Well, more accurately, it helps to protect the smarts you’ve already got, an important task considering that we will all develop some degree of cognitive decline as we age and this deterioration can begin as early as the mid twenties.[fn value=2][/fn] Low blood vitamin D levels have consistently been linked with a decline in cognitive function.[fn value=3][/fn] [fn value=4][/fn] [fn value=5][/fn]Vitamin D may be especially important in protecting cognitive function as we age too.[fn value=6][/fn] No doubt the research to come on vitamin D and cognitive function will be exciting.

It is well known that vitamin D is necessary for strong healthy bones since it is required for calcium absorption and plays a role in ensuring that calcium is delivered to the bones, but it may improve muscle strength as well. Early in the 20^th century researchers began noticing that exposure to UV radiation (the same that is necessary for vitamin D production) had a positive influence on athletic performance. Today, modern studies have found that low vitamin D levels correlate with poorer physical performance, especially in older people. And a few studies have even found that supplementation with vitamin D improves strength, speed and overall physical performance.[fn value=7][/fn]

If you’re one who misses work a lot because you or your kids are sick, vitamin D might be your ticket to good-attendance redemption. One of the main functions of vitamin D is to modulate the immune system, supporting a healthy inflammatory response and stimulating the expression of anti-microbial peptides that support a healthy immune response in the respiratory tract.[fn value=8][/fn] Vitamin D levels within the normal range help to keep the immune system strong so it can better protect us from infections.[fn value=9][/fn]

Low vitamin D levels have consistently been linked to mood issues, such as feeling blue.[10] Although more research is needed, small preliminary human trials suggest that vitamin D supplementation helps to improve sense of wellbeing and support a healthy mood.[11][12] 

And if you’re still not convinced that you need to get your levels checked and supplement appropriately, let me remind you that low vitamin D levels are also associated with impaired metabolic and cardiovascular function and altered immunity.[13]  Considering that vitamin D receptors have been found in nearly all bodily tissues, it’s likely we’ll continue to hear more about the importance of this vitamin for a long time to come as more and more research continues to prove that vitamin D is critical to optimal human function.

*By the way, there is no agreed upon “optimal” blood level of vitamin D, however most experts suggest that 50-80 ng/mL is the sweet spot.[14][15] Ask your doctor to run a simple 25(OH)D test to make sure you’re there and, if you’re too low, be sure to supplement with adequate amounts of D3, which is the most bioavailable form.

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