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Daily Dose

Can weight lifting, eating fish boost sperm count?

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Getting about an hour of daily exercise could lead to higher sperm counts and reduce infertility, new research suggests, and weight-lifting appears to be particularly helpful. On the dietary front, men may want to avoid hot dogs and eat more fish to improve their sperm quality. But they don’t need to worry too much about drinking caffeinated coffee or alcohol in moderation.

Those intriguing new findings were announced last week by Harvard School of Public Health researchers at the American Society for Reproductive Medicine’s annual meeting in Boston. They’re based on lifestyle surveys and sperm samples collected from about 150 men evaluated for infertility at the Massachusetts General Hospital Fertility Center over the past six years. The exercise study has not yet been published in a peer-reviewed journal, which means we should give it a bit of extra scrutiny.

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What’s more, the researchers could only make statistical associations and couldn’t prove that exercise or dietary habits directly affected sperm production.

That said, men struggling with infertility might want to consider trying some common sense lifestyle approaches to see whether they work to improve their sperm count and quality, said Jorge Chavarro, an assistant professor of nutrition and epidemiology at Harvard School of Public Health, who was a coauthor on all the new studies.

Many of these changes, he added, coincide with recommendations made by the American Heart Association to lower a man’s risk of heart disease.

Men who exercised for at least six hours a week, for example, had sperm concentrations that were 48 percent higher than those of men who barely exercised at all. While Chavarro and his colleagues still need to determine whether this would lead to higher pregnancy rates in the partners of the men who exercised most, he said it should provide an extra incentive for men to get active. Weight lifting, in particular, was associated with higher sperm counts, which he said might have something to do with a boost in testosterone levels that results from adding more muscle mass.

Outdoor activities such as yard work, gardening, and shoveling snow were all linked to more sperm but jogging and biking appeared to have no impact. Elite bikers have been shown in previous studies to have lower sperm counts, which is likely caused by sperm getting overheated for long periods of time because of tight biker shorts and the straddled position of the biker on the seat. Biking for shorter periods and less often might have little effect on sperm, Chavarro said.

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He couldn’t explain why jogging was not associated with better sperm counts but speculated that since the men in the study were light joggers, they may not have been running enough to see benefits.

With dietary factors, moderation might be the way to go. Men visiting the fertility clinic tended not to drink more than two to three cups of coffee per day, Chavarro said, likely because they were told by their doctors to minimize caffeine. They limited their alcohol to no more than two drinks a day, which is also recommended by the heart association to lower heart disease risk.

“We know from previous research that very high levels of alcohol — to the extent that it causes liver damage — is related to impaired sperm quality,” Chavarro said.

Whether meat lovers should abstain from processed meats such as hot dogs and cold cuts when they’re trying to get their partner pregnant also remains a big unknown, but another study published by Chavarro and his colleagues in the journal Fertility and Sterility and presented at the conference suggests that it might be a good idea.

Men who had at least half a serving a day of those meats had lower sperm quality than those who ate little or no processed meat. Those who ate at least one or two servings a week of white fish such as tilapia, cod, or halibut had improved sperm quality compared with those who ate none. Interestingly, eating two or three servings a week of fattier fish such as salmon and tuna was linked to a 34 percent higher sperm count — so it may pay to eat a variety of fish, which, yes, will also protect a man’s heart.

Deborah Kotz can be reached at dkotz@globe.com. Follow her on Twitter @debkotz2.

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