Managing Vitamin D levels may increase your chance of a pregnancy.

Vitamin D deficiency is so common that it is reported that 80% of the population have a Vitamin D deficiency. It seems strange that this would be the case when we live in a sun-drenched country, so why is this so? Is it because we don’t get outside in the sun as often as we should?

Perhaps it’s because when we do get in the sun, we cover ourselves so as to reduce the risk of skin cancer that very little of our skin is exposed to the sun. Perhaps it’s because some people do not have the enzymes and hormones necessary to convert Vitamin D into such a format that the body can use.

Other known causes of Vitamin D deficiency are:

• Kidneys cannot convert vitamin D to its active form. As people age or those who consume excessive amounts of alcohol find that their kidneys are less able to convert vitamin D to its active form, thus increasing their risk of vitamin D deficiency.
• The digestive tract cannot adequately absorb vitamin D. Certain medical problems, including Crohn’s disease, cystic fibrosis, and celiac disease, can affect the intestine’s ability to absorb vitamin D from food eaten.
• Vitamin D is extracted from the blood by fat cells, altering its release into the circulation. People with a body mass index of 30 or greater often have low blood levels of vitamin D.

At the end of the day, whatever the reason, it has become apparent that low vitamin D levels may contribute to lower IVF success. Some studies have even gone as far to suggest that Vitamin D deficiency may cause depression and increase the chance for schizophrenia.

A recent study published in the Journal of Clinical Endocrinology & Metabolism (JCEM)¹ found that women who are deficient in vitamin D were half as likely to conceive with IVF compared to women without vitamin D deficiency. What this means for you is, if you are planning a pregnancy either naturally or with assistance it would be a good idea to go to your GP and get your Vitamin D levels checked.

Why Is Vitamin D So Important?

Vitamin D is a steroid hormone that is produced in the skin as a consequence of exposure to the sun; it is also absorbed from certain foods such as fatty fish, beef liver, egg yolks, orange juice and fortified milk and cereals. At the very basics, our body requires Vitamin D to absorb calcium; a deficiency of Vitamin D will eventually lead to calcium deficiency, which in turn is linked with further bone complications.

It is also thought that Vitamin D may assist in the production of eggs in the ovaries and improve the chances of the eggs being in optimum condition – which could assist the fertilisation process and subsequent embryo development – all of which are crucial steps that precede a pregnancy.

Vitamin D’s Impact On Pregnancy

Among women, Vitamin D appears to impact on vitro fertilisation (IVF) outcomes, endometriosis and polycystic ovary syndrome (PCOS), all of which are the most common female endocrine disorders that are seen to cause fertility issues. Vitamin D levels are also thought to assist in the body producing adequate levels of the hormones progesterone and oestrogen, which regulate menstrual cycles and improve the likelihood of successful conception. Low levels of progesterone in the second half of the menstrual cycle have been associated with decreased pregnancy rates, as adequate progesterone levels are needed so that the endometrium (lining of the uterus) is maintained in optimum condition for an embryo to implant.

PCOS and Vitamin D

Vitamin D deficiency is also commonly identified in women with polycystic ovary syndrome (PCOS), with 65–85% of women with PCOS having low levels. It has been suggested that Vitamin D deficiency may make the symptoms of PCOS worse, with some observational studies revealing that lower 25-hydroxyvitamin D levels (discussed in more detail below) were correlated with insulin resistance, ovulatory and menstrual disturbances, reduced pregnancy success, along with other symptoms often experienced by women with PCOS.

Testing Vitamin D Levels and Healthy Ranges

The most accurate way to measure how much vitamin D is in your body is the 25-hydroxy vitamin D 25(OH)D blood test. There are well-demonstrated health risks of very low 25(OH)D levels, less than 30 nmol/L, most of the decrease in risk is achieved by levels >40–50 nmol/L; with only small further gains achieved at higher levels.

Male Infertility and Vitamin D

In men, vitamin D is essential for the healthy development of the nucleus of the sperm cell, and helps maintain semen quality, function and sperm count. Vitamin D also increases levels of testosterone, which may boost libido.

The most natural and inexpensive way to get vitamin D is by exposing your bare skin to sunlight (ultraviolet B rays). Despite doing this, some people still have a Vitamin D deficiency, so for these people they may have to consider a visit to a naturopath or try using vitamin D supplements. Vitamin D3 is a good way to get vitamin D if you can’t get enough sunlight, or if you’re worried about tanning your skin.

If we have a well-balanced diet our body tends to get most of the vitamins and minerals from the food we eat. However, there are few food items which naturally contain Vitamin D. Even if it is present in the food, the amount is often negligible and as such, it’s very hard to get all the Vitamin D we need to function from food alone.

What Levels Are Acceptable?

Recommended daily intakes from various organisations:

Vitamin D Counci: 5,000 IU/day.

Endocrine Society: 1,500-2,000 IU/day.

In some patients, even after consuming 2,000 to 4,000 IU of Vitamin D3 per day, test results indicate that their Vitamin D3 levels have not increased. These patients needed to consume much greater levels of Vitamin D3 – even 8,000 IU per day to achieve proper blood levels. Patients should, therefore, have their GPs test their serum (blood) 1,25-dihyroxy D3 levels to determine the proper level of supplementation required. Testing for 1,25-dihyroxy Vitamin D3 levels should be a routine part of every person’s regular blood work.

¹Reference – Vitamin D Deficiency and Infertility: Insights From in vitro Fertilization Cycles. The Journal of Clinical Endocrinology & Metabolism, 2014; jc.2014-1802 DOI: 10.1210/jc.2014-1802