This week marked the release of major trial on how diet can influence heart disease (New England Journal, vol. 368, p1279). The headline result of the trial was that a Mediterranean diet can result in a reduction in cardiovascular events like stroke and heart attack. The trial has generated a lot of interest, and as is to be expected, much controversy as well.

There’s an enormous range of diets out there: Atkins, Ornish, AHA, High-Carb, Lo-Carb. How are we to decide between the raft of options, celebrity endorsements and popular science articles?

The effects of diet are notoriously hard to study, but information about the benefits of a particular diet can come from several different sources. First, we can look at populations across the world that have very low rates of cardiovascular disease and try to study or replicate the diets they follow. For example, Okinawan islanders have particularly long lifespans, and cardiac events are much less common in some Mediterranean areas. This is a good way of getting clues about healthy diets, but healthy communities often have many different reasons for their longevity and it can be hard to be sure which lessons we should learn and apply.

A second kind of study looks at the effect of diet on blood pressure, weight loss, cholesterol and other things that we think should result in reduced heart attacks and strokes. This kind of study is relatively easy to perform but often diets have wide range of biochemical effects, some better, some worse, and it can be hard to predict the health benefit of the combination of changes.

The third kind of study, a randomised controlled trial, is the most difficult to perform but is generally thought to be the most reliable type of medical study available. The New England Journal publication by Estruch and others was this type of trial and it showed that the group that followed a Mediterranean diet had fewer cardiovascular events (strokes and heart attacks) over 5 years. Amongst other things, they recommended:

  • Increasing fresh fruit and vegetables (a total of 5 a day)

  • Using olive oil for cooking

  • Cutting back on red meat and using more fish and lean chicken

  • Increasing legumes and nuts

  • Moderate alcohol intake

  • Reducing soft drinks

These dietary recommendations are in line with the Australian Heart Foundation Healthy Heart Diet

The study had many limitations and it is important to know that different diets are appropriate for different situations, for example, to lose weight, for diabetes or for kidney disease.

The study inadvertently showed another important fact about diet. The trial was meant to be comparison of a Mediterranean diet with a low fat diet- but it wasn’t. The group of people who were just given advice to reduce fat in their diet didn’t change their fat consumption much at all.

At New South Wales Cardiology we believe that building a healthy heart involves more than just a prescription, its about comprehensive care Our team can help you achieve your long-term health goals.

Related New South Wales Cardiology research:

C. Holloway et al. A high-fat diet impairs cardiac high-energy phosphate metabolism and cognitive function in healthy human subjects. Am J Clin Nutr. 2011 Apr;93(4):748-55