By Silvia Carli
Dubbed the Sunshine Vitamin, vitamin D is a very important and often overlooked vitamin. Vitamin D benefits go beyond good bone health. It plays important roles in digestion, absorption, and even immunity. Its deficiency can affect both mental and physical health. A vitamin D deficiency can lead to brittle or misshapen bones and has been linked to depression.
Like most vitamins, vitamin D is a micronutrient that the body needs in small amounts to perform certain biological roles. It is a vitamin that is commonly found in meat and other animal products, but it can also be produced by the human body itself. Along with vitamins A, E, and K, vitamin D is one of the fat-soluble vitamins in the body.
Animal sources of vitamin D have the most bioavailable form, known as vitamin D3. Plant sources contain vitamin D2, which is the most common form found in supplements, fortified foods, and mushrooms specially grown in UV light. However, experts agree that it doesn’t really matter which form of vitamin D you’re getting since your body is capable of converting it as needed.
Its most commonly known role is to facilitate the absorption of minerals like calcium and phosphate. Hence, vitamin D plays a crucial role in bone synthesis. Vitamin D has other important benefits for cell growth, inflammation reduction, and proper immune function.
The most abundant sources of vitamin D are those produced within the human body and those contained in animal foods such as fatty fish. There aren’t very many naturally occurring plant sources for vitamin D apart from mushrooms that have been artificially exposed to UV radiation.
How does the body produce vitamin D? The human body contains vitamin D receptor cells that are activated when the skin is exposed to UVB radiation. When exposed to sunlight for a certain amount of time, humans can produce sufficient amounts of vitamin D.
However, this process requires direct exposure of skin to sunlight. You won’t get enough vitamin D by staying indoors close to a window, no matter how strong the sun is. This is because glass filters UVB radiation in sunlight, which is needed for vitamin D synthesis. Now, you might be wondering if using sunscreen, which blocks out UVB rays, lowers your vitamin D production. In this video, Dr. Rattan explains why sunscreen actually doesn’t hinder vitamin D production.
Animal sources that are abundant in vitamin D include:
The main role of vitamin D is in the regulation of calcium and phosphorus in the body. It helps to absorb calcium in the gut.
As these minerals are involved in bone mineralization and forming new bone tissue, vitamin D helps with maintaining and growing strong bones. There are strong links between vitamin D deficiencies and bone conditions such as rickets or osteoporosis in older adults. The regulation of calcium is also necessary for the muscles and the nervous system.
Another role of vitamin D is in a process called cell differentiation. This step comes after cell proliferation. Cell differentiation allows new cells to specialize in new functions or roles and is thought to reduce cell proliferation. This is why there may be a link between vitamin D deficiency and cancer because cancer involves unchecked cell proliferation.
Vitamin D also helps in insulin secretion. Some studies have shown that supplementing with vitamin D can reduce the risk of developing type 2 diabetes.
Another role of vitamin D that is gaining popularity is its regulatory role in immune function. Vitamin D is an important immune system modulator and acts locally in T-cells to regulate immune function.
It is thought that a vitamin D deficiency can reduce the efficacy of the immune system, even increasing the risk of autoimmune diseases such as multiple sclerosis. In one study, for example, women who had a vitamin D intake greater than 400 IU lowered their risk of MS by 40%. Another similar study showed that vitamin D deficiency can increase the risk of MS by 43%.
Of course, vitamin D alone does not provide enough benefits for good immune function—it needs to complement other important compounds like antioxidants. If you’re wondering how to boost your immune system, your approach needs to be holistic and cover both nutrition and emotional wellness.
The big questions now are how much vitamin D you need per day, and whether you can obtain the required amount naturally. The recommended daily intake of vitamin D is 600 IU for men and women between 19 and 69. For people over 70, the RDA is 800 IU.
Vitamin D deficiency is a huge problem around the world, affecting almost 1 billion people. Data shows that, even with supplementation, on average people only get about 308 IU a day. Of that, only 140 IU comes from food. So, to receive the benefits of vitamin D, it is essential to either supplement or ensure that you are exposed to enough sunlight. For athletes, the RDA for vitamin D is even higher, depending on their individual needs and sport.
It is also important to note that people with darker skin may have a harder time getting enough vitamin D because melanin prevents UV radiation from reaching cells that produce vitamin D. Hence, they may need to spend more time in the sun than those with lighter skin to produce the same amount of vitamin D. In either case, it is essential to wear sunscreen to prevent sun damage and increased risk of cancer.
There isn’t a clear consensus on how long you should be exposed to the sun to obtain adequate amounts of vitamin D. This is why a lot of people choose to supplement vitamin D. While you should try to obtain all vitamins naturally from your diet, vitamin supplements are really helpful for times when your diet or lifestyle may be suffering due to life events.
Vitamin D is a powerful micronutrient that aids bone density, immune function, and insulin secretion. While obtaining vitamins from food is the most bioavailable option, supplements can give people—especially older people who are at risk of bone diseases—a boost in vitamin D.