Increasing your intake of fibre will reduce your chance of a heart attack according to a large study commissioned by the World Health Organization. The review published in The Lancet of 185 observational studies and the results of 58 clinical trials found that we should be eating at least 25g of fibre a day with indications that over 30g is even better to achieve the most benefit.
In those patients that did manage to eat the most fibre, the result was a 15-30% reduction in all-cause mortality as well as a reduction of coronary disease, stroke, type 2 diabetes and colorectal cancer. For every 1000 patients who eat high-fibre foods compared with those who do not, the benefit would be 6 fewer deaths due to heart disease and 13 fewer deaths from all causes.
So how does fibre help in the fight against heart disease? The exact mechanisms are not fully understood although previous studies have suggested that a high fibre intake can lower cholesterol by preventing absorption of LDL “bad” cholesterol. There are also reported benefits to lower blood pressure and to encourage a healthier weight by giving a feeling of fullness that helps stave off hunger.
It is estimated that only 9% of the UK population consume the large amounts of fibre that are found to be of benefit in this study. There are therefore considerable challenges associated with altering intake at a population level. Foods rich in fibre include wholegrain cereals, pasta, bread, nuts and pulses. Many foods with a high fibre content also contain high levels of carbohydrates and the current drive for low carbohydrate diets will add to the challenge of increasing fibre-intake. Importantly, diets with a low glycaemic index and low glycaemic load (a measure of how much a food will raise blood glucose) had limited evidence for protection against stroke and type 2 diabetes.
The key here is to understand the difference between the simple carbohydrates such as sugar and those found in processed foods and the complex carbohydrates in foods with a high fibre content such as brown rice and whole grain cereals. Sticking to a low carbohydrate diet is likely to result in a lower intake of fibre which could reduce the benefit on preventing heart disease. As far as carbohydrates are concerned then the quality matters and it’s the type as well as the quantity that is crucial. Consuming complex carbohydrates such as whole grain foods will help make the shift in our diets from processed and refined foods to more fibre-rich foods.
This is an important study that will influence dietary guidelines. The key message is that an increase in dietary fibre intake and replacing refined grains with whole grains is expected to benefit human health.