Thiamine: An indispensable regulator of paediatric neuro-cardiovascular health and diseases.

Unlabelled: The sustainable developmental goals emphasize good health, reduction in preventable neonatal and under-five mortalities, and attaining zero hunger. However, South Asian countries report a higher incidence of neonatal and under-five mortalities when compared to the Western world, many of which are attributed to maternal and perinatal micronutrient deficiencies. Isolated nutrient deficiency in the absence of calorie deficit poses a diagnostic challenge since such deficiencies present with acute multisystemic and enigmatic manifestations. Thiamine (vitamin B1) is a micronutrient of prime importance which exerts indispensable roles in energy metabolism. Deficiency of thiamine can lead to catastrophic consequences. This review provides insight into the biochemical actions of thiamine in energy metabolism, the compromised aerobic metabolism resulting from thiamine deficiency, and the crucial role of thiamine in the proper functioning of the nervous, cardiovascular, and immune systems. The review also explores the acute life-threatening consequences of thiamine deficiencies in neonates and infants and the speculative role of thiamine in other pathologies like encephalopathy, sepsis, and autism spectrum disorders. However, routine assessment of thiamine in pregnant women and neonates is yet to be implemented, due to the lack of affordable and automated diagnostic techniques, and the cost-intensive nature of mass spectrometry-based quantification.

Conclusion: Physicians are recommended to have a low threshold for suspecting thiamine deficiency especially in vulnerable populations. Laboratory diagnosis of thiamine deficiency needs to be implemented as a standard of care, especially in endemic regions. Further, public health policies on food fortification, mandatory supplementation, and surveillance are imperative to eliminate thiamine deficiency-induced health hazards.

What Is Known: • South Asian countries report a higher incidence of neonatal and under-five mortalities, many of which are attributed to maternal and perinatal micronutrient deficiencies. • Preventable causes of neonatal/ infantile deaths include birth factors (low birth weight, birth asphyxia), infectious diseases (pneumonia, diarrhoea, tetanus, tuberculosis, measles, diphtheria, malaria, acute infections), deficiency diseases and genetic diseases (vitamin & mineral deficiencies, IEMs, congenital heart disease, unexplained PPHN, SIDS etc).

What Is New: • Acute thiamine deficiency presenting as multisystemic syndromes, has unfortunately been a long standing unresolved public health concern. However, accessible surveillance and diagnostic strategies remain elusive in most clinical settings. • Despite decades of reports and emerging guidelines, diagnosis of thiamine deficiency is often missed and policy mandates at national level are yet to be implemented even in endemic countries. • This review provides a comprehensive summary of the biochemical role of thiamine, its key functions and effects on major organ systems, the diagnostic gap, the enigmatic presentation of acute thiamine deficiency, the plausible role of thiamine in other pathologies and the preventive measures at individual and community level.