Table 1.

Selected studies on the effect of milk and dairy products on the pathogenesis of acne vulgaris.

Research	Year	Methodology	Key Result	References
Adolescents
Adebamowo C.A. et al.	2005	47,355 female participants responded and completed a questionnaire on frequency of eating in high school. This analysis includes women who fulfilled the questionnaire and replied to the question on doctor-diagnosed extreme teenage acne in 1989.	A positive association has been found between acne and the consumption of whole and skimmed milk. Cottage cheese and cream cheese are also positively related with acne.	[58]
Adebamowo C.A. et al.	2006	Using a questionnaire, 6094 girls of baseline age between 9 and 15 years from GUTS were surveyed.	Whole, low-fat, skimmed, or chocolate milk has been linked to acne.	[59]
Adebamowo C.A. et al.	2008	Using a questionnaire, 4273 boys of baseline age between 9 and 15 years from GUTS were surveyed.	A positive association between the consumption of skimmed milk and the occurrence of acne was proven. Full-fat milk, 2% milk, and low-fat milk were not associated with acne.	[60]
LaRosa C.L. et al.	2016	The study involved 225 participants aged 14 to 19 years with medium or no acne. Skin lesions were assessed and dietary history was taken using the Nutrition Data System for Research software.	Consumption of low-fat/low-fat milk, but not full-fat milk, was positively associated with acne incidence.	[63]
Okoro E. et al.	2016	A physical examination and analysis of data from interviews with 464 Nigerian students with an average age of 13.6 years was conducted.	The incidence of acne was higher in people who consumed milk like a beverage at least once a day.	[61]
Ulvestad M.	2017	A questionnaire-based study on baseline dairy intake and presence of acne after 3 years among 2489 Norwegian residents aged 15–16 years.	Consumption of at least two glasses of full-fat dairy products per day was associated with moderate to severe acne.	[55]
Alkhabbaz M. et al.	2020	A cross-sectional study was performed among 714 adolescents. The presence or absence of acne and acuteness was assessed using the Global Acne Grading Scale. Data on risk factors and potential confounders were collected from parents using a self-administered questionnaire and from adolescents by direct interview.	Factors that were not significantly associated with the development of acne vulgaris include semi-skimmed milk, full-fat cream cheese, low-fat cheese, white cheese, yoghurt, ice cream, and other dairy products.	[70]
Young adults (18–25 years old)
Burris J. et al.	2014	The study enrolled 248 participants aged between 18 and 25 years (115 men and 133 women).	Compared to attendees with no acne or with mild acne, participants with medium to extreme acne reported intaking more portions of milk daily in their diet.	[65]
Pereira Duquia R. et al.	2017	The study assessed 2201 18-year-old men living in southern Brazil by a dermatologist.	The crude analysis showed a relationship between daily whole milk intake and the incidence of inflammatory acne, but this association was only found in the proximate analysis. Although the outcomes of the adjusted analyses were not statistically considerable, the prevalence rates of daily whole milk intake may indicate a poor positive relation with the incidence of inflammatory acne.	[64]
Pontes T. de C. et al.	2013	The target group consisted of gym-goers and patients of a dermatology clinic in João Pessoa (Brazil). The study included 30 participants aged 18–30 years. Acne severity was assessed before starting the supplements, and then one month and two months after starting the supplements.	This study showed the onset of acne with the gradual use of protein and calorie supplementation over a two-month period. This effect was more pronounced in women and in people without current acne and no family history of acne.	[46]
Adults
Semedo D. et al.	2016	The study consisted of a questionnaire and physical examination in a sample of 1055 people aged between 20 and 60 who visited five healthcare centers in the Greater Porto area on random days.	Among the 1055 people surveyed, the prevalence of acne was estimated at 61.5%. Acne was associated with the intake of fully-fat milk and skimmed milk.	[56]
Juhl C.R. et al.	2018	We investigated the association between milk consumption, LCT-13910 C/T, and acne in 20,416 adults from the Danish General Population Survey (GESUS) using Mendel randomisation.	No observational or genetic link was found between milk consumption and acne	[69]
Penso L. et al.	2020	24,452 French adults completed an online questionnaire where they classified their acne condition. Associations between dietary behaviour and acne were investigated in multinomial logistic regression models. The survey was conducted as part of the NutriNet-Santé study.	A significant association was found between current acne and milk consumption.	[53]
Heng A.H.S. et al.	2022	3888 patients (2090 acne patients and 1798 controls) (17–71 years old) completed questionnaires and were examined by trained staff for severity of acne lesions and degree of scarring.	Frequent consumption of milk was associated with a protective effect for moderate acne, while frequent consumption of butter had a detrimental effect on the degree of acne scarring.	[68]
Different age range
Di Landro A. et al.	2012	The study involved 568 participants (205 people with medium to extreme acne and 358 controls). The age of the subjects was between 10 and 57 years old. Acne escalation was determined using a global scale, and trained interviewers conducted interviews.	The risk of medium to severe acne rose with increased milk consumption in those consuming more than three portions per week. This connection was more pronounced for low-fat milk than whole milk.	[57]
Juhl C. R. et al.	2018	A metanalysis in which 14 studies were included, representing 78,529 people (23,046 patients with acne and 55,483 controls) aged between 7 and 30 years.	Any dairy such as milk, yoghurt, and cheese was associated with an increased odds quotient for acne.	[54]
Aalemi A. K. et al.	2019	Using the Global Acne Severity Scale, dermatologists assessed the acuteness of acne in 279 Kabul residents with acne and 279 control subjects. Participants were aged between 10 and 24 years. Eating habits were recorded using a questionnaire.	Intake of full-fat milk at least 3 days per week was related with moderate to severe acne incidence. The association with acne incidence was less pronounced for skimmed milk than for full-fat milk.	[52]
Kara Y. A. et al.	2020	Fifty-three acne patients and fifty-three controls took part in the study. The age of the subjects was between 13 and 44 years old. The subjects’ lesions were assessed and dietary composition was calculated.	In patients with acne vulgaris, it was observed that cheese consumption increased lesion formation.	[62]
Say Y.H. et al.	2021	1840 patients (1117 acne patients and 723 controls) completed questionnaires and were examined by trained staff for severity of acne lesions and degree of scarring.	Frequent consumption (most or all days) of products commonly eaten at breakfast (butter, milk, probiotic cartridges, and cereals) reduced the risk of acne and larger acne scars.	[67]