How Important is Vitamin D?

Referred to as the “sunshine vitamin”, Vitamin D is one of the most important vitamins due to its role in a large variety of different physiological functions such as bone development, immune function, hormone production, and mood regulation. Although Vitamin D is produced naturally in the skin when in contact with direct sunlight, up to 42% of the American adult population has low Vitamin D levels. Let’s get into the importance of Vitamin D, and why you should be supplementing with it!

What is Vitamin D?

Vitamin D is a fat-soluble nutrient that is typically found in two forms, D2 (ergocalciferol) and D3 (cholecalciferol). Both forms can be found in a few foods such as some mushrooms (D2 form), and in dairy products, oily fish, and fish liver oil (D3 form). Other than dietary sources, Vitamin D can be found in dietary supplements or produced naturally when UV light hits our skin and triggers Vitamin D synthesis.

Why is Vitamin D important? 

Vitamin D plays an important role in a variety of different functions within the body that are essential for keeping us alive. Some of the most important functions of Vitamin D are normal development of bone, immune strength, and hormone/mood regulation. 

Supports Bone Development

Vitamin D is critical in the process of bone mineralization through the regulation of Vitamin D-dependent genes and calcium absorption. Once Vitamin D is consumed or produced through UV light exposure, it is transported into the cell where it turns on the expression of Vitamin D-dependent genes important for bone growth and calcium absorption. Vitamin D can also bind to receptors on intestinal cells in order to increase the absorption of calcium into intestinal cells, where calcium can then begin to play its role in bone formation. Without enough Vitamin D, the body can only absorb around 10-15% of dietary calcium. When Vitamin D levels are at adequate levels, calcium absorption increases to 30-40%. Calcium is a major component of bone, so efficient calcium absorption is essential for proper bone development.

Immune Health

Multiple research studies have shown the association between Vitamin D levels and its role in immune function. Once transported into the cell, Vitamin D regulates immunity genes that can enhance the antimicrobial effects of immune system cells within the body in order to fight off bacteria. Vitamin D also regulates the production of inflammatory proteins and inhibits the production of proinflammatory cells, both of which are part of the development of inflammatory diseases. 

Hormone/Mood Regulation

When vitamin D deficiency occurs due to inadequate intake of vitamin D or insufficient sun exposure, it causes an impairment in the regulation of steroid hormones known as glucocorticoids which results in elevated levels of these steroid hormones. Elevated levels of glucocorticoids are known to be implicated in major depressive disorders and various other mood disorders, together with other body functioning disorders. 

Vitamin D also has receptors within the brain that support overall neurological function as well as regulate the release and activation of key brain hormones known as neurotransmitters. These neurotransmitters can affect a variety of different psychological functions such as fear, pleasure, and joy. When there are inadequate levels of Vitamin D in the body, dysfunction in neurological function occurs which can contribute to mood disorder symptoms.

Should you supplement with Vitamin D?

Vitamin D is one of the most important vitamins to supplement with due to the many negative associations with Vitamin D deficiency. Multiple research studies have shown the association between low Vitamin D levels less than 20 ng/ml with an increased rate of infections, autoimmune disease, as well as mood disorders consisting of premenstrual syndrome (PMS), seasonal affective disorder (SAD), non-specified mood disorder, and major depressive disorder (MDD). Severe Vitamin D deficiency can also lead to a bone-distorting disease known as rickets in children, and in adults, an increase in bone fractures due to decreased bone mineral density,

Given the importance of having sufficient levels of Vitamin D for normal bodily functions, it’s highly recommended to supplement with a Vitamin D3 product.  D3 is the more powerful of the two types and raises vitamin D levels almost twice as much as D2. Although levels vary person to person, the National Institutes of Health recommends supplementing with roughly 400-800 IUs (10-20 mcg) of Vitamin D3.