Drinking filtered coffee associated with lower mortality
Coffee consumption and mortality from cardiovascular diseases and total mortality: Does the brewing method matter?
Introduction and methods
Whether an association exists between coffee consumption and increased risk of ischemic heart disease (IHD) is not clear. Assessment of the association between coffee consumption and IHD mortality in observational studies show different results, including no association (1-6), a protective effect (7-9), increased risk (10-12), and a J-shaped curve (13). In addition, meta-analyses suggest either no increased risk, U-shaped risk curves, or an inverse association (14-19). Given these findings, it is possible that population-specific factors affect the possible association between coffee consumption and IHD. One such factor could be the brewing method, with which either filtered or unfiltered coffee is made. Unfiltered coffee contains a substantial amount of LDL-c, which in theory could lead to higher risk of IHD (20, 21).
The present study evaluated the association between amount and type of coffee (filtered, unfiltered) consumed and mortality (total, CVD, ICD, and stroke) risk in participants (n=508747; aged 20-79 years) from Norway. Data were collected from 1985 to 2003 and stemmed from the Norwegian Counties Study (22), the Norwegian Age-40 Program (23), and the CONOR Study, a pooling of compatible cohort studies in Norway (24). Data on coffee consumption were collected with questionnaires. Brewing method was categorized as filtered only, filtered and unfiltered, and unfiltered only. Instant and decaffeinated coffee were categorized as filtered coffee. Participants were also asked about number of coffee cups per day: 0, 1-4, 5-8, ≥9. Primary outcomes were defined as risk of total mortality, CV mortality, IHD and stroke mortality. Follow-up was until participants emigrated, died, or until December 31, 2013. Results are shown from participants without a history of CV disease, diabetes or cancer.
Main results
- 59% of the participants preferred filtered coffee, 20% preferred unfiltered coffee, 9% drank both filtered and unfiltered coffee and 12% did not drink coffee.
- Total mortality was lower in the coffee groups than in the no coffee group. For men, compared to no coffee-drinkers, filtered coffee was associated with lower mortality (for stroke: adjusted HR 0.72, 95% CI: 0.59-0.87; for CVD: adjusted HR 0.88, 95% CI: 0.81-0.96; for total mortality: adjusted HR 0.85, 95% CI: 0.82-0.90). For women, compared to no coffee-drinkers, filtered coffee was also associated with lower mortality (for CVD: adjusted HR 0.80, 95% CI: 0.71-0.89; for total mortality: adjusted HR 0.85, 95% CI: 0.81-0.90).
- Men aged ≥60 years drinking unfiltered coffee had a higher CVD mortality than men not drinking coffee (adjusted HR 1.19, 95% CI: 1.00-1.41). Drinking filtered coffee still had a protective effect on total mortality for these men (adjusted HR 0.83, 95% CI: 0.76-0.91). For women aged ≥60 years, drinking filtered coffee still had protective effects on CVD mortality (adjusted HR 0.80, 95% CI: 0.68-0.95) and total mortality (adjusted HR 0.80, 95% CI: 0.72-0.88). Setting the cut-off at 70 years raised the adjusted HR for men drinking unfiltered coffee to 1.40 (95% CI: 1.04–1.88). For women, the adjusted HR did not change with 70 years cut-off.
- Compared to drinking 1–4 cups/d of filtered coffee, drinking ≥9 cups/d of unfiltered coffee had among the highest mortalities, especially for IHD (for men: adjusted HR 1.21, 95% CI: 1.06-1.39; for women: adjusted HR 1.17, 95% CI: 0.90-1.51), also after adjustment for total cholesterol. However, HRs were generally higher when total cholesterol was not among the covariates, most distinctly seen for unfiltered coffee and IHD mortality.
Conclusion
In a large cohort of middle-aged men and women from Norway, drinking filtered coffee was associated with lower mortality than drinking no coffee and drinking unfiltered coffee had no effect on mortality compared to those who did not drink coffee. When analyzing associations per coffee cups a day, those who drank ≥9 cups/d of unfiltered coffee had an increased risk in IHD mortality compared to those who drank 1–4 cups/d of filtered coffee. The increase in IHD mortality for unfiltered coffee is likely mediated partly through total cholesterol.
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