Vitamin D may be best known for its benefits within the body. Along with calcium, vitamin D helps protect against weak, brittle bones. Muscles depend on this fat-soluble vitamin to move and function properly, and your immune system needs it to combat bacteria and viruses. But researchers are also looking at the connections between vitamin D and seborrheic dermatitis, a form of eczema that causes itchiness and visible symptoms like greasy skin with scales or flaking (dandruff).

Here’s what you need to know about how much vitamin D your body needs and what researchers are learning about the role of vitamin D in seborrheic dermatitis.

Vitamin D: Where It’s Found and How Much We Need

Our bodies make vitamin D when our skin is exposed to the sun — that’s why vitamin D is called “the sunshine vitamin.” However, a number of factors can lower the amount of vitamin D that skin makes. These include:

• Clouds and smog — These can block ultraviolet B rays, reducing vitamin D production.
• Darker-colored skin — Melanin in darker skin acts as a natural sunscreen and reduces the skin’s ability to produce vitamin D​​​​​​.
• Aging — Older adults have a reduced capacity to synthesize vitamin D from sunlight​​​​.

Although sun exposure is essential for vitamin D production, too much can increase the risk of skin cancer.

Not many foods naturally contain vitamin D, although some are fortified with it. Supplements contain the vitamin’s two main forms, D2 and D3. Vitamin D2 (ergocalciferol) is produced in plants, and vitamin D3 (cholecalciferol) is made by the body or obtained from animal sources.

Vitamin D3 is slightly more potent than vitamin D2 and lasts longer, so doctors sometimes recommend it over vitamin D2 for people taking supplements. Some vitamin D supplements also contain calcium.

The best food sources of vitamin D3 are fatty fish, such as salmon and tuna, and fish liver oils. Egg yolks, cheese, and beef liver have smaller amounts. Vitamin D2 also can be found in certain mushrooms. Foods and beverages fortified with vitamin D include dairy products, orange juice, cereals, and many plant-based alternatives to cow’s milk, such as soy, almond, and oat milk.

The recommended daily amount of vitamin D for adults between ages 19 and 70 is 600 international units (IU). This may also be listed as 15 micrograms. For people 71 and older, the recommended amount is 800 IU (20 micrograms). It’s unlikely but possible to get too much vitamin D. Taking 60,000 IU a day for several months can lead to vitamin D toxicity, which is rare and potentially serious.

If your doctor believes you might not be getting enough vitamin D, they’ll order a blood test to measure the amount of the vitamin in your body. A 2023 study of more than 11,000 U.S. adults ages 50 to 79 showed that nearly 1 in 5 participants were deficient in vitamin D.

The Link Between Seborrheic Dermatitis and Vitamin D

There is some evidence that skin diseases such as psoriasis and eczema are related to vitamin D deficiency. When it comes to seborrheic dermatitis, researchers are exploring two key areas:

• Whether people with seborrheic dermatitis have lower blood levels of 25-hydroxyvitamin D (the main circulating form of vitamin D) than people who don’t have the skin condition

• Whether vitamin D might be useful to treat seborrheic dermatitis

A small 2023 study found that severe vitamin D deficiency occurred more often in people with seborrheic dermatitis compared with those who didn’t have the condition. A 2021 study with 289 participants revealed that the blood levels of 25-hydroxyvitamin D in people with seborrheic dermatitis were significantly lower than in others. The researchers also found a connection between low levels of 25-hydroxyvitamin D and more severe seborrheic dermatitis on the scalp.

One type of vitamin D treatment for seborrheic dermatitis that has received a fair amount of attention is vitamin D analogs (synthetic forms) such as calcipotriene. This topical (applied to skin) treatment is available alone and also combined with a drug called betamethasone. Calcipotriene cream, ointment, or foam can be prescribed to treat plaque psoriasis.

Early studies provided some encouraging results for treating seborrheic dermatitis with topical analogs of vitamin D, but later studies with more people weren’t as encouraging. A very small 2018 study found that a vitamin D analog topical gel paired with betamethasone for moderate to severe scalp seborrheic dermatitis helped with symptoms, but concerns about the study’s design dampened some researchers’ enthusiasm regarding the results.

No large-scale studies have explored vitamin D supplementation as a treatment for seborrheic dermatitis. Given the limited amount of information regarding the use of vitamin D for seborrheic dermatitis, be sure to talk to your dermatologist or health care provider before making any changes to your treatment regimen.

Treatment for Seborrheic Dermatitis

Scalp treatment for adults with mild cases of seborrheic dermatitis typically includes over-the-counter dandruff shampoos. For longer control, your doctor may recommend a prescription shampoo such as an antifungal (ketoconazole). Treatments that address affected areas on the face or body often include:

• Topical antifungals
• Corticosteroids
• Calcineurin inhibitors

A newer option is a topical foam version of roflumilast (Zoryve), a phosphodiesterase 4 (PDE4) inhibitor. It’s believed to work by blocking PDE4, an enzyme involved in the inflammation that leads to symptoms of seborrheic dermatitis.

Although there are many ways to treat seborrheic dermatitis, symptom relief can be elusive. “This dang seborrheic dermatitis takes up too much of our lives,” wrote one MySebDermTeam member. “It’s like a job — the first thing in the morning and the last thing at night. And sometimes, all the time in between.”

To better manage your seborrheic dermatitis, you might want to take these steps:

• Make healthy changes to your diet. While the foods you eat or avoid won’t provide a cure, a balanced eating plan can improve your overall well-being.

• Consider how weather affects your seborrheic dermatitis. If cold air is a trigger for you, wear a hat and scarf to protect affected areas of skin. If heat makes your symptoms worse, run air conditioning or fans to keep cool.

• Crowdsource ideas and consult your doctor for tips on reducing itch and feeling better.

Be sure to check with your doctor or dermatologist if you have questions about your vitamin D status or other aspects of living with seborrheic dermatitis. They’ll help you find the right treatment plan and lifestyle changes to help you manage your skin condition and have the best possible quality of life.

Talk With Others Who Understand

MySebDermTeam is the social network for people with seborrheic dermatitis and their loved ones. On MySebDermTeam, more than 12,000 members come together to ask questions, give advice, and share their stories with others who understand life with seborrheic dermatitis.

Are you living with seborrheic dermatitis? Have you tried vitamin D? Share your experience in the comments below, or start a conversation by posting on your Activities page.