Flashback Friday: Fermented or Unfermented Soy Foods for Prostate Cancer Prevention?

Michael Greger M.D. FACLM · September 3, 2021 ·

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Which appear more protective: fermented soy foods, such as miso and tempeh, or unfermented soy, like tofu and soy milk?

Discuss

Transcript

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

There is an enormous variation in the rates of prostate cancer around the globe, with among the highest rates in the U.S., and lowest rates in Asia, though that may be changing. The largest increase in prostate cancer rates in the world in recent decades has been in South Korea, for example: a 13-fold increase in prostate cancer deaths nationwide. They suggested the increase in animal foods may have played a role, since that was the biggest change in their diet over that period—nearly an 850% increase.

This is consistent with what we know in general about foods and the prevention and management of prostate cancer. Tomatoes, broccoli-family vegetables, and soy foods decrease risk. No clear benefit from fish, and an increased risk from meat and dairy. This may be because “[a]…diet, based [around] whole plant foods…effectively reduce[s] inflammation in the body.”

There is a genetic factor. If you have a first-degree relative with prostate cancer, you may be at three-fold higher risk. But non-genetic factors may increase your risk 300-fold. How do we know the low rates in Asia aren’t genetic? Because when they move to the United States, their rates shoot up. And, by the second generation, they’re almost caught up. This may be because of more Burger Kings and Dairy Queens, but could also be because of eating fewer protective foods, such as soy.

A systematic review of all soy and prostate cancer population studies to date confirmed soy foods “could lower the risk.” But, that’s kind of a broad category. There’s all sorts of soy foods. There’s fermented soy foods, like miso and tempeh, and unfermented foods, like tofu and soy milk. Which is more protective? Researchers sifted through the studies. And, it turns out that only the unfermented soy seemed to help. Tofu and soy milk consumption were associated with about a 30% reduction in risk, whereas there didn’t appear to be any protection linked to fermented soy foods.

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Sources

Acknowledgements

Image credit: Jo via Flickr. Image has been modified.

Motion graphics by Tyler McReynolds, Teetotalin LLC

Topics

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

There is an enormous variation in the rates of prostate cancer around the globe, with among the highest rates in the U.S., and lowest rates in Asia, though that may be changing. The largest increase in prostate cancer rates in the world in recent decades has been in South Korea, for example: a 13-fold increase in prostate cancer deaths nationwide. They suggested the increase in animal foods may have played a role, since that was the biggest change in their diet over that period—nearly an 850% increase.

This is consistent with what we know in general about foods and the prevention and management of prostate cancer. Tomatoes, broccoli-family vegetables, and soy foods decrease risk. No clear benefit from fish, and an increased risk from meat and dairy. This may be because “[a]…diet, based [around] whole plant foods…effectively reduce[s] inflammation in the body.”

There is a genetic factor. If you have a first-degree relative with prostate cancer, you may be at three-fold higher risk. But non-genetic factors may increase your risk 300-fold. How do we know the low rates in Asia aren’t genetic? Because when they move to the United States, their rates shoot up. And, by the second generation, they’re almost caught up. This may be because of more Burger Kings and Dairy Queens, but could also be because of eating fewer protective foods, such as soy.

A systematic review of all soy and prostate cancer population studies to date confirmed soy foods “could lower the risk.” But, that’s kind of a broad category. There’s all sorts of soy foods. There’s fermented soy foods, like miso and tempeh, and unfermented foods, like tofu and soy milk. Which is more protective? Researchers sifted through the studies. And, it turns out that only the unfermented soy seemed to help. Tofu and soy milk consumption were associated with about a 30% reduction in risk, whereas there didn’t appear to be any protection linked to fermented soy foods.

Please consider volunteering to help out on the site.

Image credit: Jo via Flickr. Image has been modified.

Motion graphics by Tyler McReynolds, Teetotalin LLC

Doctor's Note

What about other healthy plant foods, like broccoli and turmeric? See what they can do in Best Supplements for Prostate Cancer.

Dean Ornish and his colleagues got amazing results, apparently reversing the progression of prostate cancer with a plant-based diet and lifestyle program. Do you think it could be because of the soy? It wasn’t just a vegan diet, but a vegan diet supplemented with a daily serving of tofu and a soy protein isolate powder. Find out in The Role of Soy Foods in Prostate Cancer Prevention and Treatment.

More on the number-one cancer among men:

What about soy and breast cancer? I’m glad you asked!

Who Shouldn’t Eat Soy? Watch the video to find out!

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