Aspartame: an update on the ANSES investigation

New scientific studies have recently been published on health effects that could be attributed to aspartame or soft drinks containing sweeteners, including aspartame. In particular, these include an Italian study in mice on the link between aspartame and the incidence of certain tumours in these animals, and a Danish study on the association between the consumption of sweetened soft drinks and a risk of induced preterm delivery. As part of its continual monitoring of health issues, ANSES has made a preliminary examination of these new studies and interviewed Dr Soffritti, the principal author of the study on the effects of aspartame on mice.

1- The Italian study (1)

• this is a toxicological study reporting an increase in the incidence of cancer in male mice after administration of very high doses of aspartame incorporated in their feed throughout each animal's lifespan;
• it follows on from two previous studies on aspartame in rats, published by the same Italian team and reporting other types of tumour. As a result of certain methodological biases, these two studies were not deemed sufficiently robust to be a basis for modifying the risk assessments carried out on aspartame by the European health agencies (2),(3).

During Dr Soffritti's interview, several methodological issues were raised concerning his most recent study, which led the experts to request that complementary studies be carried out following internationally validated protocols. The points raised mainly concerned:

• the lack of reproducibility of the carcinogenic effects in mice in relation to concerning the previous studies in rats by the same team, illustrating specificities of species and sex (no incidence observed in female mice) and the difficulty of extrapolating the consequences to humans from them;
• the methodology adopted (exposure to a very high dose throughout the lifespan, until death) is not used by any other team and, in particular, does not follow the reference methodology (OECD);
• the paradoxical results obtained concerning the apparent lack of effect of aspartame exposure on the survival rate of the subject animals, despite a higher rate of tumours.

2- The Danish study (4)

• this is an epidemiological study carried out on pregnant women establishing a statistical association between the consumption of carbonated (fizzy) drinks containing sweeteners and an increased risk of preterm delivery induced as a result of a medical decision, because of or to avoid maternal or foetal complications;
• the authors mention that the results need to be confirmed by other epidemiological studies designed to establish whether or not there is any causal link (beyond the statistical association) with the consumption of sweeteners.

From a scientific perspective, this last study provides a new element in the debate on the possible health effects of sweeteners, particularly as it is based on a very large cohort (more than 60,000 pregnancies). It nevertheless requires complementary studies, as the authors themselves suggest, particularly concerning the fact that the association between sweetened soft drinks and preterm delivery is related to induced delivery (meaning that deliveries are medically induced because of foetal distress and are not natural premature births), without the mechanisms involved being clearly discussed.

Conclusion

The various assessments carried out at international (WHO), European (EFSA) and American (FDA) levels concluded that aspartame could be used safely and set an acceptable daily intake of 40 mg/kg of body weight. Questions are nonetheless often raised about the potential health effects of aspartame and sweeteners generally. Although a preliminary examination of the two new studies does not provide a sufficient basis for modifying the recommendations for consuming sweeteners, it suggests that further studies should nonetheless be undertaken to update the risk assessment for these substances, in the more general context of a reassessment of the usage practices and benefits of sweeteners. ANSES will be completing its work on the subject in the coming weeks and will publish an Opinion and recommendations for future action.

Finally, it is worth noting that the European Food Safety Authority (EFSA), responsible for assessing sweeteners for Europe, is soon to convene its panel of competent experts on the subject. With this in mind, ANSES has sent EFSA the preliminary conclusions of its analysis of these two new studies.

(1) Soffritti M. et al. Aspartame administered in feed, beginning prenatally through life span, induces cancers of the liver and lung in male Swiss Mice. Am. J. Ind. Med. 53: 1197-206, 2010
(2) AFSSA Report in 2002 and contribution by the Agency to the EFSA report of 2006
(3) Risk assessment made by EFSA in 2006 + opinions on the Soffritti studies in 2005 and 2009
(4) Halldorsson T. et al. Intake of artificially sweetened soft drinks and risk of preterm delivery: a prospective cohort study in 59,334 Danish pregnant women. Am. J. Clin. Nutr. 92: 626-33, 2010