A vegan bodybuilder ate more than a pound of soy every day for a month, to see what effect it would have on his testosterone levels.
Brian Turner told Plant Based News that he had his testosterone tested before and after his experiment.
He said he wanted to counter the myth that soy lowers testosterone in men and reduces their muscle mass.
"So I thought, what the hell. I love doing challenges, I love using myself to do anecdotal experiments - why not try this out myself, do a testosterone result before and after, and show you guys what the difference is."
Turner revealed to PBN that to consume enough soy over the 35-day period, he ate 30 blocks of extra firm tofu, eight Chipotle burritos with sofritas, 24 cartons of soy milk, five blocks of tempeh, and a few Gardein and Beyond Meat products and edamame snacks.
Turner shared his experience on video
"Before I started I had my testosterone tested [on January 16] which came up as 596 ng/dL," Turner told PBN. The standard range is 240-871, so it was well within the standard range.
According to Turner, while he usually consumes large amounts of protein as a bodybuilder - much of which comes from soy, he doesn't eat the quantities of soy he had during this experiment. He also said he is not encouraging people to only get their protein from soy.
"I had no adverse side effects from soy," he said. "I didn't feel bad, I didn't feel weaker throughout the entire [experiment], that being said, there are tonnes of different ways to get protein in, so have some soy, but vary your protein sources - it's always good to have variety in your diet."
Speaking about his blood results after eating so much soy for 35 days, Turner said: "According to the myth, my testosterone should have plummeted, I should feel terrible, all my muscle should have gone away."
His testosterone levels after the experiment, tested on February 22, was 698 ng/dL.
"It went up," said Turner. "So there you have it - there are my two comparisons in blood tests. I can't believe that my testosterone went up, but then testosterone levels do fluctuate throughout the day depending on so many factors...it's normal for it to fluctuate.
"But mine didn't drop from eating so much soy. It's not scientific proof, it's anecdotal proof, meaning that this is my experience. You should read more into the research."
PBN is not a doctor. If you have any concerns about your health or want to undergo a major lifestyle or dietary change, you should speak to a qualified health professional.