Doctor's Note

For more on exogenous hormones and meat, check out:
Why Do Vegan Women Have 5x Fewer Twins?
Estrogen in Meat, Dairy, and Eggs

And check out my other videos on hormones

For more context, check out my associated blog posts: Stool Size and Breast Cancer RiskTreating Breast Pain with Diet; and How Do Plant-Based Diets Fight Cancer?

If you haven't yet, you can subscribe to my videos for free by clicking here.


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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 hormones. Also, there are 1,449 other subjects covered in the rest of my videos–please feel free to explore them as well!

    • Christie

      Dr. Greger, I’ve been trying to find nutrition information that relates to the hormone prolactin, but I haven’t been able to find anything on the site. Is there anything natural you’re aware of that can reduce prolactin levels?

      Thank you!

      • I am not aware of studies relating prolactin and diet. The causes for elevated prolactin can be due to normal conditions such as pregnancy and stress, medications, tumor or abnormality in the pituitary gland, among others. It is best managed by a physician who is knowledgeable in this area. Of course eating a low fat whole food plant based diet with Vitamin B12 supplement will help prevent, reverse, cure, and/or stabilize alot of chronic conditions which are best avoided.

      • steve41337

        Macuna Pruriens is natural and reduces prolactin levels. I take a teaspoon of this 15% extract dissolved in hot water to make a cup of tea pre-bedtime

        It does not dissolve easily in water but in hot water you can get it done. If you don’t like the taste you can buy in caps. Taken at bedtime it improves my sleep or a hot cup in the morning seems to give me added energy. I find this stuff amazing and wish Dr. Greger would scan the research on this product and report to us. Oh yeah it is also supposed to be an aphrodisiac although I have not noticed too much of that effect.

  • Fantastic site…love the video format as well.

    Is there any way you can provide a pdf link to the articles you are referencing? I would love to read the full article.

    I will be sure to tweet about this video to my followers…great job!


    • Michael Greger M.D.

      Whenever available I always try to provide PDF links to the full-text of the papers in the Sources Cited section beneath each video. More and more journal publishers are joining the “open access” movement to provide unrestricted online access (check out this graph to see the trend). Since many studies are taxpayer-funded it only makes sense that we should have access to the results, right? Unfortunately, there are some holdouts, journals that continue to charge readers exorbitant rates to view papers they publish. In this case, you’re left with a few options: 1) You can check WorldCat to see if there are any local institutions that have the journal in question (such as university libraries). 2) You can also request a copy (so-called “reprint”) from the author (usually they list a contact email address in the PubMed abstracts to I link). 3) Worse comes to worst, you can pay on the journal website or order it for a fee through the federal Loansome Doc program. I’m privileged to live biking distance from the National Library of Medicine and so have easy access to just about everything, but unfortunately it’s not legal for me to directly share copyright protected materials. Otherwise I would post all the papers on the site!

  • Similarly, what do you think of the research suggesting full-fat dairy boosts fertility? And what would you suggest as good nutrient dense foods for getting body fat high enough to allow for reproduction?

  • Susan

    Can you comment on the likelihood of a woman over 40 who eats a plant-based diet to produce a child with birth defects? It seems like the current statistics are based on studies where the population of women is typical of American society, which means most eat meat, dairy and/or eggs. 

    • Toxins

      IT depends what is eaten on this diet specifically. If one is truly whole foods plant based with unrefined whole foods, than an issue could possibly be from over consumption of pesticides. But even pesticides found in meat are greater than those of plants due to bio accumulation.

      • Susan

        I saw that video. Very informative. Let’s assume the person is eating organic fruits and vegetables and whole grains and legumes. What is the likelihood of a woman over 40 (say 40 – 45) who eats such a diet to produce a child with birth defects? (compared to the average woman).

  • Amber

    I’d love to see a post addressing PCOS sometime. Thank you!

    • The current science supports a low fat whole food plant based diet as helpful in PCOS (e.g. Stamets et al, Fert & Ster, 81:3, 3/04). As you are probably aware PCOS is associated with increased male hormones, insulin resistance, obesity, decreased menstrual cycles and infertility. Losing weight consistently helps. Insulin resistance is increased with increased fats in the diet. This is why type 2 diabetics respond to a low fat diet(decreases insulin resistance and improves mitochondrial function in cells… it is a sugar processing problem caused by fats in diet). Since animal products are high in fat they need to be eliminated from the diet. Low fat also increases the sex binding hormone in the blood resulting in less free male hormone. High fiber intake further removes sex hormones from the body courtesy of increased gut transit time and decrease in the enterohepatic circulation. Of course you can go on a plant based diet and still not lose weight if you eat high calorie dense foods. A plant based diet is also higher in inositol which is present in grains, nuts and fruits and has been shown in one study to improve insulin function( Gerli et al, ERMPS 2003;7:151-9). So my recommendations for patients with PCOS is go on a low fat whole food plant based diet with Vit B12 supplements. If they have trouble I make sure they understand the concept of calorie density (best source Jeff Novick’s DVD Calorie Density: Eat More, Weigh Less and live longer and some of the potential traps leading to “Fat Vegans”. See John McDougall’s article in his Dec 2008 monthly newsletter free on his website. I did a brief pub med search for more recent articles and found many addressing PCOS but none to change or modify my recommendations. I hope this helps until Dr. Greger weighs in so keep tuned in to Nutrition Facts as the science keeps coming and our understanding keeps improving. Be well.

      • Marianne McDonald

        Thank you for this question and answer! I have been following this way of eating and noticed huge improvements in my symptoms despite the fact that many doctors have recommended a high fat moderate protein diet.

  • Great info! Thank you.

  • Catherine

    Hi, I would like to know what you think about supplementation of myo-inositol for polycystic ovary syndrome.
    For me, it looks like it’s working so well.
    I would like especially to know more about the safety. For this issue, it’s about 4 grams per day.
    Conventional gynecologists don’t make me confident, because they look like they know pretty nothing about that.
    But, it seems like there’s some good studies that show very good results.

    Thanks very much for you answer ! and for your site !

  • icaj

    Can you please tell me if there is a pork parasite that can cause female infertility and how does one get tested for it? Many thanks

  • Amy

    With my first child I consumed everything that was animal. Had no problems conceiving. Second child was a little less meat but loads of anything dairy, processed and full of sugar. So then my husband watched Forks Over Knives and the next day we threw out everything in our pantry and only ate a vegan diet with no processed foods, honey instead of sugar and loaded up on a bean and green everyday. My kids are doing great! Super leaps in growth and intellect. My husband lost 20 lbs and has so much energy and stamina and much happier. I’m the one with the trouble. Im not losing weight. I’m really tired. When I lay down my arms/legs get cold, numb and painful. I wake up to swollen/tight hands and feet. My thyroid is sluggish but I’ve been on meds for 12 years and have it checked often. Now I’ve had 3 miscarriages all in 2014. I feel I’m fertile enough but my body is just shutting down. Any ideas why some people don’t respond well to a vegan diet? Too many cruciferous veggies? The doctors have no idea and all my friends/family think I need meat and dairy to rebalance. Also I was raised a vegetarian and started meat again after leaving home. Not looking for a diagnosis really, but definitely needing a point in a new direction. Is there anything about a vegan diet that might provoke an already genetically proned autoimmune reaction like lupus or fibro?

    • Robert T.

      Perhaps you should consult with an authority in the field Reproductive Immunology. Also, vegan diets can lead to vitamin B12 and vitamin D deficiencies. Further, some women have an impaired ability to convert the plant based provitamin beta-carotene into vitamin A. Not to mention a vegan duet can lead to long chain, highly unsaturated omega-3 fatty acid deficiencies (EPA and DHA). Generally, (there are many exceptions and there are no simple sound bites) vegan diets impair fertility, unless one has PCOS and needs to lose weight and lower androgen levels.

      There is evidenče that low levels of vitamin D can impair fertility. There is a at least one reported case of vitamin B12 deficiency causing unexplained female infertility. You might have developed a sensitivity to gluten, it can happen at any time and his can cause spontaneous abortions (i.e., miscarriages.)

  • Erica Orge

    Hi, Dr Greger,

    I am a vegan for two months now and would love to stop taking the birth control pills, but I have the Polycystic Ovary Syndrome. I would like to know if the diet can have any impact on treating this syndrome or if it safe to stop the pills.

  • Maria Kondorskaya

    Dear Dr. Greger, could you provide some advice regarding the female athletic triade & vegan diet. The question is how can an active woman in her early thirties use the power of plants to avoid/treat the triad symptoms without giving up physical activity, achieving better fitness results, etc.
    Thank you!

  • Help!

    I am 25 and have recently been diagnosed with mild PCOS, not requiring treatment just yet, but have been advised to lose weight through exercise and healthier eating – and I hope I can follow through with these.

    I was a vegetarian for about 7 years, and started eating fish+chicken+meat again in the last year. I was wondering if this (artificially introduced hormones in meat) may have caused the onset of PCOS? Should I stop eating these to help my chances of getting better?

    I also wanted to know if it is okay to use a menstrual cup – I have been using the cup on and off for the last couple of years. I’ve read some contradictory accounts of menstrual cup use helping and harming/creating more problems for users with PCOS.

    Thank you!

  • Jen

    Dr. Greger, I would be so grateful to learn more about veganism and polycystic ovarian syndrome. I was vegetarian most of my life and, within the past two years, became vegan. Now, I am that rare obese vegan, and I have been recently diagnosed with PCOS. Is there any research that can help? Should I be taking particular supplements? In time, will my vegan diet increase fertility?

  • Bao

    Hello Doctor Greger,
    Thank you and your staff for the wonderful work that you all do.
    My question is, do the animal stress hormones and other chemicals produced when an animal is killed stay in the meat that people eat and causes them harm? Thanks a bunch!

  • Dianne Doyle

    A young friend and her husband have been WFPB for two years. She has been trying unsuccessfully to get pregnant for the last 5 months. Any suggestions, tips, advice?