{"ok":true,"entry":{"slug":"proline","kind":"supplement","name":"proline","aliases":["L-proline"],"brands_sg":["California Gold Nutrition","NOW Foods","Source Naturals","Vitacost","Nutricost"],"class":"amino acid","tags":["general"],"use_for":"the main amino acid of collagen · few human trials","use_after":null,"use_duration":null,"take_with":null,"pros":["proline and hydroxyproline are richest in collagen","whole-body needs are the highest of any amino acid","humans can make it from arginine and glutamate"],"cons":["the dose-response work read is in pigs, not people","no human skin or hair trial found in 1,163 hits","synthesis falls short only in neonates, birds and fish"],"dose_note":"the dose-response data read are in young pigs (0 to 2.1% of the diet) and chickens; no human supplement dose for proline could be sourced","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":["no human safety or tolerance study surfaced in the search run — that is missing data, not a clean bill","the supplementation evidence read is in pigs, chickens and fish, so human tolerance is untested in these sources"],"clashes":[],"sources":[{"id":"wu2011","url":"https://europepmc.org/article/PMC/PMC3773366","label":"Proline and hydroxyproline metabolism: implications for animal and human nutrition (Wu et al., Amino Acids 2011; PMC3773366)","quote":"On a per-gram basis, proline plus hydroxyproline are most abundant in collagen and milk proteins, and requirements of proline for whole-body protein synthesis are the greatest among all amino acids.","accessed":"2026-08-27"},{"id":"wu2011_roles","url":"https://europepmc.org/article/PMC/PMC3773366","label":"Wu et al., Amino Acids 2011 — physiological roles","quote":"Proline plays important roles in protein synthesis and structure, metabolism … as well as wound healing, antioxidative reactions, and immune responses.","accessed":"2026-08-27"},{"id":"wu2011_syn","url":"https://europepmc.org/article/PMC/PMC3773366","label":"Wu et al., Amino Acids 2011 — endogenous synthesis","quote":"While most mammals (including humans and pigs) can synthesize proline from arginine and glutamine/glutamate, rates of endogenous synthesis are inadequate for neonates, birds, and fish.","accessed":"2026-08-27"},{"id":"wu2011_animal","url":"https://europepmc.org/article/PMC/PMC3773366","label":"Wu et al., Amino Acids 2011 — dose-response data are in pigs and chickens","quote":"work with young pigs … has shown that supplementing 0.0, 0.35, 0.7, 1.05, 1.4, and 2.1% proline to a proline-free chemically defined diet … dose dependently improved daily growth rate and feed efficiency","accessed":"2026-08-27"},{"id":"epmc_pro_search","url":"https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=(TITLE:%22proline%22)%20AND%20(TITLE:%22supplementation%22%20OR%20TITLE:%22collagen%22%20OR%20TITLE:%22human%22%20OR%20TITLE:%22metabolism%22%20OR%20TITLE:%22nutrition%22)%20AND%20(SRC:%22MED%22)&format=json&resultType=core","label":"Europe PMC REST search, 27 Aug 26 — proline in title plus supplementation/collagen/human/metabolism/nutrition (1,163 hits; the first pages are tumour metabolism, plant biology and livestock feeding, with no human supplementation trial and no human skin or hair outcome)","quote":"\"hitCount\":1163 … \"Dietary Proline Supplementation Promotes Growth and Development in Weaned Foals by Modulating Gut Microbial Amino Acid Metabolism.\"","accessed":"2026-08-27"},{"id":"hsa_hs_defn","url":"https://file.go.gov.sg/hsa-hs-guidelines.pdf","label":"HSA Health Supplements Guidelines GL-CHPB-3-001 Rev. No. 020 (January 2026) — s3.1 working definition and clause 4.8 (Tables 4-5 cover vitamins and minerals only)","quote":"Vitamins, minerals, amino acids, fatty acids, enzymes, probiotics and other bioactive substances … HS for use by the general adult population should not contain vitamins and minerals exceeding the stipulated limits stated in Tables 4 and 5.","accessed":"2026-08-27"},{"id":"hsa_pr_notlisted","url":"https://file.go.gov.sg/hsa-chp-prohibited-restricted-ing-guidelines.pdf","label":"HSA Guidelines on Prohibited and Restricted Ingredients in HS and TM, GL-CHPB-1-012 Rev. No. 001 (Oct 2025), Annex A/B — full text searched 27 Aug 26, no row for proline","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/l-proline","label":"iHerb Singapore category page \"L-Proline\", default best-selling order, first 5 distinct brands","quote":"L-Proline","accessed":"2026-08-27"}],"brand_certs":null,"updated_at":"2026-08-29T16:16:29.426925+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."}