The popularity of the essential polyunsaturated omega-3 fatty acids (O3FA) is on the rise. In 2017, O3FA achieved a spot on the top 20 foods and ingredients list that Americans are adding to their diets (The Hartman Group). In addition, the global fish oil market is expected to reach a whopping 4.08 billion dollars in the next four years!  The proposed health benefits are likely the driving force behind the increasing demand.

Despite their booming popularity, a large percentage of adults are not meeting the O3FA recommended intake. There are three primary O3FAs with distinct characteristics: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Although commonly grouped under the umbrella term O3FAs, are all O3FAs created equal?

Unique Characteristics of O3FAs

Omega-3 fatty acids cannot be sufficiently produced in the body earning them the title of “essential fatty acids.” The plant-derived omega-3, ALA, is the parent precursor to EPA and DHA. Unfortunately, the conversion rate in our bodies is very low.  It is important to realize that in the process of metabolizing ALA to EPA and DHA, a series of anti-inflammatory markers are produced (leukotrienes, prostaglandins and thromboxane). As these anti-inflammatory metabolites are beneficial, direct EPA and DHA consumption is needed to meet bodily requirements.

Independent and Complementary Health Benefits

The majority of current research focuses on the health benefits of marine fatty acids.  DHA and EPA consumption portray an array of shared and complementary benefits related to the treatment of cardiovascular disease, depression diabetes, sleep disorders and more. DHA is more significantly associated with decreases in resting heart rate, blood pressure and with improvements in cellular membrane health due to its additional double bond and longer carbon chain. Increased cellular levels of EPA have been shown to benefit coronary heart disease, hypertension and to decrease inflammation. EPA and DHA are both associated with reduced gene expression related to fatty acid metabolism, reduced inflammation and oxidative stress.

Specific supplementation of ALA is not consistently associated with cardiovascular health. Although plant-derived ALA can be easily substituted in for excess omega-6 fatty acids (O6FAs). Research has shown that by reducing the O3FA:O6FA ratio, you can decrease bodily inflammation, increase anti-inflammatory markers and more efficiently utilize EPA and DHA.

An ALA, EPA and DHA-Rich Diet

The 2015-2020 Dietary Guidelines for Americans recommends that healthy adults consume at least 8 ounces of a variety of non-fried fatty seafood per week. For EPA and DHA requirements, the American Heart Association recommends fatty marine sources containing 500 mg or more of EPA and DHA per 3oz cooked serving (e.g., salmon and tuna).   ALA is the most commonly consumed O3FA in the Western diet as it is found in plant-based foods (e.g., dark green leafy vegetables, walnuts, canola oil, flax seed). Unlike EPA and DHA, an Adequate Intake (AI) level is established at 1.6 g/day and 1.1 g/day for men and women respectively.

The Final Verdict 

The wide range of benefits stemming from marine O3FAs indicates the importance of regular consumption of fatty seafood and EPA and DHA-containing products.  The incorporation of plant-derived ALA may serve more importantly as a substitute for omega-6 fatty acids to reduce bodily inflammation, decrease the high O3FA:O6FA ratio typically observed in the Western diet, and to help elevate EPA and DHA levels in the body. EPA and DHA may be featured as the health promoting “dynamic duo,” but ALA is still invited to the party!

 

References

1.         Yanni Papanikolaou JB, Carroll Reider and Victor L Fulgoni. U.S. adults are not meeting recommended levels for fish and omega-3 fatty acid intake: results of an analysis using observational data from NHANES 2003–2008. Nutrition Journal 2014.

2.         Harris WS, Mozaffarian D, Lefevre M, Toner CD, Colombo J, Cunnane SC, Holden JM, Klurfeld DM, Morris MC, Whelan J. Towards establishing dietary reference intakes for eicosapentaenoic and docosahexaenoic acids. J Nutr 2009;139(4):804S-19S. doi: 10.3945/jn.108.101329.

3.         Frits A. J. Muskiet MRF, Anne Schaafsma, E. Rudy Boersma and Michael A. Crawford. Is Docosahexaenoic Acid (DHA) Essential? Lessons from DHA Status Regulation, Our Ancient Diet, Epidemiology and Randomized Controlled Trials. Journal of nutrition 2004;134.

4.         Mozaffarian D, Wu JH. (n-3) fatty acids and cardiovascular health: are effects of EPA and DHA shared or complementary? J Nutr 2012;142(3):614S-25S. doi: 10.3945/jn.111.149633.

5.         Bork CS, Veno SK, Lundbye-Christensen S, Jakobsen MU, Tjonneland A, Schmidt EB, Overvad K. Dietary Intake of Alpha-Linolenic Acid Is Not Appreciably Associated with the Risk of Ischemic Stroke among Middle-Aged Danish Men and Women. J Nutr 2018. doi: 10.1093/jn/nxy056.

6.         Evangeline Mantzioris MJJ, Robert A Gibson and Leslie G Cleland Differences exist in the relationships between dietary linoleic and alpha-linolenic acids and their respective long-chain metabolites. Am J Clin Nutr 1995;61:320-4.

7.         Agriculture. USDoHaHSaUSDo. 2015 – 2020 Dietary Guidelines for Americans. 8th Edition. December 2015.