Does Stevia Cause Cancer?

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Despite some scaremongering articles on the subject, the National Cancer Institute, part of the National Institutes of Health, has said artificial sweeteners such as stevia do not cause cancer.

Stevia is a plant that is used as a sweetener and herbal supplement. Originally native to South America, stevia is up to 300 times sweeter than table sugar and has been used to sweeten beverages and make tea since the 16th century. It has become more popular in the United States in recent decades as consumers look for low-calorie sugar substitutes.

The Food and Drug Administration (FDA) banned stevia in the 1990s but now allows a purified ingredient from stevia as a food additive. There is ongoing research into certain chemicals naturally occurring in stevia that may cause genetic mutations and cancer.

In this article, the history and cancer risk of stevia will be discussed.

closeup of stevia plant

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The Stevia Plant

Stevia, whose scientific name is Stevia rebaudiana, is a leafy plant that looks a little like mint. Its leaves have been used in South America for centuries. Tribes in Paraguay, Brazil, and Bolivia have used stevia leaves to sweeten teas and traditional medicines.

Stevia leaves have up to 150 times the sweetness of sugar. Users report stevia as having a mild, licorice-like taste that’s slightly bitter.

The use of stevia leaves and crude stevia extracts are not considered generally recognized as safe (GRAS) by the FDA, and they are not allowed to be imported into the United States for use as sweeteners.

Why Was Stevia Banned?

In 1991, stevia was banned by the FDA due to early studies that suggested the sweetener may cause cancer. A follow-up study refuted the initial study, and in 1995, the FDA allowed stevia to be imported and sold as a food supplement, but not as a sweetener.

However, in 2008, the FDA approved high-purity (95% minimum purity) stevia extracts as GRAS. Stevia leaf and crude stevia extracts are still not GRAS.

The Sweetener

Stevia sweeteners are made by extracting a compound called steviol glycosides from the leaves of the stevia plant and purifying them to remove some of the bitter attributes found in the crude extract. During this process, the sweetness of stevia extract can increase to 300 times sweeter than sugar.

Steviol glycosides all have a common basic backbone called "steviol." They include compounds like stevioside and many different forms of rebaudioside, the most common of which is rebaudioside A (or reb A).

Like sugar, stevia comes in several forms—liquid, powder, and granules. The many sugar-substitute brands that contain stevia include Truvia, Stevia in the Raw, SweetLeaf, Sweet Drops, Sun Crystals, and PureVia.

Stevia sweeteners are also used by manufacturers as an ingredient in beverages (such as diet sodas, light or low-sugar juices, and flavored waters), canned fruits, condiments, and dairy products (such as ice cream, flavored milk, and yogurt).

Bear in mind that while stevia claims to be natural, additional ingredients such as erythritol (a sugar alcohol) and other flavoring agents are added in the processing of many manufactured products.

How stevia tastes varies from person to person. In general, when compared to sugar, it takes longer for the “sweet” flavor to kick in. But most say that the sweet flavor lasts longer.

Steviol Glycosides 

Stevia contains eight glycosides. These are the sweet components isolated and purified from the leaves of stevia. These glycosides include:

  • Stevioside
  • Rebaudiosides A, C, D, E, and F
  • Steviolbioside
  • Dulcoside A

Stevioside and rebaudioside A (reb A) are the most plentiful of these components.

Although both stevioside and reb A have been found to be mutagenic (the process of generating a genetic mutation) in laboratory animal testing, these effects have not been demonstrated for the doses to which humans are exposed.

Generally Recognized as Safe

High-purity steviol glycosides are GRAS. GRAS requires expert consensus that a food ingredient is safe for its intended use.

In 2008, the FDA made its first GRAS determination on a stevia sweetener, rebaudioside A. Whole stevia leaves and crude stevia leaf extracts are not approved food additives because there is not enough toxicological information available, according to the FDA.

What the Research Says

Concerns about stevia and cancer may stem from the earlier research that showed a slight genetic toxicity in high amounts.

In a 2002 study, a high level of steviol was shown to have a weak mutagenic activity. The amount was equivalent to what one might use in 3,000 cups of coffee. In ordinary amounts, the genetic toxicity of stevia can be regarded as "negligible" according to the study authors.

No more recent studies and meta-reviews have replicated these results.

Can Stevia Cause Cancer? 

To date, there's no clear evidence that stevia causes cancer when used in appropriate amounts.  According to the American Cancer Society, stevia appears to be safe when used in moderation.

Various researchers have evaluated the safety of steviol glycosides, and have concluded that they're safe for both adults and children. However, a review of studies in 2017 noted that while stevia-derived sweeteners were gaining wider use, there have been no studies on their long-term effects on cancer risk.

Can Stevia Help Fight Cancer?

Some studies suggesting that stevia might be helpful in preventing or fighting certain cancers include:

  • A 2012 study of a glycoside found in stevia plants suggested it may help speed up the death of cancer cells in a human breast cancer line.
  • In a 2013 study, researchers found that steviol glycoside derivatives had a toxic impact on several cancer cell lines. These included leukemia, breast, lung, and stomach cancer.

However, research on stevia is limited. More studies specific to links between stevia and cancer are needed.

Important Considerations

Consuming too much sugar can lead to weight gain, blood sugar issues, and an increased risk of heart disease. Opting for a sweetener like stevia can help reduce the amount of added sugar in your diet.

While research into the benefits and risks of stevia is ongoing, studies use different types of plants, different extraction methods, and different parts of the plants, making it difficult to compare data across studies. In addition, many of these studies are sponsored by the stevia industry.

At times, stevia supplements and extracts have been found to contain counterfeit ingredients. For your own safety, it is important to buy products certified to contain at least 95% steviol glycoside.

Some stevia products also contain sugar alcohol. People with sensitivity to sugar alcohol may experience bloating, abdominal cramps, nausea, and diarrhea, though one type of sugar alcohol, erythritol, poses less risk of symptoms than others.

Recommended Daily Intake

According to the Joint FAO/WHO Expert Committee on Food Additives, the acceptable daily intake for steviol equivalents is 4 milligrams per kilogram of body weight. That equates to about 12 milligrams of high-purity stevia extracts per kilogram of body weight per day (or 10 packets of stevia for a 150-pound person).

Summary

Stevia is a natural sweetener that has been used for centuries in large parts of South America. In the United States, the FDA considers refined extracts safe. Research on whole-leaf and raw products is lacking.

When used in moderation, stevia is associated with few side effects and can be a great substitute for refined sugar.

There is no firm evidence that stevia can cause cancer in humans. This is supported by statements from the American Cancer Society and the National Cancer Institute. There is limited research to suggest that stevia may actually help fight cancer, but more studies are needed in this area.

A Word From Verywell

Stevia is considered safe based on the scientific evidence available. But many studies are small, and products containing stevia extracts are still fairly new, so we’re still learning about long-term effects.

When used within the recommended guidelines, high-quality stevia extract should pose no health risks.

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10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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