Health Benefits of Alpha-Linolenic Acid (ALA)

Marine omega-3 fatty acids tend to get all the hype for being healthy, but the plant-based alpha-linolenic acid, or ALA, deserves its own spotlight. Potential health benefits of ALA include protection against cardiovascular disease, improved asthma control, anti-inflammatory effects, reduced risk of breast cancer, healthier bones, and benefits for pregnant women and their babies. Read on to learn more about why the short-chain omega-3 fatty acid ALA has been overlooked by many experts, and why that should change.

Classified as long-chain omega-3 fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are regularly in the headlines because of their wide-ranging health benefits. These beneficial fatty acids are abundant in oily fish and a few other non-vegan foods such as omega-3 eggs, but they can also be made by the body from short-chain omega-3 fatty acids. Alpha-linolenic acid, or ALA, is one of the most important short-chain omega-3 fatty acids, and it is found in some nuts and seeds. Some of the best sources of ALA include chia seeds, flaxseeds, sacha inchi and walnuts.

But, there is a problem: the human body is not very good at converting plant-based ALA into DHA and EPA. The range of conversion of ALA to EPA has been reported to be between 0.2% and 9%, and the conversion of ALA to DHA has been found to be even lower. That said, some experts have suggested that women of childbearing age may be able to convert up to 21% of their dietary ALA to EPA [1].

As a result of the generally low conversion rate, many researchers have concluded that ALA does not have the same health benefits as DHA and EPA.

But not having the same benefits does not mean having no benefits! Indeed, research shows that plant-derived ALA has several potential health benefits, independent of its role as a precursor to DHA and EPA. Potential health benefits of ALA include:

1. Protection Against Cardiovascular Disease

According to a review published in The American Journal of Clinical Nutrition in 2014, plant-based ALA appears to provide at least some protection against cardiovascular disease (CVD). Although the strength of the evidence is not nearly the same as for marine omega-3 fatty acids, there has been an increase in the number of studies that support the idea that ALA is good for the cardiovascular system.

It is also worth noting that when it comes to cholesterol-lowering effects, the source of ALA may relevant, with whole food sources such as walnuts and flaxseeds providing the greatest benefit. [2]

2. Improved Asthma Control

A high intake of ALA might also offer health benefits for people with asthma. A cross-sectional study published in the British Journal of Nutrition in 2014 suggests that ALA may have anti-asthmatic properties, independent of DHA and EPA. This study also found an association between diets with a high omega-6 to omega-3 ratio and an increased risk of uncontrolled asthma. [3]

In another study, supplementation with perilla seed oil, which is one of the best sources of alpha-linolenic acid, was found to improve symptoms in some asthma sufferers. This four-week placebo-controlled study found that the patients taking perilla seed oil experienced both a significant increase in lung capacity and enhanced air-flow capabilities. The researchers believe that perilla seed oil is good for asthma sufferers because the ALA it contains suppresses the production of leukotrienes, which are inflammatory substances associated with reduced respiratory function. [4]

3. Anti-Inflammatory Effects

Chronic inflammation, also known as low-grade or systemic inflammation, has been linked to a variety of diseases and conditions including heart disease, rheumatoid arthritis, psoriasis, Crohn's disease, chronic obstructive pulmonary disease, and irritable bowel syndrome. Chronic inflammation has been associated with certain dietary habits, which has made so-called anti-inflammatory diets popular among many people. This is how anti-inflammatory diets work in a nutshell: you focus on foods with anti-inflammatory properties and eat fewer foods with inflammatory properties.

Salmon and other fish high in omega-3 are famous for their strong anti-inflammatory properties, but also ALA has been shown to lower various biomarkers of inflammation in humans [5], which seems to support claims like flaxseed is good for psoriasis sufferers.

4. Protection Against Breast Cancer

A study published in the Journal of Molecular Biochemistry investigated the impact ALA on certain breast cancer and cervical cancer cell lines, and found that ALA caused cancerous cells to self-destruct, without damaging non-cancerous cells [6]. In another study, biopsies of adipose breast tissue from 123 French women with invasive non-metastatic breast carcinoma were analyzed, and a group of 59 women with benign breast cancer served as controls. The researchers found no association between breast carcinoma and fatty acids, with one exception: levels of ALA were inversely associated with the risk of breast cancer.

But not all studies on ALA and cancer have yielded such positive results. As this article on chia seeds and cancer points out, a 2004 meta-analysis of observational studies found a link between a high intake of ALA and an increased risk of prostate cancer [7]. It is worth noting, however, that a more recent meta-analysis found evidence of publication bias in some of the earlier studies done on ALA and prostate cancer risk, and concluded that if a high intake of ALA is indeed associated with an increased risk of prostate cancer, the increase in the risk is likely to be small [8].

5. Healthier Bones

Fracture risk is a common indicator of bone health, and ALA appears to have a protective effect against hip fracture in older people in general, but not in postmenopausal women. Interestingly, however, neither of the two marine-derived omega-3 fatty acids nor the intake of fish appears to be associated with hip fracture risk [2].

It has been proposed that ALA might help preserve bone by reducing resorption, as demonstrated by a study involving healthy people who got a daily dose of 6.5 grams of omega-3 from flax seeds and walnuts, in the form of ALA, for six weeks. [9]. For those who are not familiar with the term, bone resorption is the process by which osteoclasts, specialized cells that release enzymes that dissolve bone, break down bone and transfer calcium from bone tissue to the blood.

6. Benefits for Pregnant Women

There is some evidence suggesting that ALA may offer health benefits for pregnant and nursing women. A study published in the April 2017 issue of The FASEB Journal found that high blood levels of ALA during early pregnancy were associated with a longer duration of gestation and greater birth weight [10]. In another study, published in the journal Nutrients, ALA-rich chia seed oil increased the EPA content of red blood cell phospholipids as well as the DHA content of breast milk in pregnant and nursing women [11].