Nutrition

How sugar affects your body

By: Joana Lourenço

Photography by Jeff Coulson Author: Canadian Living Credits: Photography by Jeff Coulson

Nutrition

How sugar affects your body

By: Joana Lourenço

While sugar has been vilified by many because of its connection to obesity, heart disease and even some common cancers, not all experts agree that it’s the foe behind our health woes. “People are getting conflicting advice about sugar and they don’t know what’s safe to eat,” says Marie-Claude Mallet, an Ottawa- based registered dietitian with the Heart and Stroke Foundation of Canada. Should you cut back on the sweet stuff? Read on to find out.

Are you eating too much sugar?
According to Statistics Canada, the average Canadian consumes 110 grams of sugar daily—that’s 26 teaspoons a day, or 40 kilograms a year. Health Canada follows the Dietary Reference Intake system, which outlines that no more than 25 percent of daily energy should be derived from added sugars (that’s about 125 grams or 31 teaspoons a day for a 2,000-calorie diet). However, in recent draft guidelines, the World Health Organization (WHO) recommends that sugar make up less than 10 percent of caloric intake per day—but its newest recommendation says that getting the amount down below five percent is optimal (that’s about 25 grams per day). This applies to sugars “added to food by the manufacturer, the cook or the consumer, as well as sugars that are naturally present in honey, syrups, fruit juices and fruit concentrates.” It does not include “intrinsic” sugars found in fruits, vegetables or milk products. According to the WHO, meeting the 10 percent recommendation would help lower the risk of obesity, as well as dental decay.

How much is 10 percent? That works out to 12 teaspoons of sugar per day. (A can of pop, for example, contains about 10 teaspoons.) But it’s exceedingly difficult to stay below that level because sugar is now found in almost all processed foods. Dr. Elaine Chin, chief medical officer of the Executive Health Centre in Toronto, says most people don’t have a realistic sense of their intake. “They’re consuming lots of sugar without even knowing it,” she says.

To give Canadians a better idea of what they’re eating, Health Canada recently proposed changes to food labelling. The recommendations include listing both total sugars and added sugars on labels, and grouping sugars together in the ingredients list. Dr. Chin agrees this is a step in the right direction: “These new recommendations will go a long way for consumers to understand what is presently hidden.”

Does sugar cause obesity?
“The WHO commissioned a systematic review to look at sugars and their relation to weight gain,” explains Dr. John Sievenpiper, a physician and scientist at the Li Ka Shing Knowledge Institute at St. Michael’s Hospital in Toronto. “The conclusion, published in the British Med- ical Journal, was that sugars were only having an effect on weight gain insofar as they were contributing excess calories.”

Among Canadian adults, the obesity rate has tripled over the last 25 years. Sugar intake is also on the rise, says Dr. Chin. “The problem is that it’s everywhere: in our soft drinks, sauces, yogurts, cereals.” That said, Dr. Chin does acknowledge the complexity of the issue. “Does sugar make you fat? Well, it does if you don’t burn it off. What you don’t burn gets stored as fat.” Mallet agrees that sugar shouldn’t be a scape-goat. “Weight gain is mainly because of excess calories, from basically anything. It’s not specifically about sugar.”

Will consuming sugar lead to cancer or heart disease?
“There is no high-quality evidence linking sugar to cancer,” says Dr. Sievenpiper. “There are some in vitro studies showing that cancer cells proliferate more in the presence of high sugar, but no randomized trials have looked at this question.” Diets containing an excess of high glycemic index foods such as russet potatoes and pretzels—which raise blood sugar and insulin levels—are also associated with some cancers. “The high glycemic load comes in large part from refined starches, not just sugars,” explains Dr. Sievenpiper.

On the other hand, there is compelling evidence that consuming too much sugar may negatively impact cardiovascular health. In April, a study published in The Journal of the American Medi- cal Association Internal Medicine found that people with the highest consumption—25 percent or more of daily calories from sugar—had almost three times the risk of cardiovascular-related death than those with the lowest consumption. What’s more, there’s evidence that a high sugar diet raises triglycerides. Since 2009, the American Heart Association has recommended that women limit their sugar intake to five percent of their daily calories, and men to 5.7 percent. (The Heart and Stroke Foundation of Canada is finalizing its sugar recommendations, which will be available this fall.)

Is fructose worse than other sugars?
Fructose has come under fire because of the way it’s metabolized by the liver, with some experts declaring it should be “treated as alcohol.” Dr. Sievenpiper and his team of researchers have extensively studied the effects of fructose, a form of sugar found in fruits and vegetables. “What we found was that, for all the factors we studied—body weight, fatty liver, blood sugar, blood insulin, uric acid—if you match for calories, the fructose was no worse than any other carbohydrate,”he explains. However, fructose doesn’t affect satiety in the same way as glucose, meaning it could have you reaching for more food. So ease off on the soda and stick with healthier whole food sources of fructose. They contain essential vitamins and minerals your body needs, plus fibre to fill you up.

Can you really become addicted to sugar?
“People crave sugar,” says Mallet. “You acquire a taste for it—and for fat—from infancy. These tastes bring pleasure.” Some experts argue that sugar has a unique addictive effect on the brain. But Dr. Sievenpiper doesn’t buy it. “There is animal evidence showing that sugar may have a similar effect as drugs,” he admits, “but in humans, we really don’t have any evidence.” Studies have linked the activation of brain regions involved in addictive behaviours to highly processed carbohydrates, rather than sugars explicitly.

Are sugar alternatives actually better for you?
Broadly speaking, a sugar substitute is any sweetener used instead of table sugar (sucrose). Artificial substitutes such as aspartame, sucralose, xylitol and stevia are low- or no-calorie options for sweetening food and beverages. They don’t affect your blood sugar levels and are safe to consume when taken in recommended amounts, according to Health Canada.

There is some evidence that sugar substitutes can aid in weight loss because they help cut calories. However, studies show that your brain isn’t fooled. “Even though you’re not getting the calories or blood sugar effect, you won’t curb your cravings for sugar,” cautions Mallet.

So-called “natural sweeteners” are sugars such as honey, maple syrup and agave. These sweeteners are considered to be healthier, so there’s the risk that people will overconsume them. But these kinds of sweeteners do affect your blood sugar. Plus, they can be high in calories, so they should be consumed in moderation, as with other sugars.

What's the bottom line?
A little dietary sugar is OK. But stick to natural sugars in fruits and vegetables, and try to avoid added sugars as much as possible. Look for ingredients such as syrup, cane juice, fruit juice concentrate and high-fructose corn syrup (glucose- fructose on Canadian labels), as well as most words with the suffix “-ose” (dextrose, for example). You’d be surprised how much added sugar lurks in seemingly benign products: A tablespoon of ketchup contains four grams of added sugar; one granola bar had 14 grams; a popular brand of vitamin-enhanced water contains 33 grams.

Mallet advises people who want to reduce their sugar intake to eliminate foods and drinks with sugar listed as a first, second or third ingredient. And avoid sugary beverages. “Drinking sugar calories is worse than eating them,” she warns. “It’s about satiety. Liquid calories are not going to give you the feeling of fullness in the same way, or for the same amount of time.”

Experts do agree on one thing: The best way to control sugar intake is to cook meals from scratch.

 Learn more about sugar by finding out 5 ways you're getting extra sugar without knowing it.

This content is vetted by medical experts


This story was originally titled "The Sweetest Thing" in the October 2014 issue.

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Nutrition

How sugar affects your body

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