Many people are concerned that stevia is dangerous because it’s associated with infertility. This is misinformation. Stevia is a natural sweetener derived from the leaves of the Stevia rebaudiana plant, native to South America. Also known as sweet weed, sweet leaf, sweet herbs and honey leaf,1 stevia contains steviol glycosides that are 250 to 300 times sweeter than sucrose.2
Stevia is called ka’a he’e in the Paraguayan language Guaraní. The Guaraní people long used stevia for its medicinal properties, including to regulate blood sugar.3 It was also said, however, that certain tribes in Paraguay used stevia tea as a contraceptive, starting the misconception that it’s harmful to fertility.4
Stevia’s Infertility Link Tied to Two Controversial Studies
A 1968 study by Joseph Kruc of Purdue University reported that stevia reduces fertility in female rats.5 The research involved feeding the rats large amounts of stevia, which resulted in the production of fewer offspring than the control group.
However, the study has been criticized for “having dubious scientific methodology, and multiple studies attempting to replicate its findings failed. Kruc later admitted that the rats’ lower fertility rates may have resulted from his ‘overdosing’ them on the compound,” noted chiropractor B.J. Hardick.6
In 1988, Mauro Alvarez of Brazil’s University of Maringa Foundation repeated Kruc’s study, again finding that stevia caused a similar contraceptive effect. However, this study’s methodology was also heavily criticized, and Alvarez reportedly later agreed that stevia poses no threat to fertility.
Still, the U.S. Food and Drug Administration (FDA) has cited these controversial studies as a primary reason why it has not approved whole stevia leaves or crude stevia extracts for use as food additives.
According to the FDA, “With regard to use in conventional foods, stevia leaf, or its crude extract, is not an approved food additive and is not considered GRAS [generally recognized as safe] due to inadequate toxicological information.”7 That said, the FDA considers certain stevia glycosides GRAS, noting:8
“The FDA has evaluated many GRAS notices for the use of high purity (95% minimum purity) steviol glycosides, including Rebaudioside A (also known as Reb A), Stevioside, Rebaudioside D, or steviol glycoside mixture preparations with Rebaudioside A and/or Stevioside as predominant components.
FDA has not questioned the notifiers’ GRAS conclusions for these high-purity stevia derived sweeteners under the intended conditions of use identified in the GRAS notices submitted to the 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 of the upper gastrointestinal tract and are not absorbed through the upper portion of the gastrointestinal tract. Several chronic studies and clinical studies in humans have been conducted demonstrating no adverse effects.”
Research Shows Stevia Does Not Promote Infertility
Meanwhile, additional research supports the notion that stevia is safe and causes no negative reproductive effects. In 1991, researchers with the Chulalongkorn University Primate Research Centre in Bangkok, Thailand looked at the effects of stevioside, a stevia glycoside, on the growth and reproduction of hamsters.9
The scientists gave four groups of 20 hamsters different daily doses of stevioside, including none, 0.5, 1.0, and 2.5 g/kg body weight. They found no growth or fertility issues in males or females. All males successfully mated with females, and each female had three litters during the study.
The length of pregnancy, number of fetuses and number of young born each time were similar to the control group. The offspring that continued receiving stevioside also had normal growth and fertility. The researchers concluded:10
“Histological examinations of reproductive tissues from all three generations revealed no evidence of abnormality which could be linked to the effects of consuming stevioside. We conclude that stevioside at a dose as high as 2.5 g/kg body wt/day affects neither growth nor reproduction in hamsters.”
Another study that evaluated stevia’s effects on female reproduction similarly found no harm, concluding:11
“This study reports that the oral intake of water-based sweet stevia extract and stevioside, at doses 500 mg/kg body weight and 800 mg/kg body weight, respectively, does not cause any significant female reproductive toxic effect in Swiss albino mouse.”
Stevia May Have a Protective Effect on Testicular Tissues, Sperm Quality
More recent research even suggests stevia may have protective effects on fertility and reproduction. One study investigated the effects of stevia extract on the fertility of male Wistar rats exposed to tartrazine, a commonly used yellow food coloring also known as FD&C Yellow No. 5 that can affect fertility and cause oxidative stress at high dosages.12
A control group received distilled water for 56 days, while the stevia group received 1,000 mg/kg of stevia extract. A third group received 300 mg/kg of tartrazine and a fourth group received stevia extract followed by tartrazine an hour later.
Results showed that tartrazine significantly reduced testosterone levels and decreased sperm motility, viability and count, and antioxidant levels, while increasing sperm abnormalities and DNA degradation. The stevia extract, however, improved testosterone levels and antioxidant levels. There was also an improvement in sperm quality in the stevia and tartrazine-treated group compared with the tartrazine group.
Stevia also reduced malondialdehyde levels, a marker of oxidative stress, and sperm abnormalities, while improving liver and kidney function parameters. According to the study, “Stevia administration has a protective effect on the testicular tissues and sperm quality against toxicity induced by tartrazine exposure.”
In another example, researchers with Shiraz University of Medical Sciences in Iran evaluated stevia’s effects on hormone levels and testicular damage in rats with diabetes, which can affect the reproductive system.13 Stevia significantly reduced fasting blood sugar and increased luteinizing hormone levels in diabetic rats, while leading to several other beneficial reproductive effects:14
“Stevia also resulted in an increase in weight, testis volume, the number of sexual lineage cells, and sperm count and motility, compared to diabetic rats (P<0.05). Due to its antioxidant properties, Stevia enhanced the alteration in spermatogenesis and stereological characteristics in diabetic rat testes. Hence, Stevia could diminish the reproductive system problems and improve infertility in diabetic male rats.”
Stevia Has Antioxidant, Anti-Inflammatory and Additional Beneficial Effects
While stevia is most known in the modern world for its naturally sweet taste, it also contains carbohydrates, lipids, dietary fibers, essential oils, water-soluble vitamins, minerals and a number of beneficial phenolic compounds. As such, “Recent studies have shown several benefits of stevia leaf consumption on human health,” researchers wrote in the journal Nutrients, including the following properties:15
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- Antidiabetic
- Antihypertensive
- Antimicrobial
- Anti-inflammatory
- Antitumor
- Antioxidant
“Since inflammation and oxidative stress play critical roles in the pathogenesis of many diseases, stevia emerges as a promising natural product that could support human health,” the researchers, from the University of Thessaly in Lamia, Greece, explained.16
They conducted a systematic review and meta-analysis, which found “a statistically significant antioxidant restorative effect of oxidative status markers of experimentally diseased animals after they have been administered stevia leaf extracts.” In this case, they found the restorative activity was mainly due to stevia whole leaf extracts and only to a minor extent by glycosides. Further, “diabetes mellitus emerged as the disease with the highest restorative response to stevia leaf extract administration.”17
A 2021 review that summarized data on stevia extract’s and glycosides’ biological activities revealed the compounds “stimulate insulin production in diabetics, improve polycystic kidney disease, have chemotherapeutic action in cancer and possess powerful antibacterial, antioxidant and immunomodulating properties.”18
How Is Stevia Different From Artificial Sweeteners?
While stevia is a natural sweetener derived from the leaves of the Stevia rebaudiana plant, artificial sweeteners, such as aspartame and sucralose, are synthetically produced chemicals designed to mimic the sweetness of sugar.
Stevia contains natural compounds — steviol glycosides — that provide sweetness and have been used traditionally in some cultures, while artificial sweeteners contain human-made chemicals. Further, as opposed to stevia’s health benefits, artificial sweeteners are linked to a variety of health risks.
For instance, a 2022 population-based cohort study published in PLOS Medicine, which involved 102,865 adults, also revealed artificial sweeteners — especially aspartame and acesulfame-K — were associated with increased cancer risk, including breast cancer and obesity-related cancers.19
When you consume aspartame, it’s broken down into aspartic acid, phenylalanine — a precursor of monoamine neurotransmitters — and methanol, which may have “potent” effects on your central nervous system, Florida State University College of Medicine researchers noted.20
Their study linked aspartame consumption to anxiety and found the mental health changes were passed on to future generations. In another nine-year study involving 103,388 people, the artificial sweeteners aspartame (Equal), acesulfame potassium and sucralose (Splenda) were linked to cardiovascular disease and stroke.21
The study found that just 78 mg a day of artificial sweeteners — about the amount found in half a can of diet soda — posed a health risk, with those consuming that amount being one-tenth more likely to have a heart attack and one-fifth more likely to have a stroke.22
Further, artificial sweeteners may lead to shifts in gut microbiota similar to those caused by antibiotics.23
Equally disturbing, in research presented at the American Society for Biochemistry and Molecular Biology annual meeting held April 2 to 5, 2022, in Philadelphia, it was revealed that artificial sweeteners — specifically acesulfame potassium and sucralose — may interfere with your liver’s delicate detoxification process.24
Healthy Choices for a Sweet Treat
Stevia is a natural sweetener option that can be used on occasion and isn’t associated with the numerous risks linked to artificial sweeteners. While there’s talk that it may affect fertility, research shows this is a myth — and stevia may even have protective effects. Other options for a natural sweet treat include in season, ripe fruit, maple syrup and raw honey.
Analysis by Dr. Joseph Mercola
Sources & Referencces
1 Cardiovasc Hematol Agents Med Chem. 2020;18(2):94-103. doi: 10.2174/1871525718666200207105436
2, 18 EXCLI J. 2021; 20: 1412–1430 (Archived)
3 JSTOR Daily July 10, 2023
4, 6 Drhardick.com June 15, 2016
5 Science November 29, 1968, Vol 162, Issue 3857, p 1007
7 U.S. FDA October 2, 2023
8 U.S. FDA, Aspartame and Other Sweeteners in Food July 14, 2023
9, 10 Hum Reprod. 1991 Jan;6(1):158-65. doi: 10.1093/oxfordjournals.humrep.a137251
11 Journal of Endocrinology and Reproduction June 2008, Volume 12, Issue 1
12 Cell Biochem Funct. 2023 Dec;41(8):1462-1476. doi: 10.1002/cbf.3886. Epub 2023 Nov 27
13, 14 Acta Histochem. 2019 Oct;121(7):833-840. doi: 10.1016/j.acthis.2019.08.001. Epub 2019 Aug 13
15, 16, 17 Nutrients. 2023 Aug; 15(15): 3325
19 PLOS Medicine March 24, 2022
20 Florida State University News December 8, 2022
21 BMJ 2022;378:e071204
22 Daily Mail September 12, 2022
23 The ISME Journal volume 15, pages 2117–2130 (2021)
24 Newswise April 5, 2022
