Men around the world are experiencing a “sperm crisis.” Sperm counts in the western world have plummeted, perplexing scientists. But new research suggests a common supplement could make the difference.
A study conducted on 1,679 men in Denmark suggests that taking fish oil supplements is linked with improved testicular function. Compared to men who didn’t take any supplements, the 98 men who took fish oil had improved markers of reproductive health, including significantly higher semen volume, sperm count and testicle size, compared to men who didn’t take supplements.
The most prominent nutrient in fish-oil supplements are omega-3 fatty acids. In addition to being sold in capsules, they’re also found in foods like nuts and fish. But the science on how they affect the body — from the brain to the balls — is inconsistent.
This study doesn’t prove that omega-3s can improve sperm quality on their own, but the results are tantalizing. In an accompanying commentary, Alberto Salas-Huertos, a post doctoral researcher who studies nutrition and fertility, praised the study’s design.
“This is the first well-designed study from a general population and including healthy individuals published to date, making the findings more interesting,” he wrote.
The study was published this week in the journal JAMA Network Open.
Big Nut, omega-3s and sperm
In the summer of 2019, Salas-Huetos and his colleagues conducted a study which found that men who ate 60 grams of nuts per day experienced an increase in sexual desire and orgasmic function. They attributed the improvement, partially, to the effects of omega-3 fatty acids.
The study has a conflict of interest — it was funded by the International Nut and Dried Fruit Council (INC), an industry group consisting of 800 dried fruit and nut companies.
Big Nut has funded more than one study on omega-3s and sperm health. But despite the industry-funding, omega 3s are distinguishing themselves as legitimate areas of interest for health.
The authors of the most recent study on fish oil and sperm declare no conflicts of interest. Instead, omega-3s are just interesting.
A look at previous research into the fatty acids’ affects on health hints at why. For example, a large September 2019 analysis found that omega-3s, taken alongside traditional anti-depressants, may help treat the condition.
As for omega-3s impact on male fertility, past research suggests the supplements may have potential.
A February 2019 review paper re-analyzed the results of 16 previous studies on omega-3s and sperm quality. Fourteen found that sperm quality — or markers of sperm health — improved with omega-3 consumption.
But the trials included in the analysis were all small and had inconsistent data, suggesting that the initial data collection may have had flaws.
Omega-3s and sperm
Data collection for the new study, by contrast, was relatively rigorous. The study sample represents a cross-section of the Danish population. Because Denmark has a military conscription policy, all men are required to undergo physical examinations as part of their recruitment. The study group consists of volunteers who agreed to go the extra mile: during their examinations, they had their semen analyzed and provided researchers with information on their supplement habits.
Overall, the study suggests the men taking the omega-3 supplements may be experiencing reproductive benefits from their habit, including higher testosterone and higher sperm counts.
But the study also found negative associations between supplement intake and the follicle stimulation hormone, which stimulates sperm production. It also found negative associations between luteinizing hormone, involved in testosterone production, and fish oil intake.
Men who took fish oil supplements had 20 percent lower levels of follicle stimulation hormone. They also had 16 percent lower luteinizing hormone levels compared to men who didn’t take supplements.
This may be because fish oil supplements could increase the sensitivity of Sertoli cells — the cells in which follicle stimulation hormone spurs sperm production. If so, that could account for the negative association. A concurrent increase in “capacity” in Leydig cells — cells responsible for testosterone production — may explain the lower levels of luteinizing hormone, the paper suggests.
Larger study samples and more rigorous research is needed to validate the findings, the authors note.
Despite their limitations, the results add to the growing evidence on how dietary supplements affect semen and sperm quality.
Main Outcomes and Measures: Semen quality, measured as volume, concentration, total sperm count, percentage of morphologically normal spermatozoa, and motility, and serum reproductive hormone levels, measured as follicle-stimulating hormone, luteinizing hormone, testosterone, free testosterone, and inhibin B levels.
Results:Among 1679 young Danish men (median [interquartile range] age, 18.9[18.7-19.4] years) recruited to participate, 98 men (5.8%) reported use of fish oil supplements during the past 3 months, of whom 53 (54.1%) reported intake on 60 or more days. After adjustment and compared with men with no supplement intake, men with fish oil supplement intake on fewer than 60 days had semen volume that was 0.38 (95% CI, −0.03 to 0.80) mL higher, and men with fish oil supplement intake on 60 or more days had semen volume that was 0.64 (95% CI, 0.15 to 1.12) mL higher (P for trend < .001). Similarly, testicular size in men with supplement intake on fewer than 60 days was 0.8 (95% CI, −0.2 to 1.9) mL larger and in men with fish oil supplement intake on 60 or more days was 1.5 (95% CI, 0.2 to 2.8) mL larger compared with men with no supplement intake (P for trend = .007). After adjustment, men with fish oil supplement intake had a 20% (95% CI, 9%-31%) lower follicle-stimulating hormone level and 16% (95% CI, 8%-24%) lower luteinizing hormone level compared with men with no supplement intake. There were no associations of intake of other supplements with measures of testicular function.
Conclusions and Relevance: These findings suggest that intake of fish oil supplements was associated with better testicular function, which is less likely to be due to confounding by indication, as no associations of intake of other supplements with testicular function were found. This cross- sectional study did not examine the actual content of ω-3 fatty acids in the supplements; therefore, these findings need confirmation in well-designed randomized clinical trials among unselected men.