Effect of sweeteners on human blood sugar

Researchers from Israel and other countries recently reported in a new issue of the American journal Cell that certain non-nutritive sweeteners may impair the body's ability to metabolise glucose and raise blood sugar levels.

Excessive sugar intake is strongly associated with weight gain, and the use of non-nutritive sweeteners as a substitute for sugar is a more common way to combat obesity and diabetes. These sweeteners contain no calories and therefore were once thought not to trigger changes in blood sugar levels after meals. However, this new study, which conducted controlled trials on four non-nutritive sweeteners - aspartame, saccharin, sucralose and stevia - found that this was not the case.

Researchers from the Weizmann Institute of Science in Israel and other institutions divided 120 healthy adults into six groups. Four of the groups were supplemented with aspartame, saccharin, sucralose and stevia, another group was supplemented with equal amounts of glucose and another group did not consume any additional sugar or sweeteners.

To observe the effect of these sweeteners on glycaemic control, all six groups wore blood glucose monitors for 29 consecutive days of the trial, underwent regular glucose tolerance tests and recorded all food intake and physical activity in real time via a mobile app. The researchers regularly collected oral microbiological samples and faeces from the participants to observe microbial changes in them.

The results showed that the intake of saccharin and sucralose significantly raised people's blood sugar levels and exacerbated fluctuations in the participants' body sugar levels, but this disappeared when the respective sweeteners were stopped. In the test group consuming aspartame and stevia, no significant increase in blood glucose was observed. This suggests that there are differences in the effects of different types of sweeteners on human glucose tolerance, with saccharin and sucralose reducing the body's ability to metabolise glucose and thus elevating blood glucose levels.

In addition, ingesters of these four non-nutritive sweeteners showed different changes in intestinal flora, and similar changes were seen in oral microbes, suggesting that microbes in the body are quite sensitive to these sweeteners. Further observations were made by transferring microorganisms from non-nutritive sweetener consumers to rats, which showed similar changes in blood glucose as sweetener consumers; these rats showed more pronounced fluctuations in blood glucose levels after transferring microorganisms from saccharin and sucralose consumers to rats.

The researchers concluded that some non-nutritive sweeteners are not as safe for humans or gut microbes as believed and advised people to be cautious about their intake.