{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T06:05:34Z","timestamp":1784786734666,"version":"3.55.0"},"reference-count":36,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T00:00:00Z","timestamp":1784764800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Nutr."],"abstract":"<jats:sec>\n                    <jats:title>Background\/objectives<\/jats:title>\n                    <jats:p>Chronotype reflects interindividual differences in the circadian timing system. Animal studies suggest reduced mitochondrial oxidative metabolism and tricarboxylic acid (TCA) cycle activity in individuals with an evening chronotype; however, human evidence linking chronotype to mitochondrial metabolic alterations remains limited. This cross-sectional study examined whether chronotype is associated with differences in circulating TCA-related metabolites, including pyruvate, lactate, and citrate.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>A total of 272 adults from the 2022 Gangwon Obesity and Metabolic Syndrome Cohort were classified as having morning (\u226518), intermediate (12\u201317), or evening (\u226411) chronotype using the reduced Morningness\u2013Eveningness Questionnaire. Fasting serum concentrations of pyruvate, lactate, and citrate were measured. Associations were examined using general linear models adjusted for fasting status; demographic, socioeconomic, and lifestyle factors; as well as body mass index. Sensitivity analyses excluded participants taking metabolic disease-related medications.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Major clinical and metabolic indicators did not differ across chronotypes. Serum pyruvate concentrations were higher in the evening chronotype group than in the morning chronotype group across all adjusted models (\n                      <jats:italic>p<\/jats:italic>\n                      \u202f&amp;lt;\u202f0.048), whereas lactate and citrate concentrations did not differ. These findings remained consistent in sensitivity analyses excluding participants with metabolic diseases (\n                      <jats:italic>p<\/jats:italic>\n                      \u202f=\u202f0.006\u20130.010).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Across analyses that included and excluded participants using metabolic disease-related medications, evening chronotype was consistently associated with higher circulating pyruvate concentrations, a key metabolic branch point downstream of glycolysis. These findings suggest chronotype-related differences in pyruvate metabolism, with potential implications for metabolic regulation.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fnut.2026.1839777","type":"journal-article","created":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T05:37:52Z","timestamp":1784785072000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Evening chronotype is associated with higher circulating pyruvate levels in adults"],"prefix":"10.3389","volume":"13","author":[{"given":"Sarang","family":"Jeong","sequence":"first","affiliation":[{"name":"Department of Food and Nutrition, Industry-Academy Collaboration Foundation, Dongduk Women\u2019s University","place":["Seoul, Republic of Korea"]},{"name":"The Korean Institute of Nutrition, Hallym University","place":["Chuncheon, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eunjin","family":"Jang","sequence":"additional","affiliation":[{"name":"The Korean Institute of Nutrition, Hallym University","place":["Chuncheon, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jinhyun","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Food Science and Nutrition, Hallym University","place":["Chuncheon, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sang Youl","family":"Rhee","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Center for Digital Health, Kyung Hee University College of Medicine","place":["Seoul, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sohyun","family":"Park","sequence":"additional","affiliation":[{"name":"The Korean Institute of Nutrition, Hallym University","place":["Chuncheon, Republic of Korea"]},{"name":"Department of Food Science and Nutrition, Hallym University","place":["Chuncheon, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,7,23]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"286","DOI":"10.1111\/bdi.13122","article-title":"Chronotypes and circadian rest\u2013activity rhythms in bipolar disorders: a meta-analysis of self-and observer rating scales","volume":"24","author":"Meyrel","year":"2022","journal-title":"Bipolar Disord"},{"key":"ref2","doi-asserted-by":"publisher","first-page":"343","DOI":"10.1038\/s41467-018-08259-7","article-title":"Genome-wide association analyses of chronotype in 697,828 individuals provides insights into circadian rhythms","volume":"10","author":"Jones","year":"2019","journal-title":"Nat Commun"},{"key":"ref3","doi-asserted-by":"publisher","first-page":"169","DOI":"10.1080\/09291016.2024.2443826","article-title":"The effect 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