A Supplement Dose Is Not a Nutrient Requirement: When the Same Units Answer Different Questions

Clinical nutrition guidelines often contain numbers that look directly comparable but answer different questions. A supplement dose, a therapeutic total-intake target, and a population reference intake can all be expressed in grams of the same nutrient, yet they do not represent the same quantity. The risk is not that one number is wrong; it is that the wrong inference is drawn from a number that is right. Using the Nutritional Management Guidelines for Sarcopenia and Frailty 2025 as a current illustration, this commentary distinguishes 3 inferential layers: an implementation regimen, a therapeutic nutrition target, and a dietary reference value. The guideline suggests approximately 20-25 g/day of high-quality protein supplementation with exercise when intake is insufficient, while acknowledging that a recommended total daily protein intake for older people with sarcopenia or frailty cannot yet be specified. These statements are compatible, not contradictory. Moving from a tested regimen to a therapeutic total-intake target requires additional evidence on baseline intake, amount consumed, achieved exposure, comparator exposure, co-interventions, modifiers, and safety. Moving further to a dietary reference value requires a broader evidentiary scope focused on usual intake, intake-response relationships, safety, and population applicability. Guidance should therefore state what each number represents and what additional evidence is required before that number is transferred to a different inferential layer.