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| Should you freak out about a small increase in body weight in a small-scale rodent study that is attributed to the consumption of saccharin in yogurt? |
Rather than weight increases controlled human studies show that the consumption of artificially sweetened foods promote, not hinder the loss of body fat (Sørensen. 2014).
You can learn more about sweeteners at the SuppVersity
Aspartame & Your Microbiome - Not a Problem?
Will Artificial Sweeteners Spike Insulin?
Sweeteners & the Gut Microbiome Each is Diff.
Chronic Sweeten-er Intake Won't Effect Microbiome
Stevia, the Healthy Sweetener?
Sweeteners In- crease Sweet- ness Threshold
And with respect to the often-cited "evidence" from animal and observational studies, the autors of the meta-analysis submit that..."that the balance of evidence indicates that use of LES [low or no energy sweeteners] in place of sugar, in children and adults, leads to reduced EI and BW, and possibly also when compared with water" (Rogers. 2015 | my emphasis).
Figure 1: The forest plots of the practically most relevant data of individual and combined effect sizes for sustained intervention studies comparing the effects on body weight of sweeteners versus sugar (upper panel) and versus water (lower panel) shows that not a single long(er) term study found negative effects - the exact opposite is the case. Even compared to water the use of low-energy sweeteners (artificial or not) lead to measurable, yet not always significant decreases in body weight in human trials (Rogers. 2015).
"[...] the present review of a large and systematically identified body of evidence from human intervention studies, with varying designs, settings and populations (including children and adults, males and females, and lean, overweight and obese groups), provide no support for that view. The question then is whether those hypotheses should be rejected or whether, as seems unlikely, the relevant human intervention studies are consistently flawed in a way that leads, in most cases, to exactly the opposite outcome" (Rogers. 2015)I do thus want to warn you: Do not overrate the already relatively small amount of extra-weight the rodents in saccharin group of Foletto's recent study gained (see Figure 2, left).
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| Figure 2: Cumulative weight gain and total cumulative energy intake of (only) 16 male Wistar reds fed diets that were supplemented with either saccharin-sweetened or non-sweetened yogurt added (Foletto. 2015) |
Was it fat they gained or lean tissue mass? Well, I would like to answer these important questions, but Foletto did not disclose (or not even measure?) this important parameter. The practical relevance and reliability of their results is further reduced due to the small cages (44x34x16 cm individual cages) into which the rodents were confined to reduce their voluntary physical activity during the 14 weeks of the experiment, as well as the exclusion of rats who didn't consume the aspired 70% of the planned 75 kcal in form of yogurt per week (the number of rats who fell into this category is also not disclosed).
To this ends, the researchers randomly assigned 16 male Wistar rats to receive ~78kcal per week from either saccharin-sweetened (0.3% saccharin) yogurt or non- sweetened yogurt (0.5 kcal/g) in addition to chow (2.93 kcal/g) and water ad lib. For 14 weeks, Foletto, et al. measured the total food intake (from yogurt and chow) daily and the weight gain on a weekly basis (the results are plotted in Figure 2). Fasting leptin, glucose, insulin, PYY and HOMA-IR levels were measured only at the end of the 14-week study period, though. |
| Table 1: In view of the fact that any existing negative effects of dietary sweeteners may well be compound-specific. It is certainly worth noting that saccharin is no longer used in modern sweetener formulations of sodas (Wikipedia. 2015) |
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| Measurable weight increases are a common pattern in rodent studies particularly for the (today rarely used) artificial sweetener saccharin. It is thus well possible that any existing negative effects are compound-specific. For aspartame, for example, similar evidence is rare to non-existent. |
Furthermore, more relevant evidence from human clinical trials supports the use of artificially sweetened foods as dieting aids (Sørensen. 2014 | learn more).
Whether that's enough to convince you that the unproven negative effects of saccharin on caloric expenditure or increases in the glucose transport mediated by gut sweet-receptors, of which Foletto et al. speculate that they may explain the results of their study, are relevant enough to avoid non-nutritive sweeteners altogether is now up to you. For me it's not enough... | Comment on Facebook!
- Foletto, Kelly Carraro, et al. "Sweet taste of saccharin induces weight gain without increasing caloric intake, not related to insulin-resistance in Wistar rats." Appetite (2015).
- Rogers, P. J., et al. "Does low-energy sweetener consumption affect energy intake and body weight? A systematic review, including meta-analyses, of the evidence from human and animal studies." International Journal of Obesity (2015).
- Sørensen, Lone B., et al. "Sucrose compared with artificial sweeteners: a clinical intervention study of effects on energy intake, appetite, and energy expenditure after 10 wk of supplementation in overweight subjects." The American journal of clinical nutrition (2014): ajcn-081554.