Eating to prevent heart disease

Back in September last year I wrote a two part blog post (part I, part II) about the links between coronary heart disease (CHD) and diet

For many years now the associations between diet, specific nutrients and coronary heart disease has been investigated.  However, the evidence is often conflicting and sometimes the studies are weak and of poor quality.  The many different papers and literature available can be mind-boggling.

A very interesting (and much needed) paper has just been published (1) which thoroughly reviews over 50 years of research, that took place between 1950 and 2007, into dietary factors and heart disease.  A total of 146 prospective cohort studies (these are studies which look back on the habits of a particular group of individuals) and 43 randomized controlled trials were included in the review.

The authors of the study found that there was strong evidence to support a protective association between intakes of vegetables, nuts, a ‘Mediterranean’ style diet and high-quality dietary patterns and CHD.  (For more information please read my previous posts on the multiple benefits of following a Mediterranean style diet). 

Factors that were associated with an increased risk of heart disease included trans fatty acids, foods with a high glycaemic index or high glycaemic load and a western style dietary pattern.  High glycemic index foods (foods that release sugar quickly into the body) include most refined carbohydrates like white bread, long-grain rice, sweets, biscuits, sugary foods and many other processed carbohydrates.  Foods high in trans-fatty acids (sometimes called hydrogenated fats) include fried foods, baked goods and snacks.  A ‘Western diet’ is usually classified as one that is higher in red and processed meats and refined and processed foods in general.

There was also moderate evidence of a protective association between intakes of fish, long chain omega 3 fatty (EPA and DHA) acids from marine sources, fruit, folate, whole grains, dietary vitamins E and C, beta carotene and fibre.  However, there was not enough evidence to link heart disease to saturated fat or total fat intakes.  In my previous posts on heart disease mentioned at the start of this post I wrote about the evidence which shows a stronger link between refined carbohydrates and sugar and heart disease than fat, which is often singled out to be ‘the bad guy’.

It is really important to look at dietary patterns as a whole and how they link to diseases such as heart disease (as well as many others like cancer, Alzheimer’s disease, asthma, bone and joint diseases etc).  Looking at individual components such as a single specific vitamin can be useful but it is unlikely that modification of a single component in the diet would have a huge effect on disease risk.  Foods are complex and contain many different nutrients as well as flavonoids (bioactive plant compounds) and other active components.  The multiplicity of nutrient factors work together synergistically to provide our bodies with maximum protection against disease.  The authors of this study support the strategy of investigating dietary patterns as a whole when looking at chronic diseases such as CHD.  The authors also conclude (1) that more cohort studies and randomized trials should be done to evaluate dietary patterns, including their nutrient and food components.

Personally I feel that the take home message from studies such as this is that a healthy diet, based around natural unprocessed and unrefined foods, is crucially important to prevent disease.  Any health-full diet will be rich in foods such as vegetables, fruits, beans and pulses, nuts and seeds, unprocessed meats and fish (especially oily fish), wholegrain unprocessed and unrefined carbohydrates.

(1)Mente A et al.  2009. A Systematic Review of the Evidence Supporting a Causal Link Between Dietary Factors and Coronary Heart Disease.  Arch Intern Med. 169(7):659-669.

Written by Ani Kowal

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2. Refined carbohydrates linked again with increased risk of heart disease
3. More evidence links high sugar diet to increased risk of heart disease
4. Study finds that overall healthy diet may protect against depression in middle age
5. Healthy eating for life……and more life!