The association between acne in adolescents and dairy consumption is supported by 2 recent studies, bringing renewed interest in the long-established hypothesis of this link.

The association between dairy intake and acne in teenagers has gained renewed interest with 2 new studies supporting the hypothesis that acne is linked with diet. Conflicting accounts exist about the significance of different types of milk as contributing factors, however, and the cause of acne is still unknown despite several studies.^1,2 Dermatologists are still somewhat polarized in their opinion on the role of diet in acne, and it remains a controversial topic.³

A new study by Professor Maria Ulvestad and colleagues of Oslo University Hospital, Norway, published in the March 2017 issue of the Journal of the European Academy of Dermatology and Venereology, supports the argument for a connection between high consumption of milk and moderate-to-severe acne in adolescents.

According to the researchers, acne affects a significant percentage of adolescents. It leads to a reduced quality of life similar to chronic conditions like diabetes and arthritis, so it is of scientific and economic importance to understand the underlying cause.⁴

“Considering the extensiveness of acne, a great interest exists to reveal and comprehend its possible causative factors,” the authors point out. “Much is known about the pathophysiology of acne that eventually leads to a chronic inflammation in pilosebaceous units. What provokes these events to happen, however, is not fully understood. During the last decade, the acne-diet connection has been brought back to credibility, after being considered a myth for a long time. This hypothesis suggests that consumption of different foods influence the occurrence of acne.”⁴

In this latest study, adolescent participants were provided with a questionnaire for the self-assessment of their acne, and analyses of the results were done by separating the adolescents into 2 groups: those with no-to-little acne vs those with moderate-to-severe acne. The researchers then compared the level of dairy product consumption between the 2 groups, with further subgroup analyses differentiating the dairy consumed based on fat content, whether intake was low or high, as well as on gender.⁴

The investigators were unable to establish a link between low-fat or skim milk and acne, but instead, found that a correlation exists between high intakes of full-fat dairy products, defined as greater than or equal to 2 glasses per day, and moderate-to-severe acne.⁴

Low-fat dairy and acne

A slightly earlier study by Andrea Zaenglein, MD, and colleagues from the Pennsylvania State University College of Medicine, “Consumption of dairy in teenagers with and without acne,” was published in the August 2016 issue of the Journal of the American Academy of Dermatology. This study, which was supported by the American Acne and Rosacea Society, also showed a positive link with acne when including milk in the diet, but the association was only found with low-fat or skim milk, not full-fat milk or other dairy products.³ In this study, a dermatologist classified acne using the Global Acne Assessment Scale and, as with the 2017 study, self-reporting of dairy intake was included.³

“There are 4 main factors in the pathogenesis of acne: increased sebum (or oil) production from the glands in the skin, increased hyperkeratinization where the skin cells at the pores get sticky and build up blocking the pore outlet, an increase bacteria in the pore called Propionibacterium acnes, and inflammation. All of these factors are intertwined, each making the other worse. They are also influenced by such factors as diet and genetics,” Dr. Zaenglein told MedPage Today.

“The discussion was quiescent for years until a study found virtually no acne in select non-Westernized populations, leading researchers to infer that a Western diet may be to blame. Subsequent studies suggested an association between dairy, particularly skim milk and acne,” the authors also report.³

These contradictory findings in the literature may be a direct result of methodological limitations, and this should be given consideration when interpreting the results. However, whether full-fat or low-fat/fat-free dairy plays a significant role in the prevalence of acne in adolescents, both recent studies support the previous data linking milk intake with acne.^1,5

“This is very controversial and the data is mixed to be sure. There are known differences in skim versus whole milk, however. Whole milk has natural Vitamin A and D. In skim milk, it is removed and replaced after the fat is skimmed off. So, absorption might be affected. Whole milk contains some additional beneficial components such as medium chain fatty acids that promote healthy metabolism and decrease insulin resistance, as well as conjugated linoleic acid and monounsaturated fatty acids,” said Dr. Zaenglein.

The more recent results from the 2017 study suggest there may be gender differences. Data indicate an association between acne and high total dairy consumption in female adolescents, compared with a greater magnitude of association between acne and high consumption of exclusively full-fat dairy in male adolescents. It is stated though, that any gender differences observed may be confounded by other gender-specific variables such as diet preferences or some behavioral or environmental factors like smoking or exercise.⁴

Data support dairy intake link with acne

It appears that the role of dairy in our overall health is a complex issue. Earlier studies report that milk causes an elevated insulinemic response and promotes an increase in insulin-like growth factor-1. It may be possible that this spike in insulin encourages phosphorylation of the transcription factor Foxhead box protein O1 (Fox01), thereby resulting in the activation of the mammalian target of rapamycin complex 1 (mTORC1) receptor and thus the stimulation of the sebaceous glands. These findings reveal a common mechanism of action for antiacne treatments and may provide a route to the development of new medication.^3,6

“We have no explanation for why we solely found association with full-fat dairy products, and not with semi-skimmed or skimmed products. It has been proposed that different manufacturing processes of cow’s milk might alter the composition of other bioactive substances, as well as the intended change in fat content. Milk is a complex fluid, containing different proteins, carbohydrates and steroid hormones etc., which are likely to influence endogenic and possibly acne-promoting pathways. Lately, the ability of cow’s milk to increase IGF-1 and insulin levels in vivo has received much attention,” reported the authors of the 2017 study.

Although there were certain limitations of the 2017 study, the authors did highlight that their consistent results for full-fat dairy association support the hypothesis that dairy intake may be a relevant, contributing factor to acne.⁴

Future directions

The manufacturing process of skim milk where fat-soluble vitamins A and D are removed from full-fat milk and reintroduced later to the low-fat product may warrant further investigation to study the bioavailability and distribution of essential vitamins compared with full-fat milk.³

“Since I am a dermatologist and not a nutritionist, important next steps in research that need to be done before we make firm dietary recommendations to patients would be to see if switching from skim milk to whole milk actually makes a difference in acne,” Dr. Zaenglein concluded.