Caffeine and alcohol – Friends or foes of human iron stores?

Background & Aims: There is clear evidence that lifestyle factors affect iron bioavailability. However, information regarding the effect of alcohol and caffeine consumption on iron metabolism is limited. The aim of the current study was to evaluate the effect of caffeine and alcohol consumption on iron metabolism in healthy men, regarding their everyday physical activity level. Methods: The study enrolled 83 men (59 physically active and 24 sedentary men) aged 18–32 years. Fasting blood samples were collected. ELISA kits were used to determine levels of ferritin, soluble transferrin receptor, hepcidin, hemojuvelin, and C-reactive protein (hsCRP). Level of physical activity was assessed using the International Physical Activity Questionnaire (IPAQ). Caffeine and alcohol intake was assessed using a food frequency questionnaire. A general linear model was performed to evaluate the relationship between caffeine intake and levels of serum ferritin, ferritin, soluble transferrin receptor, hepcidin, hemojuvelin, and hsCRP. Results: Physically active men (but not sedentary men) who consumed alcohol in excess presented higher ferritin levels when compared to moderate drinkers and abstainers (R2 = 0.35, p = 0.0001). Heavy drinkers presented the highest hepcidin levels when compared to both abstainers and moderate drinkers (p < 0.0001 for physically active, and p = 0.0267 for sedentary men). However, moderate drinkers showed significantly lower hsCRP levels when compared to heavy drinkers and abstainers drinkers (p < 0.0001 for physically active, and p = 0.0116 for sedentary men). Greater caffeine intake was generally associated with greater serum hepcidin levels, with the strongest effect on moderate drinkers. A significant influence of caffeine intake on hsCRP was shown for physically active men but not for sedentary men - greater caffeine intake was connected with higher hsCRP levels for participants who drank alcohol. Conclusion: Based on the presented results it can be assumed that high caffeine consumption may lead to suppression of iron bioavailability through increased inflammation. Furthermore, physical activity and moderate alcohol consumption seemed to benefit reduction of inflammatory response, at least as represented by hsCRP levels.