The role of vitamin D in reproduction has been the subject of multiple studies in recent years. The health community has long been aware of the benefits of this essential vitamin, including its ability to promote calcium and phosphorus absorption in the body and facilitate bone growth and bone remodeling. Now there are indications vitamin D deficiency may negatively impact fertility.
Vitamin D is found in a limited number of food sources, such as fatty fish like tuna and mackerel. Many other foods are fortified with the vitamin. However, the body itself manufactures up to 90 percent of the vitamin D required for health.
When unprotected skin is exposed to the sun, the ultraviolet rays are absorbed, triggering the synthesis of vitamin D. For this reason, vitamin D is sometimes called the sunshine vitamin.
Without adequate vitamin D, bones can become thin, brittle and malformed. Vitamin D is also needed for cell growth and maintenance of normal immune system function. Inadequate levels of vitamin D are thought to play a role in cancer and various chronic illnesses including diabetes.
Rickets, a bone disorder associated with vitamin D deficiency that was common in the 19th century, is on the rise again – particularly in the UK. And a study published in the Archives of Internal Medicine in 2009found that up to 75 percent of US teens and adults were deficient in vitamin D.
Over the past decade, various studies have shown a link between vitamin D and fertility. Research has shown vitamin D deficiency may be associated with several disorders affecting female fertility including polycystic ovary syndrome, endometriosis, myomas and premature ovarian failure. Low vitamin D levels also may be associated with certain pregnancy complications including gestational diabetes.
There is some evidence that vitamin D deficiency in women negatively impacts IVF success, although a causal relationship has yet to be established.
Vitamin D deficiency is also a concern in male factor infertility, since the sunshine vitamin is vital to maintaining sperm quality, sperm count and adequate testosterone levels.
Although guidelines for vitamin D supplementation in fertility patients have yet to be defined, reproductive endocrinologists may recommend it for women whose vitamin D concentration falls below 30 ng/ml. Supplementation may be particularly advised for women with obesity,low ovarian reserve or insulin resistance.
Vitamin D supplementation may also be considered for male factor infertility related to oligospermia and asthenozoospermia.
