More tests are needed to monitor the long-term impact of food additives on behaviour, a campaign group says.
The Hyperactive Children's Support Group (HACSG) welcomed moves by major retailers to remove additives in their own-brand products.
M&S and Asda last week plans to phase out E-numbers and aspartame from their own-label goods.
But HACSG said the trend towards substituting aspartame with sucralose was: "... continuing a pattern of replacing one sweetener with another."
It wants drinks aimed at young children to contain only water and fruit juice.
The campaign group is calling for the European Food Safety Authority to test all additives for both their toxicological impact and their long-term effect on human behaviour.
Describing sucrose, HACSG trustee Griselda Halling said: "It doesn't occur in nature. It has to be made in a laboratory.
"We believe the best drinks for small children are fruit juice and water and food additives are unsuitable."
The group welcomed "very positive progress" from retailers in reducing their use of food additives.
