Stevia leaf extract is widely used in sugar-free products, from soft drinks to dietary supplements. But is a natural sweetener completely harmless?
Many consumers are questioning the long-term safety of stevia extract, especially when it can affect the endocrine system, digestion, or drug interaction. Initial studies have opened up many lines of debate about the biological effects of steviol glycosides in the human body.
Please refer to the summary article here to understand Stevia's origin, mechanism of action, and preparation forms.
Stevia leaf extract may cause side effects or interactions in some sensitive individuals.
What Is Stevia Leaf Extract?
Stevia leaf extract is more than just a simple sugar substitute. It results from a complex extraction process from the Stevia rebaudiana plant, which is native to South America and has been used by indigenous people for centuries. The tiny leaves contain a natural compound that is hundreds of times sweeter than cane sugar, called steviol glycosides. When properly refined, these molecules become a pure sweetener containing virtually no calories and do not raise blood sugar.
Whole leaf and refined compound
Stevia leaf extract is not the same as whole ground stevia leaves. In the food industry, only the extracted and purified essence, mainly Rebaudioside A and Stevioside, is used to ensure purity and quality control.
Clear Legal Status
The US Food and Drug Administration (FDA) has recognized purified steviol glycosides as "Generally Recognized As Safe" (GRAS). However, only these purified forms are officially permitted in foods and beverages.
Reported Side Effects of Stevia Leaf Extract
Although considered safe in many clinical studies, stevia leaf extract may still cause some side effects in some sensitive individuals. These reactions, although uncommon, have been noted in medical reports and consumer feedback. The biological properties of steviol glycosides, along with other ingredients that may be included in commercial products, create a variety of reaction scenarios in the body.
Mild gastrointestinal disturbances
Some people experience bloating, nausea, or abdominal discomfort after consuming stevia products. This phenomenon is often related to the interaction between stevia and the intestinal microflora.
Headaches and dizziness
A few cases reflect symptoms of dull headaches or transient dizziness after taking stevia leaf extract, possibly due to the effect on the cerebral vascular regulation mechanism.
Allergic reactions
Although rare, allergic reactions such as itching, rash, or difficulty breathing have been reported, especially in people with known sensitivities to plants in the daisy family, such as stevia.
Hormonal and Endocrine Concerns
Concerns regarding the endocrine effects of stevia leaf extract stem from preclinical animal studies that have shown that the bioactive steviol glycosides have the potential to interact with the endocrine axis. Although no definitive conclusions have been reached in humans, scientific concerns regarding potential effects on sex hormones and the endocrine system continue to grow, particularly in light of the increasing consumption of stevia.
Effects on reproductive hormones
Several studies in rats have reported decreased testosterone levels, ovulatory cycle disturbances, and changes in genital organ weight following chronic high-dose stevia use. These findings suggest the potential for reproductive effects with prolonged exposure.
Potential for Endocrine Axis Alteration
Steviol and its derivatives may interact with steroid receptors or indirectly affect the functioning of the pituitary, thyroid, or adrenal glands – thereby affecting homeostasis. Some scientists have called for further human studies to determine the clinical relevance.
Interaction with Medications
Stevia leaf extract may affect the efficacy or safety of some chronic medications. The active ingredient steviol glycosides not only affects glucose metabolism and blood pressure but also interacts with biological pathways involved in pharmacokinetics. When used concomitantly with medications, especially those used to treat diabetes or hypertension, stevia may alter the physiological response and produce a state that exceeds the therapeutic threshold.
Enhanced hypoglycemic effect
Stevia promotes insulin secretion and improves insulin sensitivity in some individuals. When used concomitantly with hypoglycemic drugs such as metformin or sulfonylureas, the risk of profound hypoglycemia may occur if not closely monitored.
Effects on blood pressure
Stevia has vasodilatory and mild diuretic properties, which may lower blood pressure. In patients receiving treatment with ACE inhibitors, beta-blockers, or diuretics, the additive effect may cause sudden hypotension, dizziness, or fatigue.
Unpredictable interactions
Some potential interactions with anticoagulants, drugs affecting the liver or kidneys, or hormones are still being studied further in the clinical setting.
Regulatory and Scientific Opinions
Stevia leaf extract has been the focus of rigorous evaluations by health organizations and regulatory agencies worldwide. The distinction between pure extract and whole leaf is crucial in making official recommendations. Modern scientific evaluations focus on long-term safety, biological mechanisms, and appropriate consumption levels in the community.
Recognition from the FDA and EFSA
The US Food and Drug Administration (FDA) has classified purified steviol glycosides as "Generally Recognized As Safe" (GRAS) for use in food. The European Food Safety Authority (EFSA) also agrees on the safety of these compounds, with an established tolerable daily intake (ADI) based on toxicological data.
Warnings from some countries
Some countries remain cautious about whole leaf stevia or impure extracts. Reasons include concerns about potential toxicity, endocrine risks, and a lack of long-term safety data. Here, the use in foods requires special supervision or is banned altogether.
Purity and Product Labeling Issues
Product purity and labeling are major concerns regarding the consumption of stevia leaf extract. In today's market, many products labeled as "stevia" do not actually contain steviol glycosides in their pure form but rather complex blends with other additives or sweeteners. This lack of transparency in ingredient disclosure can lead to misunderstandings and unwanted physiological reactions in consumers.
Mixing with Other Substances
Many commercial stevia products are combined with erythritol, maltodextrin, or dextrose to improve flavor and solubility. These substances may affect the glycemic index or cause bloating, especially in people with sensitive digestive systems.
Inconsistent labeling
Some manufacturers do not list the actual percentage of stevia in their products, or use generic terms such as "natural sweetener," making it difficult for consumers to assess purity. The lack of standardization in labeling poses a challenge for both consumers and the industry in monitoring product safety and efficacy.
Who Should Avoid Stevia Leaf Extract?
Although stevia leaf extract is considered safe for most users, it may cause adverse reactions in certain populations. The unique biological properties of steviol glycosides, along with the excipients or additives included in commercial products, make its use in these populations a matter of careful consideration and clear indications from a healthcare professional.
Pregnant and Breastfeeding Women
Stevia has the potential to affect the endocrine system and reproductive function. When hormonal balance is vital during pregnancy or breastfeeding, exposure to biologically active substances such as stevia should be strictly limited.
People with Asteraceae Allergies
People with allergies to stevia, chrysanthemums, asters, or other members of the Asteraceae family are at risk of cross-reactions when using stevia leaf extract, including rashes, difficulty breathing, or hives.
People with sensitive digestive systems
Products containing stevia combined with polyols such as erythritol can cause bloating, indigestion, or diarrhea in people with irritable bowel syndrome or malabsorption.
Conclusion
Stevia leaf extract is a naturally derived, highly purified sweetener recognized by major health organizations as safe when used in appropriate doses. However, individual sensitivities, underlying health conditions, and the ingredients in commercial products may influence the experience and tolerance.
Choosing a highly purified, clearly labeled, and used under medical guidance product is key to maximizing benefits and minimizing potential risks.
For a more in-depth look at the link between stevia and cancer risk, see our in-depth article on whether stevia causes cancer.
Frequently Asked Questions (FAQs)
- Does Stevia Leaf Extract Harm the Liver or Kidneys? – Current studies have not shown any significant liver or kidney toxicity when using pure steviol glycosides, but caution should be exercised with adulterated products or uncontrolled long-term use.
- Can people with diabetes use stevia leaf extract? – Stevia leaf extract helps control blood sugar because it does not contain easily absorbed carbohydrates, but patients need to monitor blood sugar levels regularly if used with diabetes medication.
- Can Stevia Affect the Endocrine System in Children? – Some theories suggest that stevia affects the hormone axis, although there is no adequate clinical data on children, so use requires specific instructions from a pediatrician.
- Is it safe to use stevia every day? – Doses of steviol glycosides below the tolerable daily intake (ADI) are considered safe, but daily consumption should be based on the type of product, the individual's constitution, and health status.
- Can stevia be used during pregnancy? – During pregnancy, hormones change dramatically, so the use of stevia – especially in its impure form – should be considered and discussed with an obstetrician.
