Diet and exercise beat mineral pills for blood pressure

Raised blood pressure is one of the most consequential and most modifiable cardiovascular risk factors, and people facing it are offered a bewildering menu of options: diets, exercise programmes, relaxation techniques and a shelf of supplements. Each option has trials behind it, but trials of varying quality and conflicting results. The practical question for a patient and their doctor is which lifestyle changes reliably move the number and which are a waste of effort and money. This review set out to quantify exactly that, intervention by intervention.

The authors searched electronic databases, existing guidelines and prior reviews for randomised controlled trials with at least 8 weeks of follow-up, comparing lifestyle interventions against control in adults with blood pressure of at least 140/85 mmHg. Two reviewers independently selected trials and extracted the data, resolving differences by discussion. They grouped trials by intervention type and used random-effects meta-analysis to combine the differences in endpoint blood pressure between treatment and control groups, across 105 trials randomising 6805 participants in total.

Robust, statistically significant reductions in systolic blood pressure were found for improved diet at 5.0 mmHg, aerobic exercise at 4.6 mmHg, alcohol restriction at 3.8 mmHg, sodium restriction at 3.6 mmHg and fish oil supplements at 2.3 mmHg, with corresponding drops in diastolic pressure. Relaxation techniques only reduced blood pressure when compared with doing nothing at all, not against active comparison groups. Potassium, magnesium and calcium supplements showed no robust evidence of any important effect on blood pressure.

The findings underpin what became standard advice: weight-reducing diet, regular exercise, and restricting alcohol and salt intake for people with elevated blood pressure. They also drew a sharp and useful line under the supplement question as it stood, finding the mineral supplements often marketed for heart health wanting. The review dates from 2006, so it cannot speak to trials published since, and how the interventions combine or compare in the same people remains a separate question.

For a reader whose readings are drifting upwards, this is a reason to expect meaningful returns from the unglamorous levers: what you eat, how much you move, how much salt and alcohol you take in. Reductions of around 5 mmHg from a single lifestyle change are clinically meaningful at a population level, and several of these changes can be made at once. Equally, it is a reason for scepticism about potassium, magnesium and calcium pills sold on blood pressure claims, since the pooled trial evidence here found nothing robust behind them.