{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,18]],"date-time":"2026-04-18T11:35:34Z","timestamp":1776512134938,"version":"3.51.2"},"reference-count":25,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2014,10,23]],"date-time":"2014-10-23T00:00:00Z","timestamp":1414022400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"name":"Michael J. Fox Foundation Rapid Response Innovation Award"}],"content-domain":{"domain":["movementdisorders.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Movement Disord Clin Pract"],"published-print":{"date-parts":[[2014,12]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>Individuals with Parkinson's disease (<jats:styled-content style=\"fixed-case\">PD<\/jats:styled-content>) can suffer from orthostatic hypotension (<jats:styled-content style=\"fixed-case\">OH<\/jats:styled-content>) resulting from reduced levels of norepinephrine (<jats:styled-content style=\"fixed-case\">NE<\/jats:styled-content>), which inhibits the sympathetic nervous system. Levodopa reduces <jats:styled-content style=\"fixed-case\">NE<\/jats:styled-content> levels even further, leading to a greater decrease in blood pressure (<jats:styled-content style=\"fixed-case\">BP<\/jats:styled-content>) and increased <jats:styled-content style=\"fixed-case\">OH<\/jats:styled-content>. Tyrosine is a nonessential amino acid that is the major precursor to <jats:styled-content style=\"fixed-case\">NE<\/jats:styled-content>. Reduced levels of tyrosine have been shown after administration of <jats:sc>l<\/jats:sc>\u2010dopa. This study was a single\u2010center, randomized, double\u2010blind, placebo\u2010controlled trial to test the effects of supplementing <jats:sc>l<\/jats:sc>\u2010tyrosine on <jats:styled-content style=\"fixed-case\">BP<\/jats:styled-content>, plasma tyrosine, <jats:styled-content style=\"fixed-case\">NE<\/jats:styled-content> levels, and autonomic responses to exercise in <jats:styled-content style=\"fixed-case\">PD<\/jats:styled-content>. Thirty\u2010six subjects with <jats:styled-content style=\"fixed-case\">PD<\/jats:styled-content> receiving <jats:sc>l<\/jats:sc>\u2010dopa medication that suffer from <jats:styled-content style=\"fixed-case\">OH<\/jats:styled-content> participated. Random assignment was to a placebo group or <jats:sc>l<\/jats:sc>\u2010tyrosine 1,000\u00a0mg (500\u00a0mg of 2\u00d7 daily) group for 7\u00a0days. <jats:styled-content style=\"fixed-case\">OH<\/jats:styled-content> testing and exercise testing was performed pre\u2010 and postsupplementation. There was no effect of tyrosine on <jats:styled-content style=\"fixed-case\">BP<\/jats:styled-content> after <jats:styled-content style=\"fixed-case\">OH<\/jats:styled-content> testing postsupplementation (tyrosine, n\u00a0=\u00a017; placebo, n\u00a0=\u00a019). There was an increase in plasma tyrosine in the tyrosine group (<jats:italic>P<\/jats:italic>\u00a0&gt;\u00a00.05). There were no significant changes in any of the secondary outcome measures. <jats:sc>l<\/jats:sc>\u2010tyrosine at 1,000\u00a0mg (500\u00a0mg\/2\u00d7 day) for 7\u00a0days is safe and well tolerated in <jats:styled-content style=\"fixed-case\">PD<\/jats:styled-content>. Our results were inconclusive as to whether an increase in plasma tyrosine has an effect on <jats:styled-content style=\"fixed-case\">OH<\/jats:styled-content> in subjects with <jats:styled-content style=\"fixed-case\">PD<\/jats:styled-content>. An increase in plasma tyrosine had no effect on <jats:styled-content style=\"fixed-case\">BP<\/jats:styled-content> or autonomic responses in subjects with <jats:styled-content style=\"fixed-case\">PD<\/jats:styled-content> during acute exercise stress. (Trial registration: <jats:ext-link xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"http:\/\/ClinicalTrials.gov\">ClinicalTrials.gov<\/jats:ext-link>.; identifier: <jats:styled-content style=\"fixed-case\">NCT<\/jats:styled-content>01676103)<\/jats:p>","DOI":"10.1002\/mdc3.12082","type":"journal-article","created":{"date-parts":[[2014,10,23]],"date-time":"2014-10-23T11:38:08Z","timestamp":1414064288000},"page":"348-353","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Effects of Tyrosine on Parkinson's Disease: A Randomized, Double\u2010Blind, Placebo\u2010Controlled Trial"],"prefix":"10.1002","volume":"1","author":[{"given":"Joanne","family":"DiFrancisco\u2010Donoghue","sequence":"first","affiliation":[{"name":"Department of Osteopathic Medicine New York Institute of Technology (NYIT) Old Westbury New York USA"},{"name":"The Adele Smithers Parkinson's Disease Treatment Center NYIT Old Westbury New York USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ely","family":"Rabin","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences NYIT College of Osteopathic Medicine Old Westbury New York USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Eric M.","family":"Lamberg","sequence":"additional","affiliation":[{"name":"Department of Physical Therapy Stony Brook University Stony Brook New York USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"William G.","family":"Werner","sequence":"additional","affiliation":[{"name":"Department of Physical Therapy NYIT Old Westbury New York USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2014,10,23]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1212\/01.wnl.0000247740.47667.03"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1002\/mds.20460"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1468-1331.2006.01512.x"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1212\/WNL.0b013e3181d55f24"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1212\/WNL.58.8.1247"},{"key":"e_1_2_8_7_1","doi-asserted-by":"publisher","DOI":"10.1001\/archneur.57.10.1461"},{"key":"e_1_2_8_8_1","doi-asserted-by":"publisher","DOI":"10.1161\/01.HYP.0000250939.71343.7c"},{"key":"e_1_2_8_9_1","doi-asserted-by":"publisher","DOI":"10.1002\/mds.22612"},{"key":"e_1_2_8_10_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jns.2011.06.047"},{"key":"e_1_2_8_11_1","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1999.86.2.531"},{"key":"e_1_2_8_12_1","doi-asserted-by":"publisher","DOI":"10.1016\/0024-3205(79)90294-7"},{"key":"e_1_2_8_13_1","doi-asserted-by":"publisher","DOI":"10.2174\/187152712800792901"},{"key":"e_1_2_8_14_1","doi-asserted-by":"publisher","DOI":"10.1212\/01.WNL.0000142083.47927.0A"},{"key":"e_1_2_8_15_1","doi-asserted-by":"publisher","DOI":"10.1126\/science.7209553"},{"key":"e_1_2_8_16_1","doi-asserted-by":"publisher","DOI":"10.1016\/0024-3205(82)90596-3"},{"key":"e_1_2_8_17_1","doi-asserted-by":"publisher","DOI":"10.1016\/0006-8993(85)90126-X"},{"key":"e_1_2_8_18_1","doi-asserted-by":"publisher","DOI":"10.2147\/IJGM.S16621"},{"key":"e_1_2_8_19_1","doi-asserted-by":"publisher","DOI":"10.1159\/000176359"},{"key":"e_1_2_8_20_1","doi-asserted-by":"publisher","DOI":"10.1136\/jnnp.55.3.181"},{"key":"e_1_2_8_21_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.neurol.2009.09.001"},{"key":"e_1_2_8_22_1","first-page":"54","volume-title":"Staying Healthy with Nutrition: the Complete Guide to Diet and Nutritional Medicine","author":"Haas EM","year":"2006"},{"key":"e_1_2_8_23_1","first-page":"456","volume-title":"American College of Sports Medicine","author":"Thompson WR","year":"2010"},{"key":"e_1_2_8_24_1","doi-asserted-by":"publisher","DOI":"10.1586\/14737175.6.8.1173"},{"key":"e_1_2_8_25_1","unstructured":"Clinical Standards Laboratory Institute. 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