Omega-3 Fatty Acid Headlines are Smelling Fishy
It makes me want to cry out with frustration when I read headlines that the there is something fishy about omega-3 supplements or that fish oil supplements do not prevent heart disease. Let me share a different perspective on the value of omega-3 supplements.
The biggest myth is that encouraging supplement use will undermine healthy food choices and contributes to unhealthy dietary behaviors. This is incorrect. The record shows that people who use dietary supplements are more likely to have better dietary patterns, to maintain a healthy weight, exercise regularly and follow healthier lifestyles.
The second misperception is there is no cardiovascular benefit from using omega-3 long-chain polyunsaturated fatty acids (LCPUFA). The interpretation is wrong. Why? Most randomized controlled trials (RCTs) involving supplements have not measured nutritional status.
Let’s review the report of the Australian National Heart Foundation. They cite 2 systematic reviews and meta-analyses, both of which did not assess omega-3 status (Kotwal et al, 2012; Rizos et al, 2012). Two of the 3 intervention trials, patients with impaired glucose metabolism or with multiple cardiovascular risk factors, did NOT measure omega-3 status, either in blood, red blood cells, or adipose tissue.
The National Health Foundation report identifies many studies reporting health benefits of fish consumption. Why? Simple answer. Most of these studies measured omega-3 status rather than relying upon a dichotomous statistical analysis: assigned to consuming fish (yes/no).
The beneficial findings of fish consumption are grounded in nutrition status measurements. Based on adipose tissue fatty acid analysis, Joensen and colleagues reported a 35% reduction in risk of acute coronary syndrome between those with the highest n-3 LCPUFA in adipose quintile (vs lowest). Mozaffarian and colleagues reported higher plasma omega-3 fatty acid concentrations are associated with a 27% reduction in risk of total mortality, mostly attributable to cardiovascular deaths.
The same is true for fish oil supplements. In the one intervention measuring omega-3 status (the Japan EPA Lipid Intervention Study (JELIS), higher plasma levels of EPA are associated with as significant 20% reduced risk of major coronary events (vs lowest group). Higher DHA concentrations were beneficial but not statistically significant.
Increasing omega-3 intake can reduce heart disease. The only reason omega-3 fish oil supplements are clearly associated with cardiovascular outcomes is because too many studies rely upon circumstantial associations (supplement vs placebo compliance) rather than actual measures of omega-3 status (blood, red blood cell phospholipids, adipose fatty acid concentrations).
A failure of researchers to conduct robust studies using measures of nutritional status, and possibly a publication bias favoring food vs supplemental sources, should not be misconstrued into an anti-supplement conclusion.
The only thing smelling fishy is the research.
Nestel P, Clifton P, Colquhoun D, Noakes M, Mori TA, Sullivan D, Thomas B. Indications for omega-3 long chain polyunsaturated fatty acid in the prevention and treatment of cardiovascular disease. 2015 Heart Lung Circ doi: 10.1016/j.hlc.2015.03.020
Dickinson A, MacKay D. Health habits and other characteristics of dietary supplement users: A review. 2014 Nutr J doi: 10.1186/1475-2891-13-14
Kotwal S, Jun M, Sullivan D, Perkovic V, Neal B. Omega-3 fatty acids and cardiovascular outcomes: Systematic review and meta-analysis. 2012 Circ doi: 10.1161/CIRCOUTCOMES.112.9661.68
Rizos EC, Ntzani EE, Bika E, Kostapanos MS, Elisaf MS. Association between omega-3 fatty acid supplementation and risk of major cardiovascular disease events: A systematic review and meta-analysis. 2012 JAMA doi: 10.1001/2012.jama.113474
The ORIGIN Trial Investigators. N-3 fatty acids and cardiovascular outcomes in patients with dysglycemia. 2012 NEJM doi: 10.1056/NEJM011203859
The Risk and Prevention Study Collaborative Group. N-3 fatty acids in patients with multiple cardiovascular risk factors. 2013 NEJM doi: 10.1056/NEJM01125409
De Groede J, Geleijnse JM, Boer JMA, Kromhout D, Verschuren WMM. Marine (n-3) fatty acids, fish consumption, and the 10-year risk of fatal and nonfatal coronary heart disease in a large population of Dutch adults with low fish intake. 2010 J Nutr doi: 10.3945/jn.109.119271
Mozaffarian D, Lemaitre RN, King IB, Song X, Huang H, Sacks FM, Rimm EB, Wang M, Siscovick DS. Plasma phospholipid long-chain ώ-3 fatty acids and total and cause-specific mortality in older adults: A cohort study. 2013 Ann Intern Med doi: 10.7326/0003-4819-158-7-201304020-00003
Itakura H, Yokoyama M, Matsuzaki M, Saito Y, Origasa H, Ishikawa Y, Oikawa S, Sasaki J, Hishida H, Kita T, Kitabatake A, Nakaya N, Sakata T, Shimada K, Shirato K, Matsuzawa Y. Relationships between plasma fatty acid composition and coronary artery disease. 2011 J Atheros Thromb doi: 10.5551/jat.5878
Joensen AM, Overvad K, Dethelefsen C, Johnsen SP, Tjonneland A, Rasmussen LH, Schmidt EB. Marine n-3 polyunsaturated fatty acids in adipose tissue and the risk of acute coronary syndrome. 2011 Circ doi: 10.1161/CIRCULATIONAHA.110.987.057