What about sweeteners?

The pressure to reduce sugar, especially in snacks and beverages is driving manufacturers to substitute sugar with sweeteners. But what are the facts? Do they benefit us? Is there a difference between natural and synthetic sweeteners?

Unfortunately the science on this is still in its infancy and there are few large scale studies to help us definitively answer these questions. However, there is mounting evidence that

1. they are not the solution

2. they may even be counter productive

3. there is no difference between artificial and natural (whatever natural actually means)

So, lets review the evidence.

• Non-caloric sweeteners do not cause an insulin response (because they are sweet but not sugar/glucose). This is was the great initial hope that they would help with reducing consumption overall and calories in particular.

• It looks like our brains do not get fooled. The brain expects a sugar rush linked to the sweet taste but when that does not happen it compensates. Alternatively, it may be that our brains dissociate the sensation of sweetness with the presence of calories. Either way we end up over-consuming.(i)

• The picture may be even more interesting: It seems that neither our brain nor our gut gets fooled, and the two are linked (see the blog on the octopus). Nobody understands this in detail, but humans and mice fed on sweeteners seem to change their gut flora, and their ability to absorb sugar appears to increase significantly. This is strange as sugar is primarily absorbed in the upper intestine and most of the gut bacteria reside in the lower intestine. (ii)

• An increasing number of studies show that people on diet drinks containing sweeteners, for example, not only do not lose weight, but end up more obese than those who drink the normal sugary syrup. (iii)

• Finally there appears to be no difference between the different high potency sweeteners, natural or artificial. Study participants in all cases simply compensated for the lack of calories by consuming more.(iv)

So in summary, if you think that sweeteners are the solution you may be barking up the wrong tree, but the momentum for the use of sweeteners is so large, that it will take some time before the evidence leads to a change in strategy.

(i) For a summary of current research see: Fowler, S.P. (2016) “Low-calorie sweetener use and energy

balance: results from experimental studies in animals, and large-scale prospective studies in humans,” Physiol Behav., 9384 (16) 30184–6.

(ii) For a recent review see, Harpaz, D. et al. (2018) “Measuring Artificial Sweeteners Toxicity Using a

Bioluminescent Bacterial Panel,” Molecules, 23 (10),2454. See also two reviews by Scientific American: here and here.

(iii) Sweeteners negatively impact the gut flora, may decrease satiety, alter glucose homeostasis, and are

associated with increased caloric consumption and weight gain. See: Pearlman, M., Obert, J., Casey, L.

(2017) “The Association Between Artificial Sweeteners and Obesity,” Curr Gastroenterol Rep., 19 (12): 64. Also see Meghan, B., Azad M. B., et al. (2017), “Nonnutritive sweeteners and cardio-metabolic health: a systematic review and meta-analysis of randomized controlled trials

and prospective cohort studies,” Canadian Medical Association Journal, 189 (28). For research on the impact of sweeteners on the gut microbiome, see: Bian, X., et al. (2017), “The artificial sweetener acesulfame potassium affects the gut microbiome and body weight gain in CD-1 mice,” PLoS One, 8, 12 (6).

(iv) There is no comprehensive study comparing different sweeteners. The hypothesis is that there are

no differences between high-potency sweeteners (e.g., sucralose, aspartame, aceK, stevia, mogroside, saccharin) as they are all used in minuscule amounts due to their high levels of sweetness (100–500 x sugar). Presumably, their impact likely comes from the gut-brain interaction. The impact from sugar alcohols (e.g., erythritol, xylitol, sorbitol, maltitol) may be different and have more of a direct effect on the gut flora, as most are consumed in larger amounts as their sweetness is similar or lower

than sugar (sucrose). Also see this clinical study (small) comparing natural and artificial sweeteners: Tey SL, Salleh NB, Henry J, Forde CG (2017). "Effects of aspartame-, monk fruit-, stevia- and sucrose-sweetened beverages on postprandial glucose, insulin and energy intake". Int J Obes (Lond). ;41(3):450-457.