USDA FoodData Central nutrition lookup. Two modes: search (query=cheddar cheese) returns matching foods with fdcId, description, data type, category, and brand; detail (fdcId=328637) returns the full analyzed nutrient profile — energy, protein, fats, carbohydrates, vitamins, minerals — with USDA nutrient numbers, amounts, and units (per 100 g/ml unless serving fields indicate otherwise), plus ingredients for branded foods. Filter search by dataType: Foundation and SR Legacy are lab-analyzed generic foods, Branded is the packaged-food label corpus, Survey (FNDDS) is as-consumed dishes. Authoritative USDA data covering ~400k foods — use real analyzed values instead of model-estimated nutrition facts.