Since 1950, the terms “diet and skin” in the medical literature have markedly increased, said Vivian Shi, MD associate professor of dermatology at the University of Arkansas for Medical Sciences, Little Rock, who talked about nutritional approaches for select skin diseases at MedscapeLive’s Women’s and Pediatric Dermatology Seminar.

Myths abound, but some associations of diet with skin diseases hold water, and diet tweaks could supplement treatments and improve results in patients with acne, hidradenitis suppurativa (HS), and rosacea, she said.

Acne

What’s known, Dr. Shi said, is that the prevalence of acne is substantially lower in non-Westernized countries, and that diets in those countries generally have a low glycemic load, which decreases IGF-1 insulinlike growth factor 1 (IGF-1) concentrations, an accepted risk factor for acne. The Western diet also includes the hormonal effects of cow’s milk products.

Whey protein, which is popular as a supplement, isn’t good for acne, Dr. Shi said. It takes a couple of hours to digest, while casein protein digests more slowly, over 5-7 hours. If casein protein isn’t acceptable, good alternatives to whey protein are hemp seed, plant protein blends (peas, seeds, berries), egg white, brown rice isolate, and soy isolate protein.

Dairy products increase IGF-1 levels, hormonal mediators that can make acne worse. In addition, industrial cow’s milk can contain anabolic steroids and growth factor, leading to sebogenesis, Dr. Shi said. As for the type of milk, skim milk tends to be the most acnegenic and associated with the highest blood levels of IGF-1.

Supplementing with omega-3 fatty acids and gamma-linolenic acid improved mild to moderate acne in a double-blind, controlled study. Researchers randomized 45 patients with mild to moderate acne to an omega-3 fatty acid group (2,000 mg of eicosapentaenoic acid and docosahexaenoic acid), a gamma-linolenic acid group (borage oil with 400 mg gamma-linolenic acid) or a control group. After 10 weeks in both treatment groups, there was a significant reduction in inflammatory and noninflammatory lesions.

Those with acne are more likely to be deficient in Vitamin D, research suggests. Researchers also found that among those who had vitamin D deficiency, supplementing with 1,000 IU daily for 2 months reduced inflammatory lesions by 35% after 8 weeks, compared with a 6% reduction in the control group.

Other research has found that those with a low serum zinc level had more severe acne and that 30-200 mg of zinc orally for 2-4 months reduced inflammatory acne. However, Dr. Shi cautioned that those taking zinc for more than 2 months also need a copper supplement, as zinc reduces the amount of copper absorbed by the body.

Dr. Shi’s “do’s” diet list for acne patients is a follows: Paleolithic and Mediterranean diets, omega-3 fatty acids, gamma-linolenic acids, Vitamin D, zinc, tubers, legumes, vegetables, fruits, and fish.

Unknowns, she said, include chocolate, caffeine, green tea, and high salt.

Hidradenitis suppurativa

Patents with HS who follow a Mediterranean diet most closely have less severe disease, research has found. In this study, those patients with HS with the lowest adherence had a Sartorius HS score of 59.38, while those who followed it the most closely had a score of 39 (of 80).

In another study, patients with HS reported the following foods as exacerbating HS: sweets, bread/pasta/rice, dairy, and high-fat foods. Alleviating foods included vegetables, fruit, chicken, and fish.

Dr. Shi’s dietary recommendations for patients with HS: Follow a Mediterranean diet, avoid high fat foods and highly processed foods, and focus on eating more vegetables, fresh fruit, corn-based cereal, white meat, and fish.

A retrospective study of patients with Hurley stage 1 and 2 found that oral zinc gluconate, 90 mg a day, combined with 2% topical triclosan twice a day, resulted in significantly decreased HS scores and nodules and improved quality of life after 3 months. Expect vitamin D deficiency, she added.

Lastly, Dr. Shi recommended, if necessary, “weight loss to reduce the inflammatory burden.”

Rosacea

Dietary triggers for rosacea are thought to include high-fat foods, dairy foods, spicy foods, hot drinks, cinnamon, and vanilla.

A population-based case-control study in China, which evaluated 1,347 rosacea patients and 1,290 healthy controls, found that a high intake of fatty foods positively correlated with erythematotelangiectatic rosacea (ETR) and phymatous rosacea. High-frequency dairy intake negatively correlated with ETR and papulopustular rosacea, which was a surprise, she said. And in this study, no significant correlations were found between sweets, coffee, and spicy foods. That goes against the traditional thinking, she said, but this was a Chinese cohort and their diet is probably vastly different than those in the United States.

Other rosacea triggers, Dr. Shi said, are niacin-containing foods such as turkey, chicken breast, crustaceans, dried Shiitake mushrooms, peanuts, tuna, and liver, as well as cold drinks, and formalin-containing foods (fish, squid, tofu, wet noodles).

As the field of nutrigenics – how genes affect how the body responds to food – evolves, more answers about the impact of diet on these diseases will be forthcoming, Dr. Shi said.

In an interactive panel discussion, she was asked if she talks about diet with all her patients with acne, rosacea, and HS, or just those not responding to traditional therapy.

“I think it’s an important conversation to have,” Dr. Shi responded. “When I’m done with the medication [instructions], I say: ‘There is something else you can do to augment what I just told you.’ ” That’s when she explains the dietary information. She also has a handout on diet and routinely refers patients for dietary counseling.

MedscapeLive and this news organization are owned by the same parent company. Dr. Shi disclosed consulting, investigative and research funding from several sources, but not directly related to the content of her talk.