None of the participants (ages 25 to 42) had PMS at the start of the new study. Over the next 14 years, the researchers found that women who consumed the most caffeine (more than 540 milligrams a day, the amount in about five cups of coffee) were no more likely to develop PMS than those who consumed almost none. Even the highest coffee consumption was not associated with PMS.
“Our results, in conjunction with those of other studies, suggest that current recommendations to reduce or eliminate caffeine to prevent PMS may be unnecessary,” the Harvard researchers concluded. The study did not look at whether caffeine intake is related to severity of symptoms in women who already have PMS.
Also see Coffee and Your Health.