"Caffeine has been shown to markedly alter...thyroid stimulating hormone (TSH), and thyroid hormones in animal studies. Similar studies in the human are lacking." (Dev Pharmacol Ther 1987;10(2):73-80) Other researchers found that "chronic caffeine therapy," constituted by high levels of caffeine use over time, "stimulated both T4 and TSH; however, TRH-stimulated TSH release was decreased, suggesting that chronic therapy may blunt pituitary TSH response." (Pediatr Res 1983 Jul;17(7):592-595)."


Once again, for those with a thyroid I can see that there might be problem....