Don’t Believe Negative Health of Omega-3 Headlines: Look for Balance
A new review by Fenton and colleagues states that increasing long chain omega 3 fatty acid (LCFA) intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may have adverse health outcomes. Let’s discuss this statement. The conclusions were drawn from a summary of mouse studies where dietary EPA/DHA intakes were manipulated and immune responses to pathogens were assessed. As expected, manipulating the type of fat (saturated, monounsaturated, polyunsaturated) and amount (% of total energy intake) in the diet exerted physiological changes in membrane and red blood cell composition and cellular signaling pathways. In effect, mice (and people) are made of what they eat.
As implied in a press release based on evidence from experimental animal studies, excessive amounts of any fatty acid group, omega-6 or omega-3, leading to extreme unbalanced fatty acid intakes can lead to dysfunctional immune responses. However, are people likely to reach such excessive extreme fatty acid intakes via fortification or dietary supplement use? Of course imbalance is possible. But fear mongering by extrapolating animal studies to humans isn’t a balanced perspective.
The amount of omega-3 fatty acids needed by mice (or humans) depends upon omega-6 fatty acid intake. If consuming a diet rich in omega-6 fatty acids (as most people are), more EPA and DHA are needed to achieve fatty acid balance. Our intake of omega-6 fatty acids, primarily α-linoleic acid from soybean oil, has increased 1000-fold in 20th century (Blasbalg et al, 2011). Americans are NOT consuming too much EPA and DHA, they aren’t consuming enough given current omega-6 intakes. We should be encouraging the consumption of fortified foods and the use of dietary supplements with DHA and EPA, not warning of excesses based on animals fed semi-purified diets.
Hibbeln and associates reviewed the literature worldwide in an effort to define/estimate healthy omega-3 fatty intakes. They write, “deficiency in n-3 LCFAs was defined as attributable risk from 13 morbidity and mortality outcomes, including all causes, coronary heart disease, stroke, cardiovascular disease, homicide, bipolar disorder, and major and postpartum depressions.” Figure 1 clearly shows significant reductions in mortality as omega-3 fatty acid intakes increase to 10% of energy; above this percent the relationship begins to flatten. Hibbeln and colleagues drew these conclusions after reviewing humanstudies with widely divergent intakes of total fat, saturated fatty acids, monounsaturated fatty acids and polyunsaturated n-3 and n-6 fatty acids. It is not derived from experimental diets formulated to create unique fatty acid ratios, often extreme, and then fed to mice.
The review by Fenton and colleagues should not be the foundation of guidance to the public. Despiteheadlines warning against excessive EPA and DHA intake, the reality is that most people face negative health outcomes because of inadequate amounts of omega-3 fatty acids EPA and DHA and excessive amounts of omega-6 fatty acids, especially α-linoleic acid.
When it comes to fatty acid recommendations, balance is key. Until omega-6 fatty acid intakes fall from 9% of energy to <2% of energy, people are encouraged to consume 3.5g EPA + DHA daily.
Fenton JI, Hord NG, Ghosh S, Gurzell EA. Immunomodulation by dietary long chain omega-3 fatty acids and the potential for adverse health outcomes. 2013 Prostaglandins, Leukotrienes and Essential Fatty Acids doi:10.1016/j.plefa.2013.09.011
Blasbalg TL, Hibbeln JR, Ramsden CE, Majchrzak SF, Rawlings RR. Changes in consumption of omega-3 and omega-6 fatty acids in the United States during the 20th century. 2011 Am J Clin Nutrdoi:10.3945/ajcn.110.006643
Hibbeln JR, Nieminen LRG, Blasbalg TL, Riggs JA, Lands WEM. Healthy intakes of n-3 and n-6 fatty acids: estimations considering worldwide diversity. 2006 Am J Clin Nutr 83:S1483-1493S