Vitamin D: What Is It and Why Do We Need It?

black woman holding a bottle of Pharmanex Vitamin D3


What is Vitamin D?

Vitamin D is a unique vitamin that is synthesized by our body when our skin is exposed to sunlight. In fact, that’s where it gets the nickname, “the sunshine vitamin”. While we are theoretically able to get most of the vitamin D we need through sunlight, the reality is that for many of us, we don’t get enough. In fact, it is estimated that 88% of people globally have suboptimal vitamin D levels.


What causes vitamin D deficiency?

There are several different reasons some people don’t get enough vitamin D from sunlight alone. One of the biggest reasons has to do with seasonal changes. During the winter months of the year, those that live in the northern parts of the world, above the 37th parallel (anything north of Los Angeles CA, Arizona, Oklahoma, and North Carolina, along with most of Europe and half of China) do not get sufficient vitamin D from the sun because it is lower in the sky. This means they must get their daily vitamin D from other sources like food or supplements. Other factors that limit the body’s ability to make vitamin D from UV rays include limited time outdoors, using sunscreen, and wearing clothing that covers all or most of the skin. While spending more time in the sun without sunscreen or long sleeves can increase your vitamin D levels, it also increases your risk of getting a sunburn or skin damage. That's why one of the easiest ways to get your vitamin D is from supplements.


Benefits of Vitamin D

Bone Health

Vitamin D has several different health benefits. A big one is that it supports bone health. Vitamin D helps the body absorb the calcium we get from our diet (or supplements). When we don’t have enough vitamin D, our calcium absorption suffers. That, in turn, could lead the body to start taking calcium from the places that use it for long term health (like our bones) so that it can use it for short-term survival (like sending signals in our nervous system so that our muscles function properly). That leaves the bones vulnerable to damage in the long run.


two girls stretching on yoga mats


Skin Health

Vitamin D also helps support skin health and immune health. Our skin is the outside barrier that separates our body from the rest of the world. It not only helps to fight against water loss, but it also acts as a first line of immune defense against harmful microorganisms from getting directly into our body. We are constantly making new skin cells and as they reach the surface, they are sloughed off in a process sometimes called cell turnover. Vitamin D plays an important role in the proliferation and differentiation of skin cells. This means that it helps to make sure that skin cells are made at the right rate and that they differentiate into the right kinds of skin cells.


Immune Health

When it comes to immune function, many of our immune cells have vitamin D receptors. This allows them to play an important role in our innate or immediate immune response, along with our adaptive response. Vitamin D helps with proper differentiation of immune cells to make sure our immune system works properly.


Forms and Dose of Vitamin D

Although sunlight is often our main source of vitamin D, we can also get vitamin D from food or supplements. Food sources of vitamin D include fatty fish like tuna or salmon, mushrooms, milk, or other fortified foods. Dietary supplements can provide vitamin D in the form of D2 or D3. Although both forms are beneficial, vitamin D3 is generally more effective.


With vitamin D playing such an essential role inside the body, it’s important to make sure we are getting enough. The RDI (Reference Daily Intake) recommended by the US FDA is 20 mcg (800 IU) per day for adults and children over 4 years old. To give an idea of how much that is, a cup of fortified milk provides around 3 mcg of vitamin D, and certain kinds of fish like salmon or trout provide about 15 mcg.

mother and daughter cooking in the kitchen


Pharmanex Vitamin D3 is a quick and easy way to meet our daily needs for this important vitamin. It’s a delicious and easy-to-take meltaway tablet that is formulated with a unique vegetarian source of vitamin D3, shiitake mushrooms. Pharmanex Vitamin D3 provides a daily dose of 25 mcg (1000 IU) and contains zero artificial colors, flavors, or sweeteners. Pharmanex Vitamin D3 helps support your immune system, bones, and skin health.*


Whether you are spending more time in the sun, including more vitamin D rich foods in your diet, or simply taking a quality supplement make sure you are getting enough of this important nutrient!




*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.


Rebecca Major



Written by: 

Rebecca Major

R&D Communication & Education Manager