Dietary reference values for thiamin

Abstract

Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) derived dietary reference values (DRVs) for thiamin (vitamin B1). The Panel considers that data from depletion-repletion studies in adults on the amount of dietary thiamin intake associated with the erythrocyte transketolase activity coefficient (aETK) < 1.15, generally considered to reflect an adequate thiamin status, or with the restoration of normal (baseline) erythrocyte transketolase activity, without a sharp increase in urinary thiamin excretion, can be used to estimate thiamin requirement. In the absence of new scientific evidence, the Panel endorses the average requirement (AR) of 0.072 mg/MJ (0.3 mg/1,000 kcal) for all adults proposed by the Scientific Committee for Food (SCF) in 1993 on the basis of one depletion-repletion study, in which both aETK and urinary thiamin excretion were measured. Results from other depletion-repletion studies are in agreement with this value. The Panel agrees on the coefficient of variation of 20% used by the SCF to cover uncertainties related to distribution of thiamin requirements in the general population, and endorses the population reference intake (PRI) of 0.1 mg/MJ (0.4 mg/1,000 kcal) set by the SCF for all adults. The same AR and PRI as for adults, expressed in mg/MJ, are proposed for infants aged 7-11 months, children aged 1 to < 18 years, and during pregnancy and lactation, under the assumption that the relationship between thiamin requirement and energy requirement is the same in all population groups. Acknowledgements: The Panel wishes to thank EFSA member of staff Fanny H eraud for the support provided to this scientific opinion.

Genetic defects of thiamine transport and metabolism: A review of clinical phenotypes, genetics, and functional studies

“…Chemically, thiamine is defined as 3‐[(4‐amino‐2‐methyl‐5‐pyrimidinyl) methyl]‐5‐(2‐hydroxyethyl)‐4‐methyl‐1,3‐thiazol‐3‐ium (C 12 H 17 N 4 OS). It has a molecular weight of 265.35 Da and it is composed of a pyrimidine and a thiazole ring linked by a methylene group, which forms a sulfur‐containing structure …”

“…Thiamine is obtained from the diet as phosphorylated thiamine vitamers and from bacteria and plants in the form of free‐thiamine in a proportion of 50% (). Thiamine is absorbed in the proximal part of the large intestine, where phosphatases hydrolyze thiamine phosphate esters and convert them into free‐thiamine (). Free‐thiamine uptake is done by thiamine transporter 1 (ThTR‐1) and 2 (ThTR‐2), encoded by SLC19A2 (MIM*603941) and SLC19A3 (MIM*606152), respectively (Figure ).…”

“…Once free‐thiamine enters the bloodstream, it is transported by high affinity free‐thiamine carries into erythrocytes, where it is phosphorylated into TPP. In cells, two enzymes phosphorylate thiamine: thiamine pyrophosphokinase, which catalyzes the formation of TPP from free‐thiamine using adenosine triphosphate (ATP), and TTP‐ATP‐phosphoryltransferase, which catalyzes the conversion from TPP to TTP, also with ATP . The most abundant thiamine kinase is thiamine pyrophosphokinase (encoded by TPK1 ; Figure ).…”

Hepatic glucose-dependent insulinotropic polypeptide expression is modified by supplementing high-dose thiamine in obese diabetic rats

“…Thi-amine functions as a cofactor in the decarboxylation of keto acids and interconversion of glucose. It is widely found in foods but is abundant in relatively few, including pork, as well as grains and seeds with intact bran (Turck et al, 2016). Of note, heat during food preparation may affect thiamine function.…”

Outcome of a public consultation on the draft scientific opinion of the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) on dietary reference values for thiamin

“…The Scientific Opinion was adopted by the NDA Panel on 22 November 2016, and is published in the EFSA Journal (EFSA NDA Panel, 2016). In line with EFSA's policy on openness and transparency, and in order for EFSA to receive comments on its work from the scientific community and stakeholders, EFSA engages in public consultations on key issues.…”