Objective_methods

Biomarkers

Biological markers that indicate cellular, biochemical, or molecular alterations measurable in biological media such as human tissues, cells, or fluids.

Objective assessment

An assessment that provides quantifiable, factual outcomes rather than subjective judgments.

Recovery biomarkers

Specific biological products directly related to intake and not subject to homeostasis or substantial inter-individual differences in metabolism.

Concentration biomarkers

Biomarkers that correlate with the intake of corresponding food or nutrient but do not translate into actual dietary intake.

Predictive biomarkers

Biomarkers that show an incomplete recovery but have a stable, time-dependent correlation with intake.

Food composition

The nutritional makeup of foods, which can sometimes be inconsistent leading to challenges in dietary assessments.

Doubly labeled water

A method for measuring total daily CO2 production and energy expenditure using isotopes of hydrogen and oxygen.

Urinary nitrogen

A measure used in dietary validation studies indicating nitrogen intake correlated with nitrogen excretion.

Serum and plasma

Biological specimens reflecting short-term intake from a few days to one month.

Adipose tissue

A biological specimen that reflects long-term intake and is most useful for assessing exposure to fat-soluble vitamins and essential fatty acids.

Biomarker validation

The process of assessing the accuracy and reliability of biomarkers against expected dietary intakes.

Homeostasis

The physiological process through which the body maintains stability despite changes in the external environment.

Nutritional status biomarkers

Indicators that may reflect the intake, metabolism of nutrients, and effects from disease processes.

Methylmalonic acid levels

A biomarker indicating vitamin B12 deficiency when elevated.

Factors affecting intake-status relationship

Factors including synthesis, mobilization, nutrient intake, biology, status, metabolism, and storage that influence the relationship between nutrient intake and biological responses.

Short-term intake vs. long-term intake

Short-term intake is generally reflected in serum and plasma, while long-term intake is reflected in adipose tissue.

Time of specimen collection

The timing of collecting biological samples, which can influence biomarker levels significantly.

Compliance in dietary studies

The extent to which participants follow the study requirements, which affects the accuracy of dietary assessments.

Biomarker measurement limitations

Challenges such as high costs, invasiveness, specificity, and variability in nutrient concentrations due to individual characteristics.

Nutritional biomarker research needs

Identified priorities for developing sensitive, specific, cost-effective, and non-invasive dietary biomarkers.

Dietary assessment methods

Various approaches used to measure dietary intake, including food frequency questionnaires, diaries, and recovery biomarker methods.