Numerous studies have reported weight loss by substituting aspartame-sweetened products in place of sucrose-sweetened products, but an overall review of the data has been lacking from the scientific literature.
"It is now the done thing to do systematic reviews for ingredients and compounds, and this has not been before for aspartame," co-author Margaret Ashwell from Ashwell Associates, an independent scientific consultancy, told FoodNavigator.com.
After saccharin, aspartame is the second most used artificial sweetener in the world. In terms of world consumption, the artificial sweetener represents 62 per cent of the value of the intense sweetener market.
"Strategies to reverse the upward trend in obesity rates need to focus on both reducing energy intake and increasing energy expenditure," explained lead author Anne de la Hunty, also from Ashwell Associates. "The use of intense sweeteners as a substitute for sucrose potentially offers one way of helping people to reduce the energy density of their diet without any loss of palatability."
Aspartame is found in about 6,000 products worldwide, including carbonated and powdered soft drinks, hot chocolate, chewing gum, candy, desserts, yogurt, tabletop sweeteners, and some pharmaceutical products, such as vitamins and sugar-free cough drops.
The reviewers pooled 16 randomised controlled trials with healthy adults. Fifteen of these 16 trials had energy intake as an outcome measure. The studies that used aspartame-sweetened soft drinks were equivalent to about two to six servings every day.
"Given the weighted average study length was 12 weeks, this gives an estimated rate of weight loss of around 0.2 kg/week for a 75-kg adult," reported the reviewers in the current issue of Nutrition Bulletin (Vol. 31, pp. 115).
Some energy compensation was reported by the trials, but only for about one third of the energy replaced, said the reviewers, and this could even be less when the aspartame is delivered from soft drinks. This means that the subjects still had a significant energy deficit compared to the sucrose-sweetened equivalent.
"This review has shown that using foods and drinks sweetened with aspartame instead of those sweetened with sucrose is an effective way to maintain and lose weight without reducing the palatability of the diet," wrote de la Hunty.
"The decrease in energy intakes and the rate of weight loss that can reasonably be achieved is low but meaningful and, on a population basis, more than sufficient to counteract the current average rate of weight gain of around 0.007 kg/week," she said.
The result is not so surprising, said Ashwell, since the laws of thermodynamics dictate that reduced-energy foods should lead to weight control or loss.
Ashwell told this website that she did not think any more questions or gaps existed for the sweetener. Doubts about the safety of aspartame were refuted earlier this year by the European Food Safety Authority (EFSA), who concluded: "there is no need to further review the safety of aspartame nor to revise the previously established Acceptable Daily Intake (ADI)".
The current ADI for aspartame is 40 mg/kg body weight. Current average intakes of aspartame in Europe, including levels up to 10 mg/kg body weight per day, are well below the ADI, say EFSA.
The EFSA review was sparked off last year after researchers at Ramazzini Foundation's cancer research centre in Italy caused a stir by claiming that their study indicated that aspartame consumption by rats leads to increase in lymphomas and leukaemias in females at dose levels "very near those to which humans can be exposed".
This report received "amazing publicity for an animal study," said Ashwell. Not only has the safety of the sweetener been reviewed and concluded safe by EFSA, but the Ramazzini study has since been slammed by world class toxicolgists, said Ashwell.