The Science Behind Plant-Based Omega-3 ALA

By Kristin Kirkpatrick, MS, RDN

A patient of mine recently came in with the goal of improving her health through a plant-based, whole foods diet. When I suggested she increase her consumption of omega-3 fatty acids, she told me it might be a challenge since she didn’t eat fish and had assumed fish was the best and only way to get in the omega-3s. This assumption could not have been further from the truth. Recent studies offer exciting data showing the benefits of omega-3 consumed from plant-based sources.

Let’s start with an omega-3 fatty acids tutorial. Omega-3s are essential fatty acids. That means our body does not make them on its own, so we need to obtain them through diet. There are three forms of omega-3s. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) come from marine-based sources, like salmon, mackerel, and trout. ALA (alpha-linolenic acid) comes from plant-based sources such as walnuts, chia seed, flaxseed, and vegetable oils. ALA can also be obtained from consuming animals that feed on ALA abundant grasses.

ALA and Heart Health

A study from Advances in Nutrition found that ALA may help improve heart health just as we have seen in studies focused on EPA and DHA.1 The literature review provided evidence showing the potentially beneficial role ALA may have in primary and secondary prevention of cardiovascular disease, including stroke and heart attack. Given the current promising data, the researchers noted the need for well-controlled clinical trials to clarify the effects of ALA on risk for cardiovascular disease and to determine the recommended amount of ALA to consume for heart health benefits.

ALA and Brain Health

A review study from Progress in Lipid Research assessed the tissue levels of omega-3 DHA formed from ALA.2 They reported several important findings. The first was that ALA leads to the synthesis of EPA in some cases, and in particular, may contribute to DHA levels in the brain. Evidence from cell, animal, and human studies suggests dietary ALA may be able to fulfill the human requirement for DHA in the body when higher levels of ALA (at least 1.2g) are consumed. Assessing the synthesis of EPA and DHA from ALA in humans is limited to blood level measurements. Thus, researchers relied on a variety of measurement methods used in cell, animal, and human studies to review the science. The takeaway from this study is that through its conversion process, ALA may play a role in maintaining DHA levels in important tissues such as the brain. But more research is needed to fully understand the effect of this process in the body.

ALA and Overall Mortality

Research from one of the largest clinical trials looking at the benefits of a Mediterranean diet suggested older Spanish individuals (ages 55-80) with a high cardiac risk who supplemented a high fish diet with dietary ALA saw a reduced risk of all-cause mortality.3Specifically, study participants who consumed at least 0.7% of their daily calorie intake from ALA had a 28% reduced risk of all-cause mortality. Whereas consuming at least 500mg of omega-3s from seafood was associated with a reduced risk of heart-related fatalities from sudden cardiac death, cardiovascular disease, and coronary heart disease by 52%, 39% and 46%, respectively. The greatest protective effects were seen when people included both marine and plant-based sources of omega-3s.
In this study, published in the Journal of the American Heart Association, participants were randomly assigned into one of three groups: Mediterranean diet supplemented with mixed nuts (15g walnuts, 7.5g almonds, and 7.5g hazelnuts), Mediterranean diet supplemented with extra virgin olive oil, and a low-fat control group. An important factor in this study was that consuming sources of ALA still had additional benefits even when people were consuming sufficient amounts of EPA and DHA from seafood. Thus, this study provides even more reason to include a variety of omega-3 sources when planning your diet.
Every study has limitations and it’s always good to take that into consideration.
  • Both of the review studies (1,2) included evidence from human, animal, and cell studies. Results from animal and cell studies provide great background for future research, but more is needed to confirm the effects on humans.
  • Review studies (1,2) provide a comprehensive look at findings among populations of varying backgrounds. However, they can be limited by the methods, reported outcomes, and quality of the individual studies involved.
  • For the aforementioned study on the Mediterranean diet (3), nutrient exposures were estimated with a food‐frequency questionnaire, which has the potential of misclassification bias; residual confounding cannot be ruled out, meaning other habits of the participants could have contributed to the results; and the generalizability of the results is limited given that participants were older persons at high cardiovascular risk living in a Mediterranean country, so larger and longer-term studies are needed in geographically diverse populations.
All omega-3s provide certain benefits, so it’s important to get these good fats from a variety of sources. As the only nut significantly high in omega-3 ALA (2.5g per one ounce), the best way to get more ALA into your diet is to start with walnuts. How about a Walnut Mocha Smoothie for breakfast, a toasted walnut, quinoa, and kale salad for lunch or Salmon with Asian Walnut Slaw for dinner. You can also top salads, soups, or morning oatmeal with walnuts as well. Finally, the versatility and deliciousness of walnuts make it a wonderful on-the-go snack in trail mix or simply eaten alone.
  • 1 Fleming JA, Kris-Etherton PM. The evidence for α-linolenic acid and cardiovascular disease benefits: comparisons with eicosapentaenoic acid and docosahexaenoic acid. Adv Nutr. 2014;5(6):863S-76S. doi: 10.3945/an.114.005850.
  • 2 Barceló-Coblijn G, Murphy EJ. Alpha-linolenic acid and its conversion to longer chain n3 fatty acids: Benefits for human health and a role in maintaining tissue n-3 fatty acid levels. Prog Lipid Res. 2009;48(6):355-74. doi: 10.1016/j.plipres.2009.07.002.
  • 3 Sala-Vila A, Guasch-Ferré M, Hu FB, et al. Dietary α-linolenic acid, marine ω-3 fatty acids, and mortality in a population with high fish consumption: findings from the PREvención con DIeta MEDiterránea (PREDIMED) study. J Am Heart Assoc. 2016;5(1):e002543. doi: 10.1161/JAHA.
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