{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,16]],"date-time":"2026-05-16T20:17:52Z","timestamp":1778962672576,"version":"3.51.4"},"reference-count":35,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2013,9,16]],"date-time":"2013-09-16T00:00:00Z","timestamp":1379289600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nutrients"],"abstract":"<jats:p>Vitamins B6, B12 and folate play crucial metabolic roles especially during the reproductive years for women. There is limited reporting of within-subject variability of these vitamins. This study aimed to determine the within and between subject variability in serum vitamins B6, B12, folate and erythrocyte folate concentrations in young women; identify factors that contribute to variability; and determine dietary intakes and sources of these vitamins. Data were obtained from the control group of a trial aimed at investigating the effect of iron on the nutritional status of young women (age 25.2 \u00b1 4.2 year;  BMI 21.9 \u00b1 2.2 kg\/m2). The coefficients of variability within-subject (CVI) and  between-subject (CVG) for serum vitamins B6, B12 and folate, and erythrocyte folate were calculated. Food frequency questionnaires provided dietary data. CVI and CVG were in the range 16.1%\u201325.7% and 31.7%\u201362.2%, respectively. Oral contraceptive pill (OCP) use was associated (P = 0.042) with lower serum vitamin B12 concentrations. Initial values were 172 \u00b1 16 pmol\/L and 318 \u00b1 51 pmol\/L for OCP and non-OCP users, respectively; with differences maintained at four time points over 12 weeks. BMI, age, physical activity, alcohol intake and haematological variables did not affect serum or erythrocyte vitamin concentrations. Vitamin B12 intakes were derived from traditional and unexpected sources including commercial energy drinks. Young women using OCP had significantly lower serum vitamin B12 concentrations. This should be considered in clinical decision making and requires further investigation.<\/jats:p>","DOI":"10.3390\/nu5093634","type":"journal-article","created":{"date-parts":[[2013,9,16]],"date-time":"2013-09-16T11:20:11Z","timestamp":1379330411000},"page":"3634-3645","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":21,"title":["Biological Variability and Impact of Oral Contraceptives  on Vitamins B6, B12 and Folate Status in Women of Reproductive Age"],"prefix":"10.3390","volume":"5","author":[{"given":"Jennifer","family":"McArthur","sequence":"first","affiliation":[{"name":"Discipline of Nutrition and Metabolism, School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"HoMan","family":"Tang","sequence":"additional","affiliation":[{"name":"Discipline of Nutrition and Metabolism, School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Peter","family":"Petocz","sequence":"additional","affiliation":[{"name":"Department of Statistics, Macquarie University, Ryde, NSW 2112, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Samir","family":"Samman","sequence":"additional","affiliation":[{"name":"Discipline of Nutrition and Metabolism, School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2013,9,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1188","DOI":"10.1093\/ajcn\/81.5.1188","article-title":"A lifecycle micronutrient perspective for women\u2019s health","volume":"81","author":"Bartley","year":"2005","journal-title":"Am. 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