Vitamin D is such a misnomer...it's not a vitamin at all. Technically, vitamin D is a prohormone. It begins as 7-dehydrocholesterol in the skin, and when that reacts with UVB light, it is converted to D3 (cholecalciferol). The next steps take place in the liver and the kidneys, creating calcitriol, the active form.

It is so important in a multitide of bodily functions. My mother who is in her 70s recently went to her doctor, and he actually sent her for a blood test for her D3 levels. She takes calcium with vitamin D, a multivitamin and vitamin E, but as we age, the body's ability to use UVB to convert vitamin D to D3 decreases. Even if she gets decent sunlight, she could still be deficient. And experts estimate that a shocking 80% of the population is deficient. For darker skinned people, it's even harder to get enough vitamin D from sunlight as they need even longer exposure to sunlight for the conversion.

I'm not going to tell you that there is direct link between vitamin D and fertility, but because vitamin D is important in many other processes in the body, it plays an indirect role. We know about vitamin D's importance in cardiovascular function, cancer prevention, calcium and phosphorus levels, and even immune function.

Some recent studies do suggest a link between ovulatory function and vitamin D deficiency. PMS and PCOS have also been linked to low vitamin D levels. It is an interesting coincidence that in countries like Sweden that have dramatic differences in the amount of sunlight in the winter versus the summer, conception rates are highest in the summer, with higher birth rates in the subsequent spring.

The possible link for vitamin D and female fertility extends to men as well. Some research has shown that men benefit from increased vitamin D supplementation, too. It may improve sperm quality and quantity. Since virtually all tissues in the body have receptors for vitamin D, its importance can't be ignored.

The acceptable daily supplementation amounts of vitamin D are considered to be outdated. The upper limit is listed as 2000 IU, but most experts would push that to 10,000 IU/day. If you plan to take that much, you probably ought to get a D3 blood level after a few months of supplementing. It takes a while to build up, so give it at least 2 months. It is possible to become toxic on D3 supplements, but since most of us start at a very deficient level, you would have to take a lot for a long time to cause problems. Maybe, if you've been trying to conceive, some extra vitamin D is all you need!