Seven studies assessed diet (n>4,194), eleven assessed washing (n=689) and seven assessed sunlight exposure (n=673).
In terms of methodological quality, most of the studies had a small sample size, were uncontrolled, or were not blinded.
Two before-and-after studies and one crossover study found no association between chocolate consumption and acne, although high fat content of the placebo bar may have been acnegenic.
One cross-sectional study found no difference in sugar consumption between controls and acne sufferers, one found that 20- to 40-year-old acne sufferers were heavier (but not 15- to 19-year-olds) compared with controls, and one found that stress and self-assessed dietary quality were correlated with acne severity.
Facial hygiene and face cleansing.
Several studies found improvements in acne following the use of a medicated face wash, addition of an abrasive to the face wash, and medicated soaps. Other studies have been unable to identify the effective component of interventions.
Two RCTs, one CCT and two before-and-after studies found improvement associated with different light sources. One cross-sectional study found that there were more patients seen in the winter months, while another study found that a third had exacerbation of symptoms in winter, a third in summer and a third did not vary according to season.