ORIGINAL RESEARCH article
Front. Endocrinol.
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This article is part of the Research TopicVitamin D and Women’s Health Across the LifespanView all articles
Vitamin D Supplementation and Its Impacton Leptin and Interleukin-6 in Women Following Religious Intermittent Fasting : A Controlled Study
Provisionally accepted
Spyridon N Karras1*
Konstantinos Michalakis1
Maria Kypraiou2
Fatme Al Anouti3
Hana Fakhoury4
Cedric Annweiler5
Stefan Pilz6Marios Anemoulis1Antonios Vlastos1Costas Haitoglou1Uwe Riedmann7
Neoklis Georgopoulos8Evangelos G Papanikolaou2Georgios Tzimagiorgis1- 1Aristotle University of Thessaloniki, Thessaloniki, Greece
- 2Assisting Nature, Thessaloniki, Greece
- 3Zayed University College of Natural and Health Sciences, Abu Dhabi, United Arab Emirates
- 4Alfaisal University College of Medicine, Riyadh, Saudi Arabia
- 5Universite d'Angers, Angers, France
- 6Universitat Graz, Graz, Austria
- 7Medizinische Universitat Graz Institut fur Pathologie, Graz, Austria
- 8Panepistemio Patron, Patras, Greece
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Background: Vitamin D deficiency is highly prevalent in populations following intermittent or religious fasting, particularly Orthodox nuns with limited sun exposure and dietary restrictions. Vitamin D may modulate adipokines and inflammatory markers, but clinical evidence remains inconsistent. Objective: To investigate the effects of vitamin D supplementation on interleukin-6 (IL-6) and leptin concentrations in Orthodox nuns compared with non-supplemented controls. Methods: In this controlled, non-randomized trial, 33 Orthodox nuns received oral vitamin D3 supplementation (2.500 IU/day) for 16 weeks, while 42 age-matched women following Orthodox intermittent fasting served as controls. Anthropometric indices and serum concentrations of 25-hydroxyvitamin D [25(OH)D], IL-6, leptin, parathyroid hormone, insulin, and C-reactive protein were measured at baseline and follow-up. Results: At baseline, serum 25(OH)D concentrations were lower in the supplementation group compared with controls (23.4 ± 10.1 vs. 27.7 ± 11.2 ng/mL, p = 0.043). After 16 weeks, 25(OH)D increased significantly in the supplementation group (23.4 ± 10.1 vs 33.9 ± 11.0 ng/mL, p < 0.001), with no change in controls (27.7 ± 11.2 vs 28.5 ± 12.2 ng/mL, p = 0.941). Leptin showed a non-significant decrease in the supplementation group (24.4 ± 18.3 vs 21.9 ± 13.5 ng/mL, p = 0.215), whereas in controls remained unchanged (23.21±14.67 vs. 24.05 ±13.89 pg/mL, p = 0.365). IL-6 did not change significantly in either group. Exploratory multivariable regression did not reveal significant predictors of leptin changes.
Keywords: Vitamin D, IL-6, Leptin, supplementation, intermittent fasting, Orthodox nuns
Received: 07 Sep 2025; Accepted: 10 Nov 2025.
Copyright: © 2025 Karras, Michalakis, Kypraiou, Al Anouti, Fakhoury, Annweiler, Pilz, Anemoulis, Vlastos, Haitoglou, Riedmann, Georgopoulos, Papanikolaou and Tzimagiorgis. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Spyridon N Karras, karraspiros@yahoo.gr
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