by Dr Agilan Arjunan , Fertility Specialist, KL Fertility Centre (Malaysia)
We consume multivitamins as daily supplements. Of all the vitamins , Vitamin D is of particular interest in the world of infertility. Let me enlighten all my readers about Vitamin D and infertility.
Vitamin D or ‘sunshine vitamin’ is a group of fat-soluable steroid hormone , synthesized mainly by the skin on exposure to sunshine. Less than 10-20% of Vitamin D is obtained from diet ! Synthesis of Vitamin D in the skin is the major natural source of this vitamin.
When skin is exposed to ultraviolet light from sunshine, it makes Vitamin D which is inactive (D3) . This inactive Vitamin D then enters our blood stream and continue its journey to the liver. In the liver, through an enzymatic reaction, it is converted to 25-hydroxyVitamin D (25(OH)D). However, this form of vitamin D is still not physiologically active. It undergoes another enzymatic transformation mainly in our kidney to become 1,25-dihydroxyVitamin D (1
-25 (OH)2 D). This final form is active and now it is ready to carry out its duties.
Vitamin D is responsible for absorption of minerals from our gut , namely calcium, phosphate,iron, magnesium and zinc. Calcium and phosphate absorption from the gut maintains adequate level of these minerals in the body which in turn maintains normal health of our bones.
Vitamin D exert its actions via a ‘vehicle’ called Vitamin D receptors. This ‘vehicle’ is not only present in our gut and bones , but also present woman’s reproductive (fertility) organs such as ovary and uterus (womb). The expression of this ‘vehicle’ in woman’s reproductive organs clearly suggest that there is a role for Vitamin D in female reproduction.
Hey, wake up! Science class is over ..Now let me bring you to the more interesting part of our article :
How does Vitamin D affect woman’s fertility & How to get your daily Vitamin D.
Let’s go..
How does Vitamin D affect woman’s fertility
Generally , Vitamin D deficiency is defined as serum level less than 20 ng/ml. Value more than 30 ng/ml is considered normal and a value between 20-30 ng/ml is considered insufficiency.
Vitamin D affects a woman’s fertility by :
- Affecting woman’s ovarian reserve test
- Affecting ‘egg’ growth
- Affecting factors related to problems with ovulation in a woman with Polycystic Ovarian Syndrome (PCOS).
- Affecting treatment outcome of In-Vitro Fertilisation (IVF).
Lets look at it one by one.
Ovarian Reserve
For couples who has gone through fertility assessment , there might be familiar with the term ‘ovarian reserve test’. If you are a woman, you may have heard someone tell you to get pregnant and complete your family before you reach late 30s’ or else it will be difficult to do so at later age. Essentially, they are talking about a woman’s ovarian reserve.
What is ovarian reserve ? Ovarian reserve is a fertility term which means ‘ How many eggs a woman is left with’. So, ovarian reserve test measures indirectly how many eggs a woman has. Currently, the best ovarian reserve test in the market is called Anti-Mullerian Hormone (AMH).
A woman with a low AMH value has less eggs left in her ovaries compared to a woman with a normal AMH level. This test has less month to month variation compared to other test such as Follicle Stimulating Hormone (FSH) .
However, research has proven that AMH levels are altered by Vitamin D deficiency. A woman with Vitamin D deficiency has lower level of AMH. This means that this group of woman will has a lower AMH value which indirectly indicates that they have lower fertility when in fact their ovarian reserve is better than what the AMH shows.
Egg Growth
Every month in a woman’s menstrual cycle, few ‘eggs’ are chosen but only one will eventually grow. The rest of the eggs will die. What AMH does is it actually protects the pool of ‘eggs’ in a woman’s ovary. This means AMH prevents many ‘eggs’ from growing. This is where Vitamin D plays an important role. Vitamin D has been shown to counteract the repressive effect of AMH on the growing ‘eggs’. This action of Vitamin D helps the ‘eggs’ to grow and reach their maturation and ovulation.
Polycystic Ovarian Syndrome
Polycystic Ovarian Syndrome (PCOS) is one of the common causes of infertility. Woman with PCOS not only suffers from infertility but also has menstrual irregularities and obesity. A fertility specialist usually will tell a woman with PCOS , “ Well, you have many eggs but they are resistant to growth and ovulation. We need to give you some medications to boost your egg growth.”
What’ s the reason? A woman with PCOS produces a substance which in fact harm the growth of her ‘eggs’. This substance is called “Advanced Glycation End Products (AGE)”. AGE is pro-inflammatory ( in layman term, it causes harm). On the other hand, woman’s body also produces a protective substance called “ soluble receptor sRAGE”. sRage binds to AGE and prevents its harmful effect on the ‘egg’ growth. So where is Vitamin D is this equation? Vitamin D causes significant increase in sRAGE level in a woman with PCOS. This means a woman with PCOS and normal level of Vitamin D level is more likely to have ‘egg’ growth and ovulation than a woman with low level Vitamin D in her body.
Furthermore, scientific evidence points to the fact that a woman with PCOS is more likely to have low Vitamin D and this phenomenon also contributes to insulin resistant and obesity , which is common in PCOS.
In-Vitro Fertilization (IVF)
Every couple going through IVF will do everything possible to maximise their success rate. There are many advises to improve success rate such as body weight maintenance, acupuncture and good nutrients. Vitamin D has been shown to improve IVF success rate. Higher Vitamin D level is associated with higher clinical pregnancy rates. This again emphasises the importance of testing women’s Vitamin D level prior to IVF treatment.
Since Vitamin D has many positive influences in a woman’s journey to motherhood, how can a woman get enough of this vitamin ? Here are a few ways how you can achieve that..
- Sunlight : I know, I know.. we have spoken about it already. Just to add a few pointer. About 20-25 minutes of sunlight exposure daily is helpful. If you are dark-skinned, you get less Vitamin D from sunlight because your skin pigment blocks sunlight.
- Eat fatty fish such as salmon and tuna. In addition, you will get omega-3-fatty acids which is also very good for fertility.
- Mushroom. Certain mushrooms are grown in ultraviolet to produce Vitamin D. So next time you buy mushrooms, see if this is ‘Vitamin D mushroom’.
- Drink fortified milk. They contain Vitamin D.
- Eat egg yolk. Surprised? Yes, eat egg yolk as it contains Vitamin D. Of course, do not eat too many as it also contains cholesterol.
6. Vitamin D supplements. This is probably an easiest way to get Vitamin D into your system.
7. Ultraviolet lights and bulbs. This is similar to a tanning beds. This method is usually needed for someone who is at high risk of Vitamin D deficiency. For the majority, the above 6 methods will suffice.
Well, we have reached the end of my article. I hope you have learned about the importance of Vitamin D in infertility.