Caffeine

Concerns about the possible health effects of consuming caffeine have been expressed for well over a hundred years. Recent concern about its physiological effects tend to focus on mutagenic and teratogenic effects. Mutagenic effects are those that change the reproductive genes, producing mutations in subsequent generations. Scientific reports have also appeared connecting the consumption of large doses of caffeine with particular types of cancer. However, the significance of such findings to the average coffee or tea drinker is unclear.

The situation with teratogenic effects—those that affect the fetus while it is still in the womb—is somewhat clearer. Caffeine passes readily across the placental lining, exposing the fetus to concentrations of the stimulant that are comparable to those in the mother's blood. Since the developing nervous system of the fetus is more likely to be affected by the drug than is the mother's, a reduction in caffeine intake is often recommended for pregnant women.