Vitamin D is essential for calcium absorption, bone growth, bone remodeling and preventing osteoporosis. It also plays an important role in modulating cell growth, reducing inflammation and aids the immune system. All of these functions are well known to scientists, but, new research suggests vitamin D may play an even bigger role in our body.

How does vitamin D affect sleepiness?

Lower levels of vitamin D are correlated with more daytime sleepiness, but only among black people, according to a recent study published in the Journal of Clinical Sleep Medicine. Researchers looked at a series of 81 sleep clinic patients who had sleep issues and nonspecific pain. Most patients were eventually diagnosed with obstructive sleep apnea. Their vitamin D levels were measured by blood sampling and sleepiness was measured based on the Epworth Sleepiness Scale.

They found that in patients with normal vitamin D levels, progressively higher levels of daytime sleepiness were correlated inversely with progressively lower levels of vitamin D.  Researchers noted that it is logical for race to play a role, as darker skin is an established risk factor for low vitamin D levels.

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Can it prevent respiratory infections?

Recent research has found that patients prone to infection that are given high doses of Vitamin D for a year significantly reduce their risk of developing respiratory tract infections, compared to their counterparts who did not receive the vitamin. The study, published in BMJ Open, was a double-blind randomized controlled trial with 140 volunteers who had respiratory infections for at least six weeks before the study began.

The volunteers were split into two groups – one group received 4000 IU daily of vitamin D3, the other group did not. They volunteers who received the vitamin had a 25 percent drop in respiratory tract infections. Researchers noted that fewer respiratory tract infections also meant fewer courses of antibiotics were needed for these patients.

Can vitamin D help osteoarthritis?

As much as helpful vitamin D can be, some things are just out of its reach. According to a recent study, taking vitamin D supplements will not improve pain relief or cartilage loss due to osteoarthritis in the knees. The study, published this month in JAMA, looked at 146 patients with osteoarthritis of the knee and split them into two groups.

 One group received 2,000 IU a day of oral cholecalciferol, while the other group took a placebo. Researchers checked cartilage volume loss by magnetic resonance imaging (MRI) and a pain scale to track pain. They found that though vitamin D levels rose in the group receiving treatment, it did not correlate with any better outcomes. Cartilage in both groups was reduced by about 4 percent by the end of the study.

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