Is junk food aging young brains?

Corbet - Dale

“Our current Western diets and lack of exercise are creating a ticking time bomb of health problems.”

– Dale Corbett

In early 2012, the international press reported widely on a British teenager who was hospitalized after having eaten almost nothing but chicken nuggets for 15 years. But you don’t have to restrict yourself to an exclusive, decade-long diet of fast food to find yourself at risk of suffering stroke or death in your early 30s or 40s.

A recent and alarming study by University of Ottawa researcher Dale Corbett and doctoral student Mariana Gomez-Smith suggests that a typical high-calorie, high-sugar, high-sodium Western diet induces most symptoms of metabolic syndrome—a combination of low levels of good cholesterol, high blood sugar and blood pressure as well as obesity—in animal subjects after only two months.

Fed what was nicknamed the Cafeteria diet or CAF, the rats used in the study were at an age roughly equivalent to 16 to 22 years in humans at the time that many of the symptoms of metabolic syndrome began to manifest.

“I don’t think it will be long before we start to see more people in their 30s or 40s having strokes and eventually developing dementia at an earlier age because of common junk food diets and adoption of a sedentary lifestyle,” says Corbett, a professor of neurosciences in the Faculty of Medicine and the scientific director of the Heart and Stroke Foundation Centre for Stroke Recovery (CSR).

“Young people eating this way today are going to have major problems much earlier in life,” he says.

According to Gomez-Smith, who led the experiment and developed the animal model on which the study is based, two groups of young, newly weaned rats were given a different diet. Both groups were offered healthy foods, but one of them was allowed access to common cafeteria junk food items, including cookies, sausages and cupcakes. Animals on the junk food diet were also given access to both water and a 30-percent sucrose solution designed to imitate colas and other soft drinks. Like many humans, the rats greatly preferred to eat the treats and drink the sugared water over the healthier foods.

Within two months, the rats on the high-fat, high-sugar, high-salt CAF diet had developed symptoms of metabolic syndrome, including low HDL, or good cholesterol, raised blood sugars and obesity—all factors that increase the risk of stroke and other serious health issues.

“Our current Western diets and lack of exercise are creating a ticking time bomb of health problems,” insists Corbett.

One of the most disconcerting consequences of a diet high in junk food is that it may also lead to premature aging of the vasculature of the brain.

“In young healthy people, blood vessels are smooth and straight,” explains Corbett. “Yet as people get older, these become twisted and encrusted with plaque, which restricts blood flow and increases the risk of stroke.”

“We think a Cafeteria diet of junk food is prema­turely doing a similar thing to the brain of much younger people,” he says.

To further investigate their suspicions, Corbett and Gomez-Smith will probe the small blood vessels in the brains of their rats using magnetic resonance imaging (MRI) and two-photon fluorescence microscopy, in collaboration with CSR colleagues at Sunnybrook Hospital in Toronto. The brain imaging will examine, at a very fine level, how the rats’ brain vasculature might be changing. By understanding the impact of the Cafeteria diet metabolic syndrome on cerebral vasculature and inflammation in their rats, the researchers will gain a better understanding of its effect on humans, including how much premature brain aging may be taking place in today’s population.

Corbett highlights the importance of the rat model that Gomez-Smith developed for characterizing metabolic syndrome in humans.

“What makes Mariana’s Cafeteria diet-induced rat model of metabolic syndrome such a good model of the human disorder is that it captures most of the characteristic symptoms of metabolic syndrome where other models capture only one or two at most,” says Corbett. “It’s not just being obese or hypertensive; it’s the combination of several things in the metabolic syndrome that makes it so dangerous.”

In addition to helping inform the Canadian public about the health dangers of a poor diet, Corbett and Gomez-Smith hope that their study will inspire other scientists to further research the problem.

“How reversible is the damage caused by junk food?” asks Corbett. “This is one of many questions we just can’t answer yet. Hopefully our research will encourage others to help look for the answers.”

 

by Sean Rushton

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