Healthy habits can mean 14 extra years:
To get an extra 14 years of life, don’t smoke, eat lots of fruits and vegetables, exercise regularly and drink alcohol in moderation. That’s the finding of a study that tracked about 20,000 people in the United Kingdom.
That’s welcome news to some of us — but it’s not exactly what the actual study found:
We examined the prospective relationship between lifestyle and mortality in a prospective population study of 20,244 men and women aged 45–79 y with no known cardiovascular disease or cancer at baseline survey in 1993–1997, living in the general community in the United Kingdom, and followed up to 2006. Participants scored one point for each health behaviour: current non-smoking, not physically inactive, moderate alcohol intake (1–14 units a week) and plasma vitamin C >50 mmol/l indicating fruit and vegetable intake of at least five servings a day, for a total score ranging from zero to four. After an average 11 y follow-up, the age-, sex-, body mass–, and social class–adjusted relative risks (95% confidence intervals) for all-cause mortality (1,987 deaths) for men and women who had three, two, one, and zero compared to four health behaviours were respectively, 1.39 (1.21–1.60), 1.95 (1.70–2.25), 2.52 (2.13–3.00), and 4.04 (2.95–5.54) p < 0.001 trend. The relationships were consistent in subgroups stratified by sex, age, body mass index, and social class, and after excluding deaths within 2 y. The trends were strongest for cardiovascular causes. The mortality risk for those with four compared to zero health behaviours was equivalent to being 14 y younger in chronological age.
So the two subtle differences are (1) they weren’t looking at fruit and vegetable consumption, but at vitamin C levels, which tend to imply fruit and vegetable consumption, and (2) they did not demonstrate 14 more years of longevity but one-fourth the mortality, which implies 14 more years of longevity, because subjects who were 14 years older died four times as often.
The real issue though is why would you convert all those variables to 0-or-1 values, then sum them, then convert the sums to four categorical variables, before running the numbers?