The beneficial effects vitamin D can provide are nothing short of amazing. So much so that optimizing your sun exposure, and hence the levels of vitamin D in your body, may indeed be one of the most crucial steps you can take in support of your long-term health.

I’ve discussed many of these benefits before (please see the related article links below), but now it turns out vitamin D may also play an important role in fertility.

Australian fertility specialist Dr Anne Clark found almost a third of the 800 infertile men included in her study had lower than normal levels of vitamin D, stating that:

" Vitamin D and folate deficiency are known to be associated with infertility in women, but the outcomes of the screening among men in our study group came as a complete surprise. Men in the study group who agreed to make lifestyle changes and take dietary supplements had surprisingly good fertility outcomes."

Previous studies, such as this one published in The Journal of Nutrition, found that although vitamin D deficient female rats were capable of reproduction, it reduced fertility by an astounding 75 percent, diminished litter sizes by 30 percent, and impaired neonatal growth.

What Causes Vitamin D Deficiency?

As Dr Clark said, concerns about skin cancer is likely one major contributing factor to the rampant vitamin D deficiency we now see around the world, along with indoor work, and other lifestyle choices that do not include direct sunlight exposure.

But evidence continues to mount in support of the obvious link between healthy vitamin D levels and getting the right amount of sunshine, which allows your body to produce it naturally. And unlike other medical fads that boomed and bombed, this evidence is very strong and keeps growing.

Why Too Little Sun May Be Far Worse Than Too Much

In fact, the concept questions the longstanding conventional belief that you should coat yourself with sunscreen whenever you're in the sun.

Vitamin D bears the nickname the "sunshine vitamin" because your skin produces it from ultraviolet ray exposure. Researchers now believe that slapping on sunscreen actually contributes to far more cancer deaths than it prevents, as doing so blocks this vital vitamin production.

Thus, while dermatologists and health agencies have long touted that such lotions are needed to prevent skin cancer, many scientists are now challenging that advice. Their main argument: Vitamin D is important for preventing at least 16 different types of cancer, including:

• Breast cancer
• Prostate cancer
• Lung cancer
• Skin cancer
• Colon cancer
• Lymphoma

So, even if too much sun can lead to skin cancer, which is rarely deadly, too little sun may be worse.

In fact, Dr. Edward Giovannucci, a Harvard professor, offered such compelling evidence in one of his studies -- vitamin D may prevent 30 deaths for each death caused by skin cancer -- that the American Cancer Society started reconsidering its own sun guidelines. Said Giovannucci in a previous interview with the Associated Press:

"I would challenge anyone to find an area or nutrient or any factor that has such consistent anti-cancer benefits as vitamin D. The data is really quite remarkable."

The mechanisms by which vitamin D reduces your risk of cancer are fairly well understood. They include:

• Enhancing calcium absorption (in the case of colorectal cancer)
• Inducing cell differentiation
• Increasing cancer cell apoptosis or death
• Reducing metastasis and proliferation
• Reducing angiogenesis

Fertility – What Does Vitamins Have to Do With It?

Now it seems we can add infertility to the list of health ailments that are made worse by too little sun exposure. But other vitamins and minerals can also be helpful in this area.

For example, did you know that vitamin C increases sperm quality and mobility?

Vitamin C -- In one study, infertile men who were given 1,000 mg of vitamin C twice daily improved their sperm count, sperm motility, and sperm morphology. The researchers stated vitamin C could be important as an additional supplement to improve semen quality and increase chances of a natural conception.

Vitamin E & Selenium -- Vitamin E and selenium can also improve sperm motility. One study published in the Archives of Andrology confirmed the protective and beneficial effects of vitamin E and selenium on semen quality, and supported their use in male infertility treatment. Men who are deficient in vitamin B12 can also suffer from poor motility (where the sperm don't swim very well) so it is thought that taking this vitamin may be helpful as well.

Zinc -- If low testosterone is the cause, zinc may help. In one study, 37 infertile men were given 60mgs of zinc a day for six weeks. 22 of the men with low testosterone dramatically increased their sperm counts and their testosterone, and 9 out of the 22 spouses became pregnant during the study.

As usual, if you want to try the vitamin therapy approach, I recommend you try to get most of your vitamins naturally, from the food you eat, and in the case of vitamin D, from the sun (as it is not naturally present in food).

Good sources of zinc include nuts and seeds. Vitamin C is abundant in oranges, strawberries and sweet potatoes. Vitamin B12 is found in butter, margarine, and eggs.

A whole food diet based on your nutritional type, and avoiding processed foods, is the best way to ensure you’re getting sufficient amounts of essential vitamins and minerals.

You should also be aware that certain drugs can interfere with your vitamin D absorption and metabolism, including cholestyramine (Questran), Dilantin, and phenobarbital.

Additionally, because vitamin D is a fat-soluble vitamin, any drug or substance that interferes with fat absorption may cause problems, as may a low-fat diet.