Is religious fasting related to iron status in Greek Orthodox Christians?

The Orthodox Christian diet is unique in regularly interchanging from an omnivore to a vegetarian-type diet, and no study to date has focused on the impact of this on Fe status. Thirty-five Greek Orthodox Christian strict fasters (n 17 male, n 18 female; mean age 43.6+/-13.2 years) and twenty-four controls (n 11 male, n 13 female; mean age 39.8+/-7.6 years) were studied before (pre) and near completion (end) of the Christmas fasting (CF) period (40 d), during which meat and dairy products are prohibited. Fe status was assessed using standard haematological parameters, and Fe deficiency was determined via serum ferritin levels (<12 ng/ml) and the tri-index model. While fasters had marginally poorer pre haematological indicators, values were well above the cut-off levels, suggesting that intermittent fasting for a mean of 22.5+/-15.5 years did not have any substantial adverse effects on Fe status. During the CF period the changes in Fe status indices were more beneficial for fasters than for control subjects. In particular, fasters increased their ferritin levels (P = 0.02) and decreased their total Fe-binding capacity (P < 0.001). Compared with males, the effect of CF was more pronounced in female fasters. No subjects were detected with Fe deficiency at the end of the CF period. End dietary Fe and fibre intake were significantly higher in the fasters as compared with the control group (P = 0.038 and P = 0.001, respectively). Adherence to the Orthodox Christian dietary guidelines does not have a major impact on Fe status and is not associated with a significantly greater degree of Fe deficiency.