This is irrelevant because it does not apply to people drinking two or fewer cups per day. It’s possible that people who drink two cups daily have an even higher risk of heart disease than people who drink five cups.

The proportion of people in the world drinking coffee is not relevant to the researchers’ decision. Lots of coffee can have negative health effects even if it’s less popular than it used to be.

This introduces an alternative explanation for the study’s results that challenges the researchers’ conclusion. If people who are stressed tend to consume lots of coffee, then simply reducing coffee intake may not reduce the risk of heart disease.

The study controlled for smoking, so a relationship between smoking habits and coffee consumption should not have influenced the results.

This explains why drinking more coffee increases the risk of heart disease, without challenging the researchers’ conclusion. It does not imply that variations in blood-cholesterol levels confounded the study’s results.