The allegation made by Danish researchers, based on epidemiological data, that the methanol produced when the aspartame (used to sweeten low calorie beverages) is digested may increase the risk of preterm delivery (specifically medically-induced preterm delivery) does not merit consideration as it is not plausible scientifically.

Aspartame is a simple molecule, which is digested in the intestine to its component parts (aspartic acid, phenylalanine and methanol) all of which occur in foods we consume as part of a normal, healthy diet, often in much greater quantities. The amount of methanol produced from the aspartame used to sweeten a 330ml can of low calorie beverage is less than that contained in a small banana, and half the amount in a 220ml glass of tomato juice. The body treats the methanol produced during digestion of food in exactly the same way no matter what its source. The human body produces methanol as part of normal metabolism, and traces of methanol occur naturally in our blood, in our saliva, and on our breath.

Aspartame has a history of more than 25 years safe use, all around the world. The science which supports the understanding of the metabolism of aspartame and its safety, has been reviewed by regulatory authorities including the European Food Safety Authority, the United States Food and Drug Administration and the Joint Expert Committee on Food Additives of the United Nations Food and Agriculture Organisation and the World Health Organisation. All of these authorities have found aspartame to be safe, including for pregnant women.

The safety of aspartame in pregnancy is well established. Sturtevant noted in 1985² that even following doses many times the Acceptable Daily Intake (ADI), "small elevations in blood methanol following such abuse doses of aspartame did not lead to measurable increases in blood formic acid, which is the product resulting in....methanol poisoning". The author concludes that "aspartame poses no risk for use in pregnancy".

Aspartame provides the sweetness of sugar without the calories, and has been demonstrated to help people to maintain a healthy weight or to lose weight. At a time when the consequences of overweight and obesity, including in pregnancy, pose a significant challenge to public health, scare-mongering about this low calorie sweetener does the public a disservice.

References:

1. Intake of artificially sweetened soft drinks and risk of preterm delivery: a prospective cohort study of 59,334 Danish women.
Halldorsson TI et al.
AJCN - published ahead of print June 30 2010

2. Use of aspartame in pregnancy
Sturtevant FM
Int J Fertil. 1985; 30(1):85-7