These days, sugar is public enemy number one, blamed for the epidemics of obesity, type 2 diabetes and more. But does sugar deserve its unfavorable reputation? And even if it does, who wants to go through life without indulging their sweet tooth?
Sugars – caloric sweeteners – can be divided into two groups: intrinsic sugars, such as lactose in dairy products and fructose in whole fruits; and added sugars, such as sucrose (table sugar), high fructose corn syrup and concentrated sugar sources such as honey, syrups and fruit concentrates.
Nutritionist Marion Nestle reports that from 1980 to 2004 the yearly supply of sugars in the United States increased from 120 pounds per person to 142 pounds per person. The U.D. Department of Agriculture (USDA) estimates the average American eats 31 teaspoons (five ounces) of sugar per day – that’s more than two pounds per week! Sugar accounts for 500 calories per day in the average American diet, or 25 percent of average daily energy requirements.
Conventional wisdom tells us that so much sugar can’t be good. Sugar is popularly associated with many of America’s health problems, from hyperactivity to heart disease. But does science support these claims?
That depends on who you ask. In 2001, Anne Mardis of the Center for Nutrition Policy and Promotion (a division of the USDA) wrote a review of the available research on sugar intake and health. Conceding only that sugar was a cause – but not the only cause – of tooth decay, Mardis concluded, “Recent evidence shows that … the intake of added sugars is not directly related to diabetes, heart disease, obesity, and hyperactivity, as was previously thought”.
Nestle disagrees, and she’s not alone. In 2004, Jim Mann refuted Mardis’ conclusions in The Lancet, the respected British medical journal. According to Mann, sugar may not directly cause chronic disease, but substantial evidence links sugar consumption to obesity, which contributes to coronary heart disease, type 2 diabetes and other chronic diseases. Also in 2004, a team of medical researchers linked type 2 diabetes to corn syrup and other refined carbohydrates.
Regardless of what it does do, sugar is notable for what it doesn’t do; namely, provide the body with essential nutrients. Sugar calories are empty calories – they provide energy and nothing else. According to Nestle, “It is all too easy to eat sweeteners in prodigious amounts, driving healthier foods out of your diet, adding unneeded calories and forcing your metabolism to go into glycemic overload”. Replacing sugar calories with healthier alternatives is a step towards better nutrition.
The Glycemic Index
Sharp increases in blood glucose (sugar) have been associated with type 2 diabetes, obesity, heart disease and cancer. To measure the impact of foods on blood sugar, scientists developed the glycemic index. The glycemic index is a measure of the increase in blood sugar after eating a particular food – the greater the increase, the higher the glycemic index. Only carbohydrates affect blood sugar levels, and fat and protein can lower the glycemic response. Pure glucose has a glycemic index of 100; in contrast, peanuts have a glycemic index of only 14.
Blood glucose levels are also affected by how much food is eaten. The combined effect of serving size and glycemic index on blood sugar is referred to as the glycemic load. Doubling the serving size of carbohydrates will double the glycemic load. To decrease your glycemic load and increase your health, eat mostly foods with a low glycemic index (such as whole grains, fruits, legumes and non-starchy vegetables) and avoid starchy foods (such as white rice, potatoes and white bread) and sugary foods (such as cookies, candy and soft drinks).
Food Science to the Rescue?
The food industry has responded to the demand for sugar alternatives with a variety of calorie-free artificial sweeteners. Some of the most popular include aspartame (NutraSweet, Equal), saccharin (Sweet’N Low, SugarTwin), acesulfame potassium (Sunett, Sweet One) and sucralose (Splenda). These sweeteners are common ingredients in diet soft drinks, low-fat yogurt products, sugar-free candy and more. Theoretically, artificial sweeteners, which are calorie free and have no glycemic impact, avoid many of the pitfalls associated with sugar.
However, many consumers are wary of artificial ingredients, and artificial sweeteners are no exception. A study from the 1970s reported a connection between saccharin and bladder cancer in rats. Although the mechanism responsible for this connection does not occur in people, concern about artificial sweeteners lives on. A quick Internet search reveals numerous Web sites claiming connections between artificial sweeteners and cancer, toxicity and more.
Clinical evidence suggests that there is no link between artificial sweeteners and cancer. (In 2006, scientists at the National Cancer Institute determined that aspartame did not cause cancer in humans, despite an earlier study reporting a link between aspartame and cancer in rats). This is not, however, to say that artificial sweeteners are free of consequences. In 2007, a team of researchers published a study in the journal Circulation that linked increased soft drink consumption with metabolic syndrome (a collection of risk factors such as obesity, high blood pressure and impaired glucose tolerance). Surprisingly, this connection also applied to those who drank artificially sweetened diet soft drinks. Clearly, the health consequences of artificial sweeteners are not yet fully understood.