How harmful are fake sugars? Understanding the real risks of artificial sweeteners

October 9, 2025 •

3 min read

Over 41% of U.S. adults reported using artificial sweeteners between 2009 and 2012, with consumption on the rise globally. Despite being calorie-free alternatives, a growing body of scientific evidence suggests that these sugar substitutes may carry a range of surprising health risks that go beyond simple weight management.

Quick Summary

An examination of artificial sweeteners reveals complex health implications beyond their zero-calorie appeal. Recent studies point to potential disruptions in the gut microbiome, metabolic function, and cardiovascular health, challenging earlier assumptions of complete safety. Evidence is often debated and inconclusive, highlighting the need for a nuanced understanding of their effects based on type, amount, and individual health factors.

Key Points

Moderate Intake: While deemed safe by the FDA within Acceptable Daily Intake (ADI) limits, artificial sweeteners should be consumed in moderation to mitigate potential risks.
Gut Microbiome Alterations: Certain sweeteners, such as saccharin and sucralose, can disrupt the balance of gut bacteria, potentially leading to impaired glucose tolerance and metabolic issues.
Controversial Weight Effects: Despite being calorie-free, long-term use of fake sugars has been controversially linked to weight gain, increased cravings, and altered metabolic responses.
Metabolic and Cardiovascular Concerns: Observational studies have associated high, long-term consumption of artificial sweeteners with a higher risk of metabolic syndrome, type 2 diabetes, heart disease, and stroke.
Complex Cancer Debate: The cancer risk debate is complex; while some research links aspartame to possible carcinogenicity (IARC Group 2B), regulatory bodies maintain its safety at typical consumption levels.
Healthiest Option: Less Sweetness: Experts recommend reducing overall sweetness preference by training your palate with whole foods rather than relying heavily on any type of sweetener.

For decades, artificial sweeteners have been marketed as a guilt-free way to enjoy sweetness without the caloric cost. These low- and no-calorie sugar substitutes appear in a wide variety of products. While regulatory bodies like the U.S. Food and Drug Administration (FDA) have deemed approved sweeteners safe within Acceptable Daily Intake (ADI) levels, scientific debate continues. Research into their long-term effects on the body suggests potential downsides.

The Complexities of Artificial Sweeteners

Artificial sweeteners provide sweetness without calories as the body processes them differently than sugar. This difference in processing can potentially impact appetite, cravings, and gut health.

The Gut Microbiome Connection

Concerns exist regarding the effect of artificial sweeteners on the gut microbiome. Studies suggest some sweeteners, including saccharin and sucralose, can alter the balance of gut bacteria, potentially leading to metabolic issues like impaired glucose tolerance. Some research suggests a link between saccharin and sucralose and increased intestinal permeability, which could trigger inflammation.

Metabolic and Cardiovascular Health Risks

Long-term studies have also linked artificial sweetener consumption to metabolic and cardiovascular risks. Research suggests a potential link between long-term, daily use and a higher risk of stroke, heart disease, and death. Despite being calorie-free, some evidence indicates that artificial sweeteners might not aid weight loss and could even contribute to weight gain. The World Health Organization advises against using non-sugar sweeteners for long-term weight control. Recent studies have raised concerns about erythritol, suggesting high consumption may increase the risk of blood clots, heart attacks, and strokes.

The Cancer Controversy

While earlier cancer fears linked to saccharin were largely dismissed for humans, the debate resurfaced in 2023 when the International Agency for Research on Cancer (IARC) classified aspartame as “possibly carcinogenic to humans” (Group 2B) based on limited evidence. Other expert panels, such as JECFA, have reaffirmed the acceptable daily intake (ADI) for aspartame.

Comparing Common Sweeteners


Sweetener	Type	Sweetness (vs. Sugar)	Calories	Key Health Notes
Aspartame (Equal, NutraSweet)	Artificial	~200x	Negligible	Classified as 'possibly carcinogenic' by IARC (2023) based on limited evidence. Linked to neurophysiological symptoms in some studies. Phenylalanine content is an issue for those with PKU.
Sucralose (Splenda)	Artificial	~600x	Negligible	May alter gut flora and affect insulin sensitivity. Some studies suggest toxic compounds can form when heated. Can cause digestive issues in large doses.
Saccharin (Sweet'N Low)	Artificial	200-700x	Negligible	Early cancer fears discredited for humans. May disrupt gut microbiota. Can cause digestive issues in large doses.
Stevia (Truvia, PureVia)	Natural	200-400x	Zero	Derived from a plant. Considered safe by FDA as a purified extract, though some studies suggest potential gut microbiome alterations or effects when consumed prenatally.
Monk Fruit (Nectresse, PureLo)	Natural	100-250x	Zero	Derived from fruit. Considered safe by FDA. Research on gut impact is still emerging, though it is often considered a healthier option.
Erythritol	Sugar Alcohol	60-80% as sweet	Low	Can cause digestive distress in large amounts. Recent studies linked to higher risk of blood clotting, stroke, and heart attack.

Healthier Alternatives and Moderation

Experts recommend reducing overall consumption of intensely sweet flavors. Strategies include:

Whole Fruits: Incorporating fruits can satisfy sweet cravings with natural sweetness, fiber, and nutrients.
Moderate Natural Sweeteners: Even natural alternatives like stevia and monk fruit extract should be used in moderation to avoid reinforcing a preference for intense sweetness.
Choose Water: Opting for water over artificially sweetened drinks is a simple way to reduce sweetener intake.

Conclusion

While regulatory bodies consider approved artificial sweeteners safe within ADI limits, research highlights potential risks associated with long-term, high consumption, including effects on the gut microbiome, metabolism, and cardiovascular health. The cancer link, particularly for aspartame, remains a subject of ongoing research, without definitive proof of harm at typical consumption levels. For most healthy individuals, occasional, moderate use is likely safe. However, minimizing overall sweetness in the diet and prioritizing whole foods is a recommended approach for long-term health, aligning with guidance from organizations like the WHO. Individuals with existing health conditions should seek personalized advice from a healthcare professional.

Disclaimer: The information in this article is for informational purposes only and does not constitute medical advice. Consult with a qualified healthcare professional before making any dietary changes or starting a new health regimen.

Frequently Asked Questions

The relationship is complex and debated. While artificial sweeteners are calorie-free, some studies suggest they may increase cravings for sweet foods or disrupt metabolic processes, potentially leading to long-term weight gain, despite short-term benefits. The World Health Organization advises against their use for weight control.

Most evidence suggests that artificial sweeteners approved for use do not cause cancer at typical consumption levels. The IARC classified aspartame as 'possibly carcinogenic to humans' based on limited evidence, but other global health organizations, like the JECFA, have not changed their safety recommendations.

Some sweeteners, particularly saccharin and sucralose, have been shown in studies to alter the composition and function of the gut microbiome. This can lead to a state of dysbiosis, which may affect glucose metabolism and cause digestive issues.

Stevia and monk fruit extract are derived from plants and are often considered healthier, natural alternatives. The FDA lists purified versions as Generally Recognized As Safe (GRAS). However, research on their long-term gut impact is ongoing, and moderation is still recommended.

The ADI is the amount of an ingredient that can be safely consumed daily over a lifetime. It varies by sweetener and is set by regulatory bodies like the FDA and JECFA. For example, JECFA maintained the ADI for aspartame at 40 mg per kg of body weight.

Artificial sweeteners typically do not raise blood sugar levels directly, which is why they are often used by people with diabetes. However, some studies indicate they can affect insulin sensitivity and glucose tolerance indirectly by altering the gut microbiome.

Sugar alcohols like erythritol can cause digestive issues such as gas, bloating, and diarrhea, especially in large amounts. Recent studies have also linked erythritol to an increased risk of blood clotting and cardiovascular events.