Acne Vulgaris
Acne vulgaris is a common dermatologic condition seen in the western hemisphere, with 40 to 50 million affected individuals in the United States annually.11,12 A landmark study that examined 1200 Kitavans from Papua New Guinea and 115 Aché individuals from a hunter-gatherer community in Paraguay found no cases of AV in either group.12 These findings have led to the speculation that AV may be associated with environmental factors, particularly the Western diet.
An investigator-blinded randomized clinical trial (RCT) explored the role of a low-glycemic diet compared to a carbohydrate-dense diet on improvement of AV lesions after 12 weeks.13 The results yielded a significant decrease in lesions in the low-glycemic group (mean [SEM], −23.5 [−3.9]) vs the control group (−12.0 [−3.0])(P=.03). Furthermore, the results indicated a significant decrease in weight (P<.001) and body mass index (P=.001) with an improvement in insulin sensitivity in the low-glycemic group vs the control group.13 Kwon et al14 conducted a similar investigator-blinded parallel study with 32 participants receiving either a low-glycemic diet or continuing their normal diet for 10 weeks. Participants in the low-glycemic group demonstrated a significant reduction in mean noninflammatory lesions (−27.6% [P=.04]) and mean inflammatory lesions (−70.9% [P<.05]). Histologic image analysis showed a significant decrease in the mean (SEM) area of sebaceous glands in the low-glycemic group (0.32 [0.03] mm2) compared to baseline (0.24 [0.03] mm2)(P=.03). At 10 weeks, immunohistochemical specimens showed reduction in IL-8 (P=.03) and sterol regulatory element-binding protein 1 (P=.03), which regulates the synthesis of lipids.14 Thus, both studies concluded that a reduction in glycemic load may improve acne overall.13,14
Another study attempted to investigate the role of additional dietary supplements in improving acne. A double-blinded RCT explored the efficacy of omega-3 fatty acids or γ-linoleic acid compared to a control group in improving mild to moderate AV lesions through clinical and histological evaluations.15 The 10-week prospective study included 45 patients who were allocated to 3 matched groups and randomized to 3 treatment arms. They were given omega-3 fatty acids (1000 mg each of eicosapentaenoic acid and docosahexaenoic acid) or γ-linoleic acid (borage oil with 400 mg of γ-linoleic acid) or no intervention. After treatment completion, patients in both treatment groups showed significant reduction in mean inflammatory acne lesions, mean noninflammatory acne lesions, and mean acne severity (all P<.05), while the control group showed no significant reduction in acne lesions or acne severity. Furthermore, hematoxylin and eosin and IL-8 immunohistochemical staining of biopsies from the affected areas showed significant reduction of inflammation in both treatment groups (P<.05) but not in the control group. Therefore, the authors concluded that both omega-3 fatty acids and γ-linoleic acid could be used as adjuvant therapies in AV treatment.15
Atopic Dermatitis
The prevalence of atopic dermatitis (AD) in children ranges from approximately 9% to 18% across the United States.16 Pyridoxine, or vitamin B6, is an important water-soluble vitamin and a cofactor for numerous biochemical processes including carbohydrate and amino acid metabolism pathways and glucocorticoid receptor regulation.17,18 However, a double-blinded, placebo-controlled RCT failed to show efficacy of once-daily pyridoxine hydrochloride 50 mg in improving erythema, itching, or nocturnal sleep disturbance associated with AD in a cohort of 48 children. The investigators concluded that pyridoxine supplementation cannot be recommended to improve the symptoms of AD in children.19