(10-10-12) Diet and acne: a review of the evidence

Elsa H. Spencer, PhD, Hope R. Ferdowsian, MD, MPH, and Neal D. Barnard, MD

From the Washington Center for Clinical
Research, and Department of Medicine,
George Washington University School of
Medicine, Washington DC

Correspondence

Hope Ferdowsian, MD, MPH
Washington Center for Clinical Research
5100 Wisconsin Ave., Suite 400
Washington DC 20016
E-mail: [email protected]

Introduction

Acne vulgaris is the most common dermatologic condition in
the USA, affecting more than 17 million Americans of all
ages, although it is especially common in adolescents.1
Moreover, approximately 80?90% of American adolescents
experience acne.2 Severe acne is associated with low selfesteem, poor body image, social withdrawal, and depression.3
Pharmaceutical acne treatments are costly and have potentially
severe side-effects.

Adolescent acne is typically the result of clogged, infected,
pilosebaceous follicles. Adults may experience fewer
comedones and more inflammatory lesions.1 Normally,
sebum travels up the follicle to the skin surface. Hormones
may increase sebum production and cause follicular cells to
hyperproliferate and block the follicular opening, forming a
comedo.4 Complete follicle blockage results in closed
comedones (i.e. ?whiteheads?), whereas incomplete blockage
results in open comedones (?blackheads?). Comedo formation
typically occurs over the course of 2?3 weeks.

Acne may manifest in the form of noninflammatory
comedones, superficial inflammatory lesions (papules,
pustules), and/or deeper inflammatory lesions (nodules, cysts).
Inflammatory lesion formation occurs most commonly when
Propionibacterium acnes colonizes the pilosebaceous unit,
triggering follicular rupture and a neutrophil cascade.5
Rarely, acne may have nonbacterial causes.6

In studies of diverse populations, individuals with acne
commonly attribute the condition3,7?9 or its exacerbation3,7,8,10
to diet. Chocolate and oily or fatty foods are commonly
implicated;7,10?12 however, reviews prior to 2007 have concluded that diet plays no important role in acne and that the
condition is primarily attributable to genetic predisposition
and hormonal influences.13?15

Two large twin studies16,17 have reported on the heritability

of acne. Estimated heritability (genetic variance/phenotypic

variance) ratios for acne risk and severity range from 0.5 to

0.9 among adolescent16 and adult17 pairs of monozygous and
dizygous twins. Walton et al.18 reported that sebum excretion
is influenced by genetic factors, but that the development of
clinical disease is mediated by environmental factors. These
studies suggest that genetic factors alone do not fully account
for the acne risk. Despite the genetic regulation of sebum
excretion and other determinants of acne, environmental
influences, such as diet, may act as modifiers of gene expression. Recently, well-designed, controlled, prospective studies
have supported the association between specific dietary
factors and acne. We therefore critically examined the quality
and strength of the published literature examining the association
between diet and acne.


Conclusions

Evidence suggests that components of Western diets, particularly
dairy products, may be associated with acne. The hormonal
effects of dietary components, such as glycemic index levels or
fat or fiber intake, may mediate the effect of diet on acne risk.

Until 2005, cross-sectional, case?control, cohort, and clinical
intervention studies designed to address the relationship
between diet and acne typically failed to incorporate adequate
controls, objective measures, and appropriate statistical
analyses. Well-designed prospective studies published since
2005 have elucidated the mechanisms whereby particular
foods and dietary constituents may influence acne risk and
severity. In order to test the efficacy of dietary interventions,
prospective, randomized trials, including controls for
environmental stressors, acne medications, age, pubertal
stage, and age at menarche, are essential.


Source: The International Society of Dermatology International Journal of Dermatology 2009, 48, 339?347

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