BBC NEWS | Health | Daily caffeine 'protects brain'A study performed this spring examined the reason why there is a link between moderate caffeine consumption and reduced dementia risk. The study, done on rabbits, learned that caffeine shored up the blood-brain barrier to protect it from the effects of cholesterol. Previous studies had determined that cholesterol compromises the blood-brain barrier, allowing potentially harmful chemical to cross. The beneficial effect was a result of rabbits consuming the equivalent of a single cup of coffee per day, administered as caffeine supplements.