Table IV.

Interventional studies on the effect of dairy and glycemic index on acne

Source; country	Design	Study population	Intervention	Control	Outcome summary	Strengths	Limitations
Smith et al,47 2007; Australia	Randomized control trial	15-25-y-old males (n = 43) with mild-to-moderate acne for >6 mo recruited from a university. Excluded if consuming acne or glucose metabolism medications. Encouraged the use of skin cleansers.	12-wk LGL or control diet.	Control group instructed to eat carbohydrate-dense foods (moderate-to-high GL) daily but were not informed about GI.	LGL diet decreased total lesion count (−22.0 ± 3.5 for LGL vs −10.9 ± 2.9 for control, P = .02) and inflammatory lesion count (−16.2 ± 2.9 for LGL vs −5.6 ± 2.5 for control, P = .01).	Appropriate sample size. Rigorous dietary compliance measures (phone calls, daily intake, urea samples, and food weights). Significant exposure differences achieved for both GI (low GI 43 vs high GI 56) and GL (low GI 101 vs high GI 171). Well-defined outcome classification (dermatologist-assessed acne).	Generalizability (young adult males).
Smith et al,48 2007; Australia	Randomized control trial	See above.	See above.	See above.	Reduced inflammatory lesion counts in LGL diet (−16.0 [−20.6 to −11.4]) vs control (−8.5 [−13.4 to −3.5]), P = .04, and did not reduce total acne lesion count after adjusting for BMI.	See above.	Generalizability (young adult males). Appears to be reanalyzed data from above trial.
Smith et al,49 2008; Australia	Randomized control trial	15-25-y-old males (n = 31) with mild-to-moderate facial acne. Remainder above.	See above.	See above.	LGL diet had decreased acne lesion counts (−59%) compared with control diet (−38%), P = .046), and decreased skin oiliness mean response score, P = .013.	See above.	Generalizability (young adult males). Appears to be reanalyzed data from above 2 trials.
Reynolds et al,50 2010; Australia	Nonrandomized controlled trial	Teenage boys (n = 43; average age: 16.5 y) recruited from boarding schools.	8 wk of high-GI diet.	Low-GI diet.	Trend toward significant association between acne severity and low-GI diet (score −0.65 ± 0.14) vs high-GI diet (−0.35 ± 0.15), P = .15.	Appropriate sample size. Significant exposure differences achieved for both GI (low GI 51 ± 1, high GI 61 ± 2) and GL (low GI 102 ± 9, high GI 157 ± 18). Well-defined outcome classification (dermatologist-graded acne).	Generalizability (teenage boys), more stringent exclusion criteria (smoking/drinking, final examinations, “dark” skin). Less rigorous dietary compliance measures (weekly assessments of weight and diet).
Kwon et al.51 2012; Korea	Randomized controlled trial	20-27 y olds (24 men, 8 women) with mild/moderate acne recruited from a clinic.	10 wk of an LGL diet.	Control group asked to maintain regular diet.	LGL diet significantly improved the number and severity of acne lesions compared with those at baseline (−70.9%) and in controls.	Significant exposure differences achieved for both GI (low GI 50.1 ± 6.3, high GI 69.5 ± 2.4) and GL (low GI 129.5 ± 22.2, high GI 207.2 ± 23.2). Well-defined outcome classification (dermatologist-graded acne severity). Investigator blinding.	Unclear sample size justification. Less rigorous dietary compliance measure (GL and GI recorded at wk 2, 5, and 10).
Pavithra et al,52 2019; India	Randomized controlled investigator-blinded trial.	14-29 y olds (26 males, 58 females) recruited from dermatology clinics.	12 wk of an LGL diet.	Control group asked to continue usual diet. Topical benzoyl peroxide gel 2.5% and noncomedogenic cleanser recommended for all participants.	No significant association between acne severity and LGL diet. All members of the intervention and control groups showed acne reduction at 12 wk.	Appropriate sample size. Well-defined outcome classification (dermatologist-graded acne severity longitudinally).	No data available to judge the success of dietary intervention. Less rigorous dietary compliance measure (GL and GI recorded at wk 4, 8, and 12). 100% improvement among all trial participants.

BMI, Body mass index; GI, glycemic index; GL, glycemic load; LGL, low glucose load.