JAMA Study Links Omega-3 Intake to Sperm Quality and Improved Reproductive Hormone Levels
Road to Zero?
Infertility affects approximately 15% of all couples, and of those, 40-50% stem from male factors. There has been a decline in semen quality and quantity in men documented during the past 50 to 70 years. A recent study by Hebrew University and Mount Sinai’s medical school of nearly 43,000 men from North America, Europe, Australia and New Zealand found that sperm counts per milliliter of semen had declined more than 50% from 1973 to 2011. This, the authors urged, is a significant public health issue and research on the causes of this continuing decline is urgently needed.
In his analysis of the study written for GQ entitled “Sperm Count Zero,” contributor Daniel Noah Halpern wrote, “We are producing half the sperm our grandfathers did. We are half as fertile.…Not only were sperm counts per milliliter of semen down by more than 50 percent since 1973, but total sperm counts were down by almost 60 percent: We are producing less semen, and that semen has fewer sperm cells in it. ”
There are many theories about this decline in quality, including changes in lifestyle or behavioral habits like smoking, alcohol and/or drug intake and diet. While others speculate that exposure to certain chemicals with endocrine disrupting abilities, such as Bisphenol A (BPA), may be to blame for decades of decline.
The Role Omega-3s Play in Sperm Development
Sperm contain a large amount of omega-3 fatty acids, just like the brain and eyes. In fact, recent studies in mice have shown that DHA plays a large role in the formation of a sperm’s pointy cap, which is called the acrosome. This crucial cap contains enzymes responsible for piercing the ovum, or egg, causing fertilization.
Without DHA, the acrosome doesn’t get made and sperm fail to mature. Although a DHA deficiency is rare, if the DHA-synthesizing enzyme is defective, this could lead to problems with fertility.
The Danish Omega-3/Sperm Study
Earlier this month, a team from the University of Southern Denmark published their study in JAMA Network Open, linking fish oil supplementation with improved reproductive hormone levels in men, as well as improved semen quality and quantity. The cross-sectional study, performed from January 2012 to December 2017 included young Danish men from the general population receiving compulsory physical exams to determine their fitness for military service.
Similar to Israel, Denmark conscription is mandatory for all physically fit men aged 18 and above. Therefore, study participants were men ages 18 to 19 years old. According to the authors, this study was unique in that it was the first of its kind to link omega-3 fatty acid supplement intake with testicular function by measuring semen quality and reproductive hormone levels.
Between January 2012 and December 2017, men attending physical exams were approached and invited to participate in a study investigating testicular function. Study participants were given a physical exam (completely unrelated to their conscription exam), completed a questionnaire, gave a semen sample and completed a blood draw.
The questionnaire asked about health, lifestyle and diet before the study. Importantly, these men were asked whether they used vitamins or dietary supplements within the last three months.
Men who reported intake of fish oil supplements had larger testes, higher semen volume and higher sperm count compared with men who did not report taking fish oil supplements. Furthermore, men who took fish oil supplements had 20% lower follicular stimulating hormone (FSH) levels, 16% lower luteinizing hormone (LH) levels and 8% higher free testosterone to LH ratios as compared to those who did not take fish oil supplements.
What are the implications and limitations of this study?
The study authors wrote, “We found positive associations of self-reported use of fish oil supplements with testicular function as measured by higher semen volume, total sperm count, and testes size, lower FSH and LH levels, and a higher free testosterone to LH ratio. As we found no clear associations of intake of other supplements with measures of semen quality, we believe that confounding by indication is not likely to explain our findings.”
The study’s authors collected information through questionnaires of the participants and did not directly measure each man’s omega-3 intake. According to the study, “Few men reported intake of fish oil without multivitamins, and we had no information on the actual concentration of omega-3 fatty acids in the fish oil supplement, which may have introduced misclassification, as supplements may contain different concentrations of omega-3 fatty acids.”
Furthermore, a detailed dietary history was not available on these men. These fatty acids are present in food, such as oily fish. One could argue that some men who did not take fish oil supplements may have had a high omega-3 intake through their diet. However, the authors of the study seemed to think there was a low possibility of this, as they included unpublished data from 2019 that showed fish consumption among these men and the general population in Denmark is statistically low at 26 grams of fish per day.
It’s worth noting that while causality was not proven with this study, it does show an association between taking omega-3s and an increase in semen volume, total sperm counts and testes size, as well as achieving optimal levels of sex hormones in men.
“This has to be confirmed in other studies,” lead author, Dr. Tina Kold Jensen of the Copenhagen University Hospital, told the NewYork Times. Dr. Jensen added, “but here we found that young healthy men who took supplements had a better sperm count. So I would advise men to take supplements if they don’t have a fish-rich diet. It’s not dangerous, and may have benefits for cardiovascular health as well.”