Does vitamin D affect fertility and conception?

We all know it: too much sun should be avoided, right?  Well, avoiding sunlight altogether is not an option either, because we need vitamin D. Sufficient sunlight exposure not only helps plants grow. It also slows down our biological clock and keeps us in a good mood and a good overall state of health.

The absorption of sunlight through the skin doesn’t just provide a warming effect. It also leads to the synthesis of vitamin D, which, among many other processes in the body, is also important for fertility and reproduction. In general, vitamin D is associated with a variety of health benefits. 37 different tissues in our body have a vitamin D receptor and science has shown that vitamin D is responsible for controlling more than 1000 of our genes. It is also particularly relevant when it comes to cell growth and our immune system. In women who are trying to conceive, it seems to be associated with improved fertility and a healthy pregnancy. Because of this, it may be beneficial to screen all female patients for vitamin D deficiency.

Vitamin D deficiency can affect hormone production, ovulation and sperm production as it is involved in the synthesis of estrogen, progesterone, testosterone and sperm development. Vitamin D deficiency can, however, be subject to strong seasonal fluctuations. This means that a single test and a resulting low vitamin D status does not necessarily mean that a long-term vitamin D deficiency and associated symptoms are to be expected.

The following symptoms may indicate vitamin D deficiency in women:

• hair loss
• increased susceptibility to infections
• fatigue
• depressive moods
• muscle weakness, muscle pain and/or aching limbs
• cycle irregularities: especially with regard to delayed or missing ovulation.

Sunlight is essential for life and also plays a very important role if you want to have children. In a study with 129 women, scientists from Novosibirsk in Russia investigated the connection between female fertility and sunlight exposure. Compared to the winter months, they were able to show that in summer the release of follicle-stimulating hormone increases, the follicle size in the ovaries is significantly larger, the frequency of cycles with successful ovulation is higher and menstrual cycles are shorter. The activity of the ovaries is therefore higher in the summer months and sunlight has a direct influence on the length of the cycle. Various studies now clearly indicate that a sufficient intake of vitamin D can support fertility.

Vitamin D deficiency does not directly lead to infertility. However, science shows that women with an adequate supply of vitamin D have a 4 times higher pregnancy rate than women with a low supply of vitamin D. It is assumed that vitamin D has a beneficial effect on the uterine lining and its receptivity. This is of course very important for successful conception and a healthy pregnancy.

In a nutshell, studies show that women with higher vitamin D levels get pregnant more quickly than women with critically low vitamin D levels or a vitamin D deficiency. According to science, this applies to both natural conception and IVF treatments.

Many people don’t know it, but vitamin D also plays a large and important role in our hormones. For example, vitamin D is involved in the function of the thyroid gland, which regulates our calcium levels. For optimal function, the thyroid needs a good supply of vitamin D. Studies also indicate that vitamin D has an influence on the pituitary gland, which is responsible for the production of a number of important hormones. One study also showed that vitamin D is an important player in the synthesis of estrogen in the body.

Experts recommend that women with a vitamin D level of less than 24 ng/ml take 4,000 IU per day. For people with a vitamin D level of 24-30 ng/ml, it is recommended to take 2,000 IU per day. 

According to the latest findings, vitamin D levels between 30 ng/ml and 70 ng/ml are considered optimal target values.

Vitamin D plays a major role in successful implantation and maintenance of a healthy pregnancy. Its positive influence on fetal bone growth and healthy brain development should also be mentioned here.

Vitamin D also plays an important role in men’s health and fertility. Possible symptoms of vitamin D deficiency in men can be:

• hair loss
• increased susceptibility to infections
• fatigue
• depressive moods
• muscle weakness, muscle pain and/or aching limbs
• low testosterone levels

Yes, studies have shown that the sperm of men with high vitamin D levels were significantly more motile than those of men with low vitamin D levels or a vitamin D deficiency. At the 19th Congress of the European Society of Endocrinology in Lisbon, it was pointed out that supplementation with vitamin D can, indeed, improve sperm quality.

Men who struggle with low testosterone levels should get their vitamin D levels checked. Studies have shown that testosterone levels and healthy sperm production are closely linked to vitamin D levels. Higher testosterone levels lead to a stronger libido and can significantly improve male fertility. At the end of winter, men often have significantly lower testosterone levels than in high summer. Endocrinologists at Med Uni Graz were able to show in a study that vitamin D could be responsible for the fluctuations in testosterone levels associated with the time of year. Since a lack of testosterone is widespread and represents a high risk factor for numerous diseases and increased mortality, this finding could be of great importance for men’s health. 

Science already knows that there is a connection between low testosterone levels and a vitamin D deficiency. This is shown very clearly, for example, by the fact that there are pronounced seasonal fluctuations in testosterone levels and almost congruent seasonal changes in vitamin D levels. In studies, men with sufficiently high vitamin D levels had significantly higher testosterone levels than men with vitamin D deficiency.

When used sensibly and appropriately, vitamin D supplements are unlikely to be overdosed. An overdose can, however, result in what is called hypercalcaemia (an excessively high level of calcium in the blood). Excessive absorption of calcium was only observed in studies at a daily dose of 40,000 IU vitamin D3. The common recommended dose of 3000 – 5000 IU is significantly lower. Nevertheless, it is advisable to discuss these matters with a doctor you trust and to get your vitamin D levels tested as a basis.

Before you think about taking a vitamin D supplement, you should definitely test your current vitamin D level. Without a test, it is very difficult to accurately determine your individual needs. Finding out the optimal dosage in advance is really useful, so it is definitely worth getting that test done.