Effects of Religious Fasting on Markers of Oxidative Status in Vitamin D Deficient and Overweight Orthodox Nuns versus Implementation of Time-Restricted Eating in Lay Women from Central and Northern Greece
Authors: Karras Spyridon N , Michalakis Konstantinos , Tekos Fotios , Skaperda Zoi , Vardakas Periklis , Ziakas Panayiotis D , Kypraiou Maria , Anemoulis Marios , Vlastos Antonios , Tzimagiorgis Georgios , Chaitoglou Konstantinos , Georgopoulos Neoklis , Papanikolaou Evangelos G. , Kouretas Demetrios 
Published: August 2024

Mediterranean diet has been widely suggested to exert significant beneficial effects on endothelial oxida-tive status and cardiometabolic health. Greek Orthodox monasteries, due to their specific nutritionaland sartorial habits, comprise a population which strictly adheres to nutritional patterns with restricted eating and a plant-based subset of the Mediter-ranean diet, often accompanied by profound hypovitaminosis D. Time &ndash;restricted eating is also adopted from a large part of general lay Greek population for health promoting reasons, without restrictions on an-imal product consumption, as imposed by Orthodox religious fasting. However, comparative effects of these nutritional patterns on oxidative stress markers remain scarce. The present study attempted to evaluate the effects of Christian Orthodox fasting (COF) in a group of vitamin D &ndash;deficient and overweight Orthodox nuns from Central and Northern Greece, compared to the implementation of TRE, 16:8 dietary regimen in a cohort of adult women from the general population from the same region, with regard to markers of endothelial oxidative status. A group of 50 women from two Orthodox monasteries in Northern Greece and one group of 50 healthy lay women were included. During enrollment a detailed recording of dietary habits was performed, along with a scientific registry of demographic and anthropometric characteristics (via bioimped-ance).Orthodox nuns followed a typical Orthodox fasting regimen[daily feeding window (8 am&ndash;4 pm)] whereas lay women followed a TRE 16:8 regimen with the same feeding time-window with recommenda-tion to follow a low-fat diet, without characteristics of the Mediterranean diet. We included a complete biochemical analysis, as well as calciotropic profiles [Calcium-Ca, Albumin, Parathyroid hormone-PTH, 25-hydroxyvitamin D- 25(OH)D] as well as and markers of TAC (trichloroacetic acid), (glutathione) GSH and thiobarbituric acid reactive substances (TBARS) concentrations, as markers of oxidative status. All groups were comparable at baseline for calcium, PTH and 25(OH)D concentrations, with no significant differences between groups. Orthodox nuns manifested a lower median GSH compared to con-trols (6.0 vs. 7.2, p 0.04) and a higher median TAC (0.92 vs. 0.77, p &lt;0.001). TBARS comparisons showed no significant difference between the two groups. No significant associations of oxidative status with 25(OH)D, PTH and markers of glucose homeostasis were evident. Results of this small pilot study indicate that both dietary regimens have advantages over oxidative markers compared to each other, with increased TAC in the groups of Orthodox Nuns after a 16th week period of COF compared to a 16:8 TRE and increased GSH concentrations in the lay women group. Future randomized trials are required to investigate superiority or non-inferiority between these dietary patterns, in the daily clinical setting.