{
  "@type": "dcat:Dataset",
  "accessLevel": "public",
  "bureauCode": [
    "009:25"
  ],
  "contactPoint": {
    "@type": "vcard:Contact",
    "fn": "NIH",
    "hasEmail": "mailto:info@nih.gov"
  },
  "description": "Background\n          Manipulation of total homocysteine concentration with oral methionine is associated with impairment of endothelial-dependent vasodilation. This may be caused by increased oxidative stress. Vitamin C is an aqueous phase antioxidant vitamin and free radical scavenger. We hypothesised that if the impairment of endothelial function related to experimental hyperhomocysteinaemia was free radically mediated then co-administration of vitamin C should prevent this.\n        \n        \n          Methods\n          Ten healthy adults took part in this crossover study. Endothelial function was determined by measuring forearm blood flow (FBF) in response to intra-arterial infusion of acetylcholine (endothelial-dependent) and sodium nitroprusside (endothelial-independent). Subjects received methionine (100 mg/Kg) plus placebo tablets, methionine plus vitamin C (2 g orally) or placebo drink plus placebo tablets. Study drugs were administered at 9 am on each study date, a minimum of two weeks passed between each study. Homocysteine (tHcy) concentration was determined at baseline and after 4 hours. Endothelial function was determined at 4 hours. Responses to the vasoactive substances are expressed as the area under the curve of change in FBF from baseline. Data are mean plus 95% Confidence Intervals.\n        \n        \n          Results\n          Following oral methionine tHcy concentration increased significantly versus placebo. At this time endothelial-dependent responses were significantly reduced compared to placebo (31.2 units [22.1-40.3] vs. 46.4 units [42.0-50.8], p < 0.05 vs. Placebo). Endothelial-independent responses were unchanged. Co-administration of vitamin C did not alter the increase in homocysteine or prevent the impairment of endothelial-dependent responses (31.4 [19.5-43.3] vs. 46.4 units [42.0-50.8], p < 0.05 vs. Placebo)\n        \n        \n          Conclusions\n          This study demonstrates that methionine increased tHcy with impairment of the endothelial-dependent vasomotor responses. Administration of vitamin C did not prevent this impairment and our results do not support the hypothesis that the endothelial impairment is mediated by adverse oxidative stress.",
  "distribution": [
    {
      "@type": "dcat:Distribution",
      "description": "Visit the original government dataset for complete information, documentation, and data access.",
      "downloadURL": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC34516/",
      "mediaType": "text/html",
      "title": "Official Government Data Source"
    }
  ],
  "identifier": "https://healthdata.gov/api/views/pdxe-ut2t",
  "issued": "2025-07-14",
  "keyword": [
    "endothelial-function",
    "forearm-blood-flow",
    "hyperhomocysteinemia",
    "nih",
    "vitamin-c"
  ],
  "landingPage": "https://healthdata.gov/d/pdxe-ut2t",
  "modified": "2025-09-06",
  "programCode": [
    "009:048"
  ],
  "publisher": {
    "@type": "org:Organization",
    "name": "National Institutes of Health"
  },
  "theme": [
    "NIH"
  ],
  "title": "The effect on endothelial function of vitamin C during methionine induced hyperhomocysteinaemia"
}