‘Landmark’ Study Finds Taking Zinc, Folic Acid Supplements Won’t Improve Male Fertility


Doctor: “For the first time, there is high-quality data that zinc and folic acid do not improve live birth outcomes or semen function.”


SALT LAKE CITY — Struggling with infertility can be hard on a man for a variety of reasons. Our culture promotes the idea that a man’s worth is directly tied to his performance in the bedroom, so men can be particularly hard on themselves if problems arise while pursuing a pregnancy with their partner. There are seemingly endless options available for men that claim to promote fertility, many of which contain zinc and folic acid. Unfortunately, a new set of research at the University of Utah found no such evidence that those two supplements improve pregnancy rates or increase sperm count and potency.

“This is a landmark trial of male infertility supplements,” says Dr. James M. Hotaling, co-author of the study and a U of U Health urologist specializing in male infertility, in a release. “The take-home message for men is that, for the first time, there is high-quality data that zinc and folic acid do not improve live birth outcomes or semen function.”

Zinc is in fact essential to sperm development, and folic acid has been proven to help form DNA in sperm. So, it does make sense that these two over-the-counter supplements would be advertised as a natural way to improve a man’s fertility. However, previous research on this matter has produced largely inconclusive results regarding the two supplements’ ability to improve sperm formation, count, and mobility.

For this project, the research team gathered 2,370 couples planning on enrolling in infertility programs being held in Salt Lake City, Minneapolis, Chicago, and Iowa City. Each participating man was randomly assigned to one of two groups: one group that took a placebo every day for six months, and another group that were given a real daily supplement containing 5 milligrams of folic acid and 30 milligrams of zinc for the same time period.

Meanwhile, the men’s female counterparts were asked to fill out incremental questionnaires for up to 18 months after the experiment in order to track which couples were able to successfully conceive.

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There were no significant differences in subsequent successful pregnancies among men who had taken the placebo and others who had taken real supplements. If anything, the placebo group ended up with slightly more live births (416 births, 35%), than the supplement group (404 births, 34%). Additionally, after the six month period, men across both groups displayed very similar measures of sperm count, mobility, and shape.

Moreover, men in the supplement group showed more broken DNA in their sperm in comparison to the placebo group. Broken DNA, technically referred to as DNA fragmentation, is known to worsen male infertility. Participants in the supplement group also reported more frequent bouts of nausea, abdominal pain, vomiting, and other stomach issues.

“This large, well-controlled, randomized study shows us that nutraceuticals like zinc and folic acid really don’t improve the chances of a couple getting pregnant and actually can cause side effects that are not beneficial,” concludes principal study investigator Dr. C. Matthew Peterson, a U of U Health reproductive endocrinologist. “It’s important for men of all ages to eat a healthy diet to maintain fertility, but you don’t necessarily need to take something extra to help you achieve better sperm parameters.”

The study is published in JAMA.

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