By Natalie Gibson
BACKGROUND: The link between dairy consumption and acne vulgaris has been a topic of interest for decades. The objective of this review is to examine four original research studies regarding the influence of dairy intake on acne vulgaris in adolescents.
DESIGN/METHODS: Two case-control studies, one longitudinal-questionnaire based study, and one cross-sectional were reviewed. The studies were found using PubMed. Search terms included “acne” “teens” “dairy” and “acne vulgaris”.
RESULTS: In one study, high intakes of full-fat dairy were associated with moderate to severe acne with an odds ratio for acne of 1.55 (95% CI: 1.02-2.39). However, no significant associations were found between acne and skim or low-fat dairy products.13 In another study a positive association was found between higher milk intake (0.7 +/- 0.7 cups/day) and moderate to severe acne than those with mild acne (0.5 +/- 0.7 cups milk/day) or no acne consuming 0.3 +/- 0.5 cups milk/day (P<0.001).14 The consumption of milk (p<0.01) and ice cream (p < 0.01) was significantly higher compared to controls in another study.15 The final study found teens with acne consumed more low-fat/skim milk products (0.61 servings) than those with no acne (0.41servings) (P=0.01). No statistically significant results were found with total dairy intake or other compositions of milk.16
CONCLUSION: There appears to be a positive association between increased dairy intake and the prevalence of acne amongst adolescents. The data is still inconclusive regarding which composition of dairy fat influences acne greatest. While complete removal of dairy intake is not necessary for acne reduction, data supports that reducing dairy intake can improve the prevalence of acne lesions.
Acne vulgaris affects millions of people worldwide. In 2015, it was estimated to affect 9.4% of the world population.1 In the United States, it is the most common skin condition, distressing 50 million people yearly.2 Acne affects about 85% of people within the ages of 12-24, commonly during pubertal years.3 Acne is a chronic inflammatory disorder of the pilosebaceous unit4, which is the structure that consists of a hair, a hair follicle, the arrector pili muscles, and the sebaceous gland. Acne lesions can be described as non-inflammatory lesions which consist of open and closed comedones or inflammatory lesions which include papules and pustules.3 The cause of acne is multifactorial. These factors include genetics, hormones, menstruation, emotional stress, medications, seborrhea, and diet.5 The pathophysiology of acne involves a series of events. Acne lesions are composed of keratinocytes that line the hair follicle. As these keratinocytes desquamate or shed, a microcomedone is created. During puberty, sebum (oil) production increases at the follicle creating an ideal environment for Propionibacterium acnes to proliferate in the follicle. This colonization of bacteria produces inflammatory compounds thus creating inflammation of the skin.6 Overactivity of these sebaceous glands during puberty causes clogged pores that can multiply resulting in numerous lesions.7-8 Acne is closely related to puberty and younger age; however, the prevalence of acne can be present in all stages of life. Other health factors such as diet and weight may be associated with the occurrence and onset of acne. Acne treatment and prevention is widely studied and many treatments are available depending on the degree of the disease. In Western philosophy, topical therapies and oral therapies can be prescribed by a dermatologist. Typical topical treatments include benzoyl peroxide, topical antibiotics, retinoids, and salicylic acid depending on the severity. Oral treatments include oral antibiotics such as tetracycline, doxycycline, minocycline, erythromycin, and trimethoprim-sulfamethoxazole. 3,9,10,11 In addition, at-home care is recommended by washing the affected areas once or twice a day and after sweating with a non-drying cleanser. Treatment is modified case by case.
TThe role of diet and acne is a widely discussed topic. Historically, early studies inferred that impaired glucose tolerance and altered carbohydrate metabolism were linked with acne.10-11 Subsequent studies were done which further analyzed the relationship between diet and acne. In 1971, a study conducted using 27 students consuming high carb diets showed no flares in acne occurrence over time.3 However, acne reports increased as people moved to Westernized populations. Self-reported data was collected from different populations. For example, surveys from rural African villages reported fewer acne lesions than surveys from communities with the same descendants now living in Westernized civilizations.16 A general practitioner, Schaefer et al. spent 30 years treating Eskimo people who were making the transition to modern culture. Later reports done by Bendiner et al. indicated no reports of acne in the Eskimo people eating in their traditional manner. Once these people acclimated to the new Western culture of eating diets rich in meat and dairy, reports of acne increased to similar reports of Western populations.12 These changes in diet with an increase in acne are notable in various observational studies and self-reported data.
Dairy and its role in acne was first studied in 1949 by Robinson et al.3 Recent studies discovered an association, specifically with skim milk or low-fat dairy products. In a study by Adebamowo et al. in 2005, a positive association is found between intake of skim milk and history of acne in women using a validated food frequency questionnaire. However, this study exhibited limitations because acne was self-assessed, and confounding factors were not considered.12 In this review, four current studies will be examined to evaluate dairy consumption and the onset of acne vulgaris in adolescents. Two case-control studies, one cohort, and one longitudinal questionnaire-based study will be reviewed.
The University of Texas Libraries, PubMed database was used to search for original research studies in September of 2016. Articles were found using keywords such as “acne” and “dairy” and “adolescents” and “acne vulgaris”. Original research papers were screened for specific studies such as “case-control” and “cohort” proceeding specifications of the number of subjects used in “their” study. Selection criteria included original human research studies with participants within the age range of 13-26. In addition, the study topics focused primarily on dairy intake and its effect on acne in teens conducted within the last 10 years. Only English language publications were included.
All four studies include a large sample size > 85. Two case-control studies15,16, one cross-sectional design14, and one longitudinal questionnaire13 based study were included in the review. Participants in all four studies included both males and females.13-16 Two of the four studies were done on adolescents in the United States.14,16 One study was conducted on Malaysian young adults15 and another on Norwegian teens13. Participants in two studies were evaluated for either having acne or not having acne.15,16 The remaining two studies included participants self-assessing the severity of their acne over time.13,14
Methodology for data collection was food-frequency questionnaire-based or diet recall for dairy intake in all four studies. The largest of the studies was the Norwegian longitudinal study in which a total of 2489 participants followed up from the baseline study after 3 years.13 Dairy product consumption which was categorized by full-fat dairy, semi-skimmed dairy, and skimmed dairy products was self-reported at the ages of 15 or 16 years old and then acne severity was self-assessed 8 years later at the ages of 18 or 19. Consuming more than 2 glasses of full-fat dairy products per day (high dairy intake) was found to be positively associated with moderate to severe acne.13 Looking at each fat category separately, the prevalence of acne among all subjects with high full-fat dairy consumption was 18.5% and 12.6% in those with no intake of full-fat dairy products. There is a 55% increase risk of acne of high full fat intake with an odds ratio of 1.55 (95% CI: 1.02-2.39).13 The adjusted odds ratio was adjusted for family income, ethnicity, mental distress, and body mass index at 1.56 (1.02-2.39).13 In boys consuming exclusively high intakes of full-fat dairy products, the odds ratio for acne was 4.81 (1.59-14.56). This data was stratified on dairy intake in every fat variety in order to prevent results in one fat content group from being influenced by other intakes of another dairy product with a different fat content. In girls, a high total intake of dairy products associated with acne had an odds ratio of 1.80 (1.02-3.16)13. Furthermore, there were no statistically significant results with acne prevalence and consumption of semi-skimmed or skimmed dairy products.13 The other self-reported and self-assessed study, was conducted on 248 young adults in New York and found a positive association between higher milk intake (0.7 +/- 0.7 cups/day) and moderate to severe acne than those with mild acne (0.5 +/- 0.7 cups milk/day) and those with no acne consuming 0.3 +/- 0.5 cups milk/day (P<0.001).14 In this study, the composition of the milk fat was not specified.14 In a case-control study done on Malaysian young adults, another risk association was found between dairy intake of milk or ice cream more than once a week and an increased risk of acne vulgaris resulting in an odds ratio of 3.99 (CI 95%: 1.39-11.43).15 Milk-fat composition was again, not specified in this study.15 In another case-control study, including 225 teenagers from 14-19 years of age found varying results. Teens with acne consumed more low-fat/skim milk products (0.61 servings) than those with no acne (0.41servings) (P=0.01).16 No statistically significant results were found with total dairy intake or other compositions of milk.16
The purpose of this review is to closely evaluate various studies that examine the effects of dairy consumption on acne vulgaris in adolescents to help identify how a Westernized diet plays a role in dermatological practice. Results from the four studies provide some answers to the question at hand; however, complications arise due to conflicting results amongst some of the studies. Although all four studies report an association between dairy intake and an increase in acne flares which supports results from previous research, further studies need to be conducted before strong conclusions can be determined. In a prospective cohort study done in 2008, a positive association was found between skim milk consumption and acne in boys.6 Another positive association was found in a 2005 retrospective study performed on teenage girls. Results showed an increase in acne with an increase in total milk and skim milk intake.12 An inconsistency across the four studies is the varying results in regards to the milk fat composition of dairy and acne prevalence. All four studies in this review report statistically significant results in at least one category, however, the parameters vary drastically. For example, in Ulvestad et al., acne data was collected in separate categories of girls, boys, and both sexes (all). The dairy groups were categorized into full-fat dairy and total dairy intake, finding significance in both dairy groups.13 In the rest of the studies, girls, and boys were not measured separately.14,15,16 Burris et al. measured dairy by the number of servings of milk, while Ismail measured dairy in categories of milk, yogurt, cheese, and ice cream, finding significance in only the milk and ice cream categories.15 Lastly, Larosa et al. measured dairy in categories separated by each milk fat content, while only finding significant results in the total low-fat/skim milk category.16 The differences in study composition and parameters regarding what is considered to be high dairy consumption versus moderate or low dairy consumption should be considered when analyzing these results. Overall, it appears that increased dairy consumption has a positive association with the risk of acne lesions, however, further studies need to be done in order to address the specific type of milk fat composition that plays a stronger role in these breakouts. Specifically, the results of Ulvsetad et al. and Larosa et al. seem to be contradictory. There was no significant report of semi-skimmed or skimmed milk consumption and reports of acne in Ulvsetad et al, compared to Larosa et al. where the only statistically significant results were with skimmed or low-fat milk group (p =0.01).16 The results of Larissa et al. are similar to that of Ademawo et al.'s study in 2005 where a positive association was found between skim milk intake and acne in girls.12 Various limitations were present in these studies. For one, major differences lie in the study design. In one study, the data analysis software was not specified and could not be confirmed as valid.13 Other limitations in this study included recall bias and self-assessed acne.13 There is a concern for recall bias or recall error when data is collected from questionnaire surveys. All four studies collected data from questionnaires increasing the likelihood of recall and selection bias.13-16 Ulvestad et al. reports no significant association between high intake of semi-skimmed or skimmed dairy products in the results, however, this data is not included in the publication.13 Two of the studies collected data on acne severity using self-assessed acne reports which is another limitation in study design.13,14 Self-reported acne is a limitation because it is subjective. One subject’s view of moderate or severe acne may be completely different from another subject’s opinion. It is best to have this data collected with controlled parameters from the same dermatologist, who counts non-inflammatory acne lesions and inflammatory acne lesions. This would create objective data collection instead of subjective data collection. Two studies used dermatologists to assess acne which can be considered a strength of these designs.15,16 All four studies use observational study designs. Observational study designs provide information over time without any intervention. These are beneficial as they are less costly, and can provide data for long-term efficacy, however, a disadvantage is that they cannot control for confounding factors or bias. Strengths among all four studies included a large number of participants.13-16 A large sample size is more representative of the population that is being studied. The study with the fewest participants was 883 and the study with the greatest number of participants was 2489.13 Additionally, three of the studies confirmed the use of validated software for data analysis.14,15,16
Studies examining dairy intake and increase in acne in teens make analysis of hormonal constituents- specifically androgens in sufficient quantities to have biological effects in consumers than previously thought.6
After reviewing these four studies, it can be determined that increased dairy intake contributes to acne vulgaris in teens. Reducing dairy intake may improve the prevalence of acne flares and breakouts. Due to conflicting data, it is still inconclusive on which type of fat composition influences acne greatest.
In future research, setting an established baseline of low, normal, and high dairy composition would be helpful to create a standard consumption quantity when comparing data among various observational studies. Additionally, a longer duration of the study, anywhere from 6 months to 2 years, would be beneficial. Conducting intervention studies may be a good alternative option for study design as you can control for confounding factors. Lastly, the influence of dairy on acne in boys vs girls would be an interesting study design due to the different hormonal changes of boys in puberty compared to girls in the pubertal stages of life. It is also important to create sufficient study designs including dermatologists assessing acne with incentives for participation. This information is relevant and important regarding the issue of adolescents with acne during their pubertal year. Acne has been shown to have many psychological effects on teens. Having strong data regarding specific foods in our diet and their influence on acne vulgaris in teens would be valuable information when treating this population with a chronic inflammatory skin condition.
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© 2022 · Natalie Gibson Cosmetic & Medical Dermatgology PA