Diet and CVD – it’s not all about cholesterol!
Despite the massive improvements we’ve seen in the prevention and treatment of cardiovascular disease (CVD) in recent decades, it remains the leading cause of death worldwide, and an ageing and growing global population is likely to cause numbers to rise further. In the UK, around 7 million people are living with heart and circulatory diseases and there have been claims that as many as half of deaths from CVD could be prevented with a healthy diet and lifestyle.
With so much recent debate about whether saturated fat has any effect on CVD risk – with media stories often taking us back to the seminal Seven Countries Study by Ancel Keys in the 1940s – you may be mistaken in thinking that the benefits of a healthy diet in the prevention of heart disease relate almost entirely to blood cholesterol levels. Indeed, until perhaps 25 years ago, this was one of a small number of modifiable factors that were recognised to mark a predisposition to heart disease (others being smoking, raised blood pressure, physical inactivity, type 2 diabetes and obesity). However, whilst these factors undoubtedly remain influential, they cannot explain all risk nor the regional, gender, socioeconomic and ethnic differences in the disease that we see, leading to a search for other novel risk factors that may play an important role in CVD.
This was the subject of a BNF Task Force report in 2005 which brought together leading academics to review more novel, or emerging, risk factors which were being widely researched at that time for their link with CVD. Recognising the considerable amount of research that has been carried out since 2005, an update of the report seemed timely. We were delighted that many of the eminent original Task Force members were once again able to be involved, particularly Professor Keith Frayn (University of Oxford), our brilliant Chair. A look at the list of the members and contributors will illustrate why listening to the discussions about how research has changed our thinking over the last 15 years, and reading the chapters that summarise what we know now, has been such a stimulating experience for us at BNF.
Since the last report, evidence of a causal direct association between some of the ‘so called’ emerging risk factors and CVD have waned (e.g. homocysteine), whilst support for others has strengthened (e.g. physical activity, maternal nutrition). New risk factors have also developed; the most notable new chapter in this edition being on the role of the gut microbiome.
Although most of our dietary recommendations - for example, around salt, saturated fat, trans fats, fruit and veg and oily fish - all date back to the COMA (Committee on Medical Aspects of Food Policy) report on diet and CVD in 1994 (the exceptions being free sugars and dietary fibre which have changed in recent years), understanding around their effects on different risk factors and the mechanisms involved has progressed considerably, and many of the messages have been clarified. And coming back round to good old saturated fat as an example, we now know that it’s not just about cutting back; what you replace the saturated fat in your diet with is key to reducing CVD risk. Replacing saturates with unsaturates, for example, may also do more than just improve blood cholesterol, it could have benefits on other risk factors including inflammation, endothelial function and platelet activity.
As well as diet, the report identifies lifestyle factors that we should be considering. For example, sleep duration and quality have been linked to an increased risk of heart disease, stroke, type 2 diabetes, obesity, and hypertension. And being sedentary for long periods of time is now widely believed to increase the risk of heart disease, with physical activity being suggested to attenuate but not eliminate the increased risk associated with high sitting time. So as well as promoting regular exercise, we should be encouraging everyone to minimise the amount of time they spend in sedentary activities, such as watching TV, using the computer and travelling by car, bus or train.
We were delighted to share the findings of this informative report at a launch event in London on 27 February. The presentations from this event, along with some other interesting resources from the report can be found here. The report itself is available as an electronic or hard copy from Wiley.
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Please note that advice provided on our website about nutrition and health is general in nature. We do not provide any personal advice on prevention, treatment and management for patients or their family members.