Popular Artificial Sweetener May Increase Insulin Levels, Research Shows

The research was inspired by a can of diet soda.

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A new study suggests that a widely used sugar substitute found in diet drinks, chewing gum, and low-sugar yogurt, may elevate insulin levels, potentially increasing the long-term risk of heart problems.

“Artificial sweeteners have penetrated almost all kinds of food, so we have to know the long-term health impact,” said senior author Yihai Cao, who studies chronic diseases related to blood vessel disorders at Karolinska Institute in Sweden.

Aspartame ‘Tricks’ the Body

The study, recently published in the Cell Press journal Cell Metabolism, found that sugar substitute aspartame triggers increased insulin levels in mice, which in turn contributes to atherosclerosis, the buildup of fatty plaque in the arteries. This buildup can lead to higher levels of inflammation, a known contributing factor that increases the risk of heart attacks and stroke over time.

Mice were fed food containing 0.15 percent aspartame every day for 12 weeks, an amount that corresponds to people drinking about three cans of diet soda each day. Compared with mice without a sweetener-infused diet, aspartame-fed mice developed larger and more fatty plaques in their arteries and exhibited higher levels of inflammation.

Researchers found a surge in insulin levels after aspartame entered the mice’s systems.

Aspartame—200 times sweeter than sugar—“tricks” the body into releasing insulin by activating the sweet taste receptors in the mouth and gut, signaling to the pancreas to prepare for incoming sugar even though no actual calories or glucose are present, leading to a small insulin spike despite the lack of blood sugar increase. Essentially, the body reacts to the sweetness as if it were real sugar, even though it isn’t.

High insulin levels in the mice led to fatty plaque buildup in their arteries, suggesting that insulin may be the connection between aspartame and heart problems, according to the researchers.

The study identified an immune signal called CX3CL1 that is activated when insulin gets released and is associated with inflammation in blood vessels.

“Because blood flow through the artery is strong and robust, most chemicals would be quickly washed away as the heart pumps,” Cao said. “Surprisingly, not CX3CL1. It stays glued to the surface of the inner lining of blood vessels. There, it acts like a bait, catching immune cells as they pass by.”

These trapped immune cells can contribute to inflammation and the development or worsening of plaque.

When researchers eliminated CX3CL1 receptors from one of the immune cells in aspartame-fed mice, the harmful plaque buildup didn’t occur. According to Cao, these results point to CX3CL1’s role in aspartame’s effects on the arteries. This also suggests that targeting the CX3CL1 interaction could be a potential treatment for heart disease, according to the study.

The research was inspired by a can of diet soda, according to Cao.

“One of my students was sipping on this sugar-free drink, and I said, ‘Why don’t you look into that?’” Cao said.

According to Chris Mohr, a dietitian and exercise physiologist, artificial sweeteners are generally considered safe based on long-term data. While some studies raise concerns, including this new one, they haven’t been strong enough to change that view, he said. However, he points out that artificial sweeteners may still affect gut bacteria, appetite, and insulin response because of the body reacting to sweetness even without real sugar, potentially influencing metabolism in unknown ways.

Cao’s team intends to confirm their results by conducting studies on human subjects.

Metabolic Consequences of Aspartame

There are a variety of proposed theories as to why aspartame increases insulin levels, but the exact mechanism is still unknown, Courtney Kassis, a registered dietitian in the Greater Philadelphia area and not associated with the study, told The Epoch Times.

“Some research suggests that the intense sweetness of artificial sweeteners alone causes insulin to spike in anticipation of sugar intake,” she said. “But because insulin is a pro-inflammatory, fat-storage hormone, this can have a negative impact on metabolic health.”

This may include “stubborn weight gain, inability to lose weight, hormone imbalances, increased cravings, blood sugar imbalances, and more,” Kassis said.

Shelley Balls, a registered dietitian and nutritionist for Consumer Health Digest, said that different types of artificial sweeteners affect blood sugar and metabolism differently.

“For example, sucralose (Splenda) has been shown to reduce insulin sensitivity and glucose metabolism,” she said. “Aspartame has been shown to increase fasting blood glucose and A1C levels, whereas allulose and monk fruit are diabetes friendly because they don’t affect blood glucose or insulin.” A1C, also known as hemoglobin A1c, is a blood test that measures the average blood sugar (glucose) level over the preceding two to three months, and is a key indicator of diabetes control and risk.

All artificial sweeteners have potential risks or side effects, Balls said.

“Drinking water is always your best option when you can,” she said, “but if you do need to use a sweetener I would recommend monk fruit or allulose as they are diabetes-friendly and have the least amount of risks and side effects.”

The best option for sweeteners are real foods, including maple syrup, honey, and fruit, according to Kassis.

“Overall, as a dietitian with over five years of experience working with clients facing metabolic complexities from insulin resistance, to inflammation or Type 2 diabetes, I recommend limiting artificial sweeteners as much as possible and opting for real-food sweeteners that pack flavor and additional nutritive benefits,” she said.