Vitamin D: Fertility Vitamin?

Vitamin D impacts fertility in a variety of ways, and it’s definitely one of the top supplements I recommend for women and men who are trying to conceive. Here I discuss 4 different ways that vitamin D may impact fertility – PCOS, AMH, sperm quality, and IVF success rates:

1. Polycystic Ovarian Syndrome (PCOS): Women with PCOS are often vitamin D deficient with some estimates ranging from 67-85% of all women with PCOS having vitamin D levels below 20 ng/mL. This deficiency has been linked to metabolic disturbances including insulin resistance and infertility. Insulin resistance, in which the cells of the body become resistant to the actions of insulin, is an exacerbating factor in PCOS ^(1). If you have PCOS, get your vitamin D level checked pronto so a deficiency can be addressed as soon as possible.

2.  Low Anti-Muellerian Hormone (AMH): AMH is used as a measure of ovarian reserve, or put more simply a measure of remaining egg supply. The news of low AMH levels can be devastating for a woman as this measure is used as an indicator of low egg supply. However, there is some hope. A study has been done noting a correlation between AMH levels and vitamin D levels. What this means is that AMH is affected by vitamin D levels – that is, AMH may appear falsely low if you are vitamin D deficient. If you are vitamin D deficient and have a low AMH level, your AMH level is likely an inaccurate representation of your egg supply ^(2). Correcting a vitamin D deficiency and then retesting AMH may give you a more accurate representation of your ovarian reserve.

3. Sperm Quality: Two of the major parameters of sperm quality, motility (movement) and morphology (shape) may be affected by vitamin D levels. If sperm have low motility, it makes it harder for them to move towards and fertilize an egg. In a study of 300 men, those with higher blood levels (>30 ng/mL) of vitamin D tended to have a higher percentage of motile sperm. In addition, men who were vitamin D deficient generally had lower proportions of motile and normal morphology sperm. Animal studies have also noted low sperm counts and motility in vitamin-D deficient males. Sperm quality returned to normal with vitamin D supplementation ^(3).

4. IVF success: Higher blood levels (>30ng/mL) of vitamin D in women have also been correlated with higher pregnancy rates when doing in vitro fertilization (IVF). While the research isn’t completely clear on a mechanism, one of the mechanisms proposed is that vitamin D may affect implantation. IVF is such a stressful and expensive process, and ensuring your vitamin D level is adequate is one simple way to help increase your chances of success ^(4).

Because vitamin D seems to play such an important role in fertility, make sure to ask your physician to test your blood level of vitamin D. The appropriate test is 25(OH) vitamin D. If you are deficient, your physician can recommend appropriate supplementation and monitoring to make sure your vitamin D level gets into normal range. While the studies presented here note that vitamin D levels higher than 30ng/mL were associated with better fertility, some physicians recommend that the target for vitamin D should be higher at 60-70 ng/mL for optimum health and disease prevention. Unlike other vitamins, we can actually make vitamin D in our skin in response to sun exposure, in addition to getting vitamin D in the foods we eat. Food sources are limited, so read on to learn how to raise your vitamin D levels with a combination of sun, food sources, and supplements when needed.

1. Take at least 2000IU vitamin D daily. I recommend up to 4000IU for healthy people, since most have sub-optimal vitamin D levels. If you are pregnant or currently actively trying to conceive, keep the total dose of vitamin D from supplements at 2000IU unless specifically instructed by your healthcare provider to take a higher dose. Note that more is not always better. Vitamin D is a fat-soluble vitamin, so there is risk of toxic effects at very high doses. However, vitamin D is unlikely to be toxic in healthy people below a daily dose of 10,000IU, according to the Linus Pauling Institute ^(5).

2. Sun exposure. As little as 5-15 minutes of sun exposure on the arms and legs or face and arms from 11am-2pm in the fall, spring, and summer can significantly increase vitamin D levels without increasing risk for skin cancer, according Dr. Michael Holick ^(6). It’s important to note that sunscreen will block vitamin D synthesis, so sun exposure needs to be without sunscreen for short periods only. I am not advocating staying out in the sun for long periods of time without sunscreen. It is definitely important to protect your skin, but small short periods of sun exposure can do wonders for your vitamin D levels and may have a very positive impact on your fertility.

3. Eat foods that contain vitamin D like fish, egg yolks, and pork. The best fish to include are wild salmon, sardines, and tilapia, as these are also low in mercury. Egg yolks contain many beneficial nutrients like choline, vitamins A and E, in addition to vitamin D. Egg whites contain protein and little else, and thus I always recommend whole eggs and not egg whites. Grassfed dairy products also contain some vitamin D. Milk and milk substitutes like almond, coconut, or hemp milk are fortified with vitamin D. Steer clear of soy milk due to the phytoestrogen content.

Vitamin D plays a very important role in fertility through its impact on 1) PCOS, 2) AMH levels, 3) sperm quality, and 4) IVF success rates. Optimizing your vitamin D status can be effective way to help maximize your fertility. I would love hear from you! Has correcting a vitamin D deficiency been helpful (or not) for you? Are there other topics you’re interested in learning more about? If so, comment below, or email me at margaret@margaretwertheimrd.com.

References
1. Thomson RL, Spedding S, Buckley JD. Vitamin D in the etiology and management of polycystic ovary syndrome. Clin Endocrinol. 2012;77(3):343-350.
2. Osorio J. Vitamin D and AMH levels are correlated in human adults. Nat Rev Endocrinol. 2012;8:380.
3.  Blomberg JM, Bjerrum PJ, Jessen TE, et al. Vitamin D is positively associated with sperm motility and increases intracellular calcium in human spermatozoa. Hum Reprod. 2011;26(6):1307-1317.
4. Ozkan S, Jindal S, Greenseid K, et al. Replete vitamin D stores predict reproductive success following in vitro fertility. Fert Stert. 2010;94(4):1314-1319.
5. Vitamin D: Linus Pauling Institute at Oregon State University. Available at: http://lpi.oregonstate.edu/infocenter/vitamins/vitaminD/. Accessed February 16, 2014.
6. Holick MF. Vitamin D deficiency: what a pain it is. Mayo Clin Proc. 2003;78(12):1457-1459.