Lifestyle changes cut heart risk most when combined

Cardiovascular disease is a leading cause of death among working-age adults, and the advice given to prevent it — eat better, move more, stop smoking, drink less — is dispensed constantly but audited far less often as a package. The question this review set out to answer is whether such advice, delivered as a formal intervention and followed for at least a year, shifts hard outcomes rather than just intentions. It also asked whether targeting one behaviour at a time performs as well as targeting several together, and whether the answer differs for people who already have heart disease compared with those who do not.

The authors conducted a systematic review of randomised controlled trials of lifestyle interventions in adults of working age, including only trials that followed participants for one year or longer. Interventions spanned diet, exercise, smoking cessation and reduction of alcohol intake. Twenty-one single-factor and 21 multifactorial interventions were analysed and grouped by outcome. Cardiovascular morbidity and mortality, plus total mortality, were treated as the main outcomes, with weight, total cholesterol, blood pressure, sodium excretion, smoking and alcohol consumption analysed alongside them. Numbers needed to treat were calculated for smoking, morbidity and mortality.

In secondary prevention — people who already had cardiovascular disease — both single-factor and multifactorial lifestyle interventions reduced morbidity and mortality, and the multifactorial approaches additionally lowered cholesterol levels. In primary prevention, the interventions reduced risk factors efficiently, and did so particularly when more than one behaviour was addressed. The picture was far from tidy, however: effect sizes were heterogeneous and confidence intervals were wide, meaning the magnitude of benefit for any given person or programme remains imprecise. The authors flagged that inconsistent reporting made effect sizes difficult to compare across trials at all.

This review supports the long-standing clinical position that behaviour change is a legitimate arm of cardiovascular prevention, not merely a supplement to drug therapy, and it does so using randomised evidence with at least a year of follow-up rather than short-term surrogate studies. It complicates the picture by showing that the evidence base was, at the time, too heterogeneous to give a confident number for how much benefit to expect. The authors' own recommendation — that interventions be multifactorial and aimed at people carrying multiple risk factors — is a judgement about where limited effort pays off, not a demonstration that single-factor change is useless. Open questions include how to standardise the description and measurement of these interventions so effects can be compared.

The most reasonable reading is that combined lifestyle change has randomised evidence behind it for cardiovascular outcomes, and that stacking changes appears to do more than isolating one. This is a reason to think of diet, activity, smoking and alcohol as a single package rather than a menu of alternatives. It is also a reason to be sceptical of anyone quoting a precise figure for how many years or events a lifestyle programme buys, because the pooled evidence here was too varied to support one. People carrying several risk factors at once were the group the authors judged most likely to gain.