Sugar-free slushees might be dangerous for young kids, research suggests

New research suggests that young children should best avoid consuming sugar-free smoothies. Scientists in the UK and Ireland reviewed the medical records of 21 children who experienced acute distress shortly after drinking smoothies containing glycerol.

Glycerol, also known as glycerin, is used in sugar-free smoothies to prevent the ice from freezing completely. Glycerol has been widely used in these regions since Ireland and the UK implemented sugar taxes in 2018 and 2019, respectively.

Of the cases studied, 20 occurred after 2018, with only one isolated case in 2009. The children ranged in age from two to nearly seven years old. The researchers' findings, published in the journal *Archives of Disease in Childhood*, indicated that in each case, the children experienced acute distress shortly after drinking the smoothie, accompanied by a range of symptoms that researchers termed glycerol-induced sickness syndrome.

These symptoms included reduced consciousness, a sudden and drastic drop in blood sugar (hypoglycemia), and a buildup of acid in the blood (metabolic acidosis). The simultaneous occurrence of these symptoms may indicate poisoning or an inherited metabolic disorder, requiring further investigation. Among the 15 children for whom the onset speed was known, 14 experienced symptoms within one hour of consumption.

Similarly, in 17 cases where consciousness status was recorded, 16 experienced "significant and abrupt reductions in consciousness," with one child even experiencing a seizure. Twenty children suffered from hypoglycemia, with 13 of them experiencing severe conditions. Other common symptoms included metabolic acidosis (16 out of 17 children), low potassium levels (12 out of 16 children), and falsely elevated lipid levels (8 out of 9 children).

All children recovered quickly after initial resuscitation and blood sugar stabilization. They were discharged with advice to avoid drinking smoothies. Twenty children followed the advice and experienced no further hypoglycemic events. However, one child, at the age of seven, drank a smoothie again and developed symptoms within an hour, rapidly progressing to vomiting and lethargy, the researchers found. The parents gave the child a glucose drink and called an ambulance. By the time paramedics arrived, the child's blood sugar had returned to normal and the symptoms had begun to subside.

The researchers believe that current recommendations in the UK and Ireland (advising children aged four and under to avoid sugar-free smoothies and children aged five to ten not to drink more than one serving) may not be sufficient. The researchers wrote, "There is poor transparency of glycerol concentrations in smoothie drinks; therefore, estimating a safe dose is not easy."

"The speed and dose of ingestion, as well as other aspects such as whether the drink is consumed with a meal or in a fasted state, or after strenuous exercise, may all be contributing factors." They suggested determining safe drinking levels based on body weight, based on the current recommendation that 125 mg of glycerol per kilogram of body weight is the lowest dose associated with negative health effects.

The researchers wrote: "Alternatively, the recommended age threshold may need to be higher (8 years) to ensure that the dose per kilogram of body weight is not exceeded, considering variations in body weight in the normal population." Sugar-free and no-added-sugar smoothies are available in Australia, as are sugary versions.