Academically speaking: people who drink coffee for a long life often drink it, okay? Will you grow old quickly by drinking coffee?

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Age and area were used as stratum covariates, plus three meals, but "smoking" was not included. From the results of the basic model analysis, we know that except for the "highest coffee group", the other three "coffee groups" have a 5-11% lower risk of death than the "white water group", both men and women. The result is very exciting. However, the "highest coffee group" had a 7-10% higher risk of death than the "white water group". It seems that coffee is good, but drinking too much is not a good thing.

However, if covariables such as "smoking and body mass index" were added to the basic model for analysis, all four "coffee groups" had a 10% 22% benefit. The most important thing is to reverse the disadvantage of the "highest coffee group". What is this all about?

This is because smoking, a covariable, is a confounding factor (confounder) in the statistical analysis of coffee's effect on longevity. First of all, it is an accepted fact that "smoking" shortens life. Secondly, the data in the report show that the proportion of smokers in the "coffee group" is significantly higher than that in the "white water group". For example, in the female group, only 11% of the Whitewater group smoked, but in the highest coffee group, 31% smoked! If it is true that drinking coffee makes people live longer, then the results of statistical analysis tell us that the benefits of coffee seem to be completely offset by smoking.

Statistical analysis also examines the benefits of "too much" drinking, that is, to explore "trends" (trend). The result is that people in the higher quartile live longer than those in the lower quartile. As a result, we come to the conclusion that "more" drinking is good.

Of the 185000 "subjects", non-whites accounted for about 75 per cent (29 per cent of Japanese-Americans, 22 per cent of Hispanics, 17 per cent of blacks and 7 per cent of Hawaiians) and 25 per cent of whites. About 84% of the people belong to the "coffee group", while 16% do not drink coffee at all and belong to the "white water group."

Statistical analysis divided people in the "coffee group" into five groups: 1-3 cups per month (7%), 1-6 cups a week (13%), 1 cup a day (31%), 2-3 cups (25%), > = 4 cups (7%). To compare with the Whitewater group.

In the first step of statistical analysis, only age, sex and race were used as stratum covariates. From the results of this analysis, there is no evidence that drinking too much coffee makes people live longer. In the model of the second step, after adding the covariable of "smoking" (including smoking age, smoking quantity, etc.), it seems that the benefits of drinking coffee suddenly "come to light." The data showed that except for the group of 1-3 cups per month, the other four groups had a 6-20% lower risk of death than the "Whitewater group".

This may also be because "smoking" is a confounding factor in the statistical analysis of the effect of coffee on longevity. Because smoking is a nemesis to longevity, and the data show that people who drink more coffee usually have a history of smoking. For example, 74% of people in the group that drank four cups a day had smoked, while only 42% of those in the "Whitewater group" had ever smoked.

The statistical analysis also compared those who drank only caffeinated coffee with the Whitewater group. In the analysis with "smoking" as a covariable, it seemed that just one cup a day reduced the risk of death by 13%. In another analysis, people who drank only decaffeinated coffee were compared with the Whitewater group. In the analysis results with "smoking" as a covariable, it seems that you have to drink 2-3 cups a day in order to have specific benefits.

The statistical analysis also examined the benefits of "more" drinking, and concluded that the more people drank, the lower the risk of death compared with those in the Whitewater group, thus drawing the conclusion that "more" drinking was beneficial.

In the report, the top 10 killers in the United States (cardiovascular disease, cancer, stroke, etc.) were selected and analyzed according to the cause of death. For example, people who drank enough coffee a day had a 16-25% lower risk of dying from cardiovascular disease than the Whitewater group. These figures can be looked at, but they cannot be used as evidence.