Doctor's Note

For some of the latest videos on the health benefits of soy foods:
BRCA Breast Cancer Genes and Soy
Breast Cancer Survival and Soy
Mineral of the Year—Magnesium
Increased Lifespan From Beans

Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out the other videos on soy. Also, there are 1,449 other subjects covered in the rest of my videos--please feel free to explore them as well!

For some context, please check out my associated blog post: The Best Foods: test your nutrition knowledge.

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  • Michael Greger M.D.

    Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out the other videos on soy. Also, there are 1,449 other subjects covered in the rest of my videos–please feel free to explore them as well!

  • David Schmidt

    Dr., is there any research that you could share regarding Sprouted Tofu?
    Thanks in advance.

  • walfaro

    Dear Mr. Schmidt: Thank you for submitting this interesting question. According to research, products from sprouted varieties of soybeans have shown an increase in protein of 7% in soymilk and 13% in tofu across varieties; a reduction in fat of 24% in soymilk and 12% in tofu; in trypsin inhibitor of 73% in soymilk and 81% in tofu; in phytic acid of 59% in soymilk and 56% in tofu across varieties. You can read the abstract of the study following this link:

  • Toothferry


  • Michael Greger M.D.

    For some context, please check out my associated blog post The Best Foods: Test Your Nutrition Knowledge!

  • Guest

    Can you make a more detailed video about soy products? From my own research and this site, I’ve concluded that soy is good for you, but that processed soy is not. Stuff like soy protein isolate is actually harmful because it helps tumors grow (I think Toxins pointed this out in another comment section). But soymilk is okay? From the video above, it also seems like fermented soy like tempeh and edamame are good sources as well. Thanks!

    • Lauren

      Thanks for your request- we have some more recent videos about soy if you do a quick search. A good rule of thumb is to stick to whole foods, whether they be soy or otherwise, and always consume organic soy products. Soy protein isolate does not have the same benefits as whole soy products. Soy milk is a whole food, as are tofu, tempeh and edamame.

  • Guest

    I came across some statements from someone identifying as a nutritionist saying only fermented soy, like miso, tempeh and natto, is healthy, and unfermented soy such as soymilk causes allergies, can affect thyroid function, and is “strongly linked to a host of auto-immune diseases such as Hashimoto’s thyroiditis as well as hypothyroidism.” The person goes on to say, “Eating unfermented soy in a strictly vegetarian diet actually increases the risk of mineral deficiency including calcium, magnesium, copper, and zinc and the consequent vitmain D deficiency. This is due to the antinutrients present in soy. For example, fresh soy contains phylates, an antinutrients which blocks the body’s absorption of minerals from the gastrointestinal tract. It also contains enzymes inhibitors that reduce protein digestion. Some evidence even suggests that processed soy protein contains carcinogens such as nitrates. … Humans need phosphorus and magnesium to build bones, not calcium! Our body makes the bone building minerals within.” Do these statements have merit, based on peer-reviewed research?

    • Lauren

      It’s great that you’re skeptical about the anti-soy lobby. Soy is a healthful bean, that can help prevent and manage a variety
      of diseases. Always go for whole, organic soy foods.

      Regarding thyroid function, please see our response to a similar question here:

      While phytates inhibit the absorption of certain nutrients to a degree, (phytates are present in quite a few plant based foods, including beans, whole grains, nuts and seeds) they also serve as potent cancer-preventative phytonutrients. See our video:

      • Nebuladancer

        Could Dr Gregor do a video or summary blog post about this issue? I am frequently called out by my family members about my use of soy milk and tofu, basically that unless it is fermented I’m harming myself and my children. It is hard to share 8 different videos as suggested above to family members who are already quite sure they are right. I have done some looking on Pubmed, but the sheer number of studies on soy make it hard to find a single good meta-study that looks at this issue. I did find the recent (2014) one that is commonly cited which hypothesises that unfermented soy is a contributing factor if not a cause of Alzheimers, but I did not read it. Currently, the argument feels like a game of ‘wack-a-mole’ where one objection is brought up, then another over here, and then another over there. A single organised explanation to share with others would be tremendously helpful. Thank you

  • Ronald Chavin

    Not all fermented soy foods are equally healthy for us to eat. Natto is the only soy food healthier for us to eat than edamame. Tempeh is LESS healthy for us to eat than edamame. Here’s why:

    In sharp contrast to the fungus used to ferment tempeh, Rhizopus oligosporus, which inhibits most of the beneficial bifidobacteria and lactobacilli, Bacillus subtilis natto protects and feeds both the bifidobacteria and lactobacilli:

    Bacillus subtilis natto strongly inhibits not only pathogenic viruses (including Rotavirus), pathogenic fungi (including Candida albicans and various Rhizopus species), and pathogenic Gram-negative bacteria (including Escherichia coli, Salmonella typhimurium, Shigella flexneri, Campylobacter jejuni, Campylobacter coli, and various pathogenic Enterobacteriaceae, including various Yersinia, various Klebsiella, various Proteus, various Serratia, and various Citrobacter) but also pathogenic Gram-positive bacteria (including Staphylococcus aureus, Streptococcus pneumoniae, Clostridium perfringens, and Clostridium difficile):

    Eating natto will remove the calcium in our arteries and put that calcium back into our bones, where it will prevent future bone fractures. No other food and no prescription medicine can reverse arterial calcification. About half of all people who suffer from heart disease have calcified arteries when examined by chest X-ray. Scientific studies indicate that people who swallow statin drugs will worsen the severity of their arterial calcification:
    [Swallowing statin drugs will also tend to deplete the human body’s reserves of coenzyme Q10].

    The nattokinase (subtilisin) that is manufactured by Bacillus subtilis natto not only kills the bad bacteria but it also melts away existing blood clots and prevents future blood clots in humans better than any other natural substance contained in any food:

    Unlike all other soy foods, which tend to cause weight loss, tempeh will tend to cause weight gain by inhibiting most of the good bacteria. Fatfree plain yogurt, soy yogurt, and natto will tend to cause the most weight loss because the good bacteria that these 3 foods promote will manufacture numerous beneficial chemicals, including propionate, acetate, and butyrate:

    The beneficial chemicals manufactured by Bacillus subtilis natto [but not bifidobacteria or lactobacilli] include vitamin C, vitamin PQQ, vitamin K2/MK-7, vitamin K2/MK-8, nattokinase (subtilisin), hyaluronic acid, and coenzyme Q10. People who eat natto will dramatically lower their risk of death from heart disease, cancer, osteoporosis, dementia, blood clots, stroke, kidney failure, high blood pressure, obesity, and a dozen other killer diseases.
    The majority of the bad bacteria are Gram-negative. Inflammation-causing bacterial endotoxins come mostly from the Gram-negative bacteria in our foods and also partly from the Gram-negative bacteria in our intestines. Eating tempeh (instead of natto) would fail to kill any of the Gram-negative bacteria and, in fact, might cause them to multiply faster because most of the beneficial Gram-positive bacteria would be inhibited:

    • Ronald Chavin

      Nattokinase (subtilisin) works well in humans, not only in dogs: well

    • Ronald Chavin

      Nattokinase (subtilisin) works well in humans, not only in dogs:

    • LarryM

      Ronald, what do you think about Miso? Would it have these same beneficial properties that natto does, or could Miso have some of the potentially harmful qualities as those you mentioned that tempeh has in regards to gram-negative and gram-positive bacteria? Thank you for any ideas on this.

  • Becky Taylor

    Woot, Tempeh! We make Tempeh locally in Austin, Texas..

  • polly gloudemans

    Which soy milk products are fermented? Kirkland is what I drink. what about other soy fermented vs non fermented products?

    • Lauren

      Soy milk is generally not fermented, but soy milk is still a healthful, whole food. Always make sure to buy it organic and sugar free. Westsoy unsweetened is a tasty, healthful brand, as is Whole foods 365 organic.

  • Michael B.

    I have a book “Fermented Vegetables” that teaches how to “lacto-ferment” vegetables. I am interested in this to increase beneficial bacteria and for health reasons. Before I get started I searched your site and listened to your video on Kombucha and Kimchi which both said these are bad for us. Do you have more info on fermented foods and more details as to if and why they may pose a health risk or benefit?

  • 4Baccurate

    Hi, Dr. Greger, Thank you for such an informative site. Question: Is there something in tempeh that may affect the body’s ability to use zinc or other minerals? Would tempeh interfere with the thyroid’s uptake of iodine? Thank you.