Louis Isaac Woolf (born 1919 in London, England; died 2021 in Vancouver, Canada) was a British biochemist who played a crucial role in the early detection (via neonatal screening) and the treatment of phenylketonuria (PKU).

[4] Woolf's idea of using activated charcoal to filter phenylalanine from casein hydrolysate laid the groundwork for future dietary interventions,[6] which he researched in the late 1940s and early 1950s.

This trialled despite Woolf and others facing scepticism and professional challenges, including the belief that PKU was untreatable due to its genetic nature.

[7] In 1957, Woolf and colleagues recommended mass screening for PKU using a ferric chloride test on urine samples from newborn babies.

[1] Woolf moved to Vancouver in 1968, where he joined the University of British Columbia and continued research on phenylalanine biochemistry and metabolic diseases.