New research has found that Mediterranean and low fat dietary programmes reduce the likelihood of death in patients at heightened risk of cardiovascular disease.
This was found as a result of the first comparative review based on randomised trials of seven popular dietary programmes.
Mediterranean dietary programmes are likely to reduce stroke risk, however, other dietary programmes showed little or no benefit over minimal intervention, for example a usual diet or brief dietary advice from a health professional.
Current guidelines suggest various dietary programmes for patients at increased cardiovascular risk, however, they have typically relied on low certainty evidence from non-randomised studies.
Several analyses of randomised controlled trials have suggested that some diets and dietary programmes can reduce major cardiovascular events in patients at risk of cardiovascular events, such as strokes, but any beneficial impact on death is still uncertain.
In order to address this, researchers examined databases for randomised trials looking at the impact of dietary programmes for preventing death and major cardiovascular events in patients at increased risk of cardiovascular disease.
From these examinations, forty eligible trials were identified involving 35,548 participants who were followed for an average of three years across seven named dietary programmes (low fat, 18 trials; Mediterranean, 12; very low fat, 6; modified fat, 4; combined low fat and low sodium, 3; Ornish, 3; Pritikin, 1).
Some trials compared two different diets (eg. Mediterranean vs low fat).
Researchers assessed the methodological quality of each trial and judged 13 to be at low overall risk of bias and 27 at high risk.
Based on moderate certainty evidence, Mediterranean dietary programmes were better than minimal intervention at preventing all cause mortality (17 fewer deaths per 1000 over five years), non-fatal heart attack (17 fewer per 1000) and stroke (7 fewer per 1000) for patients at intermediate risk of cardiovascular disease.
Low fat programmes were also superior to minimal intervention with moderate certainty for prevention of all cause mortality (9 fewer deaths per 1000) and non-fatal heat attack (7 fewer per 1000).
When compared with one another, researchers found no convincing differences between Mediterranean and low fat programmes for mortality or non-fatal heart attack.
The absolute effects for both dietary programmes were more pronounced for patients at high risk of cardiovascular disease (36 fewer all-cause deaths per 1000 and 39 fewer cardiovascular deaths per 1000 among those that followed the Mediterranean dietary programme over 5 years).
The other dietary programmes were found to have little or no benefit compared with minimal intervention typically based on low to moderate certainty evidence.
