Diet and Acne

Let food be your medicine, and let medicine be your food. (Hippocrates)

Acne vulgaris is one of the most common skin conditions in the world – so much that it affects millions of people every year. Interestingly, recent epidemiologic studies have examined non-Westernised populations (e.g., Inuit, Okinawan Islanders, Ache hunter-gatherers, and Kitavan Islanders) and concluded that acne is rather rare amongst them. This is likely to suggest that diet and glycaemic load might play a pivotal role in the context of this condition. Since these communities adopted lifestyles with Western influences, cases of acne started to increase [1,2].

One of the studies demonstrated that there is, indeed, a link between diet and acne. This study suggested that the regular, long-term consumption of high glycaemic meals, which raise insulin concentrations, may induce chronic hyperinsulinemia and insulin resistance, increasing the levels of insulin-like growth factor 1 (IGF-1) and decreasing the levels of insulin­-like growth factor binding protein 3 (IGFBP-3). This process will foster keratinocyte (skin cells that rise to the surface of the skin) production as well as corneocyte programmed cell death [1,2,3]. Some symptoms that characterise acne, such as androgen-mediated sebum production levels (androgens = hormones that play contribute to the formation of male traits and reproductive activity) as well as inflammation, are also affected by diet. High levels of insulin and IGF-1 may stimulate the synthesis of androgens as well as increased sebum production [3].

In 2007, Smith et al. investigated the effects of a low-glycaemic diet on acne lesion counts in 43 males between the ages of 15 and 25 years. The experimental diet was put into practice throughout a 12-week period and took place in parallel with ongoing blinded skin evaluations. 25% of this diet’s energy sources would come from protein, whilst 45% would be proveninent from carbohydrates with low glycaemic indexes. The skin of the subjects undertaking this diet was compared (a comparison mainly focused on acne) with that of the ones whose diet was more abundant in carbohydrates and in which the food’s glycaemic index was not a factor taken into account. The participants consuming the diet with the controlled (lowest) glycaemic load experienced significant reductions in terms of their acne lesions, and their weight and body mass index tended to decrease as well. Plus, their insulin sensitivity improved. However, none of these effects seemed to be significantly experienced by the group of participants undertaking the carbohydrate-rich diet, whose glycaemic index was not monitored [1]. 

In the same study, a comparison between the impacts (on skin and, more specifically, on acne) of an experimental low glycaemic diet and those of a conventional, tendentially high glycaemic diet was established. Subjects following the experimental diet (in which the consumption of more fish was one of the main recommendations) exhibited lower acne lesion counts than the group consuming the conventional, high-glycaemic diet, over the 12-week period. The ones undertaking the low-glycaemic diet also experienced weight loss and androgen index decrease [1].

Further studies suggest that the consumption of fish (which contains anti-inflammatory fatty acids such as omega-3) exhibits the potential to have mitigating effects on acne. The consumption of fibres and fatty acids (particularly omega-3 – there seems to be an overall preference for omega-3 over omega-6 in this regard) as well as the removal (or, at least, reduction) of saturated fats from one’s diet are steps consistently recommended by nutrition and dermatology specialists in order to help tackle acne [1].

Milk consumption and acne

Throughout the years, the potential link between milk consumption and acne eruptions has been largely discussed. In Nurses Health Study II, questionnaires completed by teenage women who consumed a so-called “high school diet” in 1998, and who were diagnosed by physicians with severe acne in 1999 were analysed by Adebamowo et al. The authors identified the existence of a correlation between the consumption of whole and skimmed milk and acne aggravation. As per Adebamowo et al., this might be due to the hormones and bioactive molecules present in milk [4]. 

In 2006, Adebamowo et al.’s study reiterated their thesis according to which there is a link between milk consumption and acne by testing 6094 female subjects. These participants were between 9 and 15 years old and reported frequent milk consumption throughout the (long-term) course of the study (1996-1999). In 1999, they responded to questionnaires evaluating the degree of severity of their acne condition. It was, once again, possible to establish a causal relationship between acne development and milk consumption – likely due to the metabolic effects of milk [5].

In the context of another study outlined by the same authors [6], 4273 male subjects responded to dietary questionnaires between 1996 and 1998 as well as questionnaires focusing on teenage acne, in 1999. These reported a positive association between the consumption of skimmed milk and acne incidence. The authors attributed such findings to skimmed milk’s hormonal components and to the fact that these are likely to affect endogenous hormones.

Danby, one of Adebamowo’s co-authors in the above-mentioned studies, acknowledged the rather unnatural nature of humans (the ones in post-weaned stages) consuming the milk provenient of other species. The author has suggested that further qualitative and quantitative research is necessary to ascertain to what extent the steroid hormones in dairy products can influence acne [7]. He also emphasised that Perricone’s [8] dietary recommendations in order to tackle acne were based on the avoidance of dairy products, on the increase of anti-inflammatory food ingredients, and on ensuring the diet’s low glycaemic load.

Acne and iodine

A considerable number of studies has argued for the inexistence of a solid link between iodine consumption and acne. Nevertheless, one particular study supported that consuming iodine may lead to an aggravation of acne symptoms [9,10].

Adebamowo et al.’s piece of research, in which potential associations between dairy intake and teenage acne were explored, also contained a section focusing on iodine. In this context, the hypothesis formulated by Arbesman [11] was that milk’s iodine content may be a factor which contributes to the hormonal changes experienced by the teenage subjects who responded to the questionnaires and whose acne symptoms were reported as being severe.

Significant levels of iodine have been traced in milk in countries such as Denmark, Norway, Italy, the United Kingdom, and the United States. Variable levels of iodine in milk are likely to occur depending on seasonality, geographic location of production, as well as different milk production methodologies [12,13,14,15,16,17,18].

A piece of research conducted by Danby argues that the consumption of iodine by individuals with acne-prone skin could generate the excretion of this component through the sebaceous glands – a process likely to lead to the irritation of the pilosebaceous unit and, consequently, to acne flare-ups (i.e., acne breakouts) [19].

Acne and chocolate

It tends to be common belief that there is a connection between chocolate intake and acne breakouts. However, in this context, the actual culprit is not chocolate itself but, instead, the sugar present in chocolate. Sugar promotes the process of glycosylation of the proteins in one's skin, which may lead to wrinkle formation and photoaging / premature aging of the skin [20].

The influence of chocolate in acne-related conditions was analysed by Mackie & Mackie [21]. The authors examined the preparation of chocolate for eating and concluded that it mostly relies on the combination of sugar (sucrose) with chocolate liquor and cocoa butter. There may, occasionally, be traces of milk solids and lecithin (in a proportion of around 0.3%), as well as secondary flavouring agents. According to these researchers' analysis, the sugar content of eating chocolate is normally about 50%. Chocolate's high glycaemic index was identified as the most significant element contributing, in this context, to acne aggravation. 




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