Eating too much protein could be as dangerous for middle-aged people as smoking, a scientific study has found.
Research that tracked thousands of adults for nearly two decades found that people who eat a diet rich in animal protein are four times more likely to die of cancer than someone with a low protein diet – nearly as high as the risk of developing cancer through smoking 20 cigarettes a day.
Although previous studies have shown a link between cancer and red meat, it is the first time anyone has quantified the risk of death caused by regularly eating too much protein.
The World Health Organisation will announce a consultation today suggesting guidelines on sugar consumption should be lowered. But there are few warnings about protein.
The study found that people with a high-protein diet were 74pc more likely to die of any cause within the study period than their more low-protein counterparts. They were also several times more likely to die of diabetes.
But, in an unexpected finding, the trend appears to reverse for over-65s. In older age, eating plenty of meat and cheese actually lowers the chance of death, researchers found. High protein food-plans, such as the Atkins Diet, have become popular in recent years because of their dramatic weight-loss results.
But the new research from the University of Southern California (USC) suggests dieters may be harming themselves in the long run.
"We provide convincing evidence that a high-protein diet – particularly if the proteins are derived from animals – is nearly as bad as smoking for your health," said Dr Valter Longo of USC School of Gerontology.
The researchers define a "high-protein" diet as deriving at least 20pc of daily calories from protein.
The researchers recommend consuming around 0.8 grams of protein per kilogram of body weight every day in middle age.
A 200ml glass of milk represents 12pc of the recommended daily allowance and a 40g slice of cheese would be 20pc. Chicken, fish, pulses, vegetables, nuts and grain are all healthier sources of protein.
The study found those eating a high-protein diet were four times more likely to die of cancer or diabetes and nearly twice as likely to die from any cause in the following 18 years. (© Daily Telegraph, London)