Within the last decade, almost 3000 articles have been published on the role of diet in the prevention and management of dermatologic conditions. Patients are increasingly interested in—and employing—dietary modifications that may influence skin appearance and aid in the treatment of cutaneous disease.1 It is essential that dermatologists are familiar with existing evidence on the role of diet in dermatology to counsel patients appropriately. Herein, we discuss the compositions of several popular diets and their proposed utility for dermatologic purposes. We highlight the limited literature that exists surrounding this topic and emphasize the need for future, well-designed clinical trials that study the impact of diet on skin disease.
The ketogenic diet has a macronutrient profile composed of high fat, low to moderate protein, and very low carbohydrates. Nutritional ketosis occurs as the body begins to use free fatty acids (via beta oxidation) as the primary metabolite driving cellular metabolism. It has been suggested that the ketogenic diet may impart beneficial effects on skin disease; however, limited literature exists on the role of nutritional ketosis in the treatment of dermatologic conditions.
Mechanistically, the ketogenic diet decreases the secretion of insulin and insulinlike growth factor 1, resulting in a reduction of circulating androgens and increased activity of the retinoid X receptor.2 In acne vulgaris, it has been suggested that the ketogenic diet may be beneficial in decreasing androgen-induced sebum production and the overproliferation of keratinocytes.2-7 The ketogenic diet is one of the most rapidly effective dietary strategies for normalizing both insulin and androgens, thus it may theoretically be useful for other metabolic and hormone-dependent skin diseases, such as hidradenitis suppurativa.8,9
The cutaneous manifestations associated with chronic hyperinsulinemia and hyperglycemia are numerous and include acanthosis nigricans, acrochordons, diabetic dermopathy, scleredema diabeticorum, bullosis diabeticorum, keratosis pilaris, and generalized granuloma annulare. There also is an increased risk for bacterial and fungal skin infections associated with hyperglycemic states.10 The ketogenic diet is an effective nonpharmacologic tool for normalizing serum insulin and glucose levels in most patients and may have utility in the aforementioned conditions.11,12 In addition to improving insulin sensitivity, it has been used as a dietary strategy for weight loss.11-15 Because obesity and metabolic syndrome are highly correlated with common skin conditions such as psoriasis, hidradenitis suppurativa, and androgenetic alopecia, there may be a role for employing the ketogenic diet in these patient populations.16,17
Although robust clinical studies on ketogenic diets in skin disease are lacking, a recent single-arm, open-label clinical trial observed benefit in all 37 drug-naïve, overweight patients with chronic plaque psoriasis who underwent a ketogenic weight loss protocol. Significant reductions in psoriasis area and severity index (PASI) score and dermatology life quality index score were reported (P<.001).18 Another study of 30 patients with psoriasis found that a 4-week, low-calorie, ketogenic diet resulted in 50% improvement of PASI scores, 10% weight loss, and a reduction in the proinflammatory cytokines IL-1β and IL-2.19 Despite these results, it is a challenge to tease out if the specific dietary intervention or its associated weight loss was the main driver in these reported improvements in skin disease.
There is mixed evidence on the anti-inflammatory nature of the ketogenic diet, likely due to wide variation in the composition of foods included in individual diets. In many instances, the ketogenic diet is thought to possess considerable antioxidant and anti-inflammatory capabilities. Ketones are known activators of the nuclear factor erythroid 2–related factor 2 pathway, which upregulates the production of glutathione, a major endogenous intracellular antioxidant.20 Additionally, dietary compounds from foods that are encouraged while on the ketogenic diet, such as sulforaphane from broccoli, also are independent activators of nuclear factor erythroid 2–related factor 2.21 Ketones are efficiently utilized by mitochondria, which also may result in the decreased production of reactive oxygen species and lower oxidative stress.22 Moreover, the ketone body β-hydroxybutyrate has demonstrated the ability to reduce proinflammatory IL-1β levels via suppression of nucleotide-binding domain-like receptor protein 3 inflammasome activity.23,24 The activity of IL-1β is known to be elevated in many dermatologic conditions, including juvenile idiopathic arthritis, relapsing polychondritis, Schnitzler syndrome, hidradenitis suppurativa, Behçet disease, and other autoinflammatory syndromes.25 Ketones also have been shown to inhibit the nuclear factor–κB proinflammatory signaling pathway.22,26,27 Overexpression of IL-1β and aberrant activation of nuclear factor–κB are implicated in a variety of inflammatory, autoimmune, and oncologic cutaneous pathologies. The ketogenic diet may prove to be an effective adjunctive treatment for dermatologists to consider in select patient populations.23,24,28-30
For patients with keratinocyte carcinomas, the ketogenic diet may offer the aforementioned anti-inflammatory and antioxidant effects, as well as suppression of the mechanistic target of rapamycin, a major regulator of cell metabolism and proliferation.31,32 Inhibition of mechanistic target of rapamycin activity has been shown to slow tumor growth and reduce the development of squamous cell carcinoma.25,33,34 The ketogenic diet also may exploit the preferential utilization of glucose exhibited by many types of cancer cells, thereby “starving” the tumor of its primary fuel source.35,36 In vitro and animal studies in a variety of cancer types have demonstrated that a ketogenic metabolic state—achieved through the ketogenic diet or fasting—can sensitize tumor cells to chemotherapy and radiation while conferring a protective effect to normal cells.37-40 This recently described phenomenon is known as differential stress resistance, but it has not been studied in keratinocyte malignancies or melanoma to date. Importantly, some basal cell carcinomas and BRAF V600E–mutated melanomas have worsened while on the ketogenic diet, suggesting more data is needed before it can be recommended for all cancer patients.41,42 Furthermore, other skin conditions such as prurigo pigmentosa have been associated with initiation of the ketogenic diet.43