The connection between diet and skin isn't folklore — it's biochemistry with published studies. Systemic inflammation generated by certain dietary patterns manifests in skin. And the nutrients that modulate the skin barrier are the same ones that diet can provide or deprive.

The Mechanism of Sugar and Sebum

High glycaemic index foods (refined sugar, white flour, sugary drinks) rapidly elevate insulin. Insulin activates insulin-like growth factor 1 (IGF-1), which directly stimulates sebaceous glands to produce more sebum. A study published in the American Journal of Clinical Nutrition (2007) showed that a low glycaemic index diet over 12 weeks significantly reduced acne lesions compared to the control diet.

Dairy and Acne

Especially skimmed milk — the fat removal process concentrates the hormones and IGF-1 precursor proteins naturally present in milk. The relationship isn't universal but there's consistent epidemiological evidence. For acne-prone skin, reducing dairy consumption is a reasonable 8-week experiment.

Omega-3s as Skin Anti-Inflammatories

Omega-3 fatty acids (EPA and DHA from oily fish; ALA from walnuts and flaxseeds) reduce synthesis of pro-inflammatory cytokines IL-1β, IL-6 and TNF-α. In skin, this translates to reduced redness, less reactivity and better barrier function. Omega-3 supplementation has studies in rosacea, psoriasis and atopic dermatitis.

Dietary Antioxidants and Photodamage

Vitamin C, E, selenium and carotenoids from fruits and vegetables form the systemic antioxidant defence that complements (not replaces) SPF. A diet rich in lycopene (tomato) and astaxanthin (salmon) has modest evidence of additional UV protection.