Nov. 5, 2004 - Postmenopausal women who take estrogen may not reap at least one of the potential health benefits of drinking coffee. According to a new study, postmenopausal estrogen use alters coffee's protective effect against Parkinson's disease.
Previous studies have shown that men who drink coffee regularly have a lower risk of developing Parkinson's disease than non-coffee drinkers. But female coffee drinkers don't enjoy the same health benefit.
In the study, researchers looked at the relationship between coffee and Parkinson's disease risk and found that estrogen appears to interfere with this protective effect in postmenopausal women.
Postmenopausal women who had never used estrogens and drank coffee had a lower risk of Parkinson's disease than women who didn't drink coffee. But postmenopausal women who used estrogens and drank coffee were more likely to develop the disease.
The results appear in the Nov. 15 issue of the American Journal of Epidemiology.
Estrogen Alters Coffee's Healthy Effect
In the study, researchers looked at the relationship between how much caffeinated coffee people drank and their later risk of death due to Parkinson's disease among more than 1 million people enrolled in a large cancer study from 1982 to 1998.
During this period, Parkinson's disease was listed as the cause of death in 909 men and 340 women.
After adjusting for factors like age, smoking, and alcohol intake, the study showed that men who regularly drank coffee were about a third less likely to have died of Parkinson's disease than non-coffee drinkers. This reduction in Parkinson's disease risk was about the same whether they drank three to six cups per week or more than six cups per day.
Yet among women there was no reduction in risk seen in coffee drinkers after adjusting for these factors.
Next, researchers looked at whether estrogen use might explain the difference in risk between the sexes. They found, as in men, the risk of Parkinson's disease was about a third lower in postmenopausal women who drank coffee and never used estrogens.
Their study also showed that there was no reduction in risk among women who drank coffee and had used estrogens.
Researchers say the findings suggest that it may be important to look at a possible interaction between estrogen and caffeine in the development in Parkinson's disease. These interactions might explain this potential health benefit of coffee among men and non-estrogen users.