Understanding Gamma Linolenic Acid (GLA)
Gamma linolenic acid (GLA) is a polyunsaturated omega-6 fatty acid that plays a distinct and beneficial role in the body, unlike some other omega-6s. While omega-6 fatty acids generally have a reputation for being pro-inflammatory, GLA and its metabolites work to resolve cellular stress and inflammation. The body converts GLA into dihomo-gamma-linolenic acid (DGLA), which can then be used to produce anti-inflammatory signaling molecules. This metabolic pathway is what sets GLA apart and makes it a sought-after nutrient for its anti-inflammatory effects.
The Primary Food Sources High in GLA
The most significant dietary sources of GLA are found in a select number of plant seed oils. Unlike other more common omega-6s found in vegetable oils, GLA is relatively rare in the standard diet.
Borage Oil
Known as one of the richest natural sources of GLA, borage oil is extracted from the seeds of the borage plant (Borago officinalis). Its GLA content typically ranges from 18% to 25%, making it the most potent option for supplementation. Beyond GLA, borage oil also contains significant amounts of linoleic acid, another omega-6 fatty acid. This oil is frequently used in both dietary supplements and topical cosmetic products for skin health due to its fatty acid profile.
Black Currant Seed Oil
Another excellent source of GLA is black currant seed oil, which is derived from the seeds of the black currant plant (Ribes nigrum). The GLA content in this oil typically falls between 13% and 17%. What makes black currant seed oil particularly notable is that it also contains the omega-3 fatty acid alpha-linolenic acid (ALA), offering a beneficial combination of both omega-6 and omega-3 fats.
Evening Primrose Oil
Perhaps the most widely known source of GLA is evening primrose oil (EPO), which has a long history of use in traditional medicine. The GLA concentration in EPO is lower than in borage oil, typically ranging from 7% to 10%. Despite the lower potency, EPO is a popular supplement, especially for addressing issues related to women's health and skin conditions.
Other Sources: Hemp Seed Oil and Spirulina
Less concentrated, but still valuable, sources of GLA include hemp seed oil and the blue-green algae, spirulina. Hemp seed oil contains a moderate amount of GLA along with a beneficial blend of other fatty acids. Spirulina is one of the few food sources of GLA that is not a seed oil, making it a viable option for those seeking a non-oil supplement.
Comparison of GLA-Rich Oils
To help visualize the differences between the main GLA-rich oils, the table below provides a quick comparison of their typical GLA content.
| Source | Typical GLA Content | Notes |
|---|---|---|
| Borage Oil | 18–25% | Highest concentration of GLA; also contains linoleic acid. |
| Black Currant Seed Oil | 13–17% | Also contains beneficial omega-3 fatty acid ALA. |
| Evening Primrose Oil | 7–10% | Widely available but has a lower GLA percentage. |
| Hemp Seed Oil | Moderate amount | Includes a mix of other beneficial fatty acids. |
| Spirulina | Varies | A non-oil, algae-based source of GLA. |
Dietary Considerations and Supplementation
For most people, the body's natural conversion of linoleic acid is sufficient for its GLA needs. However, as noted earlier, certain factors like aging, diabetes, excessive alcohol intake, and nutritional deficiencies can impair this process. In these cases, dietary supplementation can provide a more direct and efficient route to obtaining GLA. It is important to note that the FDA does not regulate supplements, so looking for independently tested products from reputable brands is recommended. Before beginning any new supplement regimen, it is wise to consult a healthcare provider, especially for those with existing health conditions or who are pregnant or nursing.
Potential Health Benefits of GLA
The potential health benefits of GLA are linked to its conversion into anti-inflammatory eicosanoids and its unique role as an omega-6 fatty acid. Some research has investigated GLA's effect on various health conditions, including skin health, diabetic neuropathy, and rheumatoid arthritis. For instance, studies suggest GLA may support skin barrier function and hydration. Research on other conditions is ongoing and the evidence is mixed, but GLA remains a popular supplement for general wellness and managing inflammatory responses.
Conclusion
While GLA is a distinct and beneficial omega-6 fatty acid, significant dietary quantities are primarily found in specific seed oils. Borage oil offers the highest concentration, followed by black currant seed oil and evening primrose oil. Other sources, such as hemp seed oil and spirulina, also contain GLA. For individuals whose bodies have difficulty converting linoleic acid, supplementation from these sources can be a strategic way to boost GLA intake. Choosing high-quality, cold-pressed oils is the best approach to obtaining this valuable nutrient, either through diet or supplements.
For more detailed scientific information on GLA, its metabolism, and its effects on the body, refer to studies and reviews such as the one titled "Gamma-linolenic acid, Dihommo-gamma ...".
Frequently Asked Questions
What is the richest source of gamma linolenic acid?
The richest and most concentrated source of GLA is borage oil, which typically contains 18% to 25% GLA.
Can you get GLA from nuts and seeds?
While some nuts and seeds contain the parent omega-6 fatty acid, linoleic acid, GLA itself is found only in trace amounts in most common foods. The most significant sources are specific seed oils like borage and evening primrose.
Is GLA an anti-inflammatory fatty acid?
Yes, GLA is metabolized into anti-inflammatory compounds, making it unique among omega-6 fatty acids, which are often associated with pro-inflammatory effects. This is one reason for its reputation as a beneficial nutrient.
What are the main benefits of GLA?
GLA is known for its anti-inflammatory properties and its potential benefits for skin health, including improving hydration and skin barrier function. It has also been studied for its potential effects on conditions like diabetic neuropathy and rheumatoid arthritis.
Do I need a GLA supplement?
For some people, especially those with impaired fatty acid metabolism due to age, diet, or certain health conditions, supplementing with GLA may be beneficial. However, it is essential to consult a healthcare provider before starting any new supplement.
Is breast milk a source of GLA?
Yes, human breast milk is one of the few natural food sources that contains a significant amount of gamma linolenic acid.
What are some non-oil sources of GLA?
For those who prefer a non-oil source, the blue-green algae known as spirulina is a good option that contains GLA.
Is GLA safe to consume?
GLA is generally considered safe when taken within recommended dosages. However, individuals should always talk to a doctor, especially if they have pre-existing medical conditions or are taking other medications.
