Aspartame, sucralose, stevia, erythritol: researchers have never studied sweeteners so closely, and people have never argued about them so much. In 2023, the WHO advised against using them for weight control, and the International Agency for Research on Cancer classified aspartame as "possibly carcinogenic". Between 2024 and 2026, the European Food Safety Authority (EFSA) re-evaluated almost every authorised sweetener. At the same time, large European trials showed that sweeteners help people maintain weight loss.
With such mixed messages, you may wonder whether to keep your diet soda, switch to water or go back to sugar. This guide gathers the data published up to October 2026, checked against primary sources: official opinions, randomised trials, large cohorts and meta-analyses.
Our promise at Diaeta: evidence-based nutrition support, without hunger and with foods you find tasty. Sweeteners can be part of that path, as long as you know which ones to choose, for whom and for what purpose.
1. The Key Facts in 10 Points
- Replacing sugar with a sweetener leads to an average loss of 0.7 to 1.6 kg over a few months to a year. Adding a sweetener without removing any sugar brings no benefit.
- Water remains the best drink. Compared with water, diet drinks show no clear difference in weight.
- Observational studies link sweeteners to more diabetes, cardiovascular disease and cancer. Much of this link comes from the fact that people already at risk choose diet products.
- The WHO guideline (2023) is a conditional recommendation on weight control. It excludes people with diabetes and does not question toxicological safety.
- EFSA confirmed the safety of aspartame and sucralose, and raised the acceptable daily intakes of saccharin, acesulfame K and neotame.
- Erythritol and xylitol, at high doses (30 g), increase blood platelet activity. Reasonable caution makes sense for people at high cardiovascular risk.
- Sucralose is not suitable for oven baking: above 120 °C, it can form chlorinated compounds.
- Polyols (sorbitol, mannitol, maltitol, xylitol) cause most digestive complaints and belong to the FODMAPs.
- During pregnancy and breastfeeding, the data remain observational. Water first, sweeteners in moderation.
- Reducing sweet taste does not change your liking for sweetness: a six-month trial showed this in 2025.
2. Three Families, Three Different Questions
The word "sweetener" covers three families of substances. They differ in chemistry, effects and regulatory status.
| Family | Examples | Calories | The question that matters |
|---|---|---|---|
| Intense sweeteners | Aspartame (E951), sucralose (E955), acesulfame K (E950), saccharin (E954), cyclamate (E952), steviol glycosides (E960) | Zero at the doses used | What do long-term studies say? |
| Polyols (sugar alcohols, the "-ols") | Sorbitol (E420), mannitol (E421), maltitol (E965), xylitol (E967), erythritol (E968), isomalt (E953) | 2.4 kcal/g on the European label; 0 for erythritol | How well does your gut tolerate them? What effect on platelets? |
| Rare sugars | Allulose, tagatose | Low | Are they authorised in Europe? |
2.1 Sweetening Power and Acceptable Daily Intake
The acceptable daily intake (ADI) is the amount a person can consume every day, over a lifetime, without appreciable health risk. It includes a safety margin, often a factor of 100 below the no-observed-effect dose in animals.
| Sweetener | Sweetening power (sugar = 1) | European ADI | Latest evaluation |
|---|---|---|---|
| Aspartame | about 200 | 40 mg/kg/day | EFSA 2013, reconfirmed in 2026 |
| Sucralose | about 600 | 15 mg/kg/day | EFSA, February 2026 |
| Acesulfame K | about 200 | 15 mg/kg/day (previously 9) | EFSA 2025 |
| Saccharin | 200 to 700 | 9 mg/kg/day (previously 3.8) | EFSA 2024 |
| Cyclamate | 30 to 80 | 7 mg/kg/day | Re-evaluation expected in 2027 |
| Steviol glycosides | 200 to 400 | 4 mg/kg/day | EFSA 2024 (increase refused) |
| Erythritol | 0.7 | 0.5 g/kg/day | EFSA 2023 |
| Xylitol | 1 | Not specified | Polyols under re-evaluation |
| Sorbitol, mannitol | 0.5 to 0.6 | Not specified | Polyols under re-evaluation |
To give you a benchmark: according to the WHO, a 70 kg adult would need to drink more than 9 to 14 cans of diet soda a day to exceed the aspartame ADI, with no other source. In Belgium, measured intakes stay well below the ADIs: at the 95th percentile, from 13 % (aspartame) to 31 % (acesulfame K) of the acceptable intake.
3. Safety: What EFSA Concluded in 2024-2026
The European Union required the re-evaluation of every additive authorised before 2009. Sweeteners came last. Here is what EFSA has published in recent years:
- Saccharin (2024): ADI raised to 9 mg/kg/day. The bladder tumours seen in male rats, which had justified the old limit, are not relevant to humans.
- Acesulfame K (2025): ADI raised to 15 mg/kg/day, with no genotoxicity concern for the molecule.
- Neotame (2025): ADI raised from 2 to 10 mg/kg/day.
- Sucralose (February 2026): ADI of 15 mg/kg/day maintained. EFSA found no genotoxicity concern, including for sucralose-6-acetate, an impurity that raised alarm in 2023. However, it could not reach a conclusion on its use in baking, because of the chlorinated compounds that can form during cooking.
- Aspartame (September 2026): EFSA reconfirms the ADI of 40 mg/kg/day.
- Erythritol (2023): ADI of 0.5 g/kg/day, set on the laxative effect. The highest consumers, children and teenagers, can exceed it.
- Steviol glycosides (2024): EFSA declines to raise the ADI of 4 mg/kg/day.
3.1 What the Label Says
- "With sweetener(s)" next to the product name, or "with sugar(s) and sweetener(s)".
- "Contains a source of phenylalanine" for aspartame. This statement concerns people with phenylketonuria, a rare genetic disease.
- "Excessive consumption may produce laxative effects" above 10 % added polyols.
Foods for infants and children aged 1 to 3 (infant formula, baby food jars, infant cereals) may not contain any sweetener.
3.2 The Newcomers
- Allulose: not authorised in the European Union. In 2025, EFSA concluded that its safety "cannot be established" for lack of sufficient data. It is still sold online.
- Monk fruit (luo han guo): since October 2024, water-based decoctions of the fruit count as a traditional food. Purified mogroside extracts are not authorised.
- Brazzein (sweet protein): authorised in the United States in 2024, not in Europe.
4. The 2023 WHO Guideline: What It Actually Says
In May 2023, the WHO recommended against using sweeteners to control weight or reduce the risk of chronic disease. The media often summed up this text as "sweeteners are dangerous". Four details change how you should read it:
- The recommendation is conditional, based on low-certainty evidence.
- It excludes people who already have diabetes.
- It does not cover polyols or rare sugars.
- It is not a toxicological evaluation and changes no ADI.
Other institutions read the same data differently. The American Diabetes Association (2026) accepts sweeteners "in moderation and in the short term" to replace sugary products, and puts water first. British dietitians and diabetes specialists (2025) see them as a useful tool to cut sugar. The European recommendations for diabetes (EASD 2023) state that they can replace sugars in foods and drinks.
Key insight: All institutions agree on one point. Water comes first, and sweeteners serve as a transition tool to reduce sugar. They disagree on how long that use remains acceptable.
5. Why Studies Contradict Each Other
If you read the press, you will find opposite headlines from one week to the next. This confusion comes from two types of studies that answer different questions.
| Randomised trials | Cohort studies | |
|---|---|---|
| Comparison | Sweetener versus sugar or versus water | Consumers versus non-consumers |
| Duration | A few weeks to one year | Several years |
| Result | Small benefit on weight, neutral effect on blood sugar | Risks increased by 10 to 70 % depending on the disease |
| Strength | Establishes cause | Follows large populations over a long time |
Three biases explain the gap:
- Reverse causation. People with overweight, prediabetes or cardiovascular risk switch to diet products. The disease then comes before the consumption, and the sweetener becomes a marker of risk.
- Confounding. High consumption of diet products often goes with an eating pattern rich in ultra-processed foods.
- The wrong comparator. Cohorts compare sweeteners with "nothing". The useful question is: sweetener instead of sugar?
An umbrella review published in 2025 illustrates this. Analysed crudely, cohorts link sweeteners to more obesity, diabetes and mortality. Analysed as "sweetener instead of sugary drinks", they link them to lower weight, less coronary heart disease and lower mortality.
6. Weight: The Randomised Trials
| Study | Participants | Result |
|---|---|---|
| Rogers and Appleton, 2021 (meta-analysis) | 88 studies | Sweetener versus sugar: −1.06 kg. Versus water: no difference. |
| McGlynn, 2022 (meta-analysis) | Adults with overweight, at risk of diabetes or with diabetes | Diet drinks instead of sugary drinks: −1.06 kg, less body fat and less liver fat. |
| SWEET, 2025 (one-year European trial) | Adults with overweight after weight loss | 1.6 kg of additional weight loss maintained at one year with sweeteners. |
| DRINK, 2012 (18 months, double-blind) | Children aged 4 to 11 | A diet drink instead of a sugary drink: less weight gain and less body fat. |
The benefit depends on how much sugar you remove. If you drink a litre of sugary soda a day, switching to the diet version makes a real difference to your intake. If you already drink water, adding diet products does nothing for your weight. To learn more about appetite regulation, read our article on the science of satiety.
7. Blood Sugar and Diabetes
A meta-analysis of 36 trials (2023) found no effect of sweetened drinks on blood sugar, insulin or gut hormones in the following two hours. The response resembles that of water.
An Israeli study published in Cell in 2022 added nuance to this picture. In 120 adults, two weeks of saccharin or sucralose changed glucose tolerance, with large differences from one person to the next, linked to the microbiota. However, the sachets contained glucose as a carrier, and the study lasted only two weeks. The one-year SWEET trial found no difference in insulin sensitivity.
In the French NutriNet-Santé cohort (105,588 adults followed for nine years), the highest sweetener consumers had a 69 % higher risk of type 2 diabetes. The threshold for "high consumption" was low, about half a can of diet soda a day, and the authors acknowledge that reverse causation cannot be ruled out.
In practice, if you have diabetes: sweeteners do not raise your blood sugar and let you cut carbohydrates. Water remains preferable. Watch out for "sugar-free" products that contain polyols, flours or fats: those count. Our complete guide to type 2 diabetes explains these choices in detail.
8. Heart and Blood Vessels: The Case of Erythritol and Xylitol
Large cohorts link diet drinks to a slightly higher cardiovascular risk. In NutriNet-Santé, the absolute difference remains small: 346 versus 314 cases per 100,000 people per year. Among people with diabetes in the UK Biobank, replacing a sugary drink with a diet drink did not change the risk of atrial fibrillation.
8.1 A More Precise Signal: Platelets
A Cleveland Clinic team published three studies between 2023 and 2024:
- In cardiology patients, a high blood level of erythritol was associated with nearly twice as many heart attacks and strokes over three years.
- In healthy volunteers, 30 g of erythritol raised its blood level more than 1,000-fold and increased platelet aggregation in every one of them. The same dose of glucose had no such effect.
- Xylitol showed the same profile.
These results call for careful interpretation. Your body makes erythritol itself, and its blood level rises with hyperglycaemia and metabolic syndrome. No study links dietary erythritol intake to heart attacks, and no trial has measured this risk.
Our advice: if you have a history of thrombosis, heart attack or stroke, keep large doses of erythritol and xylitol modest ("keto" drinks, sugar-free pastries, powdered table sweetener by the spoonful). A xylitol chewing gum contains about 0.3 g: you would need nearly 90 to reach the 30 g studied.
9. Cancer: What Does the Aspartame Classification Mean?
In 2023, the International Agency for Research on Cancer placed aspartame in group 2B, "possibly carcinogenic to humans", on limited evidence of a link with liver cancer. This classification measures the strength of the evidence for a hazard, not the size of the risk at the doses people consume. The same year, the FAO/WHO expert committee concluded that the ADI of 40 mg/kg remained valid.
- In NutriNet-Santé, the highest consumers had a 13 % higher cancer risk.
- In the Women's Health Initiative (98,786 women followed for 21 years), diet drinks showed no link with liver cancer. Sugary drinks did.
- A 2025 review even found an inverse association with colorectal cancer.
A 2025 study in mice showed that sucralose could reduce the effectiveness of cancer immunotherapy by altering the microbiota. In 157 patients, higher sucralose intake was associated with a weaker response. This work remains a hypothesis. If you are receiving immunotherapy, water remains the simplest choice.
10. Gut Microbiota
The effects of sweeteners on the microbiota depend on the molecule, the dose and the person:
- Saccharin and sucralose account for most of the signals, in trials lasting two to ten weeks.
- Pure saccharin, pure aspartame and sucralose, stevia: several trials show no change.
- A 2026 meta-analysis on sucralose found no overall effect on microbiota diversity or on blood sugar.
- The SWEET trial, the longest (one year), shows an increase in bacteria that produce short-chain fatty acids, a favourable profile.
To date, no study shows clinical harm linked to the microbiota. To understand the role of these bacteria, see our guide to the human microbiome.
11. Digestion, Polyols and Irritable Bowel Syndrome
Your gut absorbs polyols poorly. They draw water into the intestine and ferment in the colon: gas, bloating, loose stools. These effects depend on the dose and add up when you combine several polyols.
| Polyol | Tolerance | Observed threshold |
|---|---|---|
| Erythritol | The best | 35 g in a drink with no notable symptoms |
| Xylitol | Intermediate | Watery stools from 35 g in a single dose |
| Sorbitol, mannitol | Low in IBS | 10 g is enough to trigger symptoms |
| Maltitol, isomalt, lactitol | Low | Laxative effect at moderate doses |
If you have irritable bowel syndrome, polyols count among the FODMAPs. During the reduction phase, Monash University sets the threshold at 0.4 g of polyols per serving:
- Swap sorbitol, mannitol, xylitol, maltitol, isomalt and lactitol for other options.
- Erythritol, mostly absorbed, often goes down well: test it during reintroduction.
- Intense sweeteners (aspartame, sucralose, stevia, acesulfame K) are not FODMAPs. Still check the label of table sweeteners: many contain polyols or inulin.
Our complete FODMAP guide walks you through it step by step.
12. Appetite and Sweet Taste
You often hear that sweeteners "keep sugar cravings going" or "trick the brain". The trials do not confirm this:
- Sweeteners increase neither appetite nor the amount eaten at the next meal.
- In the SWEET trial, a sweetened drink even reduced the desire for sweet foods compared with water.
- The Sweet Tooth trial (2025) assigned 180 Dutch adults to a low, medium or high sweetness eating pattern for six months. Result: no difference in liking for sweetness.
So removing sweet taste does not "retrain" your liking for sweetness. This finding matches our approach: we do not ask you to give up the pleasure of sweet foods, but to build an eating pattern that keeps you full. Find out how in Eat what you love.
13. Pregnancy, Children and Special Situations
13.1 Pregnancy
Canadian and Danish cohorts link daily diet drink consumption during pregnancy to more overweight in the child. These studies remain observational, and no randomised trial exists. Sweeteners cross the placenta, but no health authority recommends keeping them below the ADI. Our advice: water first, occasional use without worry.
13.2 Breastfeeding
Acesulfame K passes into breast milk and appears in the blood of every infant studied. Sucralose passes far less. The consequences remain unknown. While breastfeeding, choose water and unsweetened drinks.
13.3 Children
Water and milk remain the reference drinks. If the choice comes down to a sugary drink or a diet drink, the diet version limits weight gain. The American Heart Association recommends against prolonged use in children, except in diabetes.
13.4 Other Situations
- Phenylketonuria: aspartame is contraindicated.
- Migraine: a double-blind trial showed that some people sensitive to aspartame had more headaches. A personal elimination test remains reasonable.
- Kidney failure: the kidneys clear erythritol, and it accumulates when kidney function declines. Keep amounts modest.
- After bariatric surgery: polyols can worsen diarrhoea and dumping symptoms.
- Dental health: the European Union recognises that chewing sugar-free gum for at least 20 minutes after meals helps protect tooth enamel.
- Pets: xylitol is highly toxic to dogs. Keep your chewing gum out of their reach.
14. In the Kitchen: Which Sweetener for Which Use?
| Use | Good choices | Why |
|---|---|---|
| Cakes, oven baking | Acesulfame K, erythritol | They withstand heat. Sucralose can form chlorinated compounds above 120 °C, and stevia can lose part of its sweetening power. |
| Cold desserts, yoghurts, drinks | All | No temperature constraint. |
| Hot sweet dishes | Add aspartame after cooking | Aspartame breaks down with heat: about 50 % disappears after 20 minutes at 180 °C. |
| Texture and volume | A small amount of polyol | Intense sweeteners provide neither volume nor browning. Keep an eye on your digestive tolerance. |
15. Our Personalised Approach at Diaeta
We give you no forbidden foods and no blacklist. We start from your real habits to build a strategy that suits you:
- Do you drink sugary sodas? The diet version is a real step forward. We then work towards water, still, sparkling or flavoured at home, at your own pace.
- Do you already drink diet versions? Nothing urgent. Other levers weigh far more on your health.
- Do you have diabetes? We build sweeteners into your plan and teach you to spot hidden polyols.
- Do you have a sensitive gut? We identify the polyols that trigger your symptoms and the ones you tolerate.
- Do you have a history of cardiovascular disease? We choose the best-suited options together.
Our goal stays the same: an eating pattern without hunger, made of foods you find tasty, and results that last.
Do you have questions about sweeteners, your blood sugar or your weight? Book an appointment for a personalised consultation in Brussels. Together, we will build your tailored nutrition plan.
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