A dermatologist takes 5 supplements every day that help with smooth skin and anti-aging

• Dr. Azadeh Shirazi is a dermatologist based in California.
• She takes five supplements daily to help her skin stay smooth and glowy.
• They include a daily multivitamin, vitamin D, and nicotinamide.

As a dermatologist, Dr. Azadeh Shirazi knows the secret to glowy, smooth skin. The doctor, who is based in La Jolla, California, knows that for truly healthy skin, what goes inside your body matters as much as what you put on your skin.

That's why she takes several daily supplements, both for their skin benefits and anti-aging properties. Some of them also have other perks, like improving bone strength and reducing skin cancer risks, she told Insider.

Shirazi shared the five vitamins she takes for her skin every day.

Vitamin D

While Shirazi takes a multivitamin that already contains vitamins D and E, she takes extra supplements of each.

When she got bloodwork done three years ago, her vitamin D levels were low. Because Shirazi tries to avoid the sun to protect her skin, she started taking vitamin D supplements, which also have anti-aging properties.

Not only do vitamin D supplements reduce the need for prolonged sun exposure that can damage skin and lead to skin cancer, but Shirazi said they can slightly lower the risk of melanoma in women with a history of nonmelanoma skin cancer, according to a 2011 study.

She also emphasized that the older people get, the more they can benefit from vitamin D supplements. This is especially true for adults age 70 or older, according to the Mayo Clinic.

"As we age, our skin becomes less efficient at making vitamin D from the sun and our kidneys' ability to convert vitamin D to its active form is less effective," Shirazi said.

Vitamin E

Shirazi said that she also takes both vitamins D and E to boost bone strength. Vitamin E has been shown to prevent some bone loss in postmenopausal women.

"Our bones make up the scaffold that holds up our skin," she said.

Especially in women approaching their 40s and 50s, declining estrogen levels lead to greater bone loss, which Shirazi said makes extra supplementation very important.

Nicotinamide

The only vitamin Shirazi takes twice daily is 500mg of nicotinamide, a form of vitamin B3, which she said is currently popular in the skincare world.

"It helps improve skin barrier function by increasing ceramides, which is the glue that holds our skin cells together strengthening our skin barrier," Shirazi said.

As a result, it works as a powerful antioxidant and anti-inflammatory supplement that can help reduce redness and irritation caused by skin conditions like acne and rosacea.

Another perk is potential skin cancer prevention: a 2015 study found that people who already had skin cancer and took nicotinamide twice daily reduced the incidence of new skin cancers by 23%.

Shirazi said this is because "nicotinamide helps the skin replenish the body's DNA-repair enzymes" to help mitigate sun damage.

According to the National Institutes of Health, most Americans already consume more than the recommended dietary allowance of niacin (the generic name for nicotinamide) through their food.

Resveratrol

Shirazi takes resveratrol, a plant compound she said can be naturally found in many foods like grapes and peanuts.

Like nicotinamide, it has antioxidant properties, and "also helps brighten the skin's complexion and boosts elasticity," Shirazi said.

Resveratrol is also a popular supplement in the anti-aging world. David Sinclair, a Harvard biologist and anti-aging researcher, takes resveratrol supplements daily. But research is mixed on whether these supplements can actually improve longevity.

A multivitamin

Finally, Shirazi takes a daily women's multivitamin. She's been taking one for the last 20 years that contains "all the essential vitamins."

In particular hers includes zinc, which has "many anti-inflammatory properties, therefore improving many skin conditions such as rosacea, acne, and eczema," Shirazi told Insider.

The formula she uses also includes vitamin A, which she said "helps improve skin texture, reduce fine lines, and boost hyaluronic acid levels."

Vitamin A "also promotes cell turnover, reduces collagen breakdown, evens out your skin tone, and regulates oil production, which is helpful in acne," she said.