Vitamin D: Way More than a Sunshine Vitamin

“After you understand about the sun and the stars and the rotation of the earth, you may still miss the radiance of the sunset” - Alfred North Whitehead

Vitamin D, commonly defined as “the sunshine vitamin,” is a steroid hormone originating from cholesterol. So, although we think of Vitamin D as “vitamin” it actually functions more like a hormone, which has been shown to affect the expression of almost 1,000 different genes in the body by acting on multiple receptor sites. Normally, we convert ultraviolet rays striking our skin into the hormone vitamin D, which is further converted to its active compound in our liver and kidneys.

The form you typically consume (in food or supplements, or indirectly via the sun) is vitamin D3, but your body converts this into a steroid hormone, called calcitriol. Once vitamin D is turned into this active form, it travels throughout the body and plays a part in a number of diverse (and vital) functions: It builds bones and muscles; it also has anti-inflammatory effects, and helps to make enzymes and proteins that prevent diseases; it affects aging. As if that is not fascinating enough, nearly every cell and tissue in our body has vitamin D receptors (proteins that bind to vitamin D); and in its active form, vitamin D can interact with the vast majority of the body’s cells and even has an impact on aging by influencing DNA repair genes and anti-inflammatory genes to reduce damage of the telomere, which in turn shortens our biological age.

Few foods naturally contain vitamin D, which is mostly synthesized in human skin through sun exposure. As vitamin D is absorbed by the skin after exposureto ultraviolet B light, its synthesis is influenced by latitude, season, lifestyle and skin pigmentation. High levels of vitamin D have been linked to stronger immune systems, while low levels are associated with cardiovascular disease, diabetes, and cancer. 

It is generally thought that the main reasons why vitamin D3 levels have decreased over the last few decades is due to more sunscreen use and spending more time indoors on computers. Since UVB radiation from sunlight is required to produce vitamin D in the skin, anything that blocks UVB rays such as sunscreen will also prevent your skin from making vitamin D3.

Another possible contributing factor to low vitamin D3 is the increased obesity epidemic. Vitamin D3 is a fat-soluble vitamin, which means it is stored in our fat. A higher body fat percentage can decrease the bioavailability of vitamin D3 by as much as 50% by soaking up the vitamin D and preventing it from making its way to our other tissues. This means that overweight and obese individuals may have less vitamin D that is available to be used by the body.

Other factors that regulate the ability of the skin to make vitamin D3 include age (a seventy-year-old makes about four times less vitamin D3 from the sun than a twenty-year old); melanin, which acts as a natural sunscreen; and latitude, which dictates whether UVB rays can reach the atmosphere.

Vitamin D protects the gut barrier by regulating tight junction proteins and inhibiting intestinal apoptosis. Vitamin D enhances innate immunity by inducing antimicrobial peptides and regulates adaptive immunity by promoting anti-inflammatory T cells and cytokines. Vitamin D may also alter the gut microbiota. The prevalence of vitamin D deficiency in IBD is 30–40% and many have to take large amounts of the supplement to get their levels to budge into the normal range.

Low vitamin D is associated with increased disease activity, inflammation, and clinical relapse.  By contrast, vitamin D deficiency may lead to excessive immune cell activation in the gut and, thus, inflammation.

So get in the sun for a few minutes without sunscreen on, gaze at the beautiful sunsets without sunglasses on. Let that sunlight uplify your mood and serotonin levels, absorb that vitamin D, which is so essential to our proper and healthy functioning and do not be afraid of the sun. We have co-evolved with sunlight and would not be here without this amazing star. Eat your greens as they literally transform sunlight into energy. Foods that are high in chlorophyll act as a protection against harmful rays, so protect yourself from the inside out. Foods that are rich in chlorophyll include, spinach, collard greens, mustard greens, chlorella, spirulina, alfalfa, parsley, broccoli, green cabbage, asparagus, green beans and peas, matcha green tea. And if all of that fails? Vitamin D3 is readily available as 1,000, 2,000, 5,000 and 10,000 IUs in tiny gel caps, and is also available in drops.