Vitamin D deficiency can be characterized by the following symptoms; general bone pain or muscle pain and weakness; muscle cramping; unexplained depression; fatigue; lack of concentration; mood swings; anovulation; low sperm motility; childhood asthma; sleep irregularities. Unchecked Vitamin D deficiency can lead to severe conditions involving the Cardiovascular, Musculoskeletal, and Neurological systems. If you are experiencing any of the above symptoms as well as infertility, you may have a level of Vitamin D deficiency.
There are many underlying causes associated with infertility, but there is one nutritional concern that seems to be popping up more frequently, Vitamin D deficiency. The common occurrence of Vitamin D deficiency, “the sunshine vitamin”, is a hot topic right now. The debate rages as to why so many people are testing low for this essential vitamin, 90% of which comes from our exposure to sunlight.
Vitamin D is a pro-hormone vitamin, meaning it is necessary in the production of reproductive hormones in both men and women. Vitamin D receptors have been found on male testes and sperm, the ovaries of women, and placenta. The research on how Vitamin D affects fertility is limited, but what they have found so far seems very promising. There have been several studies linking Vitamin and Polycystic Ovarian Syndrome, which is one of the most common causes of anovulation in women.
One such study, from the Yale University School of Medicine, concluded that of the women testes only 7% had normal Vitamin D levels. 
Dr. Lubna Pal, from Yale, said: "Of note, not a single patient with either ovulatory disturbance or polycystic ovary syndrome demonstrated normal Vitamin D levels; 39 per cent of those with ovulatory disturbance and 38 per cent of those with PCOS had serum 25OHD levels consistent with deficiency.
Another study found that Vitamin D worked as a modulator for implantation of the fertilized egg and formation of the placenta.  Which if deficient, could lead to miscarriage.
Researchers from Denmark found an increase in sperm motility when men with low sperm motility were given Vitamin D supplementation. 
So, how much Vitamin D do you need? Well, that varies depending on your age, skin type and underlying health conditions. The body can make between 10,000-20,000IU from sun exposure alone. Often those suffering from deficiencies will need to take high doses of vitamin D to alleviate their symptoms, but it is always best to consult a professional before taking any vitamin supplements.
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