Carbohydrates are causing an obesity epidemic and fats silt up your arteries. But protein? It provides the building blocks for essential stuff such as cells, muscles, bone, nails, hormones and enzymes. The word “protein” comes from the Greek and means first, as in most important. We can’t get enough of it. Bodybuilders take protein supplements in the form of milkshakes, energy drinks or bars to build up their muscle bulk. But even ordinary folk see protein as their new best dietary friend. The world market for protein supplements is now firmly mainstream and estimated to reach £8bn a year by 2017.
The solution
The UK government’s dietary guidelines state that men need 55.5g and women 45g of protein a day. A chicken breast has at least 23.5g while a 100g steak has 20.9g. In western Europe and the US, people are already eating twice as much protein as recommended by the World Health Organisation. The most recent US dietary guidelines warn that teenage boys and adult men should “reduce overall intake of protein foods” and eat more vegetables. Teenage girls, who often have disturbed eating patterns, and elderly people, who are prone to lose muscle mass as well as appetite, were the only groups identified as being protein-deficient. The New York Times has an ongoing debate about the risks and benefits of protein. Last week, its print edition carried an article with the headline “Is protein a magic bullet?”, though the online version asked “Can you get too much protein?”.
Alarm bells sounded after research published in the journal Cell Metabolism in 2014 (using data from more than 6,000 Americans) concluded that people aged between 50 and 65 who got 20% or more of their calories from protein were 74% more likely to die from cancer than those who ate less protein. The study has been criticised for taking dietary records for only 24 hours. It also surprisingly found that a high-protein diet actually reduced the risk of dying early in those aged over 65. It’s not clear why the results should be so different for the two age groups.
The evidence on protein remains inconclusive. Some studies show that more protein – and fewer carbohydrates – reduces blood pressure and protects against heart disease. What the evidence does suggest is that red or processed meat as a main source of protein is linked to an increase in colon cancer, while fish, chicken and plant sources of protein are healthier. You can only absorb 20g to 40g of protein in one sitting and I could find no robust evidence that guzzling it will increase muscle mass. So, unless you are old, poorly and not eating, you are probably getting enough protein and are unlikely to benefit from supplements – whatever they promise you.
