Acne vulgaris (acne) is a common dermatology condition involving the pilosebaceous unit. It is caused by a complex interaction between androgens, increased sebum production, inflammation with subsequent colonization of Propionibacterium acnes, and abnormal keratinocyte actions within the gland’s epithelial lining (Bellew, Thiboutot, & Del Rosso, 2011).
Worldwide prevalence of acne is estimated to be 9.38% (Vos et al., 2013). The onset of acne generally coincides with puberty when androgen levels start to rise and affects an estimated 85% of school-aged adolescents (Bhate & Williams, 2013). Acne may persist well into adulthood or make its first appearance in young adults. It is estimated to affect approximately 43% of individuals in their 30s (Collier et al., 2008).
Decades ago, dermatologists believed that certain foods, specifically chocolate and greasy foods, caused an increase in sebum production and aggravated the severity of acne. This belief was partially disputed by a research study published by Fulton, Plewig, and Kligman (1969). The researchers provided 65 adolescents with either a chocolate bar or a nonchocolate control bar containing sugar and fats to ensure similar caloric value. There was no increase in acne severity in the group who ingested chocolate leading to the conclusion that chocolate had no influence on acne. A similar study by Anderson (1971) gave adolescents chocolate, nuts, and cola in addition to their normal diet for a period of 1 week with no substantial impact on acne severity. Many dermatologists remained unconvinced that diet had no influence on acne and encouraged the Nurses’ Health Study II (NHS II) group to analyze the relationship between diet and acne (Danby, 2005).
Dairy and Acne
The NHS II asked over 47,000 women to recall their high school dietary habits and compared the results with women who stated that they had been provider-diagnosed with severe acne during the same age range. Their conclusions indicated that intake of milk, instant breakfast drink, cream cheese, and cottage cheese was associated with acne. Interestingly, intake of skim milk was more highly correlated with acne (Adebamowo et al., 2005). This led to an additional study examining the relationship of acne to the intake of milk in the adolescent daughters of participants in the NHS II where they found that greater consumption of milk was positively associated with a high prevalence of acne (Adebamowo et al., 2006). An additional study by the same group showed a positive correlation between skim milk consumption in over 4,000 teenage boys (Adebamowo et al., 2008). LaRosa and colleagues (2016) also reported that individuals consuming high intakes of low-fat/skim milk had a higher incidence of acne. In other studies, the dietary effects of daily intake of 200-mg lactoferrin added to fermented milk in 36 male and female subjects with acne showed a decrease in acne lesion count and skin surface sebum levels (Kim et al., 2010).
In the previous studies, the fat content in milk is apparently not the culprit as the intake of skim milk had a greater influence on acne. Hormones within milk include both growth hormones and anabolic steroids, which lead to elevated levels of Insulin-like growth factor 1 (IGF-1) within the individual consuming the milk. Many cows are treated with bovine growth hormone to increase their milk supply, creating even higher levels of IGF-1 (Katta & Desai, 2014). High IGF-1 levels increase the total amount of adrenal androgen synthesis and promote androgen bioactivity by increasing availability of dihydrotestosterone, increased dehydroepiandrosterone, and increased affinity of androgen receptors. These actions ultimately lead to increased sebum triglyceride synthesis, increased Propionibacterium acnes concentration, and activation of inflammatory cytokines (Kucharska, Szmurlo, & Sinska, 2016; Melnik, 2015). The ingestion of milk also increases pancreatic secretions of insulin. Hyperglycemic carbohydrates increase the bioactivity of serum IGF-1 and serum androgens, thus adding glycemic index (GI) as another piece of the puzzle of milks’ influence on acne (Melnik, 2015). A simplified version of the effects of hyperinsulinemia and IGF-1 is shown in Figure 1.
GI, Glycemic Load, and Acne
GI is a numerical index that measures a rise in blood glucose triggered by ingestion of a carbohydrate. Glycemic load (GL) is the rank given to a carbohydrate upon the GI and portion size (Reynolds et al., 2010). Examples of foods with a high GI include white bread, fruit juice, dried fruit, dairy, carbonated cola drinks, and sweets. The typical Western diet generally contains ample amounts of high GI. All foods high in carbohydrates may cause increases in acne prevalence (Mahmood & Bowe, 2014). Populations with low-GI diets such as the Kitavan Islanders of Papua, New Guinea, and the Ache hunters of Paraguay have no incidence of acne. Genetic predisposition may contribute to the absence of acne, but the researchers studying these groups conclude that low-GI diet plays a major factor (Cordain et al., 2002).
Several research studies examining GL and acne are found in the recent literature. Some of the most notable of these studies include a study of 54 subjects undergoing a 12-week low GL (LGL) diet that showed improvement in acne (Smith, Mann, Braue, Makelainen, & Varigos, 2007). Low-glycemic diet influences on the hormonal markers of acne were investigated by Smith et al. (2008). Twelve men were divided into two groups, with one group receiving a high-GL (HGL) diet and the other group receiving an LGL diet. The conclusions of this study indicated that subjects with the HGL diet had increased androgen bioavailability. Kwon et al. (2012) studied acne in 33 Korean subjects adhering to an LGL diet. A significant reduction in the number of noninflammatory and inflammatory acne lesions was associated with LGL. In addition, histological studies on these subjects noted a decrease in the size of sebaceous glands as well as a reduction in inflammatory cells. Other recent research studies involving diet and acne in terms of methodology, number of participants, and outcomes are summarized in Table 1.
Whey Protein and Acne
Whey protein is a mixture of globulin proteins isolated from milk and has an elevated level of essential amino acids. It is a popular supplement for body builders as it is purported to improve performance and gain muscle mass. Resolution of truncal acne was noted when individuals stopped taking whey protein supplementation (Cengiz, Cevirgen Cemil, Emiroglu, Gulsel Bahali, & Onsun, 2017).
Chocolate Intake and Acne
Chocolate intake on acne severity was explored by Caperton and colleagues (2014). A clinical trial of 14 men 18–35 years old exhibiting mild acne were given six ounces of cocoa encapsulated in gelatin daily for 7 days. The trial was double-blind, placebo controlled, and randomized. Increases in acneiform lesions of comedones, papules, pustules, and nodules were noted in the experimental group receiving the cocoa capsules as early as Day 4 of the study.
Fatty Acids and Acne
Traditional Western diet is often associated with high intake of omega-6 fatty acids such as corn, safflower, cottonseed, and soybean oils. Omega-6 acids are noted to induce more inflammatory mediators (Pappas, 2009), whereas omega-3 fatty acids have been shown to reduce inflammatory cytokines (Meydani et al., 1991). Populations whose diets contain elevated levels of omega-3 fatty acids appear to have less incidence of acne (Khayef, Young, Burns-Whitmore, & Spalding, 2012). Daily omega-3 fish oil supplements for a 2-month duration in five patients with acne showed a significant reduction in acne lesions (Rubin, Kim, & Logan, 2008). However, an additional study by Khayef and colleagues (2012) indicated that omega-3 supplementation in 13 subjects did not show improvement in both acne grade and lesion count.
DISCUSSION AND NURSING IMPLICATIONS
Preliminary research findings suggest that there is a dietary link to the development of acne and acne severity. Many of the studies reviewed here have very small sample sizes. More clinical investigation is needed in large-scale studies to investigate the dietary effects on acne. However, it will likely be difficult to undertake large-scale studies because of a paucity of funding sources for dietary influences as well as the high expense of tightly controlled dietary interventions.
Many questions are left unanswered, particularly regarding skim milk and acne. Although fat content has been removed from skim milk, the hormonal content remains the same as that of whole milk. Medium-chain fatty acids found in whole milk may assist in promoting healthy metabolism by decreasing insulin resistance (La Rosa et al., 2016). Further studies are needed to determine why skim milk and not all dairy products appear to influence acne. The physiological effects of IGF-1 and hyperinsulinemia on hormonal levels and sebaceous gland activity are well described but not totally explained. Further studies are needed in exploring the role of hyperinsulinemia on the development of acne. The conflicting data on omega-3 influences on acne severity need further exploration.
The American Academy of Dermatology currently recommends no specific diet changes in acne treatment but recognizes that emerging evidence supports the association of high-GI diets with development of acne and that milk, particularly skim milk, may aggravate acne. The American Academy of Dermatology identifies that there are many practice gaps in the role of dietary influences on acne and more prospective studies are needed (Zaenglein et al., 2016).
Providers should consider routine assessment of dietary patterns and use of whey protein supplements in patients with acne. Counseling patients that whey protein supplements might adversely affect the severity of their acne may encourage discontinuation. Providers should discuss dietary changes in those individuals who are found to intake high-GI foods and beverages. Promotion of LGL diet may not cause resolution of the patient’s acne but will certainly improve overall health.
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