Stevia is a natural, zero-calorie sweetener derived from the leaves of the Stevia rebaudiana plant, native to South America. It has gained widespread popularity as a sugar alternative for those looking to manage calorie intake or blood sugar levels. Despite its natural origin and common use, public concern persists about a potential link between stevia consumption and an increased risk of cancer. This article examines the current scientific consensus and official regulatory positions.
What Stevia Is
The term “stevia” is often used broadly, but it is important to distinguish between the whole leaf and the commercial product. The sweetness comes from compounds in the leaf called steviol glycosides, such as Rebaudioside A (Reb A) and Stevioside. The whole or crude stevia leaf and its unrefined extracts are not approved as food additives in many countries, including the United States, due to a lack of adequate safety data.
The sweetener found in nearly all commercial food and beverage products is a highly purified extract of these steviol glycosides. This extract must meet purity specifications of at least 95% steviol glycosides to be used legally as a sweetener. These purified extracts are incredibly potent, providing a sweet taste that is between 200 and 400 times sweeter than regular table sugar.
The Research on Stevia and Cancer
Rigorous scientific investigation has thoroughly examined the potential for purified stevia extracts to cause cancer. The overwhelming consensus from global food safety authorities is that high-purity steviol glycosides are neither carcinogenic nor genotoxic. Long-term animal feeding studies, designed to detect cancer-causing effects, have consistently shown no evidence of tumor formation linked to stevia consumption.
The initial concerns about a cancer link arose from early, poorly designed studies or confusion surrounding a metabolite of steviol glycosides called steviol. Some in vitro (test-tube) studies showed that steviol could exhibit weak mutagenic activity, meaning it could potentially cause changes to genetic material. However, this effect was only observed at extremely high concentrations that are physiologically impossible to reach through normal dietary intake.
The body effectively processes and excretes steviol glycosides and their metabolites without harmful accumulation. Rigorous testing confirmed that, at realistic human consumption levels, purified stevia extracts do not damage DNA or promote the growth of cancerous cells. Some preliminary research suggests that certain steviol glycosides may possess anti-inflammatory or anti-cancer properties, though these findings require further research.
Official Regulatory Status and Safety
The safety of purified steviol glycosides is supported by the official approval of major food safety organizations. The U.S. Food and Drug Administration (FDA) has granted high-purity stevia extracts “Generally Recognized As Safe” (GRAS) status for use as a general-purpose sweetener in foods and beverages, based on a thorough review of scientific data.
The European Food Safety Authority (EFSA) approved steviol glycosides as a food additive in 2011 after a comprehensive safety assessment. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has also evaluated the evidence and confirmed the safety of these extracts. These organizations establish a conservative safety limit known as the Acceptable Daily Intake (ADI).
The ADI for steviol glycosides is set at 4 milligrams per kilogram of body weight per day, expressed as steviol equivalents. This level represents the amount a person can safely consume every day over an entire lifetime without appreciable health risk. This conservative figure incorporates a large safety factor, typically 100-fold, below the level where no adverse effects were observed in animal studies.