Artificial sweeteners have been added to soft drinks and other diet foods since 1981 to help satisfy our sweet tooth – and/or control blood sugar – without sugar and its calories.

Yet evidence that consuming artificially sweetened products leads to weight loss or better blood sugar control is weak. In fact, recent studies have suggested that regular consumption of such sweeteners may actually contribute to weight gain and type-2 diabetes.

Open this photo in gallery If you’re accustomed to sprinkling a packet of artificial sweetener into coffee or tea or over breakfast cereal, cut back gradually. BigRedCurlyGuy

Now, new research supports these findings. The study, published last month in the American Journal of Clinical Nutrition, suggests that regular consumption of an artificial sweetener called sucralose may impair blood sugar control.

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What are artificial sweeteners?

Sucralose, aspartame, acesulfame potassium, cyclamate and saccharin are zero-calorie sweeteners approved in Canada.

Cyclamate (brand names Sucaryl, Sugar Twin, Sweet’N Low) and saccharin are not allowed to be added to foods; they’re sold only as tabletop sweeteners.

Acesulfame potassium, aspartame and sucralose are allowed to be added to all sorts of foods including yogurt, baked goods, pancake syrup, ketchup, chewing gum, fruit juice and soft drinks. Sucralose (Splenda) and aspartame (Equal) are also available as tabletop sweeteners.

Health Canada considers these five artificial sweeteners safe when consumed in amounts up to the acceptable daily intake (ADI). The ADI is the maximum amount thought safe to consume each day over a lifetime.

For sucralose, the ADI is 5 milligrams per kilogram of body weight per day, or 340 mg for a 150-pound (68 kg) person, the amount found in 28 packets of Splenda or 19 100-gram tubs of Yoplait’s Source strawberry yogurt.

The latest findings, however, suggest that consuming even half of the ADI of sucralose isn’t safe.

About the study

The study, a randomized controlled trial, investigated the effect of daily sucralose consumption on insulin sensitivity in 66 healthy, normal-weight adults who didn’t regularly use artificial sweeteners.

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Insulin sensitivity describes how sensitive the body is to the effects of insulin, the hormone that clears glucose (sugar) from the bloodstream. Someone who is insulin-sensitive will require a small amount of insulin to lower blood glucose.

Someone who has a low insulin sensitivity (also called insulin resistance) will need a larger amount of insulin to clear the same amount of glucose from the bloodstream. Insulin resistance is a risk factor for type-2 diabetes.

The researchers assigned 33 participants to consume 45 per cent of the acceptable daily intake (ADI) of sucralose for 14 days. They were told to add, on average, three packets of sucralose to beverages at meals three times daily.

Blood samples were evaluated for insulin sensitivity over a three-hour period both before and after consuming the artificially sweetened drinks. The control group went through the same testing but did not consume sucralose.

People in the sucralose group experienced a statistically significant 18-per-cent reduction in insulin sensitivity compared to a non-significant drop of 2.8 per cent in the control group.

This finding is provocative because it suggests that regular consumption of sucralose can lead to insulin resistance in healthy, normal-weight people.

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Sucralose may affect blood sugar control by activating sweet taste receptors in the gut, triggering the release of insulin. Artificial sweeteners are also thought to disrupt the balance of good gut bacteria in a direction that can lead to insulin resistance and weight gain.

Mounting evidence for potential harm

This isn’t the first study to challenge the assumption that artificial sweeteners are metabolically inert substances.

A study published in 2014 in the journal Nature found that mice fed water infused with sucralose, saccharin or aspartame developed glucose intolerance, a precursor to type-2 diabetes. Mice who drank water sweetened with real sugar didn’t develop the condition.

The same researchers tested the effect of saccharin in seven lean, healthy people; four of the seven volunteers developed glucose intolerance.

A review of observational studies published last year in the Canadian Medical Association Journal found that regular use of artificial sweeteners was tied to weight gain, increases in waist circumference, as well as a higher incidence of obesity, high blood pressure, type-2 diabetes and cardiovascular events.

What to do

The evidence that suggests regularly consuming artificial sweeteners may harm long-term health should give us pause.

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If you’re a daily user of artificial sweeteners, I recommend that you take steps to eliminate them from you diet, or use them only occasionally.

Replace diet soft drinks with sparkling water or water flavoured with a splash of pure fruit juice.

If you’re accustomed to sprinkling a packet of artificial sweetener into coffee or tea or over breakfast cereal, cut back gradually. Each week incrementally reduce the amount of sweetener you use.

Switch to plain yogurt and sweeten it with fruit, even a teaspoon of honey.

It’s entirely possible to acclimate your taste buds and get used to – and prefer – a less sweet taste.

Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan.