Artificial sweeteners: more controversy

splendaUse of artificial sweeteners has grown for the past 40-50 years, right along with the obesity epidemic.  Coincidence?  Flimsier evidence has been used to blame obesity on other foods, like high fructose corn syrup or fast food.  So why are artificial sweeteners above reproach?

One good reason: they have no calories.  And as we all know, obesity is caused by too many calories.  But what if the metabolic roots of obesity are more complicated than that?  Recent studies on artificial sweeteners suggest that it’s not just the calories; it’s the sweet taste.  When sweet taste is perceived by taste buds, the metabolism gets ready for carbohydrate calories.  Insulin goes up.  But if no calories are absorbed because the sweet taste was from artificial sweeteners, the insulin has nothing to do.  Stimulate insulin like that over and over, throughout everyday, and insulin resistance could develop.  At least that’s how the thinking goes.

Most studies on the metabolic effects of artificial sweeteners are done on animals, and done in a sort of food vacuum.  Give sugar or give an artificial sweetener in water and see what happens.  But as Dr. M Yanina Pepino, the author of a new study, notes “in real life, people rarely consume a sweetener by itself.”  Sweeteners are eaten along with food, and high insulin levels could impact how the calories from that food are handled.

The study, done at the University of Washington, used 17 severely obese subjects.  They were given plain water or sucralose mixed in water, and then 2 hours later drink a glucose solution.  The aim was to see whether the artificial sweetener affect glucose metabolism.  The sucralose test resulted in higher glucose peaks and higher insulin after the glucose drink compared to plain water.  In other worse, even though sucralose has no calories, it impacted metabolism as if it did have calories.

Why is high insulin bad?  Insulin rises in reaction to rising blood glucose.  Insulin pushes glucose out of blood and into cells.  If that glucose isn’t burned for energy, it’s stored as fat.  Chronic over-production of insulin can lead to insulin-insensitivity,  linked to metabolic syndrome.  Your body may shift to calorie storing rather than calorie burning.  Ironically weight loss can become more difficult, even though you’re controlling calories with fake sweeteners.

Dr. Perino concludes that more research is needed to investigate the effects of chronic consumption of artificial sweeteners in the real world, where people eat fake sweeteners along with other foods and beverages.  Investigating the effects in people who are less obese, or normal weight would be helpful, and comparing the effects of different artificial sweeteners would be very important.

Should you give up artificial sweeteners?  If you’re normal weight and drink an occasional diet soft drink, these products probably aren’t causing you problems.  If you’re obese and you consume many artificially sweetened foods and beverages everyday in an endless struggle to lose weight, you might want to rethink that strategy.  In a healthy balanced diet of simple whole foods, there’s little room for processed junk food that contains artificial sweeteners anyway.

photo: DaveCrosby via Flickr

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