Is aspartame dangerous?

The IARC classed it as "possibly carcinogenic" (Group 2B) in July 2023, on limited evidence. The same month, JECFA kept the acceptable daily intake (ADI) at 40 mg per kilo of body weight per day, and EFSA had concluded in 2013 that it was safe at authorised doses. The classification reflects the strength of the evidence for a hazard, not the risk at a given dose. According to WHO, a 70 kg adult would need to drink more than 9 to 14 cans of diet drink a day to exceed the ADI.

Do sweeteners help you lose weight?

Not demonstrably. WHO advises against using them to control weight: its review found no lasting benefit on fat mass, with a conditional recommendation. ANSES likewise found no proven benefit for weight. Gradually reducing the sweet taste of the diet is the approach ANSES puts forward.

Who should avoid aspartame?

People with phenylketonuria, a rare genetic disease, because aspartame contains phenylalanine, which they must strictly limit. This is why the products concerned carry the wording "contains a source of phenylalanine". For any medical question, consult a health professional.

Why do sugar-free chewing gums carry a warning about laxative effects?

They often contain polyols (sorbitol, xylitol, maltitol...), which are partly poorly absorbed by the intestine. In Europe, a food containing more than 10% added polyols must carry the wording "excessive consumption may have a laxative effect".

Sweeteners: aspartame, sugar, which to avoid?

What is a sweetener?

A sweetener is an additive that gives food a sweet taste. EFSA, the European Food Safety Authority, classes them among thesweetenersauthorised in the European Union, each with an E number. Two main families are distinguished:

Intense sweeteners: according to ANSES, their sweetening power is several dozen to several thousand times that of table sugar. Very little is therefore needed, and they provide very few or no calories. These are aspartame (E951), acesulfame K (E950), sucralose (E955), saccharin (E954), cyclamates (E952) or steviol glycosides extracted from stevia (E960).
Polyols, or sugar alcohols: sorbitol (E420), maltitol (E965), xylitol (E967), erythritol (E968)... Their sweet taste is closer to that of sugar. WHO also points out that they contain calories and does not group them with non-sugar sweeteners.

The most used in France are aspartame, acesulfame K and sucralose, often combined in one product to achieve the desired taste. Like alladditives, they are authorised only after an EFSA evaluation, and the agency re-examines them gradually: some have already been re-evaluated, others are still under review.

Where are they found?

First in "light" or "zero" drinks, then in products labelled "sugar-free" or "reduced": yoghurts, desserts, confectionery, chewing gums, sauces, cereals. Polyols are found mainly in sugar-free chewing gums and sweets. To spot them, read the ingredient list, where the sweetener is named or given its E number. The mentions "no added sugar" or "sugar-free" do not say what replaces the sugar.

Aspartame: what the agencies say

Aspartame is the most debated sweetener, because two opinions issued in July 2023 seem to conflict. In reality, they answer two different questions.

The IARC(International Agency for Research on Cancer) placed it in theGroup 2B, "possibly carcinogenic to humans", based onlimited evidenceof liver cancer in humans. This classification measures the strength of the evidence for a hazard, not the level of risk at a given dose.
JECFA, the expert committee of WHO and FAO, assessed the risk at the doses consumed andkept the acceptable daily intake (ADI) at 40 mg per kilo of body weight per day, finding the association with cancer in humans "unconvincing".
EFSAhad already concluded in 2013, after its full re-evaluation, that aspartame is safe for the general population at authorised doses, with the same ADI of 40 mg/kg per day. This dose does not apply to people with phenylketonuria.

To put it in perspective, WHO gives an example: a 70 kg adult would need to drinkmore than 9 to 14 cansof diet drink a day (depending on the can's aspartame content) to exceed the ADI, assuming no other source of aspartame. This does not mean that everything is fine below that level: it gives an order of magnitude.

Sweeteners and health: what do the studies say?

In 2023, WHO published a guideline thatadvises againstusing non-sugar sweeteners to control weight or reduce the risk of chronic disease. It rests on a systematic review: no lasting benefit on fat mass in adults or children, and a possible increased risk of type 2 diabetes, cardiovascular disease and mortality with prolonged use. Two important nuances: the recommendation is classed asconditional(it calls for discussion depending on national contexts), and WHO acknowledges that the links observed may be skewed by participant characteristics and complex consumption habits. It does not concern people who already have diabetes.

In France, ANSES reached a similar conclusion: no demonstrated benefit of intense sweeteners for weight control, nor for blood glucose in people with diabetes or for preventing type 2 diabetes, and no argument for recommending that sugar be replaced with them as a public health measure. It advises instead reducing the overall sweet taste of the diet, from the earliest age. On the other hand, it had not established a link with an increased risk of diabetes or cancer at the time.

The FrenchNutriNet-Santécohort has produced two widely cited studies. They areobservational studies: they identify associations, not causes.

Cancer (PLOS Medicine, 2022): among 102,865 adults followed for about 8 years, the heaviest consumers of sweeteners had a slightly higher cancer risk than non-consumers (risk ratio of 1.13 overall, 1.15 for aspartame and 1.13 for acesulfame K). No association was found for sucralose. The authors stress that causality cannot be established and that biases (other lifestyle habits, reverse causation) are not fully ruled out.
Cardiovascular disease (BMJ, 2022): among 103,388 participants, higher consumption was associated with a slightly higher cardiovascular risk (risk ratio of 1.09), with signals for stroke (aspartame) and coronary disease (acesulfame K, sucralose). Here again, the authors describe suggestive, non-causal results.

These cohorts consist mainly of women, generally well educated and attentive to their health: their results cannot automatically be transposed to the whole population. They justify caution and further research, not a verdict.

Polyols: a laxative effect to know about

Polyols are partly poorly absorbed by the intestine. At high doses they can cause bloating and a laxative effect. European regulation takes this into account: a food containing more than 10% added polyols must carry the wording "excessive consumption may have a laxative effect". A "sugar-free" chewing gum or sweet often contains some, and the warning is easy to spot.

Phenylketonuria: the aspartame warning

Aspartame contains phenylalanine, an amino acid that people with phenylketonuria (a rare genetic disease) cannot metabolise normally and must strictly limit. This is the reason for the mandatory warning on the products concerned: "contains a source of phenylalanine" when aspartame is named in the ingredient list, "contains aspartame (source of phenylalanine)" when it is indicated only by its E number. The 40 mg/kg ADI does not apply to these people.

Sugar or sweetener: which to choose?

Sugar provides calories, intense sweeteners very few or none. On paper, the replacement therefore seems logical, but the data do not confirm that it helps control weight in the long term, as WHO and ANSES both say. For its part, WHO recommends limiting free sugars toless than 10% of daily energy(strong recommendation), or even less than 5% (conditional recommendation). High intakes of free sugars are linked to overweight and more tooth decay. For people with diabetes, the question should be settled with their healthcare team: our article ondiabetes and the low glycaemic indexgives dietary benchmarks.

Both options therefore have their limits. Sugar is a known and quantified excess. Sweeteners raise questions that remain open, but they do not cure the craving for sweetness: they maintain it. WHO stresses that reducing sugar should be done without resorting to sweeteners. To find out how much sugar is hiding in your basket, read our article onhidden sugar and salt.

What to take away in practice?

Reduce rather than replace: gradually cutting the amount of sugar in coffee, yoghurts or drinks gets the palate used to less sweetness.
Prefer waterday to day. An occasional diet drink is nothing to worry about given the admissible doses, but it should not become an everyday drink. To compare, seefruit juice vs soda.
Read the labels: look out for E950 to E969 (and sorbitol E420), the warnings about phenylalanine and the laxative effect.
Keep frequency in mind: a "zero sugar" product consumed every day weighs more than one consumed now and then.

In Yumiq, the product page shows the number of additives detected and sorts them into three groups: harmless, to watch and high risk. The Yumiq-Score penalises controversial additives assessed by EFSA and ANSES, and the Yumiq star requires the absence of high-risk additives.