Coffee drinkers on both sides of the Atlantic can refill from their coffee machines (See Leascoffee.com for coffe machine reviews). Two prospective observational studies in the Annals of Internal Medicine certify that they have a higher life expectancy – provided the associations described there are based on causality.
Association of Coffee Consumption With All-Cause and Cardiovascular Disease Mortality
Coffee is one of the most popular drinks. Worldwide, 2.25 billion cups are to be consumed every day. Coffee doesn’t just contain caffeine, which increases alertness and concentration. The infusion from the roasted and ground coffee beans is also rich in polyphenols, diterpenes and antioxidants, which are said to have various positive effects on health. Previous studies have shown that coffee drinkers are less likely to develop type 2 diabetes, liver disease and Parkinson’s. Coffee consumption was associated with a reduced risk of liver and colon cancer and is also said to protect against the development of depression.
It is therefore not surprising that frequent coffee consumption in two prospective observational studies from the USA and Europe was now associated with a reduced risk of death.
Marc Gunter from the International Agency for Cancer Research ( IARC ) in Lyon and co-workers evaluated the data from the EPIC study (European Prospective Investigation into Cancer and Nutrition), which asked 521,330 adults from ten EU countries about their coffee consumption, among other things. 41,693 participants had died during a follow-up period of 16.4 years. Coffee drinkers were affected a little less often. For the quarter of the participants with the highest coffee consumption, Gunter and co-workers determined a hazard ratio of 0.88 (95 percent confidence interval)0.82 to 0.95) for men and a hazard ratio of 0.93 (0.87-0.98) for women. Strong coffee drinkers among men have a 12 percent lower risk of death, while women with high coffee consumption suffered 7 percent fewer deaths.
The lower death rate in both sexes was mainly due to a reduced number of gastrointestinal deaths (hazard ratio 0.41; 0.32-0.54, for men and 0.60; 0.46-0.78 for women). In women, there was also a statistically significant inverse association with deaths from circulatory diseases (hazard ratio 0.78; 0.68-0.90) and to and cerebrovascular diseases (hazard ratio 0.70; 0.55-0.90) . On the other hand, deaths from ovarian cancer occurred more frequently in women with high coffee consumption (hazard ratio 1.31; 1.07-1.61).
It is interesting that the association in countries with the highest coffee consumption (Denmark 900 ml per day) and the lowest coffee consumption (Italy 92 ml per day) was detectable and also hardly influenced by the type of preparation (espresso in Italy, filter coffee in Germany) has been.
In a sub-study with 14,000 participants in which blood samples were examined, higher coffee consumption was associated with better liver values (alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase). In women, coffee drinkers also had lower levels of C-reactive protein, lipoprotein, and long-term blood sugar HbA 1c.
As always in prospective observational studies, reverse causality cannot be completely ruled out. It is possible that people will lose the pleasure of coffee as a luxury drink due to illness.
This objection also applies to the evaluation of the MEC study (Multiethnic Cohort), which is presented by a team led by Veronica Setiawan from the Keck School of Medicine in Los Angeles. The cohort accompanies a group of 185,855 Americans from five different ethnic groups (African American, Native Hawaiian, Japanese American, Latino, and white). Setiawan started to determine a dose-response relationship: one cup of coffee a day reduced the risk by 12 percent (hazard ratio 0.88; 0.85-0.91), with two to three cups a day it decreased by 18 percent ( Hazard ratio 0.82; 0.79-0.86), as well as when consuming more than four cups a day (hazard ratio 0.82; 0.78-0.87).
In the US study, too, there were associations across ethnic boundaries. They were found for both caffeine-containing and caffeine-free coffee, which is why, according to Setiawan, other ingredients than caffeine must be present for the protective effect. Coffee drinkers died less frequently of heart diseases, cancer, respiratory diseases, stroke, diabetes and kidney diseases.