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| DERMONUTRITION | ARTICLE


peroxisome proliferator-activated receptors (PPARs). The exact sequence of events and their interaction with other factors are still not well understood2,3


.


Acne and food: myth or reality? The relationship between diet and acne onset has always been a controversial topic over the years. A number of studies4


, carried out in diverse populations


from different societies and cultures, have shown that it is a very common belief that acne can be caused or exacerbated by diet, with chocolate and fatty foods implicated as the most frequent offenders. However, all reviews prior to 2007 have found no significant correlation between acne and diet, stating that this condition is primarily owing to genetic factors and hormonal influences4


. Recently, there has been much


more awareness on the cause-and-effect relationship between food and health and so, the association of some nutrients and acne has been called back into question. In fact, a range of population-based studies5, 6 have suggested that acne prevalence is lower in rural societies compared with Westernised populations, and diet is thought to be the main reason for this, suggesting that low fat intake and the absence of high-glycaemic index foods can explain the low presence of this skin condition in these populations. Furthermore, other studies have reported that acne


prevalence increases when migrations or cultural changes occur and populations adopt a Western diet, with increased acne lesions, increased weight, increased free-androgen index and decreased IGF-1 binding protein compared with patients following a low glycaemic-load diet6, 7, 8


. In particular, the evidence that


consumption of dairy products and high-glycaemic foods, such as carbohydrates, can exacerbate acne has been very compelling. Milk, and particularly skimmed milk (which also has a lower oestrogenic content), is the most common food implicated in acne flares, supporting the hypothesis that the disease can be caused by the presence of some hormones and other active substances ® not by its fat content. As a matter of fact, milk contains placenta-derived progesterone, 5α-reduction in steroid hormones and DHEA precursors, which can be processed in DHEA by specific enzymes available in the human pilosebaceous unit. Milk also contains a number of growth-stimulating


hormones, such as insulin and IGF-1 to a greater extent, that are capable of fostering ovarian, adrenal and testicular androgen synthesis and inhibiting hepatic synthesis of sex hormone-binding globulin (SHBG), affecting hair follicle (with hyperkeratinisation) and sebocyte growth with a comedogenic effect9


. In


addition, the whey component (20% of milk protein) and casein can raise insulin and increase IGF-1 respectively, as well as stimulating androgen production. An alternative hypothesis suggests that the iodine content of milk might also affect acne development10 With regard to fatty foods and high glycaemic index


.


foods, it has been proposed that they can cause acne by leading to hyperglycaemia and reactive


 Declaration of interest None  Figure image 1 ç Tripo and Ghersetich


Key points


n Acne is the most common skin condition in Western countries


n Acne is an inflammatory disease of the pilosebaceous unit, in particular of the sebaceous glands associated to skin hair follicles


n Acne is influenced by a genetic predisposition, but the onset of the disease is mediated by many environmental factors


n The evidence that consumption of dairy products and high- glycaemic foods can exacerbate acne has been very compelling


n Dermatologists cannot completely dismiss the association between acne and diet any longer


hyperinsulinaemia, increasing insulin resistance and activating an endocrine cascade that releases larger amounts of androgens and IGF-111, 12


. It is also generally


accepted that acne worsens with increasing sebum secretion and that these kinds of food may exacerbate this by increasing blood lipid levels with production of more comedogenic sebum, which has an altered composition (high levels of monounsaturated fatty acids rather than saturated) and is less fluid, leading to pilosebaceous follicle obstruction11, 12


. Regardless of this,


the available scientific data are insufficient to prove such correlations beyond any doubt. The question of whether chocolate worsens acne or


how omega 3 fatty acids, antioxidants, zinc, vitamin A and dietary fibre affect this skin condition still remains unanswered13


. However, studies examining the


hunterÐ gatherer diet, which is rich in seafood, wild plants and other important elements, have shown that an increased consumption of these nutrients may suppress inflammatory cytokine production and help reduce pore plugging, thereby having a therapeutic effect on acne13


. Therefore, their supplementation may be of value in the treatment of this disease.


Conclusions Despite the fact that more prospective studies are needed to solve such uncertainties, dermatologists cannot completely dismiss the association between acne and diet any longer14


. Counselling their patients to


reduce high-glycemic load and dairy product intake, for at least 6 months to evaluate the effect, could then be of help in the management of the disease.


References


1. Williams HC, Dellavalle RP, Garner S. Acne vulgaris. Lancet 2012; 379(9813): 361–72


2. Kurokawa I, Danby FW, Ju Q et al. New developments in our understanding of acne pathogenesis and treatment. Exp Dermatol 2009; 18(10): 821–32


3. Spencer EH, Ferdowsian HR, Barnard ND. Diet and acne: a review of the evidence. Int J Dermatol 2009; 48(4): 339–47


4. Di Landro A, Cazzaniga S, Parazzini F et al; GISED Acne Study Group. Family history, body mass index, selected dietary factors, menstrual history, and risk of moderate to severe acne in adolescents and young adults. J Am Acad Dermatol 2012 [Epub ahead of print]


5. Cordain L, Lindeberg S, Hurtado M, Hill K, Eaton SB, Brand-Miller J. Acne vulgaris: a disease of Western civilization. Arch Dermatol 2002; 138(12): 1584–90


6. Bowe WP, Joshi SS, Shalita AR. Diet and acne. J Am Acad Dermatol 2010; 63(1): 124–41


7. Simpson RC, Grindlay DJ, Williams HC. What’s new in acne? An analysis of systematic reviews and clinically significant trials published in 2010–11. Clin Exp


Dermatol 2011; 36(8): 840–3


8. Davidovici BB, Wolf R. The role of diet in acne: facts and controversies. Clin Dermatol 2010; 28(1): 12–6


9. Veith WB, Silverberg NB. The association of acne vulgaris with diet. Cutis 2011; 88(2): 84–91


10. Melnik BC. Evidence for acne-promoting effects of milk and other insulinotropic dairy products. Nestle Nutr Workshop Ser Pediatr Program 2011; 67: 131–45


11. Adebamowo CA, Spiegelman D, Berkey CS et al. Milk consumption and acne in teenaged boys. J Am Acad Dermatol 2008; 58(5): 787–93


12. Melnik BC, John SM, Schmitz G. Over-stimulation of insulin/IGF-1 signaling by western diet may promote diseases of civilization: lessons learnt from laron syndrome. Nutr Metab (Lond) 2011; 8: 41


13. Melnik B. Diet in acne: further evidence for the role of nutrient signalling in acne pathogenesis. Acta Derm Venereol 2012; 92(3): 228–31


14. Danby FW. Nutrition and acne. Clin Dermatol 2010; 28(6): 598–604


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