Artificial sweeteners are often the topic of heated debate.

On one hand, they're claimed to increase your risk of cancer and harm your blood sugar and gut health.

On the other hand, most health authorities consider them safe, and many people use them to reduce their sugar intake and lose weight.

This article reviews the evidence on artificial sweeteners and their health effects.

Artificial sweeteners, or sugar substitutes, are chemicals added to some foods and beverages to make them taste sweet.

People often refer to them as "intense sweeteners" because they provide a taste similar to that of table sugar but up to several thousand times sweeter.

Although some sweeteners contain calories, the amount needed to sweeten products is so small that you end up consuming almost no calories (1).

Summary Artificial sweeteners are chemicals used to sweeten foods and beverages. They provide virtually zero calories.

The surface of your tongue is covered by many taste buds, each containing several taste receptors that detect different flavors (2).

When you eat, your taste receptors encounter food molecules.

A perfect fit between a receptor and molecule sends a signal to your brain, allowing you to identify the taste (2).

For example, the sugar molecule fits perfectly into your taste receptor for sweetness, allowing your brain to identify the sweet taste.

Artificial sweetener molecules are similar enough to sugar molecules to fit on the sweetness receptor.

However, they are generally too different from sugar for your body to break them down into calories. This is how they provide a sweet taste without the added calories.

Only a minority of artificial sweeteners have a structure that your body can break down into calories. Given that only very small amounts of artificial sweeteners are needed to make foods taste sweet, you consume virtually no calories (1).

Summary Artificial sweeteners taste sweet because they are recognized by the sweetness receptors on your tongue. They provide virtually zero calories, as your body can’t break them down.

The following artificial sweeteners are allowed for use in the United States and/or European Union (3, 4):

  • Aspartame. Sold under the brand names NutraSweet, Equal, or Sugar Twin, aspartame is 200 times sweeter than table sugar.
  • Acesulfame potassium. Also known as acesulfame K, it’s 200 times sweeter than table sugar. It’s suited for cooking and baking and sold under the brand names Sunnet or Sweet One.
  • Advantame. This sweetener is 20,000 times sweeter than table sugar and suited for cooking and baking.
  • Aspartame-acesulfame salt. Sold under the brand name Twinsweet, it’s 350 times sweeter than table sugar.
  • Cyclamate. Cyclamate, which is 50 times sweeter than table sugar, was used for cooking and baking. However, it has been banned in the United States since 1970.
  • Neotame. Sold under the brand name Newtame, this sweetener is 13,000 times sweeter than table sugar and suited for cooking and baking.
  • Neohesperidin. It’s 340 times sweeter than table sugar and suited for cooking, baking, and mixing with acidic foods. Note that it is not approved for use in the United States.
  • Sacchari. Sold under the brand names Sweet'N Low, Sweet Twin, or Necta Sweet, saccharin is 700 times sweeter than table sugar.
  • Sucralose. Sucralose, which is 600 times sweeter table sugar, is suited for cooking, baking, and mixing with acidic foods. It's sold under the brand name Splenda.
Summary Many types of artificial sweeteners exist, but not all are approved for use in every country. The most common ones include aspartame, sucralose, saccharin, neotame, and acesulfame potassium.

Artificial sweeteners are popular among individuals who are trying to lose weight.

However, their effects on appetite and weight vary among studies.

Effects on appetite

Some people believe that artificial sweeteners might increase appetite and promote weight gain (5).

The idea is that artificial sweeteners may be unable to activate the food reward pathway needed to make you feel satisfied after you eat (6).

Given that they taste sweet but lack the calories found in other sweet-tasting foods, they're thought to confuse the brain into still feeling hungry (7, 8).

Additionally, some scientists think you'd need to eat more of an artificially sweetened food, compared with the sugar-sweetened version, to feel full.

It's even been suggested that sweeteners may cause cravings for sugary foods (5).

That said, many recent studies do not support the idea that artificial sweeteners increase hunger or calorie intake (9, 10, 11, 12, 13).

In fact, several studies have found that participants report less hunger and consume fewer calories when they replace sugary foods and beverages with artificially sweetened alternatives (14, 15, 16, 17, 18).

Summary Recent studies have found that replacing sugary foods or drinks with artificially sweetened ones may reduce hunger and calorie intake.

Effects on weight

Regarding weight control, some observational studies report a link between consuming artificially sweetened beverages and obesity (19, 20).

However, randomized controlled studies — the gold standard in scientific research — report that artificial sweeteners may reduce body weight, fat mass, and waist circumference (21, 22).

These studies also show that replacing regular soft drinks with sugar-free versions can decrease body mass index (BMI) by up to 1.3–1.7 points (23, 24).

What's more, choosing artificially sweetened foods instead of those with added sugar may reduce the number of daily calories you consume.

Various studies ranging from 4 weeks to 40 months show that this may lead to weight loss of up to 2.9 pounds (1.3 kg) (13, 25, 26).

Artificially sweetened drinks can be an easy alternative for those who regularly consume soft drinks and want to decrease their sugar consumption.

However, opting for diet soda will not lead to any weight loss if you compensate by eating larger portions or extra sweets. If diet soda increases your cravings for sweets, sticking to water might be best (27).

Summary Replacing sugar-containing foods and beverages with artificially sweetened ones may help you lose some weight.

Those with diabetes may benefit from choosing artificial sweeteners, as they offer a sweet taste without the accompanying rise in blood sugar levels (18, 28, 29).

However, some studies report that drinking diet soda is associated with a 6–121% greater risk of developing diabetes (30, 31, 32).

This may seem contradictory, but it's important to note that all of the studies were observational. They didn’t prove that artificial sweeteners cause diabetes, only that people likely to develop type 2 diabetes also like to drink diet soda.

On the other hand, many controlled studies show that artificial sweeteners do not affect blood sugar or insulin levels (33, 34, 35, 36, 37, 38).

Thus far, only one small study in Hispanic women found a negative effect.

Women who drank an artificially sweetened drink before consuming a sugary drink had 14% higher blood sugar levels and 20% higher insulin levels, compared with those who drank water before consuming a sugary drink (39).

However, the participants weren't used to drinking artificially sweetened drinks, which may partially explain the results. What's more, artificial sweeteners may have different effects depending on people's age or genetic background (39).

For example, research shows that replacing sugar-sweetened beverages with artificially sweetened ones produced stronger effects among Hispanic youth (40).

This could be related to the unexpected effect seen on Hispanic women above.

Although research results have not been unanimous, the current evidence is generally in favor of artificial sweetener use among those with diabetes. Still, more research is needed to evaluate their long-term effects in different populations.

Summary Artificial sweeteners can help those with diabetes reduce their intake of added sugar. However, more research is needed on the effects of artificial sweeteners in various populations.

Metabolic syndrome refers to a cluster of medical conditions, including high blood pressure, high blood sugar, excess belly fat, and abnormal cholesterol levels.

These conditions increase your risk of chronic disease, such as stroke, heart disease, and type 2 diabetes.

Some studies suggest diet soda drinkers could have up to a 36% higher risk of metabolic syndrome (41).

However, higher-quality studies report that diet soda either has no effect or a protective one (42, 43, 44).

One recent study had people with obesity and excess weight drink either a quarter gallon (1 liter) of regular soda, diet soda, water, or semi-skimmed milk each day.

By the end of the six-month study, those drinking the diet soda weighed 17–21% less, had 24–31% less belly fat, 32% lower cholesterol levels, and 10–15% lower blood pressure, compared with those drinking regular soda (44).

In fact, drinking water offered the same benefits as drinking diet soda (44).

Summary Artificial sweeteners are unlikely to increase your risk of metabolic syndrome. Replacing sugary drinks with artificially sweetened ones might decrease your risk of several medical conditions.

Your gut bacteria play an important role in your health, and poor gut health is linked to numerous problems.

These include weight gain, poor blood sugar control, metabolic syndrome, a weakened immune system, and disrupted sleep (45, 46, 47, 48, 49, 50).

The composition and function of gut bacteria vary by individual and are affected by what you eat, including certain artificial sweeteners (51, 52).

In one study, the artificial sweetener saccharin disrupted gut bacteria balance in four out of seven healthy participants who were not used to consuming them.

The four “responders” also showed poorer blood sugar control after as few as 5 days after consuming the artificial sweetener (53).

What’s more, when gut bacteria from these people were transferred into mice, the animals also developed poor blood sugar control (53).

On the other hand, the mice implanted with the gut bacteria from “non-responders” had no changes in their ability to control blood sugar levels (53).

Although interesting, more studies are needed before strong conclusions can be made.

Summary Artificial sweeteners may disrupt the balance of gut bacteria in some people, which could increase the risk of disease. However, more studies are needed to confirm this effect.

Since the 1970s, debate about whether there is a link between artificial sweeteners and cancer risk has raged.

It was ignited when animal studies found an increased risk of bladder cancer in mice fed extremely high amounts of saccharin and cyclamate (54).

However, mice metabolize saccharin differently than humans.

Since then, more than 30 human studies have found no link between artificial sweeteners and the risk of developing cancer (1, 55, 56, 57).

One such study followed 9,000 participants for 13 years and analyzed their artificial sweetener intake. After accounting for other factors, the researchers found no link between artificial sweeteners and the risk of developing various types of cancer (55).

Furthermore, a recent review of studies published over an 11-year period did not find a link between cancer risk and artificial sweetener consumption (58).

This topic was also evaluated by U.S. and European regulatory authorities. Both agreed that artificial sweeteners, when consumed in recommended amounts, do not increase cancer risk (1, 59).

One exception is cyclamate, which was banned for use in the United States after the original mouse-bladder-cancer study was published in 1970.

Since then, extensive studies in animals have failed to show a cancer link. However, cyclamate was never re-approved for use in the United States (1).

Summary Based on the current evidence, artificial sweeteners are unlikely to increase the risk of cancer in humans.

Dental cavities — also known as caries or tooth decay — occur when the bacteria in your mouth ferment sugar. Acid is produced, which can damage tooth enamel.

Unlike sugars, artificial sweeteners do not react with the bacteria in your mouth. This means they do not form acids or cause tooth decay (60).

Research also shows that sucralose is less likely to cause tooth decay than sugar.

For this reason, the Food and Drug Administration (FDA) allows products containing sucralose to claim that they reduce tooth decay (60, 61).

The European Food Safety Authority (EFSA) states that all artificial sweeteners, when consumed in place of sugar, neutralize acid and help prevent tooth decay (28).

Summary Artificial sweeteners, when consumed instead of sugar, decrease the likelihood of tooth decay.

Some artificial sweeteners may cause unpleasant symptoms, such as headaches, depression, and seizures in some individuals.

While most studies find no link between aspartame and headaches, with two noting that some people are more sensitive than others (62, 63, 64, 65, 66).

This individual variability may also apply to aspartame's effects on depression.

For instance, people with mood disorders may be more likely to experience depressive symptoms in response to aspartame consumption (67).

Finally, artificial sweeteners do not increase most people's seizure risk. However, one study reported increased brain activity in children with absence seizures (68, 69, 70).

Summary Artificial sweeteners are unlikely to cause headaches, depression, or seizures. However, some individuals could be more sensitive to these effects than others.

Artificial sweeteners are generally considered safe for human consumption (1).

They are carefully tested and regulated by U.S. and international authorities to make sure they are safe to eat and drink.

That said, some people should avoid consuming them.

For example, individuals with the rare metabolic disorder phenylketonuria (PKU) cannot metabolize the amino acid phenylalanine, which is found in aspartame. Thus, those with PKU should avoid aspartame.

What’s more, some people are allergic to sulfonamides — the class of compounds to which saccharin belongs. For them, saccharin may lead to breathing difficulties, rashes, or diarrhea.

Additionally, growing evidence indicates certain artificial sweeteners like sucralose reduce insulin sensitivity and affect the gut bacteria (71, 72).

Summary Artificial sweeteners are generally considered safe but should be avoided by people who have phenylketonuria or are allergic to sulfonamides.

Overall, the use of artificial sweeteners poses few risks and may even have benefits for weight loss, blood sugar control, and dental health.

These sweeteners are especially beneficial if you use them to decrease the amount of added sugar in your diet.

That said, the likelihood of negative effects can vary by individual and depend on the type of artificial sweetener consumed.

Some people may feel bad or experience negative effects after consuming artificial sweeteners, even though they are safe and well-tolerated by most people.

If you'd like to avoid artificial sweeteners, try using natural sweeteners instead.