- While there are some associations drawn from observational data between NNS and overweight/obesity, these are not seen in randomised controlled trials
- It is likely that observational associations between NNS and obesity are due to correlation not causation
- Non-nutritive sweeteners are not meaningfully associated with negative health outcomes in humans
- Further research should explore any potential effects on the human microbiome more thoroughly
- Overall, the moderate use of NNS is unlikely to be of concern for human health outcomes
The topic of artificial, or more commonly called ‘non-nutritive sweeteners’ (as many common sweeteners such as stevia leaf are ‘natural’), and health is a controversial one. Overall, there is no conclusive proof that non-nutritive sweeteners are beneficial to weight management or blood sugar control, but similarly, there is no conclusive evidence that they increase the risk for cancer, diabetes, obesity, or increase habituation to ‘sweetness’,1 claims that are commonly made in popular media.
Some observational studies have suggested an association between NNS consumption and development of metabolic diseases or obesity;2 however, while sweeteners are associated with higher body weight and metabolic disease in observational studies, randomised controlled trials demonstrate that non-nutritive sweeteners may support weight loss, particularly when used alongside behavioural support.3, 4 This suggests that the observed association between sweeteners and obesity is one of correlation, not causation.
Similarly, consumption of NNS during childhood and adolescence is associated with significant increase in BMI of around 15% (OR 1.15, 95% CI 1.06-1.25),5, 6 however, this association is unclear as the use of non-nutritive sweeteners is common amongst those with higher BMI wanting to lose weight and there might be a greater effect of ‘sweet’ sensitivity in those with existing or underlying metabolic disorders. Exposure levels to non-nutritive sweeteners may also play a role in their effects on the human body. It has been observed that lower doses of non-nutritive sweeteners are associated with reduced weight gain compared to higher doses (but this result is also unclear and lacking clinical meaningfulness). This review also found no evidence of any effect of sweeteners on overweight or obese adults or children actively trying to lose weight, and in children, a smaller increase in body mass index was observed when sweetener intake was compared with sugar.7
The effect of non-nutritive sweeteners on glucose metabolism is also unclear. Experimental animal studies show that consumption of these can induce glucose intolerance, increase food consumption and weight gain, possibly due to disturbances of the gut microbiome, inhibition of protective intestinal enzymes, and increased appetite. The evidence from human studies is more controversial. Meta-analyses have suggested that non-nutritive sweeteners have little or no effect on blood glucose control in humans,8 and the results of clinical trials are contradictory and are not comparable because of significant differences in methodology.9
While further research is needed to evaluate the effect of non-nutritive sweeteners on the gut biome (and on non-alcoholic fatty liver disease), 10 It has been suggested that they do not lead to clinically relevant changes in gastrointestinal health. In a recent review, Bryant and Mclaughlin, 11 reported that exposure to non-nutritive sweeteners “fails to replicate any of the effects on gastric motility, gut hormones or appetitive responses evoked by caloric sugars.” Likewise, the majority of animal research shows no clinically meaningful changes in gastrointestinal hormones associated with taste receptor activation by ‘sweet’ and furthermore, research demonstrates that overall, non-nutritive sweeteners are safe and with few robust and verifiable negative functional effects on the human gut having been observed.11
A question of taste?
The question of ‘taste is an interesting one…
Taste has important implications for human health because we do not exist in a vacuum and our relationship with food is determined by not only its chemical makeup, but also by taste and sensory pleasure and psychosocial associations with particular foods, tastes, textures, and other aspects of foods. Furthermore, activation of sweet taste receptors triggers physiological responses which modulate glucose homeostasis. However, non-nutritive sweeteners activate receptors but do not improve glucose homeostasis.12
Summary of potential adverse effects
from Adverse effects of the consumption of artificial sweeteners – systematic review; Bernado et al., 201613:
- Daily consumption of artificially-sweetened soft drinks by pregnant women can increase the likelihood of prematurity.
- The consumption of artificially-sweetened drinks by pregnant women may be associated with the diagnosis of asthma in their children up to the age of 7 years.
- There is no association between aspartame consumption during pregnancy, lactation or by the child and brain tumours in childhood and adulthood.
- There is no association between aspartame consumption and risk of hematopoietic cancer.
- There is no association between the consumption of sugar or other sweeteners, particularly aspartame, and the development of cancer in the digestive and reproductive systems.
- Consumption of artificial sweeteners is not associated with the development of kidney or bladder cancer in humans.
- The association between intake of artificially-sweetened drinks and type 2 diabetes is uncertain.
- There is no association between the consumption of cyclamate and male infertility.
While there are associations between artificial or non-nutritive sweeteners overall and some health outcomes (premature birth, overweight and obesity) these associations are unclear and demonstrated in observational research but not backed up by RCT evidence, which typically instead shows a benefit to weight-loss from moderate use of non-nutritive sweeteners. The results of observational studies are likely to be confounded by pre-existing or latent metabolic syndrome, and overweight/obesity, and psychosocial impactors of diet.
Overall, it seems unlikely based on the evidence that occasional and moderate use of artificially sweetened foods and beverages poses any meaningful human health risks.
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