As people get older, their skin naturally has a lot less of a substance called hyaluronic acid — by the time they're 75, they've got only about a quarter left compared to when they were 19.

Measure hyaluronic acid concentration in skin samples from a large, representative sample of healthy humans across multiple age groups (e.g., 19, 30, 45, 60, 75) using standardized biochemical assays (e.g., ELISA or HPLC) to determine if a 75% decline occurs between the youngest and oldest groups.

Track the same individuals over time by measuring hyaluronic acid concentration in skin biopsies at baseline (age ~19) and follow-up (age ~75) to directly observe the magnitude of decline within individuals.

Compare hyaluronic acid levels in skin samples from individuals aged 19–25 (controls) versus 70–75 (cases) to determine if a 75% reduction is consistently observed in older adults.

Use human dermal fibroblasts cultured from young (e.g., 20-year-old donor) and old (e.g., 75-year-old donor) individuals to measure hyaluronic acid synthesis and degradation rates under controlled conditions.

Measure hyaluronic acid concentration in skin of mice or primates at young (e.g., 3 months) and old (e.g., 24 months) ages to approximate the human 75% decline trend.