Meat lovers are used to the fact that their favorite food does not get positive coverage, but the latest issue of the scientific Journal Cell Metabolism contains some upsetting news also for those who crave for cheese, milk or fish, as two new studies published on it found evidence that a high-protein diet can shorten lifespan.
The two teams carrying out the research were headed by Prof. Valter Longo of the University of Southern California and by Stephen Simpson from the University of Sydney respectively and showed similar conclusions, although their researches were carried out independently.
The study conducted by Prof. Longo, an expert in longevity and cell biology, found that the insurgence of cancer, diabetes and other illnesses, that are common causes of death among middle-aged adults, is closely linked to a high consumption of proteins, especially of animal ones.
Surprisingly enough, the research showed that older adults aged 65 or over benefit from a diet moderately rich in proteins, on grounds of the lower propensity to process proteins typical of older individuals. However, in both cases the negative effects are much lower if the proteins originate from plants and vegetables.
Prof. Simpson’s research was conducted on mice and came to similar conclusions, showing that a diet poor in proteins and rich in carbohydrates accounts for a longer lifespan.
Previous researches found it was important to reduce the consumption of red meat, fat, sugar and salt in order to avoid illnesses. Nevertheless, the new findings unearthed more comprehensive evidence that other type of foods such as cheese, fish and pulses can also shorten life, as their consumption contributes to create a high-protein diet.
Over the last decades there has been a proliferation of diets prescribing the increase of proteins and the reduction of carbohydrates as an infallible solution to lose weight. The loss of weight has been often regarded as sign of a healthy diet, though the new studies show that the quick reduction of fat following a higher intake of proteins results in deleterious long-term effects as negative as those produced by smoking as much as 20 cigarettes per day.
South California University’s research found that people aged 50 or over consuming food high in protein are four times more likely to die before the age of 70 because the amino acids that compose proteins weaken the cells and contribute to mutate their DNA, exposing them to the risk of cancer, diabetes and other illnesses.
Analyzing the effect of different diets on mice, the researchers from Sydney observed that the longest-living mice were those fed with a high amount of carbohydrates and a low amount of proteins. They also found that a high intake of calories and the presence of body fat are not necessarily life-reducing factors.
A high-protein diet is – according to the researchers – one where at least 20 percent of the calories are derived by proteins.
Prof. Longo thinks that one of the most important findings is that calories have very different quality and different effects on the body, depending on which food they stem from and the way they interact. This has, in his words, “enormous implications for how much food we eat, our body fat, our heart and metabolic health, and ultimately the duration of our lives.”
While it might be wrong and dangerous to compare the effects of smoking with those of eating meat and cheese, as the nutrition scientist Gunter Kuhnle put it, the results found by the two universities present very convincing links between a high-protein diet and a shortened life expectancy.
By Stefano Salustri
Medical News Today