Department of Research
Innlandet Hospital Trust
Vitamin B12 deficiency in early life remains a substantial yet underrecognized global health challenge. This presentation reviews current evidence on vitamin B12 status during pregnancy, infancy, and early childhood. Although deficiency is most common in populations with limited access to animal-source foods, clinically meaningful deficiency is also observed among vulnerable subgroups in high-income settings. A major limitation in vitamin B12 research lies in the interpretation of biomarkers, especially in marginal or subclinical states and during vulnerable phases of life stages, where the choice of biomarkers and their cut-offs is debated. Randomized controlled trials of vitamin B12 supplementation in pregnant women and young children consistently demonstrate improvements in biochemical indicators, including plasma cobalamin, methylmalonic acid, and homocysteine. In contrast, effects on functional outcomes, such as linear growth, neurodevelopment, and infection risk, have generally been modest, heterogeneous, and context dependent. These findings underscore the methodological complexities inherent in nutrition trials, including baseline heterogeneity in nutritional status, coexisting micronutrient deficiencies, uncertainty regarding optimal dose and timing, measurement limitations of developmental outcomes, and the difficulty of isolating single-nutrient effects within multifactorial biological systems. Future research should focus on more precise biomarker characterization, especially in the marginal range and vulnerable phases of life, and strengthen the connection between biochemical indicators and clinically meaningful functional outcomes. These improvements are vital for refining definitions of deficiency and establishing biologically valid, clinically relevant diagnostic thresholds.
Professor Tor A. Strand, M.D., Ph.D., received his medical degree and doctoral training from the University of Bergen, where he completed formal education in clinical medicine, epidemiology, and nutrition research. His research focuses on understanding how micronutrient deficiencies, particularly deficiencies of essential vitamins and minerals, shape early childhood health and development in low- and middle-income countries. He is especially concerned with the impact of these deficiencies on infection susceptibility, growth, immunity, and neurodevelopment during critical windows of early life. His long-term objective is to generate robust, policy-relevant evidence that informs effective, context-appropriate nutritional strategies to improve child health outcomes and support developmental potential in resource-constrained settings. He has led and collaborated on numerous observational studies and randomized controlled trials across diverse settings, including Nepal, India, and Norway. A defining feature of his work has been the establishment of large, well-characterized biobanks that support mechanistic sub-studies and enable in-depth exploration of biological pathways linking nutrition to functional child health outcomes. In recent years, he has increasingly integrated metabolomics and other systems biology approaches into his research to elucidate the mechanistic effects, or absence of effects, of nutritional interventions. This strategy moves beyond conventional efficacy assessments toward a deeper understanding of biological plausibility, response heterogeneity, and context dependence. In addition to his academic research, he chairs the Nutrition Panel of the Norwegian Scientific Committee for Food and Environment and leads a team conducting evidence syntheses and technical analyses on growth and mortality for the World Health Organization.