If dull or thinning hair and less-than-glowing skin has you reevaluating your everyday beauty routine, then you might want to hold up a sec and consider this — vitamin D, or lack thereof, might be the source of your frustration.

It’s true: Research shows that the nutrient plays a hefty role in overall health. But what are vitamin D benefits when it comes to hair and skin? To help you learn more about how it plays a part in skin and hair health, we reached out to a dermatologist to find out everything you need to know about vitamin D.

What Is Vitamin D?

Here’s the gist: Vitamin D is a fat-soluble vitamin that is necessary for the proper function of our hair and skin, according to Dr. Joshua Zeichner, the director of cosmetic and clinical research in dermatology at Mount Sinai Hospital in New York City.

In fact, vitamin D promotes proper calcium absorption in your gut, according to the National Institutes of Health (NIH). This means the vitamin keep your bones from becoming thin and brittle, and — along with calcium — even thwarts against osteoporosis. Zeichner says the nutrient is even involved in cell turnover, which ultimately improves the appearance of skin.

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Does It Affect My Hair and Skin?

In addition to brittle bones and muscle weakness, a vitamin D deficiency can lead to changes in your mood, exhaustion, chronic pain, and unexplained infertility, according to Medical News Today. And Zeichner says that while the biggest health issue associated with vitamin D deficiency is weak bones, there may also be a link to the health of your hair and skin.

“We do not have good data proving that vitamin D deficiency directly affects the skin, however there are thoughts that it may be linked to everything from hair thinning to dry skin to acne,” he says.

During a recent study published in Dermatology and Therapy, researchers linked a lack of vitamin D to stress-related thinning hair (telogen effluvium), balding or hair loss, and even alopecia areata, an autoimmune condition that results in the immune system attacking the hair follicle.

And a 2018 study published in Skin Pharmacology and Physiology showed that a lack of vitamin D can lead to certain skin conditions, including psoriasis and atopic dermatitis.

Zeichner says prescription vitamin D creams — popular ones include Calcitrene, Dovonex, and Sorilux — are often used to treat conditions like psoriasis.

How Do You Get Vitamin D?

Sunlight plays a major role in helping your body to generate vitamin D, but not in the way you might think. In fact, doctors are quick to assure patients that obtaining vitamin D from sunlight does not mean laying out in the sun or using a tanning bed.

“One of the biggest challenges we’ve faced in dermatology and in the world of skin cancer prevention has been a lot of misinformation about vitamin D metabolism,” Dr. David J. Leffell, a Yale Medicine dermatologist and chief of Dermatologic Surgery, told a Yale Medicine publication. “There are claims that one needs to get a certain amount of sun exposure every day in order to produce enough vitamin D to be healthy. It’s just not true.”

Zeichner agrees, adding that you’re better off taking a vitamin D supplement or eating vitamin D-rich food to boost your levels. According to NIH, males and females ages one to 70 requires 600 IUs (10 micrograms) of vitamin D per day. Solid food sources of the vitamin include cod liver oil, salmon, swordfish, vitamin D fortified milk, sardines, and eggs.

As always, if you suspect a vitamin D deficiency might be the culprit behind your drab hair or skin, talk to a healthcare professional before making any dietary changes or taking a supplement.