Irregular Cycles? Check Your Vitamin D

kali's picture

A new review released in March 2015, from the journal Reproductive Biology and Endocrinology, has shown that low vitamin D levels are related to a number of gynecological problems – PMS, uterine fibroids, painful or irregular periods and early menopause, to name a few.


We know of vitamin D’s importance for fertility, and I often test patients for vitamin D because of its huge role in a couple’s ability to conceive and carry a baby to full term.


Interestingly, the researchers suggested that the reason vitamin D has such a strong effect on gynecology is due to the influence that vitamin D has on the gene encoding for anti-Mullarian hormone (AMH).  AMH is a glycoprotein, a type of cellular messenger, that has many effects in both males and females.  In women specifically, AMH is associated with the number of eggs she has left in her ovaries – AMH declines as we age, to eventually undetectable levels around menopause.  It also has a role to play in egg development, which is why the researchers think vitamin D plays a role in menstrual regularity.


In the study, very low levels of 25(OH)-vitamin D (10ng/mL, or about 25nmol/L) was associated with 1.9 times the odds of having irregular menstrual cycles (p = 0.04).  Interpreted this way it makes more sense: a woman whose 25(OH)-vitamin D level was below 20ng/mL (about 50nmol/L) has almost two and a half times the odds of having irregular menstrual cycles when compared with women who are above 20ng/mL (p = 0.13).  These vitamin D values are in American units (ng/mL); I’ve added the conversion for the numbers to Canadian values (nmol/L).


Vitamin D also has a role to play in the production of androgens, male hormones like testosterone and DHEA, and with the regulation of insulin levels.  Thus, it could also be that by causing an imbalance in androgens and insulin, low vitamin D causes cycles become more irregular.  These effects on androgens and insulin are the reason that vitamin D is an especially important intervention for women with PCOS.


And of course, there are conventional ranges for vitamin D that are accepted (in Canada, 75-150nmol/L is considered adequate), and then there are the ranges that I like to see.  Functionally, a vitamin D level between 150-250nmol/L is necessary for proper hormonal balance and immune system function.  That’s why I want to test vitamin D levels - to find out if your levels are low, conventionally adequate, or functionally optimal.  In the study, they were looking at differences between women whose levels were 25-50mnol/L, which is very deficient!  I would love to see a follow up study where they bring these levels up and watch how the cycles change.


If you’re interested in having your vitamin D levels tested, feel free to ask me when you see me around at Acubalance, or book in for a free 15 minute consult and we can talk about its importance for your fertility and overall health.


In health,


Dr. Kali MacIsaac HBSc, ND
Naturopathic Doctor