Evidence check: Östradiol in the context of skin aging

The provided context does not contain specific information on estradiol and skin aging. In general, estradiol (the primary form of estrogen) plays a key role in skin health: it promotes collagen synthesis, maintains skin thickness and hydration, and supports wound healing. With menopause, estradiol levels drop significantly, which is associated with accelerated skin aging (wrinkling, loss of elasticity, dryness). Clinical studies indicate that hormone replacement therapy (HRT) can partially reverse these effects, but the evidence is not uniform and depends on dosage, duration, and individual genetics. Importantly, measuring estradiol alone in blood or saliva without medical interpretation is insufficient for assessing skin aging risk. The provided context (including entries on lactase persistence, CYP2C19, and cortisol) is not relevant to this question. Therefore, the evidence is rated as human-moderate, based on general medical knowledge rather than the supplied sources.