Having too much body fat makes arteries become stiff after middle age, a new study has revealed.
In young people, blood vessels appear to be able to compensate for the effects of obesity. But after middle age, this adaptability is lost, and arteries become progressively stiffer as body fat rises – potentially increasing the risk of dying from cardiovascular disease.
The researchers suggest that the harmful effects of body fat may be related to the total number of years that a person is overweight in adulthood. Further research is needed to find out when the effects of obesity lead to irreversible damage to the heart and arteries, they said.
Obesity is known to be a major risk factor for heart disease, but the reasons for this are not fully understood.
Researchers at the Medical Research Council (MRC) Clinical Sciences Centre at Imperial College London scanned 200 volunteers to measure the speed of blood flow in the aorta, the biggest artery in the body. Blood travels more quickly in stiff vessels than in healthy elastic vessels, so this allowed them to work out how stiff the walls of the aorta were using an MRI scanner.
In young adults, those with more body fat had less stiff arteries. However, after the age of 50 increasing body fat was associated with stiffer arteries in both men and women.
Body fat percentage, which can be estimated by passing a small electric current through the body, was more closely linked with artery stiffness than body mass index, which is based just on weight and height. Men are on average about 21 per cent fat and women 31 per cent fat.
The research was funded by the MRC, the National Institute for Health Research (NIHR) Imperial Biomedical Research Centre, and the British Heart Foundation, and published in the journal Hypertension.
Dr Declan O'Regan, who led the study, said: "The effects of having more fat seem to be different depending on your age. It looks like young people may be able to adapt to excess body fat, but by middle age the cumulative exposure to years of obesity may start to cause permanent damage to the arteries. One implication is that the potential beneficial effects of weight loss may depend on your age and how long you have been overweight. This is something we plan to study further.
"We don't know for sure how body fat makes arteries stiffer, but we do know that certain metabolic products in the blood may progressively damage the elastic fibres in our blood vessels. Understanding these processes might help us to prevent the harmful effects of obesity."
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Notes to editors
1. B Corden et al. 'Body Fat Is Associated With Reduced Aortic Stiffness Until Middle Age' Hypertension, June 2013. DOI: 10.1161/HYPERTENSIONAHA.113.01177
2. About Imperial College London
Consistently rated amongst the world's best universities, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 14,000 students and 6,000 staff of the highest international quality. Innovative research at the College explores the interface between science, medicine, engineering and business, delivering practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.
Since its foundation in 1907, Imperial's contributions to society have included the discovery of penicillin, the development of holography and the foundations of fibre optics. This commitment to the application of research for the benefit of all continues today, with current focuses including interdisciplinary collaborations to improve global health, tackle climate change, develop sustainable sources of energy and address security challenges.
In 2007, Imperial College London and Imperial College Healthcare NHS Trust formed the UK's first Academic Health Science Centre. This unique partnership aims to improve the quality of life of patients and populations by taking new discoveries and translating them into new therapies as quickly as possible.
3. About the Medical Research Council
Over the past century, the Medical Research Council has been at the forefront of scientific discovery to improve human health. Founded in 1913 to tackle tuberculosis, the MRC now invests taxpayers' money in some of the best medical research in the world across every area of health. Twenty-nine MRC-funded researchers have won Nobel prizes in a wide range of disciplines, and MRC scientists have been behind such diverse discoveries as vitamins, the structure of DNA and the link between smoking and cancer, as well as achievements such as pioneering the use of randomised controlled trials, the invention of MRI scanning, and the development of a group of antibodies used in the making of some of the most successful drugs ever developed.
Today, MRC-funded scientists tackle some of the greatest health problems facing humanity in the 21st century, from the rising tide of chronic diseases associated with ageing to the threats posed by rapidly mutating micro-organisms. http://www.mrc.ac.uk The MRC Centenary Timeline chronicles 100 years of life-changing discoveries and shows how our research has had a lasting influence on healthcare and wellbeing in the UK and globally, right up to the present day. http://www.centenary.mrc.ac.uk
4. About the National Institute for Health Research
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