Does Dairy Really Break You Out?

Milk, Whey Protein, and Acne

Milk

Milk contains bioactive hormones, including insulin-like growth factor 1 (IGF-1), estrogen, progesterone, and androgens, as well as iodine, which may influence the pilosebaceous unit and contribute to acne. Observational studies show that even skim milk is linked to acne, suggesting that fat content does not affect milk’s acne-promoting potential. Milk can increase IGF-1 levels in the body, which stimulates androgen production, sebum secretion, and keratinocyte proliferation—factors known to contribute to comedone formation and acne development.

Women with post-adolescent acne often exhibit elevated IGF-1 and mild insulin resistance, supporting the role of insulin/IGF-1 signaling in acne pathogenesis. Additionally, iodine in milk—derived from dietary supplementation of cows or iodine-based milking equipment—may exacerbate acne.

Whey Protein Supplements

Whey protein, a milk-derived product high in branched-chain amino acids, is commonly used for muscle building, particularly among adolescents. Studies and case reports link whey protein supplementation to increased acne. Users of protein-calorie supplements, especially whey, have shown significant rises in acne lesion counts, which often improve upon discontinuation of supplementation. The proposed mechanism involves hormonal effects similar to those of milk: concentrated whey may raise IGF-1 levels, promoting androgen activity, keratinocyte proliferation, and comedogenesis.

Both milk and whey protein may contribute to acne through hormonal pathways, primarily involving IGF-1, and their consumption has been correlated with increased lesion counts in adolescents and adults.