We ask a lot of questions about our diet.

What's the right way to treat a chronic illness, fight off a virus, lose weight?

The problem is we get a lot of different answers.

Well, I'm here to help.

Welcome to the Nutrition Facts podcast.

I'm your host, Dr. Michael Greger.

A century ago, the age of first menstruation averaged as late as nearly 17.

So why is sexual maturity coming so much earlier now?

Here's our first story.

Healthy Seventh-day Adventist vegetarians, maybe longest living, but might that come at a cost?

A semen analysis at a fertility clinic in Loma Linda, California, home to a large population

of Adventists, raised questions about their sperm quality. Though still within that normal range,

vegetarians had about a 25% lower sperm count.

The few vegans tested also had a lower sperm concentration, but they made up for that

with their 30% greater ejaculate volume.

The vegans did have significantly fewer activated sperm, though, which is a sign of decreased

fertility.

The researchers suggested soy consumption as a possible mechanism, as Adventist

vegetarians in California average about a half-serving a day of plant-based meats, many

of which contain soy.

Soy phytoestrogens have been put to the test, though, and months of consuming up to the equivalent of nearly

20 servings of soy a day did not result in any adverse effects on sperm parameters.

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