Omega-3 fatty acids, found in marine and plant-based foods, have long been studied in the nutrition world, but emerging science is examining the unique benefits of the three types of omega-3s.
A study published in the Journal of the American Heart Association, indicates that both plant and marine-based sources of omega-3s are complementary against mortality in a population with high seafood consumption1.
The study found that consuming omega-3s from plant-based sources, such as walnuts, may reduce risk of all-cause mortality, whereas marine-derived omega-3s, from fatty fish, may reduce the risk of heart-related fatalities. The greatest protective effects from total mortality were observed in diets that include both plant-based and marine-derived omega-3s, as they appear to act synergistically.
Most interestingly is that ALA provided additional health benefits even in a population with high consumption of EPA and DHA from seafood, adding to the growing body of evidence that ALA may contribute health benefits of its own, aside from its conversion to EPA and DHA.
Walnuts were the most prominent nut featured in the daily serving of mixed nuts (50% walnuts, 25% hazelnuts, 25% almonds) consumed by participants. They were also the only nut in the mixture that contain alpha-linolenic acid (ALA), the plant-based omega-3. Previous research has shown that plant-based omega-3 ALA may contribute to lowering the risk of cardiovascular disease2 and that daily consumption of walnuts provides heart health benefits3.
As with any study, limitations should be considered. Participants were older persons at high cardiovascular risk living in a high fish-consuming, Mediterranean country, so the results may not be generalizable to other populations. In addition, there was a relatively low number of fatal cardiovascular events, nutrient intakes were estimated with a food-frequency questionnaire, and residual confounding is possible given that this was a longitudinal cohort analysis.
Resources:
[1]Sala-Vila A, Guasch-Ferré M, Hu FB, Ros E, et al. Dietary a-Linolenic Acid, Marine ѡ-3 Fatty Acids, and Mortality in a Population With High Fish Consumption: Findings From the PREvenciόn con DIeta MEDiterrάnea (PREDIMED) Study [published online ahead of print January 26, 2016]. J Am Heart Assoc. 2016. doi:10.1161/JAHA.115.002543.
2 Kris-Etherton, P and Fleming, J. The evidence for linolenic acid and cardiovascular disease benefits: comparisons with eicosapentaenoic acid and docosahexaenoic acid. Adv. Nutr., 2014
3 Supportive but not conclusive research shows that eating 1.5 ounces of walnuts per day, as part of a low saturated fat and low cholesterol diet, and not resulting in increased caloric intake may reduce the risk of coronary heart disease (FDA). One ounce of walnuts provides 18g of total fat, 2.5g of monounsaturated fat, 13g of polyunsaturated fat, including 2.5g of alpha-linolenic acid, the plant-based omega-3.