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The main way our bodies absorb vitamin D is through the skin — when sunlight hits us.
Vitamin D deficiency is a phrase we've all heard before, but to which we probably rarely take heed. Every so often we might remember the vitamin supplement bottles we have stashed in our rooms somewhere, but by the time we get home from work each day, we've forgotten about them again.

More and more research is finding that a vitamin D deficiency isn't just bad for your bones - it also contributes to a variety of other disorders and chronic illnesses. Now, a new study points out that low levels of vitamin D actually increase mortality. The researchers out of the University of Copenhagen in Denmark have established for the very first time that there is a causal relationship between low vitamin D levels and higher mortality rates.

In the study, researchers used participants from the Copenhagen City Heart Study and the Copenhagen General Population Study and examined any genetic defects as well as their vitamin D levels through blood tests. They found that genes associated with low vitamin D had an increased mortality rate of 30 percent and a higher cancer-related death rate of 40 percent.

Past studies often left researchers with the unanswered question of the chicken or the egg. "In previous studies, a close statistical relationship has been established between low vitamin D levels and increased mortality rates," Børge Nordestgaard, clinical professor at the Faculty of Health and Medical Science at the University of Copenhagen, said in the press release. "However, the fact that vitamin D deficiency can be a marker for unhealthy lifestyles and poor health in general may have distorted the results."

For example, scientists didn't know if vitamin D deficiency was causing problems, or if people already had health issues that were causing vitamin D deficiencies. Could it be the unhealthy lifestyle of a patient that led to both vitamin D deficiency and other health problems?

"This led to our current study," Nordestgaard continued, "which was based on an examination of the participants' genes - genes which cannot be explained by unhealthy lifestyles."

Another study done recently found that low levels of vitamin D were associated with a higher chance of brain damage after cardiac arrest. Researchers found that 65 percent of cardiac arrest patients with vitamin D deficiencies had a poor neurological outcome after six months compared to only 23 percent of patients who had normal and healthy levels of vitamin D.

D Deficiency

Vitamin D, sometimes referred to as the sunshine vitamin, isn't usually naturally found in foods (except in small amounts in eggs and oily fish like salmon) - unlike a lot of other vitamins. Need some vitamin C? Eat some oranges or drink some OJ. Need more calcium to fortify your bones? Drink more milk. Easy. But vitamin D requires sitting in the sun for about 15 minutes per day. While this may be easy in the summer, the majority of the year - at least in many parts of the world - provides us with cold winters and heavy cloud-set skies, blocking the chance for our skin to absorb the much-needed vitamin D. This is why many North Americans and Europeans - especially those who wear sunscreen in the summer months or work in offices all day - are sorely lacking this vital vitamin.

Vitamin D is important because it regulates over 200 genes and is crucial for growth and development. There are two types: vitamin D2 (ergocalciferol) and D3 (cholecalciferol). Both can enter the body through sun exposure (about 50-90 percent of the vitamin D that we receive is through our skin, from the sun).

In 2010, researchers dubbed the global health problem "an ignored epidemic," noting that over a billion people worldwide are vitamin D deficient. They explained that vitamin D3 deficiency could lead to obesity, diabetes, hypertension, depression, fibromyalgia, chronic fatigue syndrome, osteoporosis, and neuro-degenerative diseases like Alzheimer's, in addition to some types of cancers like breast, prostate, and colon. Vitamin D3 also assists in maintaining the immune system, keeping your mood up and stable, and protecting the brain. So this little vitamin does a lot for our physical and mental state, meaning we ought to be more cognizant about getting our fill through sunlight, food like oily fish or egg yolks, or even through supplements.

"Our study shows that low vitamin D levels do result in higher mortality rates, but the best way of increasing vitamin D levels in the population remains unclear," Nordestgaard said in the press release. "We still need to establish the amount of vitamin D to be added, as well as how and when it is most effective: Should we get vitamin D from the sun, through our diet or as vitamin supplements? And should it be added in the fetal stage via the mother, during childhood or when we have reached adulthood?"

Click here to watch a video about the study and learn more about how it was conducted.