The mainstream dietetic guidelines of the past decades have been all about carbohydrates. Listen to any of the respected modern-day health authorities and they all keep repeating the same dietary rules of the high-carbohydrate, low-fat diet. Carbs are the right choice and the message is clear: If you want to be healthy, you should be favoring starchy foods such as potatoes, rice, bread, pasta and cereals. But what if that whole concept was completely wrong? Or yet worse, what if our fondness for stodgy foods was increasing cancer risk or sending us to an early grave? This article questions one of the present-day dietary stereotypes of the high-carbs diet.
In a series of spectacular experiments, scientists from the University of California managed to extend the lifespan of roundworms a 6-fold by manipulating key genes responsible for ageing. Key to their findings was the discovery of a gene named daf-2 that is thought to speed up ageing. Just by altering this gene, the ageing process of the roundworm was dramatically slowed down. But in order for the roundworms to live longer, it was also necessary to activate another gene, daf-16, a kind of ‘fountain of youth’ gene. This gene was later nicknamed ‘Sweet Sixteen’ for its ability to promote youthfulness in the worms by mobilizing various other genes that stimulate repair and renovation of the cells and eventually extend lifespan.
And here is the point. These genes, so closely involved in ageing, are known to be under the influence of the insulin/IGF-1 system. Consuming a lot of carbohydrates promotes insulin production, switching off the ‘Sweet Sixteen’ gene. This in turn speeds up ageing of the cells. But by consuming fewer carbohydrates, less insulin is produced, which leads to inhibiting the insulin/IGF-1 signalling pathway and ultimately switching on the ‘Sweet Sixteen’ elixir of youth gene and its anti-ageing effects. And what diet does Professor Kenyon, the chief scientist of the team that carried out this experiment and a prominent expert in ageing, follow? Inspired by her research, she practices what she preaches, following a low-carbohydrate diet based on chicken, meat, fish, vegetables, fruits that are not too sweet, eggs, nuts, cheese, as well as a glass of red wine a day. In her diet there is little place for potatoes, rice, bread, pasta, desserts and confectionary.
Then there is another recently published scientific paper, making the case for carbohydrate restriction in the prevention and treatment of cancer. It is a challenging hypothesis, supported by the observation that the metabolic syndrome is linked to increased risk of dying from cancer, indicating that the glucose-insulin axis could be decisive. The paper also describes how carbs and glucose encourage the proliferation of tumour cells. Unlike normal healthy cells, most cancer cells have a high demand for glucose. Moreover, high levels of insulin / IGF-1, the consequence of constantly consuming carbohydrate-rich meals also fosters the proliferation of cancer cells. In comparison, when blood glucose and insulin levels are low, ketone bodies increase, which seem to interfere with the cancer cell proliferation. Hence, this raises a question; could our carbohydrate-laden modern-day diets be closely connected to cancer?
Where does all this recent knowledge leave the high-carbohydrate, low-fat dietary concept that reigns today? But are any of these findings really so surprising? We only need to look at our Paleolithic hunter-gatherer past to see that throughout our evolution we existed on low to moderate carbohydrate diets of animal-based foods and low-GI (Glycemic Index) plant-based foods. This is in strong contrast to the nation obsessed with carbs-rich diets we have become, many of us with a dangerously high Glycemic Index too. The harmful effect of these wrong dietary habits is yet magnified by our increasingly sedentary lifestyles.
The aim of this article is not to suggest that all carbohydrates are bad for our health and that we should all now be adopting some extreme low-carb dietary plans. The aim is to question the basic logic of modern-day dietary regimes based around a lot of carbohydrate and starchy foods, specifically those with a high GIycemic Index, which leaves us wondering where the balance is in the so-called ‘well-balanced’ diet?