A survey from California has concluded that middle-aged people who eat a lot of meat, dairy products and eggs are four times more likely to die early from cancer or diabetes.
Researcher Valter Longo, of the University of Southern California’s Longevity Institute, said that people should be more aware of the amount of protein they eat. “Spend a couple of months looking at the labels on your food. There is a little bit of protein everywhere.”
Longo told The Daily Telegraph: “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.”
The scientists drew their conclusions from a study of 6,381 people aged 50 and over who took part in the National Health and Nutrition Examination Survey (NHANES) in the US.
A link between high protein intake and raised levels of the growth hormone IGF-1 might be a possible cause for the raised mortality rate. However, the health risks almost disappeared when the main source of dietary protein was plant-based. Longo said that only around ten per cent of the calories we consume should come from protein, and “the ideal sources are plant-based”.
The survey recommends a protein intake of no more than 0.8 g per kg of body weight per day during middle age (e.g. 51 g for a person weighing 10 stones, 61 g for a person weighing 12 stones). The British Nutrition Foundation provides similar figures, noting that the daily protein requirement is 45 g and 56 g for the average woman and man respectively. It notes that most people eat far more protein than they need, with average intakes around 88 g per day for men and 64 g per day for women. The findings call into question the long-term safety of the Atkins and Paleo diets which recommend high intakes of meat and other animal proteins.
Read the survey here.