- Many dermatologists and nutritionists are interested in understanding the connection between diet, nutrition, and dermatological health.
- A review that includes 150 studies has found that few rigorous randomized controlled trials have looked at these potential links.
- The authors conclude that despite the varying levels of association, diet and nutrition, with limited exceptions, do not modify dermatological conditions.
There is substantial interest in the relationship between diet, nutrition, and dermatological conditions. New research assesses the existing research literature.
The review reports that much of the evidence supporting such relationships is based merely on associations or laboratory studies rather than on randomized controlled trials, which are the gold standard for medical research.
The study is the work of lead author Dr. Kabir Sardana and senior investigator Dr. Soumya Sachdeva, both of whom are affiliated with Atal Bihari Vajpayee Institute of Medical Sciences and Dr. Ram Manohar Lohia Hospital in Delhi, India.
“While it is plausible,” write the authors, “that certain nutritional supplements may help, they may not transcend research settings to real-life clinical scenarios. Apart from the role of gluten in celiac disease, very few dietary factors have been irrevocably linked to disease in dermatology.”
After reviewing 150 published articles about diet, nutrition, and dermatology over the last 15 years, they report that the “data is not on a firm footing and leaves the dermatologist in a quandary and the patient confused.”
This is unfortunate, the authors say, since “[a] proper knowledge of the role of nutritional supplements in dermatological diseases can be a useful tool in advising the patients and, in certain cases, ameliorating the disorder.”
The review appears in JCD: The Journal of Cosmetic Dermatology.
Studies so far
“There have been interesting studies looking at the role of diet and/or specific supplements in acne, atopic dermatitis, psoriasis, vitiligo, [and] photoprotection, and as anti-aging agents,” dermatologist Dr. Patricia Farris told Medical News Today.
“And while every study may not meet the most rigorous study design criteria,” she continued, “the information gleaned from these studies can still be of value to dermatologists.”
Regarding the lack of randomized controlled trials, Dr. Farris explained:
“It’s important to remember that most of the large, randomized placebo-controlled studies are funded by manufacturers or pharmaceutical companies marketing the products being tested. In the case of foods or supplements, these treatments do not have to go through the FDA [Food and Drug Administration] approval process. Thus, there is little incentive for companies to undertake rigorous and expensive studies.”
There is another potential obstacle, as diet and dermatology expert Dr. Rajani Katta told MNT. ”We have a lack of safety data on supplements in general because manufacturers don’t have to investigate safety at all before bringing a supplement to market.”
The study’s assessment of existing evidence
“The lack of comparison of nutritional or dietary modification with conventional validated agents makes the data difficult to translate in real-world patient management,” say the authors.
The researchers found varying levels of evidence for significant associations of:
- a low glycemic diet with acne
- fish oil and weight loss with psoriasis
- fish oils and probiotics with atopic dermatitis
- vitamins and botanical extracts with vitiligo
They also found “scarce” evidence for the relationships that diet and nutrition have with bullous disorders and photoaging.
However, the review did find that a low histamine diet can be helpful for episodic urticaria and that hot and spicy food can trigger rosacea.
“Most of the role of diet in skin disorders,” says the review, “is at best adjunctive and is not disease-modifying.”
More rigorous research needed
Dr. Farris said to MNT, “Dermatologists should keep abreast of the literature as it relates to nutrition and supplements so that they can offer their patients a more holistic approach to treating skin disorders.”
Said Dr. Katta, “There are several supplements that I’m keeping a close eye on because preliminary studies have been promising.” She cites in particular:
- “The use of nicotinamide in the prevention of nonmelanoma skin cancer in people with a history of skin cancer.
- The use of prebiotics and probiotics in the treatment of atopic dermatitis — although we have a number of randomized controlled trials, translating the results of these trials to actual patient care has been challenging because the trials have used such different doses, types, and duration of supplement treatment.
- Studies of foods providing extra photoprotection, such as tomatoes and grapes.
- The use of zinc supplements for the treatment of acne — some preliminary studies have shown benefit, but again, with so many different forms, doses, and durations, it’s hard to translate the studies into practical treatment recommendations.”
The study’s authors are also concerned about the quality of supplements that companies are marketing.
“Notably,” they write, “there are various unapproved combinations, which are licensed as food supplements, making their composition and rationale difficult to discern in skin disorders.”
Dr. Katta also cautioned: “One important point about this review is that it is focused on published reports of efficacy, not on issues of safety. This is an important consideration since we have many reports of potential safety concerns with OTC [over-the-counter] nutritional supplements.”
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