Thought Sugar-Free Was the Better Choice? Read This First

For decades, artificial sweeteners have been promoted as a healthier alternative to sugar. But new research suggests they may have unexpected effects on your metabolism.

What Are Artificial Sweeteners?

Artificial sweeteners, sometimes called nonnutritive sweeteners, are synthetic sugar substitutes that add little or no calories to your diet, according to Mayo Clinic. Some are made from natural sources like fruits or sugar, and they are often added to processed foods such as soft drinks, candy, canned foods, dairy products, and baked goods. Common examples include aspartame, sucralose, and saccharin.

RELATED: Are Artificial Sweeteners Making Weight Loss HARDER?

How are Sweeteners Regulated?

Sweeteners and other ingredients are added to food in the U.S., and must be safe for consumption under the federal Food, Drug and Cosmetic Act.

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In the United States, the Food and Drug Administration allows the following sugar substitutes to be used:

• Acesulfame potassium (Sweet One, Sunett).
• Advantame.
• Aspartame (NutraSweet, Equal).
• Neotame (Newtame).
• Thaumatin (Talin).
• Saccharin (Sweet’N Low).
• Sucralose (Splenda).
• Luo han guo (Monk Fruit in the Raw).
• Purified stevia leaf extracts (Truvia, PureVia, others).

“What makes our analysis notable is that by focusing on non-caloric comparators, we better isolated the direct physiological effects of the sweeteners themselves, not the calories they replace,” said first author Meng Wang, a research assistant professor at Tufts University’s Friedman School of Nutrition Science and Policy in Boston. 

“When pooling findings from individual trials, we see signals that these compounds may have metabolic harms,” she added in a news release.

The researchers analyzed 21 randomized clinical trials comparing artificial and low-calorie sweeteners with non-caloric options like water or a placebo.

The result: Artificial sweeteners were linked to higher fasting insulin levels and a higher HbA1c — a measure of long-term blood sugar control. The analysis also showed a trend toward reduced insulin sensitivity.

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Researchers said one possible explanation involves the gut microbiome. Previous evidence suggests certain non-nutritive sweeteners can alter the makeup and function of your gut bacteria.

The review also found that people who consume more artificial sweeteners may have a higher risk of cardiometabolic conditions, including type 2 diabetes and heart disease.

Researchers said their overall findings suggest these compounds may have metabolic harms, but more studies are needed to establish cause and effect.

In the meantime, “if you’re replacing large amounts of added sugar in your diet, such as in multiple servings of soda, these low-calorie sweeteners may be a better alternative.” said study senior author Dr. Dariush Mozaffarian, a cardiologist and director of Tufts’ Food is Medicine Institute. “We can’t simply assume they are safe and innocuous, and avoiding them whenever possible appears a prudent choice.”

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While the findings raise important questions, they do not prove that artificial sweeteners directly cause diabetes, heart disease, or other metabolic problems. Experts say more long-term research is needed to better understand how different sweeteners affect the body over time.

For now, moderation remains the best approach. If artificial sweeteners help you cut back on large amounts of added sugar—such as replacing several sugary sodas each day—they may still be a useful tool. However, they shouldn’t be viewed as a “healthy” food on their own. Instead, focus on building an eating pattern centered on whole, minimally processed foods and beverages whenever possible.

Tips for patients

What can you do if you use artificial sweeteners?

• Don’t panic. This study does not mean you need to eliminate all artificial sweeteners overnight.
• Reduce added sugar gradually. If you’re using sweeteners to cut back on sugary drinks or desserts, continue working toward drinking more water and eating fewer highly sweetened foods overall.
• Read food labels. Artificial sweeteners can be found in products beyond diet soda, including yogurt, protein bars, flavored waters, chewing gum, and sugar-free snacks.
• Focus on your overall diet. Eating plenty of fruits, vegetables, whole grains, lean proteins, legumes, and healthy fats has a much bigger impact on long-term health than any single ingredient.
• Support your gut health. A diet rich in fiber from fruits, vegetables, beans, and whole grains helps nourish beneficial gut bacteria, which play an important role in metabolism.
• Monitor your blood sugar if you’re at risk. If you have prediabetes, diabetes, or other cardiometabolic risk factors, talk with your healthcare provider about the best sweetener choices for your individual needs.
• Choose water more often. Water is still the healthiest choice for staying hydrated. If plain water feels boring, try adding slices of lemon, lime, cucumber, or fresh berries for flavor.
• Talk with your healthcare provider or a registered dietitian. They can help you develop a nutrition plan that reduces added sugars without relying heavily on artificial sweeteners.