For decades, studies have tied higher sugar intakes to an increased risk of numerous health issues, including obesity, high blood pressure, heart disease, Type 2 diabetes, fatty liver and certain cancers.
Different study designs, varying measures of sugar intake and inconsistent findings, however, have made it challenging to draw definitive conclusions about sugar and health.
Now, a comprehensive evaluation of evidence from past studies, conducted by researchers from China and the United States, has linked an excessive sugar intake to 45 harmful health effects. Here’s what to know.
Current sugar intake guidelines
In 2015 the World Health Organization (WHO) released guidelines recommending children and adults reduce intake of “free” sugars to less than 10 per cent of daily calories. For someone who eats a 2,000-calorie diet, that’s a daily maximum of 50 grams of free sugars (12.5 teaspoons worth).
The current Dietary Guidelines for Americans also recommends that kids and adults keep their intake of added sugars to less than 10 per cent of daily calories.
Health Canada does not have a quantitative sugar intake guideline. Canadians are advised to choose foods with little to no added sugars and to replace sugary drinks, which include fruit juice, with water.
Added sugars versus free sugars
Added sugars are those used in food manufacturing (and at home) to sweeten foods, or to provide other benefits such as thickening, texturizing or browning. They go by more than 60 different names including table sugar, cane syrup, brown rice syrup, maltose, dextrose and glucose-fructose.
“Free” sugars, as defined by WHO, include added sugars plus sugars present in honey, maple syrup, agave syrup, fruit juice and fruit juice concentrates which have been removed from whole foods and are “free” to sweeten foods.
Natural sugars are ones that occur naturally in whole fruits (fructose) and unsweetened dairy products (lactose). Naturally occurring sugars come packaged with other nutrients and, in the case of fruit, protective phytochemicals.
The latest research, recommendations
The evidence review, published online April 5 in the journal The BMJ, analyzed the results of 73 meta-analyses, which included 8,601 individual studies, that investigated the association between sugar consumption and 83 different health outcomes. (A meta-analysis is a merging of data from many studies; it’s a statistical technique used to summarize the results of multiple studies.)
The findings revealed that higher intakes of dietary sugar – especially fructose-containing sugars – were linked to a significantly greater risk of 45 adverse health effects, including obesity in children, accumulation of body fat, hypertension in adults and kids, increased liver fat, coronary heart disease and depression.
The evidence for the association between sugar intake and cancer was limited but the findings suggested a need for further research.
Based on the conclusions, the researchers recommended consuming no more than 25 grams of added or free sugars a day, about six teaspoons worth.
They also include advised limiting consumption of sugar-sweetened beverages (e.g., pop, iced tea, lemonade, chocolate milk, sports drinks, energy drinks) to less than one serving (200 to 355 millilitres) per week. For perspective, one 355 millilitre can of sugar-sweetened pop has 36 grams of sugar, nine teaspoons worth.
Sugar intake of Canadians
According to the latest data from Statistics Canada, the majority of Canadians – two-thirds – get more than 10 per cent of their daily calories from free sugars.
Canadians, aged one and older, consume an average of 67 grams of free sugars each day, almost 17 teaspoons worth. Desserts/sweets and beverages were the two main contributors of free sugars in the Canadian diet. Other sources included breakfast cereals, baked products and snacks.
- Read labels to find added sugars in food products. The grams of total sugars on the nutrition facts table doesn’t distinguish between free sugars and natural sugars.
- For foods that contain little or no dairy or fruit, though, you can assume that the sugar grams are free sugars; four grams of sugar is equivalent to one teaspoon of sugar.
- Scan the ingredient list, too. All free sugars added to a food product are grouped together under the common name “Sugars.”
- Most often, choose unsweetened products including non-dairy milks, yogurt, instant oatmeal, ready-to eat breakfast cereals and canned fruit. Sweeten cereal and yogurt naturally with fruit; add flavour with cinnamon or other spices.
- Replace sugar-sweetened beverages with water, herbal tea or unsweetened green or black tea.
- If you add free sugar to coffee, tea, hot or cold cereal or smoothies, cut back gradually.
- Reduce the amount of sugar you use by one-half teaspoon each week. When you’re used to the new level of sweetness, cut back again. Your taste buds will adjust to a less-sweet taste.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD