Nutrition & DietHow Selenium Shapes Longevity and Healthspan Through a Narrow Dietary Window
Selenium is an essential trace mineral that supports health only within a narrow concentration range — too little or too much both cause serious harm. This review examines how selenium exerts its biological effects through three routes: small selenium-containing molecules, a family of proteins using the rare amino acid selenocysteine, and selenium-binding proteins. Deficiency raises risk for type 2 diabetes, immune dysfunction, prostate and colorectal cancer, cognitive decline, skeletal muscle disorders, and a fatal heart condition called Keshan disease. Excess selenium causes selenosis, damaging nails, skin, hair, and the nervous system. Critically, other dietary factors — including copper, zinc, folic acid, resveratrol, and vitamin A — as well as exercise and caloric restriction, modulate how selenium works in the body. The authors argue that understanding this complex biology is essential for designing interventions that meaningfully extend healthspan.
