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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

The effect of vitamin D on estrogen levels in women

I have written before that vitamin D increases testosterone levels in men. It is not a minor effect.

Pilz S, Frisch S, Koertke H, Kuhn J, Dreier J, Obermayer-Pietsch B, Wehr E, Zittermann A. Effect of vitamin D supplementation on testosterone levels in men. Horm Metab Res. 2011 Mar;43(3):223-5.

Now, a group in Canada, led by Dr. Julia Knight at Mount Sinai Hospital, discovered that administration of 24,000 IU/week for four weeks was associated with lower estrogen levels and progesterone levels. Per 4 ng/ml increase in vitamin D, progesterone levels decreased by 10% and estrogen decreased by 3%. Unlike men, the study was confounded by what estrous cycle phase the women were in.

Knight JA, Wong J, Blackmore KM, Raboud JM, Vieth R. Vitamin D association with estradiol and progesterone in young women. Cancer Causes Control. 2010 Mar;21(3):479-83.

The favorable implications for breast cancer come immediately to mind, but as an old GP, I can tell you that lower female hormones sometimes help women in all kinds of ways, including psychologically. I suspect the women also became more fertile.


  About: John Cannell, MD

Dr. John Cannell is founder of the Vitamin D Council. He has written many peer-reviewed papers on vitamin D and speaks frequently across the United States on the subject. Dr. Cannell holds an M.D. and has served the medical field as a general practitioner, emergency physician, and psychiatrist.

9 Responses to The effect of vitamin D on estrogen levels in women

  1. jannz says:

    Considering this study was on cycling, young women, I’m wondering about the effects of vitamin D level on older women taking BHRT – [bio-identical hormone replacement]. ..??…

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  2. boston says:

    as a woman seventy years of age, I believe my hormones are already lower—so do I want them even lower? I thought the idea of natural hormone replacement was to make them higher–
    now you tell me vit d is going to lower them.
    I don’t use any kind of hormone replacement therapy, so is lower levels of hormones going to be a good thing for me?

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  3. jannz says:

    As a aging woman I do NOT want my hormone levels lower — it’s my impression that it’s lower hormone levels that cause DISease. I try to keep my vitamin D level optimal at 75ng/ml — based on this study I’m wondering if perhaps this is why I require a lot of estrogen in my BHRT therapy. ..??..

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  4. stefan says:

    Unfortunately only the abstract of the study is available on line, and it leaves more questions unanswered than it answers!
    It isn’t mentioned how much the 25(OH)D rose and we have to guess the total fall in Estradiol and Progesterone! And was there even a winter control group or did every woman in winter receive Vitamin D?
    Only two menstrual cycles of participating women were analysed, with only one single blood test during each of the 14 days of two compared Luteal Phases.
    There are wild ups and downs of Estradiol during the lutal phase (steep fall at the beginning, then the secondary surge, followed by a brisk fall towards the end), and Estradiol measures anywhere between 600 pmol/L and 70 pmol/L, depending on which day of the 14 days of the Luteal Phase the blood test is taken.
    What are 3% when the range of normal is already nearly 900% wide?

    And isn’t Progesterone antiproliferative and protective?

    Couldn’t one argue that a 3% fall in Estrogen and a 10% decrease in Progesterone may cause Estrogen dominance and increased cancer risk?

    I worry that referring to such a weak study abstract does a disservice to the Vitamin D cause!

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  5. jjayes says:

    I am 33 years old and my progesterone level is a bit low (6). This is something that actually prevents me from sustaining a pregnancy. I was hoping you would expand on your statement that lower progesterone levels would make women more fertile. Does the study pertain to women who had progesterone levels that were too high?

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  6. jannz says:

    @stefan — you’ve posed lots of good questions. Thanks for posting.

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  7. Brant Cebulla says:

    Stefan, I think you hit the nail on the head. This study leaves more questions than answers, and we simply need more research on the matter.

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  8. boston says:

    I would like to hear some input from Dr. Cannell regarding my comment, which seems to be of concern to others as well….
    will lower hormone levels in a person well past menopause whose levels are already lower than during one’s younger years, cause more problems???

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  9. There is no evidence that vitamin D lowers estrogen levels in post-menopausal women. Higher estrogen levels in pre-menopausal women is associated with an increased risk for breast cancer.

    When all one is doing is restoring the body to its natural state (5,000 IU/day), the chance of causing harm is close to zero.

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