The seeds of Evening Primrose (left) and Borage (right) are rich sources of GLA and have been used by indigenous people for many centuries.
What is GLA and why is it controversial?
Gamma-Linolenic Acid (GLA) is an omega-6 fatty acid that is found naturally in certain plants and foods. It has a wide range of health benefits, including improved skin health, reduced inflammation and pain relief. GLA is also believed to help reduce the risk of some chronic diseases such as heart disease and diabetes. Additionally, it may help improve mood and cognitive function, as well as boost immunity. For these reasons, GLA supplements are becoming increasingly popular among people looking to improve their overall health.
The main reason that taking GLA is controversial goes back to the 1980’s. Then, a highly qualified researcher, David Horrobin, became so excited by the possible benefits of GLA, he decided to set up a private company (Scotia Holdings) to promote GLA in the form of Evening Primrose Oil. He was subsequently accused (in the USA) of selling Evening Primrose Oil without legally demonstrating its safety and efficacy. He was also accused of research fraud. Although his reputation never completely recovered, Horrobin went on to focus on Omega 3 fatty acids and for a very long time, the ’world’ largely ignored GLA.
How does my Age affect my need for GLA?
As far as I am aware, there has only ever been one detailed study of fatty acids in a population of normal people. This study was undertaken in Dundee, Scotland in the 1980’s and 1990’s is known as the Scottish Heart Study. The study involved 10,359 men and women between the ages of 40 and 59, from 22 districts. In the analysis of fatty acids, the levels of individual fatty acids were found to change with age. I have produced the following Table of Gamma Linolenic Acid levels from the publication referenced below[i].
Table: Average levels of Gamma Linolenic Acid in Adipose Tissue in a large, normal Scottish Population – (reference to full publication below)
| GENDER | AGE GROUP | AVERAGE GLA LEVEL |
| Male | 40-44 | 0.210 |
| Male | 45-49 | 0.205 |
| Male | 50-54 | 0.200 |
| Male | 55-59 | 0.190 |
| Female | 40-44 | 0.176 |
| Female | 45-49 | 0.169 |
| Female | 50-54 | 0.160 |
| Female | 55-59 | 0.140 |
It is easy to see that within these age groups, the level of GLA decreases with age and that the effect is more dramatic in females, who have lower levels to start with. The reasons for these changes in fatty acids are clearly outlined in my book ‘Why We Age’[ii] but everything we know about the changes that occur with ageing, would lead us to expect that this decline in GLA levels will continue until we die!
The males in the Scottish study have higher levels GLA at all ages but as yet there appears to be no research that explains these differences.
GLA metabolism to DGLA and its importance
Arachidonic Acid, AA, is a long chain fatty acid that is found in high amounts in red meat. Whilst small amounts of AA are necessary for good health, too much is associated with inflammation. Because GLA is part of the same metabolic pathway as AA, many practitioners were concerned that GLA would be converted into AA and advised against GLA supplementation. However, several studies have now proven that whilst GLA supplements are converted into DGLA, the DGLA is not converted further into AA.
DGLA (dihomo-g-linolenic acid) is a ‘GOOD FATTY ACID’. It has both anti-inflammatory and anti-proliferative properties and is a great adjunct to healthy ageing. Moreover, as we age, it becomes increasingly difficult for us to convert plant-based fatty acids (mostly from nuts and seeds) through to DGLA. Although DGLA is only found in trace amounts in some animal-based foods, GLA is readily converted into DGLA, which then reduces ageing and age-related inflammation.
In a recent study published in the journal Nutrients[iii], serum levels of DGLA were found to be inversely associated with death in elderly patients who had suffered from a recent myocardial infarction. This was a large study of 1002 patients, aged between 70 and 82, who were followed up for two years and those with the lowest levels of DGLA were nearly 1.5 times as likely to die.
What are the Health Benefits of Consuming a GLA supplement?
There are few or no studies that adequately test the benefits of ‘disease-free’ adults consuming GLA. There are some studies that show benefits for women with menstrual problems and there are high quality studies showing that GLA supplementation has beneficial effects on the course of diabetic neuropathy[iv].
Do any Foods contain high levels of GLA? where do I get it?
The answer is that apart from the oils of the plant seeds of evening primrose oil (7-10 gm GLA/100 gm); borage oil (18-26 gm/100 gm) and blackcurrant oil (15-20 gm/100 gm), GLA is only found in human milk and in small quantities in foods such as organ meats.
Should everyone take a GLA supplement and is Evening Primrose Oil as good as Borage Oil?
Because of the lack of controlled research in people of different age groups, it is difficult to give clear advice on taking a GLA supplement. Based on the data presented here – namely (a) the reduction in GLA levels with age, (b) the knowledge that GLA does not lead to increased levels of arachidonic acid (generally regarded as a bad fat) and (c) its established benefits in diabetics and (d) the importance of DGLA levels in older people who suffer from myocardial infarctions, I think that most people aged 60 and older would benefit from taking a GLA supplement.
I don’t think there is any evidence at this stage to suggest that one supplement (e.g. Evening Primrose Oil or Borage Oil) is better than another but borage oil and blackcurrant have about twice the concentration as EPO and this should be considered.
[i] Bolton-Smith C et al (1997) Evidence for age-related differences in the fatty acid composition of human adipose tissue, independent of diet. Eur J Clin Nutr 51:619–624.
[ii] Dr Judy Ford (2019) Why We Age, Solving the Puzzle of Ageing.
[iii] Nilsen DWT et al (2021) Serum levels of DGLA are inversely associated with LA and total death in elderly patients with a recent myocardial infarction. Nutrients 13: 3475
[iv] The γ-linolenic acid multicenter trial group (1993) Treatment of diabetic neuropathy with γ-linolenic acid. Diabetes Care 16 (1): 8-15