Vitamin D has a bigger impact on the skin, hair, and nails than you may even know. It's key to maintaining healthy skin, supporting thick and strong hair and nails, and keeping aging skin glowing. But knowing how much you actually need and how to get it can be tricky.
As a Dermatologist, patients ask me this question all the time: How much vitamin D do I need?
In reality, it depends. A general recommendation is that healthy adults take 2,000 IU (or 50 mg) of vitamin D daily. This value is also dependent on how much sun exposure one has throughout the day and certain risk factors that may prevent the absorption or production of vitamin D.
Benefits of Vitamin D
Soaking up some vitamin D can feel good—and it has so many benefits for your overall health. Vitamin D is a fat-soluble micronutrient that boasts anti-microbial, anti-inflammatory, and anti-proliferative effects in cells and tissues.
This means that vitamin D is essential to healthy wound healing, reducing inflammation, lowering risks of autoimmune disease, and even tackling hair loss. Those with a low vitamin D level may experience slower healing.
How Much Vitamin D Do I Need?
The amount of vitamin D you need depends on factors like your age, where you live, and your skin color.
Vitamin D and Aging Skin
Aging may reduce your body (and therefore your skin's) levels of vitamin D. As you age, your skin has a lower level of a vitamin D precursor in the epidermis (i.e., the top layer of the skin). This may be why hair and skin thinning and brittle nails tend to be a nuisance of aging. Not only does your skin have lower levels of vitamin D, but aging skin is actually less responsive to ultraviolet (UV) light, so when it comes to absorbing and promoting the formation of previtamin D3, your body is working more slowly.
Geographic Location
Studies have shown that your location has an impact on your vitamin D levels. The further from the earth's equator you live, the fewer UVB rays that reach you. For example, people living in Boston produce very little vitamin D in the winter months.
Skin Color
People of color typically have lower levels of vitamin D due to the melanin in their skin. Melanin is a natural substance that makes skin dark in color; the more melanin, the darker your skin. It also "competes" for UVB, limiting your body's absorption of vitamin D.
Sources of Vitamin D
The main source of vitamin D is, of course, the sun. UV light promotes the formation of vitamin D in your skin. With that being said, prolonged—and unprotected—sun exposure is not the answer for taking in vitamin D. Sun safety should always be front of mind to reduce your risks of sun damage and skin cancer.
According to the Journal of Pharmacology and Pharmacotherapeutics, 50 percent of the world's population is low in vitamin D. If your levels are low, talk with your physician about other ways to increase your intake and absorption. Foods like seafood, fish oil, eggs, dairy, and fortified products (like cereal, milk, and juice) are rich in vitamin D. Committing to a balanced diet will boost your overall health—your skin included.
Your physician can check your levels with a simple blood test and may recommend prescription or over-the-counter vitamin D supplements.
Role of SPF and Vitamin D Levels
Broad-spectrum sunscreen blocks both UVA and UVB rays—UVB rays, specifically, are important in your body's formation of vitamin D. There are several anecdotal reports suggesting a reduction of vitamin D levels with daily SPF use. So, is this a true statement?
While theoretically, yes, sunscreen may reduce your vitamin D intake, it's not a significant amount. There are no clinical studies to date showing that everyday SPF use can cause or lead to severely low vitamin D levels. So, keep up with the daily sunscreen habit and don't worry about it affecting your vitamin D levels.
Long story short, when it comes to keeping your skin, hair, and nails strong, make sure you maintain a healthy relationship with the sun. Get outside, stay protected, and soak up that vitamin D.
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