FROM THE ACADEMY Question of the Month
What Are n-7 Fatty Acids and Are There Health Beneﬁts Associated with Them?
IETARY FATTY ACIDS ARE often characterized by their saturation status. Of all the fatty acid categories, monounsaturated fatty acids (MUFAs) are consumed the most, comprising 36% of total fat intake, and the majority of MUFA consumption is oleic acid at 27 g/day. Second to oleic acid is palmitoleic acid at 1.2 g/day. Palmitoleic acid is an n-7 fatty acid, which is a small family of unsaturated fatty acids in which the site of unsaturation is seven carbon atoms from the end of the carbon chain. Palmitoleic acid is not commonly found in food but is a product of palmitic acid metabolism in the body. Food sources that naturally contain palmitoleic acid are limited and include certain blue-green algae, macadamia nuts (3.7g/oz; 17% of fat content), and sea buckthorn oil extracted from the seed or berries of the plant.1 Considering the small contribution that palmitoleic acid makes to fatty acid intake in the American diet, it is not surprising that there is not a large body of research on palmitoleic acid. There are other fatty acids in this group, but palmitoleic acid has garnered the attention of researchers. Palmitoleic acid comes in two forms: a cis isomer when a source like macadamia nuts are consumed or produced endogenously in the body, and a trans isomer that is naturally present in fullfat dairy products and meat fat.2 Because previous studies in animals suggested that the cis form of this fatty acid may have beneﬁcial effects,
This article was written by Eleese Cunningham, RDN, of the Academy of Nutrition and Dietetics’ Knowledge Center Team, Chicago, IL. Academy members can contact the Knowledge Center by sending an e-mail to know[email protected]
researchers wanted to see whether blood levels of the trans isomer, which is derived from diet only (no endogenous production), would be similarly associated with health beneﬁts. Researchers found an association with lower insulin resistance, atherogenic dyslipidemia, and incident diabetes in study participants with higher levels of circulating trans palmitoleate. Their observational ﬁndings were striking, but the need for detailed further clinical and experimental investigation was stressed.3 A Google search of the Internet brings up 848,000 results indicating that palmitoleic acid is currently being widely marketed as a supplement with claims of preventing or reducing heart disease. However, in an April 2014 interview, Irena B. King, PhD, one of the authors of the study on trans-palmitoleic acid, stated, “There are both positive and negative associations with omega-7 intakes. It’s not so clear-cut.”2 The Natural Medicines Comprehensive Database states that sea buckthorn oil from the seed is used for heart disorders including angina and high cholesterol.4 This publication cites emerging research in China suggesting that taking 10 mg of a particular sea buckthorn extract three times daily for 6 weeks lowers cholesterol, reduces angina, and improves heart function in people with heart disease. Overall, however, the evidence is insufﬁcient to rate the effectiveness for cardiovascular disease and more research is needed.4 The Academy recommends a foodbased approach through a diet that includes the regular consumption of fatty ﬁsh, a variety of nuts (including macadamia nuts) and seeds, and lean meats and poultry. Nutrition and dietetics practitioners can help clients set and maintain realistic goals for the intake of total fat and fatty acids by encouraging food-based consumption ﬁrst and supplements second when the science supports it.
JOURNAL OF THE ACADEMY OF NUTRITION AND DIETETICS
Academy of Nutrition and Dietetics. Position of the Academy of Nutrition and Dietetics: Dietary fatty acids for healthy adults. J Acad Nutr Diet. 2014;114(1): 136-153.
Weisenberger J. The omega fats. Today’s Dietitian. 2014;16(4):20.
Mozaffarian D, Cao H, King IB, et al. Transpalmitoleic acid, metabolic risk factors, and new-onset diabetes in US adults: A cohort study. Ann Intern Med. 2010; 153(12):790-799.
Sea buckthorn. Natural Medicines Comprehensive Database. http://naturaldatabase. therapeuticresearch.com/nd/Search.aspx? cs¼&s¼ND&pt¼100&id¼765&ds. Accessed November 21, 2014.
ª 2015 by the Academy of Nutrition and Dietetics.