GLOSSARY

Predictive Biomarker A biomarker whose relationship to intake is established through a calibrated predictive model rather than assumed complete recovery.

A recovery biomarker quantitatively relates to intake or expenditure under a specified balance model, whereas a concentration biomarker is influenced by absorption, metabolism and other factors. Predictive biomarkers use a calibrated relationship that may depend on the studied population. Distinguish intake biomarkers from markers of tissue status, function or disease. Blood, urine and tissue measurements answer different questions. Sampling conditions, recent exercise, hydration and inflammation can affect interpretation; no single biomarker provides a complete nutritional assessment or proves the cause of poor performance.

Nutrient status reflects intake, absorption, distribution, stores, losses and physiological demand. A normal blood concentration may not exclude depleted stores, while an abnormal result can have non-nutritional causes. Calcium in blood, for example, does not directly measure dietary calcium adequacy or skeletal reserves. Different nutrients require different assessment strategies. Select tests for a defined clinical question and interpret them with symptoms, diet, relevant disease and sampling conditions instead of ordering a broad panel and assuming every number is a performance target.

Laboratory markers provide information within a clinical context rather than a complete nutrition diagnosis. Albumin and prealbumin are affected by inflammation, fluid balance, organ function and other processes, so they should not be interpreted as direct isolated measures of protein intake or muscle mass. A reference interval is not automatically the optimal target for an athlete. Combine relevant tests with intake, physical findings, symptoms and trends, and consider the method and timing before attributing a result to diet alone.