Fish oil supplements support male fertility, but follow-up research warranted

20 Jan 2020 --- Consuming fish oil supplements, which are high in omega 3 fatty acids, has been associated with better testicular function, as measured by semen quality and reproductive hormone levels among healthy young men. This is according to a recent study published in JAMA Network Open, which highlights the fact that young men have poor semen quality, with the causes often unknown. While a well-designed randomized clinical trial among unselected men is still warranted, industry remains ever-conscious of the potential of fish oil supplements in the male fertility sector.

“This is the first observational study conducted on the association between improved testicular function and fish oil supplementation intake, but of course, controlled, randomized trials are necessary to continue this research,” Dr. Tina Kold Jensen, University of Southern Denmark, tells NutritionInsight.

The cross-sectional study included 1679 men in Denmark at a military recruitment center, with a median age of 19 years. Ninety-eight men reported taking fish oil supplements during the past three months, of whom 53 took supplements for 60 or more days. 

After adjustment, it was found that the study participants taking the supplements were associated with larger testicular size, higher semen volume and total sperm count than men not taking supplements. Men who consumed fish oil on 60 or more days during that period had semen volume that was 0.64 mL higher than men not using the supplements.

Similarly, compared to those who did not take supplements, testicular size in men who consumed fish oil on fewer than 60 days was 0.8 mL larger. Among those who consumed it for 60 days or more, the size was 1.5 mL larger than those with no supplements intake.

The research team also revealed a higher calculated free testosterone to luteinizing hormone ratio, as well as lower follicle-stimulating hormone and luteinizing hormone levels after adjusting for confounders. Active in this field of research for the last 25 years, Dr. Jensen highlights that this study provides additional evidence that fish oil supplementation can be beneficial to male health.

The study indicated positive effects on testicular function when supplementing with fish oil.Expert reaction
Fellow researchers within this field of research concur that this study is “well-conducted” however, there still remains much to be researched. A key limitation is that this study was an observational study, as opposed to a clinical trial, where supplements are tested as an intervention for poor sperm quality.

The researchers admit in their study that their findings need to be followed up using a randomized, double-blind clinical trial before definitively suggesting whether taking fish oil supplements can improve reproductive function in men from the normal population. 

“Such a trial would be able to exclude the possibility that men taking fish oil supplements may simply be more health-conscious and in a better reproductive state because of this, rather than the supplement itself having any effect,” Professor Richard Sharpe of the MRC Centre for Reproductive Health, University of Edinburgh, Scotland, comments.

Healthy diets count
There is increasing evidence for a link between diet and reproductive health. Indeed, Dr. Jensen promotes cod fish consumption to increase fish oil dietary intake, as well as following physicians’ nutritional advice.

“Fish oil products have been common as dietary supplements for a long time and have been shown to be safe,” Dr. Kevin McEleny, Consultant Andrologist and British Fertility Society Committee member, highlights. 

However, within this study’s parameters, he also points out that there were “very few men” who took only fish oil and no other supplement. “They also tended to have healthier lifestyles and in particular tended not to smoke. Being fit and healthy is important for male and female reproductive health. This doesn’t point to whether fish oil specifically is helpful,” he argues.

“Interestingly, the men who received fish oil supplements were less likely to be regular smokers. Although the study did take account of smoking status in their analysis, modification of lifestyle factors, such as obesity and smoking, remain important for male fertility,” adds Dr. Rod Mitchell, Research Group Leader at the MRC Centre for Reproductive Health.

Not a silver bullet
While fish oil supplementation is touted for being beneficial for treating cardiovascular disease and inflammation, research in this field continues to demonstrate it does not have an effect on other symptoms. Increasing omega 3 consumption has little or no effect on the risk of Type 2 diabetes, according to research from the University of East Anglia, UK. Nor has there been evidence found that omega 3 fish oil supplements can help aid or improve the reading ability or memory function of underperforming schoolchildren. 

This latest study comes as a contrast to last week’s research on how zinc and folic acid supplements do not appear to improve pregnancy rates, sperm counts or sperm function. 

Indeed, folic acid is a buzzword in the pregnancy sector, touted as essential for ensuring fetuses’ healthy development. Pregnant mothers may not be supplementing enough, a study found last November, indicating that active folate supplementation may be more beneficial to fetuses’ development than folic acid itself. 

Finally, the International Alliance of Dietary/Food Supplement Associations (IADSA) also underlines the importance of folic acid as well as omega 3 in the first 1,000 days of a baby’s life.

By Anni Schleicher