There is No Question: EPA and DHA are Important for Cardiovascular Health
Epidemiologists slice and dice datasets trying to identify the single most important health indicator. Teasing out the relative impact of risk factors is difficult so keep in mind the words of Mark Twain, “Facts are stubborn things, but statistics are pliable.” So let’s look at the reports coming from one study.
The Cardiovascular Health Study enrolled older (≥ 65 years) men and women from 4 counties in the US beginning in the early 1990s. Almost 12,000 people were contacted. 3,654 recruits completed an extensive home interview and 4 hour clinic examination. Another 1,547 age-eligible persons participated, yielding a total of 5,201 participants. A search for the term “cardiovascular health study” in Google Scholar yields > 130 peer-reviewed publications on this cohort! What are the results? Here are summaries from select studies:
1. Trans fatty acids increase risk of fatal ischemic heart disease (IHD) and sudden cardiac death (measured in a subset using single blood samplesdrawn at baseline.) (Lemaitre et al, 2006).
2. Consumption of some types of fish, but not other types, reduces risk of cardiovascular death. (Mozaffarian et al, 2003).
3. Higher dietary intake of DHA and EPA reduces risk of IHD, consistent with antiarrythmic effects of these fatty acids. (Lemaitre et al, 2003).
4. Consumption of some types of fish, but not other types, reduces risk of ischemic stroke. (Mozaffarian et al. 2005)
5. Consumption of some types of fish, but not others, reduces risk brain abnormalities and it may be DHA and EPA (Virtanen et al, 2008)
6. Some types of fish, but not others, is related to larger gray matter volumes. Findings suggest lifestyle factors influence brain health. (Raji et al, 2014)
If you read the last sentence of each abstract above, the commonality of language will amaze. What does it all mean? First, food frequency records are poor indicators of nutrient intake. However, a meta-analysis by many of the same authors reviewed self-reported dietary records from 32 prospective case-control studies involving 512,420 participants with follow-up ranging from 5 to 23 years. They report a 22% reduced risk for coronary disease for total long-chain omega-3 fatty acid intake. Using circulating blood docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) concentrations from 13 studies, Chowdhury et al (2014) reported a 25% relative risk reduction. Unfortunately, methodological errors by the authors led to media misinterpretations which were not corrected. In the words of Ernest Rutherford, famous physicist, “If your experiment needs a statistician, you need a better experiment.”
The facts are: Eating foods which are cooked or fried with corn and soy oils leads to fatty acid imbalances in cells and blood. People do not consume enough omega-3 fatty acids. Our bodies are not very capable of synthesizing EPA and DHA from α-linolenic acid. Dietary sources of DHA and EPA are needed to maintain healthy cardiovascular system, eyes, brains, and livers. Using foods or supplements containing DHA and EPA helps maintain normal triglycerides, a cardiovascular risk factor. Experts recommend consuming at least 250 mg of EPA and DHA daily.
Raji CA, Erickson KI, Lopez OL, Kuller KH, Gach HM, Thompson PM, Riverol M, Becker JT. Regular fish consumption and age-related brain gray matter loss. 2014 Am J Prev Med doi: 10.1016/j.amepre.2014.05.037
Lemaitre RN, King IB, Mozaffarian D, Sotoodehnia N, Rea TD, Kuller LH, Tracy RP, Siscovick DS. Plasma phospholipid trans fatty acids, fatal ischemic heart disease, and sudden cardiac death in older adults. 2006 Circ doi: 10.11161/CIRCULATIONAHA.106.620336
Fried LP, Borhani NO, Enright P, Furberg CD, Gardin JM, Kronmal RA, Kuller LH, Manolio TA, Mittlemark MB, Newman A, O’Leary DH, Psaty B, Rautaharju P, Tracy RP, Weiler PG. The cardiovascular health study: design and rationale. 1991 Ann Epidemiol doi: 10.1016/1047-2797(91)90005-W
Mozaffarian D, Lemaitre RN, Kuller LH, Burke GL, Tracy RP, Siscovick DS. Cardiac benefits of fish consumption may depend on the type of fish meal consumed: The cardiovascular health study. 2003 Circ doi: 10.1161/o1.CIR.000055315.79177.16
Lemaitre RN, King IB, Mozaffarian D, Kuller LH, Tracy RP, Siscovick DS. n-3 polyunsaturated fatty acids, fatal ischemic heart disease, and nonfatal myocardial infarction in older adults: the Cardiovascular health Study. 2003 Am J Clin Nutr 77(2)319-325
Mozaffarian D, Longstreth Jr WT, Lemaitre RN, Manolio TA, Kuller LH, Burke GL, Siscovick DS. Fish consumption and stroke risk in elderly individuals: The Cardiovascular Health Study. 2005 Arch Intern Med doi; 10.1001/archinte.165.2.200
Virtanen JK, Siscovick DS, Longstreth Jr WT, Kuller LH, Mozaffarian D. Fish consumption and risk of subclinical brain abnormalities on MRI in older adults. 2008 Neurol doi: 10.1212/01.wnl.0000434414.12665.b0
Chowdhury R, Warnakula S, Kunutsor S, Crowe F, Ward HA, Johnson L, Franco OH, Butterworth AS, Forouhi NG, Thompson SG, Khaw K-T, Mozaffarian D, Danesh J, Di Angelantonio E. Association of dietary, circulating, and supplemental fatty acids with coronary risk: A systematic review and meta-analysis. 2014 Ann Intern Med doi:10.7326/M13-1788 (corrected paper).