Approaches to improving micronutrient status assessment at the population level

Abstract

Optimising micronutrient status globally is a major health priority. Nutritional biomarkers are critical for the identification of nutrient inadequacies in light of the limitations of dietary assessment methods. Early diagnosis and prevention of nutrient inadequacies require sensitive, validated and harmonised methods to determine and monitor micronutrient status in individual healthcare and population-based surveys. Important criteria in the identification, validation and implementation of nutritional biomarkers include the testing of biomarker specificity and sensitivity, and their response to dietary as well as physiologic changes, e.g. age or pregnancy. Nutritional status can be categorised into deficient, suboptimal, adequate and excess status, where appropriate, and provided cut-offs are available. Cut-offs are quantitative measures to reflect health outcomes and are important in validating nutritional surveys, interventions and monitoring of populations. For many biomarkers, available cut-offs have limited interpretability and are most commonly derived in adult populations only. For the comparison of studies from across the globe, the harmonisation of analytical methods is essential and can be realised with the use of internationally available reference material and interlaboratory comparison studies. This narrative review describes current efforts on identifying and validating existing and new biomarkers, the derivation of biomarker cut-offs, and international efforts on harmonisation of laboratory methods for biomarker quantitation and their interpretation, in the example of B-vitamins. Establishing sensitive, reliable and cost-efficient biomarkers and related cut-offs for use in populations across the globe are critical to facilitating the early diagnosis of micronutrient inadequacies on the clinical and community-based level for timely intervention and disease prevention.

Pitfalls in the interpretation of blood tests used to assess and monitor micronutrient nutrition status

“…Methods based upon the intracellular biochemical function of individual MNs are becoming available. However, not only chronic MN deficiencies but also suboptimal MN status, sometimes referred to as marginal or subclinical deficiencies, have been associated with an increased risk of degenerative diseases, as in the case of B‐vitamins 56 . The investigation of general populations for MN depletion relies largely upon the clinical and epidemiological evaluation of responses to controlled trials of supplementation 10,57 …”

“…However, not only chronic MN deficiencies but also suboptimal MN status, sometimes referred to as marginal or subclinical deficiencies, have been associated with an increased risk of degenerative diseases, as in the case of B-vitamins. 56 The investigation of general populations for MN depletion relies largely upon the clinical and epidemiological evaluation of responses to controlled trials of supplementation. 10,57 In addition, using only plasma/serum tests in the presence of inflammation, which inevitably leads to altered values, can be misinterpreted by clinicians and researchers as confirming poor status.…”

Nutrient Intake and Nutritional Status in Adult Patients with Inherited Metabolic Diseases Treated with Low-Protein Diets: A Review on Urea Cycle Disorders and Branched Chain Organic Acidemias

“…However, it is difficult to compare data from these studies because some authors evaluated the dietary intake of micronutrients and other authors their plasma level. Moreover, micronutrient plasma level is not always a good biomarker of adequacy [30], and the estimation of habitual dietary intake in a study population is often inaccurate [31]. Specifically designed studies using appropriate biochemical indicators are needed for assessing the true prevalence of vitamin and mineral deficiencies in UCD and BCOA patients.…”

Winning by losing? : Nutritional consequences of bariatric surgery

“…However, it is unclear whether these changes are accompanied with changes in nutrient composition of the diet [57]. Furthermore, the decrease in energy intake may not only be a consequence of simply eating smaller portions of the same food items but also from a change in intake towards healthier, less energy-dense foods [58].…”

“…Functional deficiencies may exist in the presence of apparently normal blood levels because of poor transport of nutrients across the cell membrane, missing cofactors, circadian rhythms and fluctuation of blood levels with recent supplement or food intake [56]. For that reason, the diagnosis of nutritional deficiencies for some micronutrients may be best assessed by functional indicators or a combination of both direct and functional indicators [58]. Direct indicators are circulating concentrations of the micronutrient under investigation [58].…”