmful ones, such as cholesterol and, possibly, even reversing the effects of excess trans fatty acids.
DHA is the primary structural component of brain tissue, so it stands to reason that a deficiency of DHA in the diet could translate into a deficiency in brain function. In fact, research is increasingly recognizing the possibility that DHA has a crucial influence on neurotransmitters in the brain, helping brain cells better communicate with each other. Asian cultures have long appreciated the brain-building effects of DHA. In Japan, DHA is considered such an important "health food" that it is used as a nutritional supplement to enrich some foods, and students frequently take DHA pills before examinations.
Journal article
- Men are more efficient at converting ingested fat to energy than women [2,3]. For men ALA conversion was 33% versus 22% for women.
- The conversion of ALA to EPA is strongly linear (what percent?) Thus increased consumption of ALA should lead to an equally large increase in the amount of EPA in the blood.
- There is no relationship to the consumption of ALA and the blood levels of DHA. Thus ALA consumption should not substitute for the consumption of DHA. Unfortunately DHA is found widely in resources that are being harvested unsustainably.
Conversion percent
- Role of gender in conversion
Health benefits of ala, epa, and dha
Omega-3s anddepression
Alzheimer's
Colon cancer
CiteULike link
[1] G.C. Burd, Metabolism of α-linolenic acid in humans Prostaglandins, Leukotrienes and Essential Fatty Acids, Volume 75, Issue 3 , September 2006, Pages 161-168
[2] A.E. Jones, J.L. Murphy, M. Stolinski and S.A. Wootton, The effect of age and gender on the metabolic disposal of 1-13C palmitic acid, Eur. J. Clin. Nutr. 52 (1998), pp. 22–28. Abstract-EMBASE | Abstract-MEDLINE | Abstract + References in Scopus | Cited By in Scopus
[3] A.E. Jones, M. Stolinski, R.D. Smith, R.J.L. Murphy and S.A. Wootton, Effect of fatty acid chain length and saturation on the gastrointestinal handling and metabolic disposal of dietary fatty acids in women, Br. J. Nutr. 81 (1999), pp. 37–43. Abstract-MEDLINE | Abstract-EMBASE | Abstract + References in Scopus | Cited By in Scopus
[4] Omega-3 fatty acids in health and disease and in growth and development
Am J Clin Nutr, Vol. 54, No. 3. (1 September 1991), pp. 438-463.
by Simopoulos A
[5] Human requirement for N-3 polyunsaturated fatty acids.
[5] Human requirement for N-3 polyunsaturated fatty acids.
Poult Sci, Vol. 79, No. 7. (July 2000), pp. 961-970.
by Simopoulos AP
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