Does Stevia Promote Infertility?

Many people are concerned that stevia is dangerous because it is linked to infertility. This is false information. Stevia is a natural sweetener extracted from the leaves of the Stevia rebaudiana plant, which is native to South America. It is also known as sweet weed, sweet leaf, sweet herb, and honey leaf.^One

Stevia contains steviol glycosides, which are 250 to 300 times sweeter than sucrose.²

Stevia is called kaahye in the Guarani language, a Paraguayan language. The Guarani have long used stevia for its medicinal properties, including to regulate blood sugar.^three However, there are also theories that certain tribes in Paraguay used stevia tea as a contraceptive, which led to the misconception that stevia tea is harmful to pregnancy.⁴

Stevia’s Infertility Link, Two Controversial Studies Link It

A 1968 study by Joseph Krug of Purdue University reported that stevia decreased fertility in female rats.⁵ In a study, rats fed large amounts of stevia had fewer offspring than controls.

However, the study was criticized for having “questionable scientific methodology, and several studies that attempted to replicate the results failed.” Kruc later admitted that the mice’s low fertility rates may have been due to him “overdosing” the compound, chiropractor BJ Hardick noted.⁶

In 1988, Mauro Alvarez of the University of Maringa Foundation in Brazil repeated Krug’s study and again found that stevia had similar contraceptive effects. However, the methodology of this study was also heavily criticized, and Alvarez later agreed that stevia did not pose a threat to fertility.

Nevertheless, the U.S. Food and Drug Administration (FDA) cited these controversial studies as the main reason for not approving the use of whole stevia leaf or crude stevia extract as a food additive.

According to the FDA, “When used in foods, stevia leaf or its crude extract is not an approved food additive and is not considered GRAS. [generally recognized as safe] Because of the lack of toxicological information.”⁷ Nonetheless, the FDA considers certain stevia glycosides as GRAS, stating:⁸

“FDA has evaluated numerous GRAS notifications for the use of highly pure (at least 95% purity) steviol glycosides, including rebaudioside A (also known as Reb A), stevioside, rebaudioside D, or mixtures of steviol glycosides with rebaudioside A and/or stevioside as the principal ingredient.

FDA did not question the notifier’s GRAS conclusion for high-purity stevia-derived sweeteners under the intended conditions of use stated in the GRAS notification submitted to FDA.

… the safety of steviol glycosides has been extensively studied and reported in the scientific literature. In humans, steviol glycosides are not hydrolyzed by digestive enzymes in the upper gastrointestinal tract and are not absorbed through the upper part of the gastrointestinal tract. Numerous chronic and clinical studies in humans have demonstrated no adverse effects.”

Studies show that stevia does not promote infertility.

Meanwhile, additional research supports the notion that stevia is safe and does not cause negative reproductive effects. In 1991, researchers at the Primate Research Center at Chulalongkorn University in Bangkok, Thailand, looked at the effects of stevioside, a stevia glycoside, on the growth and reproduction of hamsters.⁹

The scientists administered stevioside to four groups of 20 hamsters at different doses daily, including 0.5, 1.0, and 2.5 grams per kilogram of body weight. They found no growth or reproductive problems in either males or females. All males successfully mated with females, and each female gave birth to three pups during the study period.

The duration of pregnancy, the number of fetuses, and the number of children born were all similar to the control group. Offspring who continued to receive stevioside also showed normal growth and fertility. The researchers concluded:¹⁰

“Histological examination of reproductive tissues from all three generations revealed no evidence of abnormalities that could be related to the effects of stevioside intake. We conclude that stevioside administration at doses as high as 2.5 g/kg body weight/day does not affect growth or reproduction in hamsters.”

Another study evaluating the effects of stevia on female fertility similarly concluded that there was no harm.¹¹

“This study reports that oral administration of water-based sweet stevia extract and stevioside at doses of 500 mg/kg and 800 mg/kg body weight, respectively, did not induce significant female reproductive toxicity in Swiss albino mice.”

Stevia may have a protective effect on testicular tissue and sperm quality

Recent studies have shown that stevia may have protective effects on fertility and reproduction. One study examined the effects of stevia extract on fertility in male Wistar rats exposed to tartarzine. Tartarzine is a commonly used yellow food coloring, also known as FD&C Yellow No. 5, which can affect fertility and cause oxidative stress at high doses.¹²

The control group was administered distilled water for 56 days, the stevia group was administered 1,000 mg/kg of stevia extract, the third group was administered 300 mg/kg of tartazan, and the fourth group was administered stevia extract followed by tartazan 1 hour later.

The results showed that tartazan significantly decreased testosterone levels and decreased sperm motility, viability and count, antioxidant levels, while increasing sperm abnormalities and DNA degradation. However, stevia extract improved testosterone levels and antioxidant levels. In addition, sperm quality improved in the group treated with stevia and tartazan compared to the tartazan group.

Stevia also improved liver and kidney function parameters while reducing malondialdehyde levels, a marker of oxidative stress, and sperm abnormalities. The study concluded that “stevia administration has a protective effect on testicular tissue and sperm quality from tartrazine exposure-induced toxicity.”

In another example, researchers at Shiraz University of Medical Sciences in Iran evaluated the effects of stevia on hormone levels and testicular damage in diabetic rats, which may affect the reproductive system.¹³ Stevia significantly lowered fasting blood glucose and increased luteinizing hormone levels in diabetic rats, while also exhibiting several beneficial reproductive effects.¹⁴

“Stevia also increased body weight, testicular volume, sex lineage cell count, sperm count and motility compared with diabetic rats (P<0.05). Due to its antioxidant properties, stevia enhanced the changes in spermatogenesis and stereological properties of diabetic rat testis. Therefore, stevia may reduce reproductive problems and improve infertility in diabetic male rats."

Stevia has antioxidant, anti-inflammatory and other beneficial effects

Stevia is best known in the modern world as a natural sweetener, but it also contains carbohydrates, lipids, dietary fiber, essential oils, water-soluble vitamins, minerals, and several beneficial phenolic compounds. “Recent studies have shown that consuming stevia leaves may provide several health benefits for humans,” the researchers wrote in the journal Nutrients, including:¹⁵

“Since inflammation and oxidative stress play a key role in the pathogenesis of many diseases, stevia emerges as a promising natural product to support human health,” explained researchers from the University of Thessaly in Lamia, Greece.¹⁶

They conducted a systematic review and meta-analysis and found “a statistically significant antioxidant recovery effect of oxidative status markers in experimentally diseased animals following administration of stevia leaf extract.”

In this case, they found that the recovery activity was primarily due to the stevia whole leaf extract, with only a minor contribution from the glycosides. Additionally, “diabetes appeared to be the disease with the highest recovery response to stevia leaf extract administration.”¹⁷

A 2021 review summarizing data on the biological activities of stevia extracts and glycosides found that the compounds “stimulate insulin production in diabetic patients, improve polycystic kidney disease, have chemotherapeutic effects in cancer, and have potent antimicrobial, antioxidant, and immunomodulatory properties.”¹⁸

How does stevia differ from artificial sweeteners?

Stevia is a natural sweetener extracted from the leaves of the Stevia rebaudiana plant, while artificial sweeteners such as aspartame and sucralose are synthetically produced chemicals designed to mimic the sweetness of sugar.

Stevia contains steviol glycosides, a natural compound that provides sweetness and has been used traditionally in some cultures, while artificial sweeteners contain man-made chemicals. In addition, despite the health benefits of stevia, artificial sweeteners have been linked to a number of health risks.

For example, a 2022 population-based cohort study published in PLOS Medicine of 102,865 adults found that artificial sweeteners (specifically aspartame and acesulfame-K) were associated with an increased risk of cancer, including breast and obesity-related cancers.¹⁹

Researchers at the University of Florida School of Medicine noted that when aspartame is consumed, it breaks down into aspartic acid, phenylalanine (a precursor to monoamine neurotransmitters) and methanol, which can have a “powerful” effect on the central nervous system.²⁰

Their study linked aspartame consumption to anxiety, and found that mental health changes were passed on to future generations. Another nine-year study of 103,388 people linked the artificial sweeteners aspartame (Equal), acesulfame potassium, and sucralose (Splenda) to cardiovascular disease and stroke.²¹

According to research, consuming as little as 78 milligrams of artificial sweetener a day—about the amount in half a can of diet cola—can be hazardous to your health, increasing your risk of heart attack by one-tenth and stroke by one-fifth.²² Moreover, artificial sweeteners can alter the gut microbiome in a similar way to what happens with antibiotics.²³

Even more concerning is that artificial sweeteners—particularly acesulfame potassium and sucralose—may interfere with the liver’s delicate detoxification process, according to research presented at the annual meeting of the American Society for Biochemistry and Molecular Biology in Philadelphia, April 2-5, 2022.²⁴

A healthy choice for a sweet treat

Stevia is a natural sweetener option that can be used occasionally and is not associated with many of the risks associated with artificial sweeteners. There are rumors that it can affect fertility, but research suggests that this is a myth and that stevia may have protective effects. Other options for natural sweet treats include seasonal, ripe fruits, maple syrup, and raw honey.