In addition to the omega-3 discussion as a crucial aspect of our nutritional and metabolic health, vitamin D comes up again and again as a crucial parameter of health.
It remains under-rated, under-tested and therefore undiagnosed.
It’s interesting that I posted recently a cheeky video about sending my husband to his doctor with a list of labs to be ordered, including vitamin D which had never been checked. It was an incredibly controversial post which I attribute to the authoritative tone and labs that deviate from the “standard” labs.
The defenders of “standard” dismissed the labs that I ordered as unnecessary, not recommended and not covered by insurance. Mind you, none of these online people know my husband’s history or symptoms.
One such comment cited the USPSTF recommendations not to screen the general population. The commenter also added that most people are deficient as a reason not to check. This gets into a common misconception: that common = normal.
I’m not speaking for insurance companies or guideline societies. I’m speaking in my professional opinion that vitamin D is worth checking, especially if a majority of people are deficient.
It turns out his vitamin D was low. Mine was low when I had it checked months ago. I’ve been supplementing (even though sunshine is better, that’s rarely possible for me right now) and need to be checked again.
So why did I want vitamin D to be checked? I’ll discuss here how this crucial hormone relates to women’s health at every stage of life, though some of these are applicable to males also.
What is vitamin D?
Vitamin D is actually a hormone, well known for its beneficial effect to bone health. In a severe deficient presentation, rickets ensues which is a bone disorder of children characterized by soft, weak bones and even bone deformities.
What does vitamin D do?
The job description of vitamin D has really expanded in recent years, particularly in relation to the immune system and metabolic health.
Vitamin D Receptors (VDR) have been found on cells throughout the body, including immune cells. The receptor is a hormone’s doorway into the cell, suggesting that wherever the receptor is found, vitamin D has a role.
What’s more is that immune cells even have a way to make the active form of vitamin D from its inactive form. If our immune cells can do this, they must be able to use vitamin D for their function.
In the immune system, vitamin D increases the antimicrobial (infection fighting) function of our immune cells. It also helps prevent infection by strengthening our skin barrier, our largest fighter against infection.
Vitamin D is anti-inflammatory. Inflammation is an underlying source of chronic disease. Vitamin D has been found to decrease the IL-6 and IL-1beta inflammatory markers in septic patients. It has been shown in animal studies to help resist inflammatory bowel disease.
How much of the population is deficient?
This is a wide range, but reportedly 20-90% of reproductive-aged women in North America are deficient in Vitamin D.
What levels are considered normal and abnormal?
The Endocrine Society of North America defines levels of vitamin D as follows:
Deficient = less than 20 ng/mL
Insufficient = 20-30 ng/mL
(Caution with any interpretation of lab values, the units and ranges may vary between labs and institutions)
How does Vitamin D affect women at different stages of life?
Childhood and Adolescence
Short of rickets, low vitamin D can prevent children and adolescents from reaching their expected peak height and bone mass.
A lower than expected peak bone mass in adolescents is associated with fracture risk later in life. This makes logical sense, if you don’t ever reach a high bone mass plus add in the expected losses with aging and lifestyle choices, the bones are more prone to fracture.
The bone-building of vitamin D is in conjunction with adequate calcium. Studies of children with low dietary calcium have increased turnover of vitamin D.
Peak bone mass is achieved in girls between ages 18-20 and in boys between ages 20-23.
As we will see, low vitamin D is associated with many chronic diseases that we find in adulthood. As to whether the low vitamin D found in adolescents particularly in winter contributes to these adulthood diseases is the subject of research.
At the very least, if we continue to have a population affected by vitamin D deficiency, we are precluding their peak bone mass.
Reproduction, PCOS:
There is growing evidence that vitamin D deficiency and polycystic ovarian syndrome (PCOS) are related. Not only is vitamin D deficiency more common in women with PCOS, the deficiency may contribute to the insulin resistance, obesity, and metabolic syndrome that frequently occur with PCOS.
Vitamin D has been shown to increase the expression of the FSH (follicle stimulating hormone) receptor on the ovaries. This means that when the brain is releasing FSH in order to grow a dominant ovarian cyst which will ovulate an egg each cycle, vitamin D is priming the ovaries to receive that signal by increasing the receptors. Without a dominant ovarian follicle releasing an egg, ovulation does not occur.
Since infertility is increasing in prevalence and frequently encountered by women with PCOS, vitamin D could be playing a crucial role in the balance of androgens and estrogens and proper cycling.
I recently started checking vitamin D status on PCOS patients, whether I’m diagnosing them with PCOS or they’ve come to me already with a diagnosis. I’m finding they are low or deficient.
In a randomized, blinded controlled trial (the epitome of scientific study design) of women with PCOS and vitamin D deficiency, the group receiving vitamin D supplementation had improved metabolic markers: fasting glucose, insulin, HOMA-IR. Another study showed that vitamin D deficient PCOS patients who were supplemented had improvements in testosterone levels, which are frequently elevated in the PCOS population.
Vitamin D also acts as an antioxidant, counteracting the higher levels of oxidative stress seen in PCOS patients.
Pregnancy
The fetus is entirely dependent on maternal vitamin D.
Before a pregnancy is clinically recognizable, vitamin D is critically important in the implantation process of a pregnancy into the uterus. I have a patient taking 4,000 IU of vitamin D3 through a Reproductive Immunology practice. This is higher than most prenatal vitamins which contain 400 to 1,000 IU.
Vitamin D has been found to increase estrogen and progesterone production by human placental cells.
Many observational studies have confirmed low vitamin D levels in patients with pre eclampsia. There are randomized controlled trials showing that vitamin D3 can decrease the risk of pre-eclampsia and fetal growth restriction. Beyond the pregnancy, deficiency in mom can lead to offspring disorders like asthma, insulin resistance, diabetes
Perimenopause
This is the term to describe the time and process that occur to lead up to menopause as well as the first year of menopause (the first year after the last period). There is increasing awareness among the general population of this process and many women feel validated and educated about symptoms that can be attributed to perimenopause.
While awareness is beneficial, I don’t agree with the acceptance of a chaotic time period as our fate. Social media posts can be entertaining and funny in a “it’s funny because it’s true” way that speaks to many symptomatic women but I don’t think we are exonerated from some agency we have over our symptoms.
In one small study of women between the ages of 45 and 65, 78% had below normal levels of vitamin D.
Our ovaries have receptors for vitamin D and even house the enzyme that makes the active form of vitamin D. This enzyme is found in the kidneys where we attribute much of the production of active vitamin D but it is also found in the brain, breast, prostate, colon and the ovaries. This suggests that these organs have a biological need for active vitamin D because they can create it themselves.
It follows from the PCOS discussion of vitamin D and its role in making our steroid hormones that it can be involved in perimenopause as well.
Since vitamin D increases the sensitivity of the FSH receptor on the ovarian cells responsible for ovulation, adequate vitamin D can help maintain proper cycling.
For some women in perimenopause, getting pregnant may still be a consideration beyond trying to control new hormonal symptoms. Vitamin D has also been shown to positive effect ovarian reserve, often marked by anti-mullerian hormone. Whether this finding translates into improved pregnancy rates and outcomes remains to be seen.
Vitamin D also increases the production and release of progesterone, the hormone we naturally make to support a pregnancy and tends to have a calming effect on us. In perimenopause, low progesterone or an imbalance between estrogen and progesterone may manifest as common symptoms: anxiety, irritability, difficulty sleeping to name a few.
Menopause
We typically associate vitamin D (and calcium) with bone health and with good reason. This is particularly important for older menopausal women since our loss of estrogen with menopause leads to a decline in bone density. When bone density is measured as 2.5 standard deviations lower than a young comparison, osteoporosis is diagnosed. Over 70% of osteoporotic fractures occur in women. These are frequently debilitating either in short term or long term,
As we’ve seen, the effects of vitamin D are far more wide-reaching than just bone health and that continues into the menopausal decades.
Low vitamin D is associated with:
Inflammatory bowel disease
Metabolic syndrome
Type 2 Diabetes
Cardiovascular disease
Cancer
Depression
Impaired cognition
Increased mortality (dying)
In one meta-analysis, breast cancer risk was found to be reduced in women with vitamin D levels between 27 and 35 ng/mL, though above that level the risk wasn’t further decreased. This means there was a ceiling to the benefit, so more is not always better, but it was better to a certain extent.
These are not just problems of the menopausal population but several will have a higher prevalence in that population.
In conclusion,
I was interested in and researching vitamin D as it relates to women’s health before my unexpected controversial Instagram post where reactants stated that checking vitamin D is not in the guidelines. Guidelines are just that - guidelines. Clinical experience, learning and new knowledge should not be dismissed by guidelines.
To be clear, I generally follow guidelines. I know them. We also need to understand that science is imperfect and it is always changing, we have to have an open mind and change with it, maybe even incite the change, especially if we want to take the best care of people and optimize health rather than just follow protocols.
Resources:
Some of the information contained in this article is the result of my training, medical knowledge, and personal experience without a specific source to be cited.
https://www.sciencedirect.com/science/article/pii/S0002916522037674
Pawel Pludowski, Michael F. Holick, Stefan Pilz, Carol L. Wagner, Bruce W. Hollis, William B. Grant, Yehuda Shoenfeld, Elisabeth Lerchbaum, David J. Llewellyn, Katharina Kienreich, Maya Soni,
Vitamin D effects on musculoskeletal health, immunity, autoimmunity, cardiovascular disease, cancer, fertility, pregnancy, dementia and mortality—A review of recent evidence,
Autoimmunity Reviews,
Volume 12, Issue 10,
2013,
Pages 976-989,
Elisabeth Lerchbaum,
Vitamin D and menopause—A narrative review,
Maturitas,
Volume 79, Issue 1,
2014,
Pages 3-7,
Sassi F, Tamone C, D’Amelio P. Vitamin D: Nutrient, Hormone, and Immunomodulator. Nutrients. 2018; 10(11):1656. https://doi.org/10.3390/nu10111656
https://adc.bmj.com/content/103/9/901
https://my.clevelandclinic.org/health/diseases/22459-rickets
https://link.springer.com/article/10.1007/BF01623435
https://link.springer.com/article/10.1007/S00431-015-2524-6
https://www.mdpi.com/2077-0383/11/15/4509#B26-jcm-11-04509
https://www.thieme-connect.com/products/ejournals/html/10.1055/s-0043-107242
https://ppm.pum.edu.pl/docstore/download/@PUM1549d3675a2545f7a3a1efd6543c2296/Eur Rev Med Pharmacol Sci 2022, 3493-3505, CC-BY-NC-ND.pdf
