Daily consumption of coffee may reduce risk for total mortality and mortality related to CVD and neurological diseases, according to study results published in Circulation.
Health risks associated with drinking coffee have been investigated in numerous studies with varied results. Some studies have concluded that moderate coffee consumption is linked to a lower risk for mortality, whereas heavy coffee consumption has been associated with both no effect on mortality and a higher risk for mortality in other studies. One recent study found that drinking coffee may improve survival for patients with colon cancer, and another study demonstrated that daily coffee could slow the progression of fatty liver disease.
For the current study, Ming Ding, MD, of the departments of nutrition and epidemiology at Harvard School of Medicine Health, and colleagues evaluated whether there is a nonlinear relationship between coffee consumption and risk for mortality, and whether smoking is a confounding factor. The researchers also wanted to determine associations with coffee consumption and cause-specific mortality related to CVD and cancer.
Study participants were culled from the Nurses’ Health Study (n = 74,890 women), Nurses’ Health Study II (n = 93,054 women) and the Health Professionals Follow-up Study (n = 40,557 men). Lifestyle and medical history questionnaires were administered, and participants in all three cohorts were followed up with every 2 years. Data also were collected for age, weight, smoking status, physical activity, medication use and medical conditions, including hypercholesterolemia, CVD and cancer.
The primary endpoint was death from any cause. Using the National Death Index and reports from family members and the postal service, the deaths of 19,524 women and 12,432 men were recorded during 28 years of follow-up. When comparing nondrinkers with those who drank one to five cups per day, the coffee drinkers had a lower mortality risk, and for those who drank more than five cups of coffee per day, consumption was not associated with risk for mortality. Compared with no consumption, the researchers reported a pooled HR for death of 0.95 (95% CI, 0.91-0.99) for participants who drank one or fewer cups of coffee per day; 0.91 (95% CI, 0.88-0.95) for 1.1 to three cups per day; 0.93 (95% CI, 0.89-0.97) for 3.1 to five cups per day; and 1.02 (95% CI, 0.96-1.07) for more than five cups per day.
The researchers also restricted their analysis to never-smokers “because smoking is a strong confounder of the coffee-mortality relationship.” When smokers were excluded from the coffee drinkers, The HRs for mortality were 0.94 (95% CI, 0.89-0.99) for participants who drank one or fewer cups per day; 0.92 (95% CI, 0.87-0.97) for 1.1 to three cups per day; 0.85 (95% CI, 0.79-0.92) for 3.1 to five cups per day; and 0.88 (95% CI, 0.78-0.99) for more than five cups per day (P for nonlinearity = .32; P for trend < .001).
In the analysis of cause-specific mortality, coffee consumption was positively associated with lung cancer (P < .0001) and respiratory diseases (P < .05). When the researchers restricted the analysis to never-smokers, coffee consumption was inversely associated with CHD, neurologic diseases and suicide, but not with lung cancer mortality (P < .05).
The researchers concluded that moderate coffee consumption, whether caffeinated or decaffeinated, could lower mortality risk, when a part of a healthy lifestyle.
Ding and colleagues noted several limitations of the study, including the observational design, coffee-intake assessment based on food-frequency questionnaires and a cohort that is primarily white. – by Tracey Romero
Disclosure: One researcher reports receiving research funding from Nestec S.A.