Is there a link between low vitamin D and PCOS?
Polycystic ovarian disease, or PCOS, is the most common hormonal or endocrine disorder that affects women of child-bearing age. PCOS is thought to affect between 3 to 10% of women between the ages of 18 and 40. While you might think that PCOS is only a disease of the ovaries, many women with PCOS will also have abnormal hormone levels as well.
Women with PCOS can suffer from infertility, weight gain, excessive hair growth (hirsutism) due to higher levels of testosterone, and in extreme cases, some women with PCOS can go on to develop Type 2 diabetes because of increasing insulin resistance.
Recent studies have shown that some women with PCOS also have low levels of Vitamin D (less than 25 ng/dl). Low levels of vitamin D have also been associated with women that have PCOS with insulin resistance and diabetes and increased cardiovascular risk markers (1)https://pubmed.ncbi.nlm.nih.gov/22574874/
Because of a possible link between low levels of vitamin D and PCOS, researchers have been looking at the impact of vitamin D replacement in women with PCOS. (2)https://pubmed.ncbi.nlm.nih.gov/29271278/
One study looked at the effect of giving a weekly Vitamin D supplement (50,000 IU) to women with PCOS and measuring any changes in blood glucose, insulin sensitivity, visceral fat, and adiponectin levels after just 8 weeks of Vitamin D replacement.
The women in the vitamin D and PCOS group showed improvement in their fasting glucose levels, insulin sensitivity, and adiponectin compared to the women that did not receive the weekly dose of vitamin D.
Adiponectin is a protein produced by adipose or fat cells in response to a starvation mode. In polycystic ovary disease, adiponectin levels are typically much lower and low circulating levels of adiponectin is thought to be related to developing insulin resistance, type 2 diabetes as well as other metabolic diseases.
Another study from Scotland looked at the relationship between Vitamin D and PCOS found that Vitamin D deficiency was more common in Scottish women with PCOS than women that did not have PCOS (3)https://pubmed.ncbi.nlm.nih.gov/21550088/
While these studies demonstrate a possible correlation between vitamin D and PCOS, it has been more difficult to determine if vitamin D supplementation helps PCOS symptoms or improves some of the hormonal changes seen with PCOS long-term until two more recent studies.
Women that have low levels of vitamin D an PCOS may have a higher incidence of insulin sensitivity and increased risk of developing Type 2 diabetes according to a 2020 study from the journal Frontiers in Endocrinology. (4)https://pubmed.ncbi.nlm.nih.gov/32296394/ In this study, the women with the lowest levels of vitamin D also had higher rates of insulin resistance and increased metabolic disease markers such as c-reactive protein and elevated total and LDL cholesterol and triglycerides.
Testosterone, Vitamin D and PCOS
Another vitamin D and PCOS meta-analysis study published in April 2020 in the journal of Experimental and Therapeutic Medicine (5)https://www.spandidos-publications.com/10.3892/etm.2020.8525 look at 11 previous studies on vitamin D and PCOS with a total of 483 participants.
In reviewing these 11 studies, the researchers found that vitamin D supplementation decreased testosterone levels, improved insulin resistance, and some cholesterol measurements in the PCOS and vitamin D supplement groups. There was no noticeable difference
Depression, Vitamin D and PCOS
Many women that have PCOS also suffer from depression and there does also appear to be a correlation between low levels of vitamin D and depression. (6)https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908269/ Just because researchers found that people with depression also have low levels of vitamin D, it doesn’t necessarily mean causation. The low levels of vitamin D may not have caused the depression (or the reverse, where depression causes the lower levels of vitamin D).
But there is research that shows that parts of the brain do have vitamin D receptors so there is continuing research looking at the impact of vitamin D on mood and memory.
Calcium, Vitamin D and PCOS
One problem with looking at the effect of a single supplement on a disease is many vitamins and minerals work synergistically and not in isolation. Vitamin D and calcium (as well as Vitamin K2 for heart health) often work together. Someone who is low in both vitamin D and calcium may not see much improvement if they only supplement vitamin D without also supplementing calcium. A 2015 study in the Clinical Nutritional journal looked specifically at the impact of supplementing either vitamin D, calcium or both in women with PCOS and found that the women that received both vitamin D and calcium supplementation for eight weeks had a more significant improvement in their insulin sensitivity than the women that only had either vitamin D or calcium supplemented. (7)https://pubmed.ncbi.nlm.nih.gov/25300649/
Should you take a Vitamin D supplement if you have PCOS?
Unfortunately, simply taking a daily vitamin D supplement won’t make your PCOS disappear overnight. That doesn’t mean that there are not some health benefits of taking a vitamin D supplement if you have low vitamin D levels, just don’t expect that vitamin D pill to magically reverse your PCOS as well.
The causes for polycystic ovarian disease are a little more complicated that replacing vitamin D with either more sun exposure or with a pill.
It’s important to remember that PCOS is fundamentally a metabolic disease that we believe is caused by insulin resistance that then sets off a cascade of other hormone dysfunction, ultimately ending up with infertility, weight gain, and excessive hair growth (hirsutism) due to higher than normal testosterone levels.
While medications can definitely help with most of the symptoms with PCOS, any treatment for PCOS should also focus on reversing insulin sensitivity as well.
I spend a lot of time talking with patients about making lifestyle changes with PCOS (and other metabolic diseases). Low carbohydrate diets like a well-formulated ketogenic diet can help with weight loss and PCOS. Intermittent fasting can help with weight loss and with improving insulin sensitivity.