- People who don't ('currently') drink fall into three groups; those who have never drunk, those who have given up drinking and those who lie.
- Those who have never drunk never started becayse may carry a greater burden of ill health or they are predisposed to a high risk of disease
- Those who have given up drinking have given up through ill health
- Those who lie say they don't/haven't drunk, but they have/are.
The implication being that those who do not drink aren't drinking because they're ill, or going to be soon, or they actually are drinking so that's why they die earlier.
However numerous studies since 1987 have controlled for all these factors, and still it has been observed that the J curve phenomena persists - moderate drinkers are less likely to suffer from CHD than teetotalers and heavy drinkers.