Safety of sugar substitutes remains inconclusive

On a June day in 1878, Constantin Fahlberg, a research chemist conducting experiments in a Johns Hopkins University lab, sat down to eat, bit into a roll - some accounts say it was bread - and found it amazingly sweet. Because he had forgotten to first wash his hands, he assumed something he’d touched in the lab had contaminated his food. He searched his workspace, tasting vials, beakers and dishes until he found it. A beaker had boiled over, mixing o-sulfobenzoic acid with phosphorus (V) chloride and ammonia.

The result was benzoic sulfimide - or, as we know it today, saccharin. Fahlberg’s discovery ushered in a burgeoning new industry that promised hope for millions struggling to lose weight, and for people with diabetes who needed to control their blood sugar.

Saccharin provided the sweetness they craved, but without the sugar or calories. Other sugar substitutes followed, including more than a half-dozen products approved by the Food and Drug Administration. (The use of sugar alcohols such as sorbitol and xylitol - also sweet, but which contain about half the calories as sugar also became popular.)

Yet, if something seems too good to be true, maybe it is.

In recent years, studies have questioned the safety of sugar substitutes - collectively called artificial sweeteners, although some come from natural substances - and whether consuming them helps or harms the body. The research still is inconclusive. Even saccharin came under scrutiny during the 1970s after research suggested it might cause bladder cancer in rats, and the government attempted to ban it. Subsequent studies, however, could not prove the link in humans, and saccharin remains on the market.

Because of the ongoing confusion, experts suggest consumers use them with caution.

“I advise my patients to use them sparingly because we do not fully understand the scope of their impact on our bodies and our health,” says Jessica Murgueytio, a dietitian in Bethesda, Maryland. “I tell them to use them in moderation, so they don’t get used to consuming sweet foods in excessive quantities. The ‘poison’ is most likely in the dose, so while a pack of stevia in your coffee should be OK, I would suggest not having a large amount of diet soda routinely.”

Donald D. Hensrud, associate professor of preventive medicine and nutrition at the Mayo Clinic College of Medicine, suggests that the first goal for consumers should be to try to avoid the real thing sugar - as much as they can.

“Sugars should be restricted in the diet as they are a ‘quadruple whammy,’ “he says. “They provide extra calories, do not provide any nutritional value, have direct adverse effects on health - for example, dental cavities, inflammation and heart disease - and displace other nutrients and foods that are more beneficial, such as drinking milk.”

Nevertheless, sugar substitutes might be useful for weight loss when used in an overall weight loss plan, he says, noting that consumers save about 150 calories by drinking a diet soda instead of a sugarsweetened one.

“However, if used less rigorously, for example, as part of a meal that includes a double cheeseburger, a large order of fries and a diet soda, it probably will not be of much help,” he adds.

The American Diabetes Association says that these products can be “great alternatives to sugar” for some people, saying that they could improve blood sugar, weight, and cardiovascular and metabolic health. However, the group also warns that definitive evidence is still lacking over their long-term benefits. Using them “doesn’t make an unhealthy choice healthy,” the organization adds. “It just means it’s less unhealthy.”

Studies raise doubts over whether they have an impact on weight loss, including some that suggest they actually may contribute to weight gain. One study, in fact, found there were differences among four sweeteners in how much weight was gained.

A 2009 study found a relationship between drinking diet sodas and developing metabolic syndrome, a cluster of symptoms, including hypertension, high blood sugar, excess body fat around the waist and abnormal cholesterol or triglyceride levels, all of which raise the chances for type 2 diabetes, stroke and heart disease. Other research indicates artificial sweeteners may alter gut microbes and, in doing so, actually contribute to developing diabetes and other diseases.

How do nonnutritive sweeteners increase body weight when they have no calories? One working idea is that they “trick” the brain into craving other sources of simple sugars, thus increasing overall caloric intake, experts say. Another theory, experts say, is that they alter the microbiome - intestinal bacteria - in ways that promote glucose intolerance, which results in higher than normal blood sugar levels.

Although some clinical studies report they help in decreasing overall calorie intake, the studies may not reflect reality, Hensrud says. “In real world situations, other mechanisms emerge that promote increased calorie intake from other foods,” he says.

At least one study suggests that problems caused by sweeteners could be the result of their being consumed in combination with other foods, namely carbohydrates such as pasta, rice, french fries and snack foods.