No impact of maternal exposure to low/no calorie sweeteners on body weight

ISA statement in response to animal study by Nettleton et al.

Brussels, 30th January 2020: The International Sweeteners Association (ISA) responds to a new animal study by Nettleton et al.1 Contrary to the claims by Nettleton et al., the collective evidence suggests that exposure to low/no calorie sweeteners during pregnancy and lactation does not increase body weight in offspring.

Indeed, the outcomes of this animal study by Nettleton et al. are in contrast with the collective body of evidence that was reviewed recently in a systematic review and meta-analysis of animal studies by Morahan et al. and published in October 2019.2 The latter thorough review considered the totality of available studies investigating the metabolic and behavioural effects of maternal exposure to low/no calorie sweeteners during pregnancy and lactation. It pointed to the balance of evidence suggesting that maternal exposure to low/no calorie sweeteners in the diet does not increase body weight in offspring.

It is also worth putting the results of the study by Nettleton et al. into perspective. This study suggests that the effects of low/no calorie sweeteners, and especially of aspartame, on the gut microbiota played a causal role in mediating adverse body composition outcomes. However, this is neither supported by current data nor can be explained by the well-established metabolic fate of aspartame in the human body. In fact, aspartame does not even reach the colon as it is already digested and absorbed in the small intestine. Therefore, this sweetener and its metabolites do not reach the human gut microbiota; thus, any direct effect is simply not possible. No other mechanism has ever been confirmed in human or animal studies. Similarly, research investigating effects of steviol glycosides on the gut microbiota does not confirm any negative effect.

Overall, strong evidence from high-dose, long-term studies support the assertion that low/no calorie sweeteners have no adverse effect on gut function or health. Recent reviews of the published literature provide no evidence of any adverse effect of low/no calorie sweeteners on the gut microbiota at doses relevant to human use.3 Results of metabolism and safety studies further show no evidence of a likely mechanism for a clinically relevant effect on gut microbiota. Importantly also, there are large differences between the gut microbiome profile in laboratory animals and humans, so translating data from animal studies that test effects of extremely high doses of low/no calorie sweeteners is highly questionable.

Used in foods, beverages and tabletop sweeteners, low/no calorie sweeteners can provide people, including pregnant and lactating women, with a wide choice of sweet-tasting options with low or no calories, and thus can be a useful tool, when used in place of sugar and as part of a balanced diet, in helping reduce overall sugar and calorie intake, as well as in managing blood glucose levels. Low/no calorie sweeteners are also not fermentable by oral bacteria, which means that they do not contribute to tooth decay.

  1. Nettleton JE, Cho NA, Klancic T, et al. Maternal low-dose aspartame and stevia consumption with an obesogenic diet alters metabolism, gut microbiota and mesolimbic reward system in rat dams and their offspring. Gut 2020 – Published Online First: 29 January 2020. doi: 10.1136/gutjnl-2018-317505
  2. Morahan HL, Leenaars C.H.C, Boakes R.A., Rooney K.B. Metabolic and behavioural effects of prenatal exposure to non-nutritive sweeteners: A systematic review and meta-analysis of rodent models. Physiol Behav. 2019 Oct 21:112696
  3. Lobach A, Roberts A, Rowland I. Assessing the in vivo data on low/no-calorie sweeteners and the gut microbiota. Food and Chemical Toxicology 2019; 124: 385-399