Abstract
Purpose
Different studies have pointed towards a positive effect of religious fasting on human health. Orthodox fasting (OF) regime could be characterized as a periodical vegetarian diet, demonstrating several common characteristics with the typical Mediterranean diet. The present systematic review aimed to synthesize available results regarding the potential impact of OF on human health.
Methods
Key biomedical databases were searched to identify studies examining the effects of OF on humans. Following implementation of specific criteria, ten studies were included in the analysis and their results were systematically reported and critically appraised in this review.
Results
According to the available limited results, OF periods are characterized by a restriction in total energy and fat intake, an increase in carbohydrate and fiber consumption, while in terms of protein intake, results are contradictive. The overall effect of OF on lipids profile seems to be optimal, with the reduction of total cholesterol and LDL-C levels, being a consistent finding across studies (up to 17.8 and 31.4%, respectively). However, the effect on HDL-C is still unclear. Conclusions regarding the impact on body weight and glucose homeostasis cannot be drawn, given that relevant data are limited with conflicting results. Any potential negative aspects of OF, mainly attributed to reduced dietary intake of vitamin D and B12 and minerals (mainly calcium), require further investigation.
Conclusions
Given the limitations of available evidence, more studies are required before reaching definite conclusions about the effects of OF on human health.

Similar content being viewed by others
References
Trepanowski JF, Bloomer RJ (2010) The impact of religious fasting on human health. Nutr J 9:57. doi:10.1186/1475-2891-9-57
Persynaki A, Karras S, Pichard C (2017) Unraveling the metabolic health benefits of fasting related to religious beliefs: a narrative review. Nutrition 35:14–20. doi:10.1016/j.nut.2016.10.005
Trepanowski JF, Canale RE, Marshall KE, Kabir MM, Bloomer RJ (2011) Impact of caloric and dietary restriction regimens on markers of health and longevity in humans and animals: a summary of available findings. Nutr J 10:107. doi:10.1186/1475-2891-10-107
Lazarou C, Matalas AL (2010) A critical review of current evidence, perspectives and research implications of diet-related traditions of the Eastern Christian Orthodox Church on dietary intakes and health consequences. Int J Food Sci Nutr 61(7):739–758. doi:10.3109/09637481003769782
Temizhan A, Tandogan A, Dönderici O, Demirbas B (2000) The effects of Ramadan fasting on blood lipid levels. Am J Med 109(4):341–342
Sarri KO, Tzanakis NE, Linardakis MK, Mamalakis GO, Kafatos AG (2003) Effects of Greek Orthodox Christian Church fasting on serum lipids and obesity. BMC Public Health 3:16. doi:10.1186/1471-2458-3-16
Papadaki A, Vardavas C, Hatzis C, Kafatos A (2008) Calcium, nutrient and food intake of Greek Orthodox Christian monks during a fasting and non-fasting week. Public Health Nutr 11(10):1022–1029. doi:10.1017/S1368980007001498
Kafatos A, Verhagen H, Moschandreas J, Apostolaki I, Van Westerop JJ (2000) Mediterranean diet of Crete: foods and nutrient content. J Am Diet Assoc 100(12):1487–1493
Keys A, Menotti A, Karvonen MJ, Aravanis C, Blackburn H, Buzina R et al (1986) The diet and 15-year death rate in the seven countries study. Am J Epidemiol 124(6):903–915
Sarri KO, Linardakis M, Tzanakis N, Kafatos AG (2008) Adipose DHA inversely associated with depression as measured by the Beck depression inventory. Prostaglandins Leukot Essent Fatty Acids 78(2):117–122. doi:10.1016/j.plefa.2007.12.004
Sarri K, Linardakis M, Codrington C, Kafatos A (2007) Does the periodic vegetarianism of Greek Orthodox Christians benefit blood pressure? Prev Med 44(4):341–348. doi:10.1016/j.ypmed.2006.11.009
Sarri KO, Linardakis MK, Bervanaki FN, Tzanakis NE, Kafatos AG (2004) Greek Orthodox fasting rituals: a hidden characteristic of the Mediterranean diet of Crete. Br J Nutr 92(2):277–284. doi:10.1079/BJN20041197
Sarri KO, Kafatos AG, Higgins S (2005) Is religious fasting related to iron status in Greek Orthodox Christians? Br J Nutr 94(2):198–203
Basilakis A, Kiprouli K, Mantzouranis S, Konstantinidis T, Dionisopoulou M, Hackl JM et al (2002) Nutritional study in Greek-Orthodox monasteries-effect of a 40-day religious fasting. Akt Ernähr Med 27(4):250–255. doi:10.1055/s-2002-33359
Sarri K, Bertsias G, Linardakis M, Tsibinos G, Tzanakis N, Kafatos A (2009) The effect of periodic vegetarianism on serum retinol and alpha-tocopherol levels. Int J Vitam Nutr Res 79(5–6):271–280. doi:10.1024/0300-9831.79.56.271
Karras S, Persynaki A, Petroczi A, Barkans E, Mulrooney H, Kypraiou M, et al (2017) Health benefits and consequences of the Eastern Orthodox fasting in monks of Mount Athos: a cross-sectional study. Eur J Clin Nutr. doi:10.1038/ejcn.2017.26. (Epub ahead of print)
Elshorbagy A, Jernerén F, Basta M, Basta C, Turner C, Khaled M, et al (2016) Amino acid changes during transition to a vegan diet supplemented with fish in healthy humans. Eur J Nutr. doi:10.1007/s00394-016-1237-6. (Epub ahead of print)
U.S. Food and Drug Administration (2013) A food labeling guide. https://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/LabelingNutrition/ucm2006828.htm. Accessed 8 May 2017
Ross AC, Manson JE, Abrams SA, Aloia JF, Brannon PM, Clinton SK et al (2011) The 2011 report on dietary reference intakes for calcium and vitamin d from the Institute of Medicine: what clinicians need to know. J Clin Endocrinol Metab 96(1):53–58. doi:10.1210/jc.2010-2704
Robinson B, Kelley L (1996) Concurrent validity of the Beck depression inventory as a measure of depression. Psychol Rep 79(3 Pt. 1):929–930. doi:10.2466/pr0.1996.79.3.929
Muscogiuri G, Annweiler C, Duval G, Karras S, Tirabassi G, Salvio G et al (2017) Vitamin D and cardiovascular disease: from atherosclerosis to myocardial infarction and stroke. Int J Cardiol 230:577–584. doi:10.1016/j.ijcard.2016.12.053
Asztalos B, Lefevre M, Wong L, Foster TA, Tulley R, Windhauser M et al (2000) Differential response to low-fat diet between low and normal HDL-cholesterol subjects. J Lipid Res 41(3):321–328
Barnard ND, Scialli AR, Bertron P, Hurlock D, Edmonds K, Talev L (2000) Effectiveness of a low-fat vegetarian diet in altering serum lipids in healthy premenopausal women. Am J Cardiol 85(8):969–972
Barter P, Gotto AM, LaRosa JC, Maroni J, Szarek M, Grundy SM et al (2007) HDL cholesterol, very low levels of LDL cholesterol, and cardiovascular events. N Engl J Med 357(13):1301–1310
Jensen MD, Haymond MW, Gerich JE, Cryer PE, Miles JM (1987) Lipolysis during fasting. Decreased suppression by insulin and increased stimulation by epinephrine. J Clin Invest 79(1):207–213. doi:10.1172/JCI112785
Burr ML, Butland BK (1988) Heart disease in British vegetarians. Am J Clin Nutr 48(3 Suppl):830–832
Key TJ, Davey GK, Appleby PN (1999) Health benefits of a vegetarian diet. Proc Nutr Soc 58(2):271–275
Key T, Davey G (1996) Prevalence of obesity is low in people who do not eat meat. BMJ 313(7060):816–817
De Lorenzo A, Petrone-De Luca P, Sasso GF, Carbonelli MG, Rossi P, Brancati A (1999) Effects of weight loss on body composition and pulmonary function. Respiration 66(5):407–412
Maislos M, Khamaysi N, Assali A, Abou-Rabiah H, Zvili I, Shany S (1993) Marked increase in plasma high-density-lipoprotein cholesterol after prolonged fasting during Ramadan. Am J Clin Nutr 57(5):640–642
Miller GD, Jarvis JK, McBean LD (2001) The importance of meeting calcium needs with foods. J Am Coll Nutr 20(2 Suppl):168S–185S
Tedesco MA, Di Salvo G, Caputo S, Natale F, Ratti G, Iarussi D et al (2001) Educational level and hypertension: how socioeconomic differences condition health care. J Hum Hypertens 15(10):727–731. doi:10.1038/sj.jhh.1001249
Teucher B, Olivares M, Cori H (2004) Enhancers of iron absorption: ascorbic acid and other organic acids. Int J Vitam Nutr Res 74(6):403–419. doi:10.1024/0300-9831.74.6.403
Li Y, Li GP (2016) Oxidative stress in asthma: a distinct clinical and pathologic feature? J Biol Regul Homeost Agents 30(4):1053–1057
Lodge JK, Hall WL, Jeanes YM, Proteggente AR (2004) Physiological factors influencing vitamin E biokinetics. Ann N Y Acad Sci 1031:60–73. doi:10.1196/annals.1331.006
Arab K, Rossary A, Flourie F, Tourneur Y, Steghens JP (2006) Docosahexaenoic acid enhances the antioxidant response of human fibroblasts by upregulating gamma-glutamyl-cysteinyl ligase and glutathione reductase. Br J Nutr 95(1):18–26
Huang CW, Chien YS, Chen YJ, Ajuwon KM, Mersmann HM, Ding ST (2016) Role of n-3 polyunsaturated fatty acids in ameliorating the obesity-induced metabolic syndrome in animal models and humans. Int J Mol Sci 17(10):1689. doi:10.3390/ijms17101689
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of interest
The authors declare that they have no conflict of interest.
Rights and permissions
About this article
Cite this article
Koufakis, T., Karras, S.Ν., Antonopoulou, V. et al. Effects of Orthodox religious fasting on human health: a systematic review. Eur J Nutr 56, 2439–2455 (2017). https://doi.org/10.1007/s00394-017-1534-8
Received:
Accepted:
Published:
Issue date:
DOI: https://doi.org/10.1007/s00394-017-1534-8


