Introduction to Gamma-Linolenic Acid (GLA)
Gamma-linolenic acid, or GLA, is a type of omega-6 polyunsaturated fatty acid that plays a significant role in human health. Unlike some other omega-6 fatty acids, GLA is known for its anti-inflammatory properties, as it is converted in the body into anti-inflammatory eicosanoids. Most people get plenty of the parent omega-6 fatty acid, linoleic acid (LA), from common vegetable oils, but the conversion of LA to GLA in the body can be hampered by various factors. These can include aging, poor nutrition, high alcohol intake, and certain health conditions. For these reasons, obtaining GLA directly from dietary sources can be beneficial. While relatively few foods contain significant amounts of GLA, concentrated sources are available in both food and supplement form.
Primary Food Sources of GLA
Borage Oil (Starflower Oil)
Among the most potent dietary sources of GLA is borage seed oil, also known as starflower oil. Extracted from the seeds of the Borago officinalis plant, borage oil boasts the highest concentration of GLA, typically ranging from 20% to 27%. This makes it a popular ingredient for dietary supplements. Its high GLA content contributes to its anti-inflammatory effects and skin health benefits. Borage oil is often cold-pressed to preserve its valuable fatty acids. Due to its potency, it is often favored for targeted supplementation rather than as a general cooking oil.
Evening Primrose Oil (EPO)
Evening primrose oil, extracted from the seeds of the Oenothera biennis plant, is another well-known source of GLA. EPO contains between 8% and 10% GLA, making it a good, though less concentrated, source compared to borage oil. Historically used as a folk remedy for various ailments, EPO is now widely available in supplement form. It is often sought for its potential benefits for skin conditions like eczema and for supporting hormonal balance, although some research findings are mixed.
Black Currant Seed Oil
Black currant seed oil is a valuable source of GLA, providing a concentration typically in the 14% to 17% range. What makes this oil unique is that it also contains omega-3 fatty acids, specifically alpha-linolenic acid (ALA). This makes black currant seed oil a balanced source of both omega-6 and omega-3 essential fatty acids. It is available in capsule form and used for both internal supplementation and topical applications for skin health.
Hemp Seed Oil and Hemp Seeds
Hemp seed oil, extracted from the seeds of the hemp plant (Cannabis sativa), contains a beneficial profile of fatty acids, including both GLA and the omega-3 ALA. The concentration of GLA in hemp oil is typically lower than in borage or evening primrose oil but is still a significant food source. What makes hemp seed oil a standout is its near-perfect omega-6 to omega-3 ratio, often cited as approximately 3:1. This balance is considered ideal for promoting overall health. Hemp seeds themselves can also be eaten, offering GLA along with protein, fiber, and other nutrients.
Spirulina
Spirulina, a type of blue-green algae, is one of the few food-based sources of GLA that is not a seed oil. It is available as a powder or in tablet form and contains GLA in its total lipid fraction. The GLA content in spirulina can vary depending on growing conditions but is a notable source for vegans and those seeking nutrient-dense whole foods. Its role as a GLA source contributes to its reputation as a superfood.
Comparison of GLA Sources
| Source | GLA Concentration (Approximate) | Other Notable Fatty Acids | Format | Key Health Association |
|---|---|---|---|---|
| Borage Seed Oil | 20–27% | High in linoleic acid | Oil, capsules | Highest GLA concentration, anti-inflammatory |
| Evening Primrose Oil | 8–10% | High in linoleic acid | Oil, capsules | Women's health, skin health |
| Black Currant Seed Oil | 14–17% | Contains omega-3 ALA | Oil, capsules | Balanced omega profile |
| Hemp Seed Oil | Lower concentration than Borage/EPO | Ideal omega-6:3 ratio (approx. 3:1) | Oil, seeds | Balanced fatty acid profile |
| Spirulina | Varies, can be 1–2% or higher | Omega-3 ALA, other nutrients | Powder, tablets | Whole food source for vegans |
The Role of GLA in Your Diet
While GLA is an omega-6 fatty acid, it functions differently in the body than some of the more common, pro-inflammatory omega-6s. Instead of contributing to inflammation, GLA and its metabolite, DGLA, are precursors to beneficial, anti-inflammatory compounds. It is suggested that a healthy balance of omega-6s and omega-3s is important, and GLA can play a positive role in this balance. Consuming sources of GLA, especially when combined with omega-3 fatty acids like EPA from fish oil, may help enhance the anti-inflammatory effects and support overall cellular health. Some research suggests that GLA, particularly in combination with EPA, can help inhibit the production of pro-inflammatory arachidonic acid, further solidifying its unique beneficial role among omega-6 fats. This complementary relationship highlights the importance of a balanced dietary approach to essential fatty acids.
Important Considerations for GLA
While incorporating these GLA-rich foods and oils into your diet can be beneficial, it's important to do so with care. Borage oil, for example, should be certified free of hepatotoxic pyrrolizidine alkaloids (PAs). Always choose high-quality, reputable brands for supplements. Additionally, consult a healthcare provider before starting any new supplement, especially if you have pre-existing conditions or are pregnant, as safety has not been fully established in all populations. Combining sources of GLA with vitamin E can also be a good practice, as it's a fat-soluble antioxidant that protects polyunsaturated fats like GLA from oxidation.
Conclusion
GLA is a beneficial omega-6 fatty acid found in concentrated amounts in several plant-based sources. Borage oil provides the highest concentration, followed by black currant seed oil and evening primrose oil. Hemp seed oil and spirulina also offer valuable amounts of this fatty acid in a whole-food format. For individuals whose bodies may struggle to convert linoleic acid to GLA efficiently, integrating these specific food sources can be a straightforward way to obtain this important nutrient. By understanding these options, you can make informed choices to support your anti-inflammatory pathways and overall health. You can find more information about GLA and fatty acids from reputable health sites such as the Icahn School of Medicine at Mount Sinai.
