Sweeteners such as aspartame are often added to diet sodas Kazitafahnizeer/Shutterstock
Two reports on the sweetener aspartame came out this week, noting that some research has linked its consumption to liver cancer. This comes after the World 午夜福利1000集合 Organization (WHO) advised most people to avoid most kinds of 鈥渘on-sugar sweeteners鈥, after a 2022聽聽found they don鈥檛 help with weight control long term and may cause diabetes, heart attacks and death.
Which sweeteners are the concern?
In May, the WHO said most sweeteners are problematic, both artificial ones, such as aspartame and saccharin, as well as ones made from plants, such as stevia. The exception is sweeteners made from sugar alcohols called polyols, which don鈥檛 fall under the 鈥渘on-sugar sweeteners鈥 umbrella and weren鈥檛 included in the review.
Does aspartame carry any extra risk?
Two separate international bodies this week issued reports on the long-used sweetener aspartame and they are seemingly somewhat contradictory. The WHO鈥檚 International Agency for Research on Cancer (IARC) has classified the substance as 鈥減ossibly carcinogenic鈥, which sounds alarming, but actually means there is limited 鈥 and not convincing 鈥 evidence that it could be a cause of liver cancer.
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A separate report, there was no reason to change its existing recommendations on aspartame consumption. This advice says it is safe for people to have up to 40 milligrams of aspartame per kilogram of their body weight, which would be up to 14 cans of diet soft drinks a day for someone who weighs 70 kilograms.
鈥淭he findings of limited evidence of carcinogenicity in humans and animals, and of limited mechanistic evidence on how carcinogenicity may occur, underscore the need for more research to refine our understanding on whether consumption of aspartame poses a carcinogenic hazard,鈥 said at the IARC Monographs programme .
Would it be safer to avoid all sweeteners altogether?
The idea is that food and drinks with sweeteners help people reduce their sugar intake, as too much sugar is linked with higher weight, type 2 diabetes and heart disease. The trouble is that the evidence supporting this is mixed. Some short, randomised trials have found that consuming drinks with sweeteners instead of the full-sugar versions can聽, but others have failed to show a benefit.
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Population studies tend to show that sweetener consumption correlates with higher rates of diabetes and heart disease, but this could be because people are more likely to use sweeteners if they are heavier to start with, says聽聽at Aston University in Birmingham, UK. The WHO says: 鈥淭he available evidence suggests that聽use of non-sugar sweeteners does not confer any long-term benefit in reducing body fat.鈥
What about managing diabetes?
The WHO said its broad recommendations in May don鈥檛 apply to people who already have diabetes, because making recommendations for this group was outside the scope of the review and studies in people with diabetes weren鈥檛 included. That said, people with type 2 diabetes, where blood sugar can get too high, generally need to limit the amount of sugar they eat.
Are there any other concerns over sweeteners?
Some research has suggested unexpected harms from specific kinds of sweeteners, generally from small studies in people or those involving animals. For instance, last year, it was found that聽saccharin and sucralose may raise blood sugar levels. This year, preliminary evidence emerged that a聽common polyol sweetener called erythritol聽could promote blood clots, although the polyols weren鈥檛 included in the WHO鈥檚 review anyway.
Findings such as these contradict initial assumptions that sweeteners are biologically inert. Nevertheless, current official health advice in most countries says people should choose artificial sweeteners over sugar.
So, do others agree we should ditch sweeteners?
It鈥檚 complicated. Researchers say聽, despite the WHO advising against them. 鈥淭he recommendation could have been a bit more nuanced in acknowledging the potential utility of non-sugar sweeteners to support short-term weight loss when used judiciously,鈥 says聽聽at The George Washington University in Washington DC.
You also may find it difficult to avoid sweeteners, as many foods and drinks now contain them without necessarily being marketed as diet products. This is especially true in countries such as the UK, South Africa and Portugal where 鈥渟ugar taxes鈥 have nudged drink manufacturers into using more sweeteners. But that isn鈥檛 necessarily a bad thing, says Mellor. 鈥淚f you鈥檙e going to consume a soft drink, it鈥檚 better to switch to one with less sugar and more sweeteners,鈥 he says. 鈥淏ut the perfect solution is going for water.鈥
What happens now?
Countries aren鈥檛 obliged to follow WHO recommendations, but its reports may carry weight when national policies are being set. Because of the uncertainties in the evidence, the WHO says these recommendations are 鈥渃onditional鈥, meaning that they may need to be implemented differently by different countries. Some nations may just ignore the WHO guidelines, says聽聽at King鈥檚 College London. 鈥淚t鈥檚 going to cause some ructions.鈥
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