Biswas 2010: shilajit and sperm count study

This study, from the J. B. Roy State Ayurvedic Medical College and Hospital in Kolkata, is the only human research on shilajit and sperm. Men with low sperm counts took processed shilajit capsules for three months, and most measures of semen quality improved from where they started.

The catch is the design. Every man took shilajit; nobody took a placebo. That makes it a useful first look, but it can’t separate the effect of shilajit from chance, the passage of time, or men changing their habits once they were in a fertility study.

What did the Biswas 2010 study do?

Researchers assessed 60 men attending for infertility and enrolled the 35 whose total sperm count was below 20 million per ml of semen, the cut-off they used for oligospermia (low sperm count). Each took a 100 mg capsule of processed shilajit twice a day after main meals for 90 days. Semen and blood were tested before and after (Biswas et al., 2010).

What did it find?

Among the 28 men who finished, total sperm count rose by 61.4% and the count of normally shaped sperm by 18.9% compared with their starting values. Motility, the share of sperm that swim properly, improved by 12.4% to 17.4% at different time points. Pus and epithelial cells in the semen fell. Malondialdehyde, a marker of oxidative damage, dropped by 18.7%.

In the blood, testosterone rose by 23.5% and FSH by 9.4%. The researchers also used a lab technique called HPLC to show that compounds from the shilajit turned up in semen. Liver and kidney blood tests did not change.

What does this mean?

It is an encouraging signal, consistent with shilajit’s traditional use in Ayurveda as a remedy for male vitality, and with a later placebo-controlled trial by some of the same researchers that found higher testosterone in healthy middle-aged men (see Pandit 2016). A 2014 review cited it as part of the evidence that shilajit “enhances spermatogenesis” (Stohs, 2014).

On its own, though, it is weak evidence. That is why we grade the fertility claim as weak.

What doesn’t it show?

• That shilajit caused the improvement. Sperm counts vary widely between samples. Men picked because their first count was low will, on average, score higher next time even if nothing changes, a statistical effect called regression to the mean. Only a placebo group can account for that.
• That partners got pregnant. The abstract reports semen and hormone results, not pregnancies or live births, which are what matter to couples.
• What happened to the seven men who dropped out. Results are for the 28 who completed. If those who left were doing less well, the average improvement could be overstated.
• That it works for other causes of infertility. Only men with low sperm counts were studied.

How much should we trust it?

Treat it as a reason to run a proper trial, not as proof. The study was small, had no comparison group, lost a fifth of its participants and measured surrogate outcomes. The abstract does not name a funder or a branded product. Sixteen years on, no randomised trial of shilajit for male fertility has been published.

If you and your partner are having trouble conceiving, the NHS suggests seeing a GP if you have not conceived after a year of trying, or sooner if the woman is 36 or over or you already know of a possible problem. Shilajit is not a substitute for that assessment.

Where does this study fit?

This study is the main evidence on our shilajit and fertility page, and it gives the lowest dose on our dosage page. For safety considerations, including hormone-sensitive conditions, see is shilajit safe?. The full list of trials is in the research library.