Diet and Skin: What is the Evidence?

ORLANDO — Amid all the hype, claims, and confusion, there is evidence linking some foods and drinks to an increased risk for acne, psoriasis, atopic dermatitis, rosacea, and other common skin conditions. So, what is the connection in each case? And how can people with any of these skin conditions potentially improve their health and quality of life with dietary changes?

What is clear is that there has been an explosion of interest in learning which foods can improve or worsen skin issues in recent years. It’s a good idea to familiarize yourself with the research and also to Google ‘diet’ and ‘skin’, said Vivian Shi, MD, associate professor of dermatology at the University of Arkansas for Medical Sciences, Little Rock. “As practitioners, we should be well prepared to talk about what patients want to talk about.”

Acne

One of the major areas of interest is diet and acne. “We’ve all heard sugar and dairy are bad, and the Western diet is high in sugar and dairy,” Shi said at the annual ODAC Dermatology, Aesthetic & Surgical Conference.

Dairy, red meat, and carbohydrates can break down into leucine, an essential amino acid found in protein. Leucine and sugar together, in turn, can produce insulin and insulin-like growth factor 1 (IGF-1), which, through different pathways, can reach the androgen receptors throughout the body, including the skin. This results in sebogenesis, lipogenesis, and keratinization, which triggers follicular inflammation and results in more of the acne-causing bacteria Cutibacterium acnes. 

Milk and other dairy products also can increase IGF-1 levels, which can alter hormonal mediators and increase acne.

Not all types of dairy milk are created equal, however, when it comes to acne. Shi wondered why 2% milk has a very similar overall color and nutritional content to whole milk. “I looked into this.” She discovered that when milk manufacturers remove the fat, they often add whey proteins to restore some nutrients. Whey protein can increase acne, Shi added. 

“So, if you’re going to choose any milk to drink, I think from an acne perspective, it’s better to use whole milk. If you can get it organic, even better.” Skim milk is the most acnegenic, she said.

Psoriasis

A systematic review of 55 studies evaluating diet and psoriasis found obesity can be an exacerbating factor. The strongest evidence for dietary weight reduction points to a hypocaloric diet in people with overweight or obesity, according to the review. Other evidence suggests alcohol can lower response to treatment and is linked with more severe psoriasis. Furthermore, a gluten-free diet or vitamin D supplements can help some subpopulations of people with psoriasis. 

“An overwhelming majority of our psoriasis patients are vitamin D deficient,” Shi said. 

The National Psoriasis Foundation (NPF) publishes dietary modification guidelines, updated as recently as November 2023. The NPF states that “there is no diet that will cure psoriatic disease, but there are many ways in which eating healthful food may lessen the severity of symptoms and play a role in lowering the likelihood of developing comorbidities.”

Healthier choices include fruits, vegetables, whole grains, and fat-free or low-fat dairy products. Include lean meats, poultry, fish, beans, eggs, and nuts. Adherence to a Mediterranean diet has been linked to a lower severity of psoriasis.

Atopic Dermatitis

Atopic dermatitis (AD) is “one of the prototypical diseases related to diet,” Shi said. A different meta-analysis looked at randomized controlled trials of synbiotics (a combination of prebiotics and probiotics) for treatment of AD.

These researchers found that synbiotics do not prevent AD, but they can help treat it in adults and children older than 1 year. In addition, synbiotics are more beneficial than probiotics in treating the condition, although there are no head-to-head comparison studies. In addition, the meta-analysis also found that prebiotics alone can lower AD severity.

However, Shi said, there are no recommendations from the American Academy of Dermatology (AAD) on prebiotics or probiotics for AD, and the AAD does not recommend any supplement or essential oil for AD.

In a 2022 review, investigators ranked the efficacy of different supplements for AD based on available evidence. They found the greatest benefit associated with vitamin D supplementation, followed by vitamin E, probiotics, hemp seed oil, histidine, and oolong tea. They also noted the ‘Six Food Elimination Diet and Autoimmune Protocol’ featured the least amount of evidence to back it up. 

Rosacea

Rosacea appears to be caused by “all the fun things in life” like sunlight, alcohol, chocolate, spicy foods, and caffeine, Shi said. In people with rosacea, they can cause facial flushing, edema, burning, and an inflammatory response.

Certain foods can activate skin receptors and sensory neurons, which can release neuropeptides that act on mast cells in blood that lead to flushing. The skin-gut axis may also be involved, evidence suggests.

“And that is why food has a pretty profound impact on rosacea,” Shi said. 

Shi reported no relevant financial relationships.

Damian McNamara is a staff journalist based in Miami. He covers a wide range of medical specialties, including infectious diseases, gastroenterology and critical care. Follow Damian on X @MedReporter.

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