The New England Journal of Medicine offers a perfect illustration of this pattern. But a second study, published in the journal just 13 months later, concluded that one to two cups of coffee per day may indeed increase risk of miscarriage. It's really up to you, Allina says. The National Women's Health Network just isn't comfortable offering advice on such a seesaw topic. The research on headaches seems more convincing.
Caffeine is suspected to help with headaches in two key ways.
By narrowing the blood vessels, caffeine restricts blood flow. And since blood vessels tend to widen prior to some headaches, especially migraines, narrower arteries help minimize headache pain. Caffeine also increases the production of stomach acid, helping the body absorb headache medicine more effectively. At least that's what the research shows. Those who drank at least 28 ounces of coffee a day were five times less likely to develop Parkinson's.