They say you are what you eat, but it’s not quite that simple when it comes to healthy skin.

“People looking to improve their skin health may think that changing their diet is the answer, but a dermatologist will tell you that’s not necessarily the case,” says board-certified dermatologist Rajani Katta, MD, FAAD, a clinical professor of dermatology at McGovern Medical School at the University of Texas Health Science Center at Houston. “While diet can impact your skin in certain conditions, a lot of the information that’s out there on the web is not based on sound scientific research.”

Since anyone can post anything they want on the internet, the public should be wary of the information they find there, Dr. Katta says. Many websites are sponsored by companies trying to sell products, she says, so any recommendations they make should be taken with a grain of salt.

While individuals may post on blogs or social media about dietary changes that they believe made a difference for their skin, many other factors could have played a role in their situations, she says, and other people may not experience the same effects.

“You should not be making changes to your diet based on anecdotal evidence,” Dr. Katta says. “One success story is not enough to prove something will work for everyone.”

Among the biggest misconceptions related to diet and dermatology is an overemphasis on the role of food allergies in skin conditions, Dr. Katta says. While some food allergies can affect the skin, she says, they play a limited role in skin disease overall.

“Food allergies are not the cause of every skin condition,” she says. “People tend to blame them a lot more than they should.”

Gluten, in particular, may be mistakenly identified as a source of skin inflammation, Dr. Katta says. Those with inflammatory skin disease like psoriasis and eczema may cut gluten from their diet in an attempt to improve their condition, she says, but such a change would only make a real difference for those with a diagnosed gluten allergy or hypersensitivity.

“Gluten is not inherently inflammatory,” she says. “The vast majority of people can eat gluten without any problems.”

Dr. Katta warns against elimination diets in general because they could cause people to miss out on important nutrients or eat too much of other foods to compensate for what they’re cutting out. On the other side of the coin, she says, individuals should exercise caution in adding supplements to their diets. Because these substances are not regulated the way medications are, the claims on a bottle may not be verified by scientific evidence, she says, and the public should not just take those claims at face value.

“You can’t just pick a supplement up off the shelf and say, ‘This is going to work for me,’” Dr. Katta says. “In order for a supplement to be helpful, it needs to be the right supplement taken at the right dose for the right person. A board-certified dermatologist can help you determine whether a supplement would help your skin and explain how to take it correctly.”

A board-certified dermatologist also can help patients with skin diseases like acne and rosacea determine if there are any foods that may cause their condition to flare, Dr. Katta says, and if that’s the case, the doctor can recommend dietary changes that might be helpful. She recommends that those considering such dietary changes speak to their doctor first. In addition to providing an accurate diagnosis for patients’ skin conditions, she says, a dermatologist can explain what existing scientific research says—and doesn’t say—about how diet can affect the skin.

And while more research in this area is necessary, Dr. Katta says, the existing evidence does indicate that a diet supporting overall health also supports good skin health. “Nutrient-rich whole foods like fruits and vegetables, whole grains, and healthy fats are good for your whole body, and that includes your skin,” Dr. Katta says. “If you’re considering changing your diet for the sake of your skin, however, talk to a board-certified dermatologist first.”