{"ok":true,"entry":{"slug":"threonine","kind":"supplement","name":"threonine","aliases":["L-threonine"],"brands_sg":["California Gold Nutrition","Life Extension","NOW Foods","Doctor's Best","Nutricost"],"class":"amino acid","tags":["general"],"use_for":"an essential amino acid — complete protein foods supply it","use_after":null,"use_duration":null,"take_with":null,"pros":["one of the nine essential amino acids (nih ods)","a requirement in adults is measured: 19 mg/kg a day"],"cons":["limited human evidence for supplementing it","hospital study: threonine levels tracked no outcome","no hsa limit and no ul — absence is not a clearance"],"dose_note":"an indicator-amino-acid-oxidation study in six healthy young men put the mean threonine requirement at 19.0 mg per kg a day, with an 'upper safe intake' of 26.2 mg per kg a day — those are dietary requirement figures for the population, not a supplement dose and not a ceiling. no supplement dose is set by any source read here.","dosage":{"ul":null,"unit":"g","fda_dv":null,"rda_ai":null,"ul_status":"none_established","population":"general adult","hsa_max_daily":null},"ul_status":"none_established","sg_class":null,"cautions":["not listed on hsa's prohibited/restricted annexes — that list is not exhaustive","no human safety study of supplemental threonine was found in the search run here"],"clashes":[],"sources":[{"id":"ajcn2000","url":"https://europepmc.org/article/MED/10702170","label":"Threonine requirement of young men determined by indicator amino acid oxidation with use of L-[1-13C]phenylalanine (Wilson et al., Am J Clin Nutr 2000; PMID 10702170)","quote":"Threonine is an indispensable amino acid with a complex degradative pathway ... the mean threonine requirement, based on indicator oxidation, was 19.0 mg*kg(-)(1)*d(-)(1) with an upper safe intake of 26.2 mg*kg(-)(1)*d(-)(1)","accessed":"2026-08-27"},{"id":"nutrients2024","url":"https://europepmc.org/article/PMC/PMC11357570","label":"The Association of the Essential Amino Acids Lysine, Methionine, and Threonine with Clinical Outcomes in Patients at Nutritional Risk: Secondary Analysis of a Randomized Clinical Trial (Nutrients 2024; PMC11357570)","quote":"Lysine, methionine, and threonine are essential amino acids with vital functions for muscle and connective tissue health, metabolic balance, and the immune system ... The results for lysine and threonine did not show statistically significant differences regarding clinical outcomes.","accessed":"2026-08-27"},{"id":"epmc_thr_search","url":"https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=(TITLE:%22threonine%22)%20AND%20(TITLE:%22supplementation%22%20OR%20TITLE:%22requirement%22%20OR%20TITLE:%22review%22)%20AND%20(SRC:%22MED%22)&format=json&resultType=lite","label":"Europe PMC REST search, 27 Aug 26 — threonine in title plus supplementation/requirement/review, MED source, sorted by citations (133 hits; the most-cited supplementation studies are in poultry and pigs, not people)","quote":"\"hitCount\":133 ... \"Effects of threonine supplementation on the growth performance, immunity, oxidative status, intestinal integrity, and barrier function of broilers at the early age.\"","accessed":"2026-08-27"},{"id":"nih_ods_eaa","url":"https://ods.od.nih.gov/factsheets/ExerciseAndAthleticPerformance-HealthProfessional/","label":"NIH ODS — Dietary Supplements for Exercise and Athletic Performance (Health Professional), protein section","quote":"The nine EAAs are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Most complete proteins (those that contain all EAAs) are composed of about 40% EAAs","accessed":"2026-08-27"},{"id":"hsa_hs","url":"https://file.go.gov.sg/hsa-hs-guidelines.pdf","label":"HSA Health Supplements Guidelines (GL-CHPB-3-001 Rev. 020, January 2026) — working definition and Tables 4–5 (vitamins, minerals)","quote":"HS are products that are used to supplement a diet ... contains one or more, or a combination of the following ingredients: a. Vitamins, minerals, amino acids, fatty acids, enzymes, probiotics and other bioactive substances","accessed":"2026-08-27"},{"id":"hsa_restricted","url":"https://file.go.gov.sg/hsa-chp-prohibited-restricted-ing-guidelines.pdf","label":"HSA Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines (GL-CHPB-1-012, Oct 2025), Annexes A/B","quote":"The objective of this guideline is to highlight the substances of concern when used in HS and TM and is not meant to be an exhaustive list.","accessed":"2026-08-27"},{"id":"iherb_sg","url":"https://sg.iherb.com/c/amino-acids","label":"iHerb Singapore — Amino Acids category page (default sort), read 27 Aug 26; sg.iherb.com has no L-threonine category","quote":"Amino Acids 1 - 48 of 1,602 results ... California Gold Nutrition, L-Theanine ... Life Extension, Glutathione, Cysteine & C ... NOW Foods, L-Arginine ... Doctor's Best, PepZin GI(R) ... Nutricost, L-Theanine","accessed":"2026-08-27"}],"brand_certs":null,"updated_at":"2026-08-29T16:16:33.302383+08:00"},"disclaimer":"kozen-x is not a medical device and does not give medical advice. it lists what published sources have written down. absence of a record is not the same as safe."}