The scientific literature is full of conflicting articles showing that people who take artificial sweeteners are either more likely or not more likely to gain weight and to be at increased risk for diabetes. Current research is focusing on whether artificial sweeteners may affect gut bacteria in ways that change how food is digested and absorbed.
Studies in Mice So far, the most dependable studies on the subject are those where mice have been fed artificial sweeteners and tracked to see if they gain weight or develop diabetes. In one study, artificial sweeteners changed the types of bacteria in the guts of mice to those that increase absorption of calories and cause higher rises in blood sugar levels (Obstetrical & Gynecological Survey, January 2015;70(1):31–32).
In another study, artificial sweeteners caused mice to absorb more calories from their food that led to weight gain and higher rises in blood sugar levels, which can lead to diabetes (Nature, October 9, 2014;514:181–186). In this study,
• Giving certain antibiotics to the mice with high blood sugar and weight gain changed back the bacteria in their colons so they stopped gaining weight and blood sugar levels returned to normal.
• Transferring the bacteria-laden stool of mice with artificial-sweetener-induced high blood sugar levels to bacteria-free mice who had never been given artificial sweeteners and who had normal blood sugar levels, caused them to develop high blood sugar levels.
• Stool of mice that had never had artificial sweeteners was incubated on growth plates with artificial sweeteners and then was given to bacteria-free mice who had never been given artificial sweeteners. This caused the mice to develop high blood sugar levels.
Studies in Humans Humans lack the ability to break down most artificial sweeteners, so they are not absorbed in the upper intestinal tract and pass to the colon where bacteria can ferment them. Since your intestinal bacteria eat the same foods that you do, what you eat determines which types of bacteria grow in your colon (Science, Oct 7, 2011;334(6052):105-8). The studies on mice discussed above showed that giving saccharin, sucralose, or aspartame can cause growth of gut bacteria that lead to weight gain and higher rises in blood sugar.
While researchers have not proven that artificial sweeteners can cause weight gain or diabetes in humans, the evidence is mounting. One study showed that artificial sweeteners changed colon bacteria in humans in just a week (Nature, Sep 17, 2014). The authors took people who did not use artificial sweeteners and fed them artificial sweeteners regularly for one week. Some of the subjects had their blood sugar levels rise and their gut bacteria changed from the types associated with low blood sugar levels to those associated with high blood sugar levels.
Researchers followed 6,814 Americans, ages 45 to 84, for five years and found that those who drank diet soda at least once a day were 67 percent more likely to develop diabetes and 36 percent more likely to develop pre-diabetes, even if they did not gain weight (Diabetes Care, 2009 Apr; 32(4): 688–694).
Almost 80,000 women aged 50-69 were followed for one year, and those who used artificial sweeteners gained more weight (Yale Journal of Biology and Medicine, June 8 2010).
In another study, the more artificial sweetener a person ingested, the greater the increase in waist circumference, a known indicator of diabetes (Journal of the American Geriatrics Society, Mar 17, 2015;63(4)). Further studies have shown that people who use artificial sweeteners are more likely to:
• be diabetic (J. Nature, Oct 4, 2012;490(7418):55-60),
• have changes in their gut bacteria associated with being fatter (Nature, Dec 21, 2006;444(7122):1022-3), and
• have higher blood sugar levels (Nature, 2013 Jun 6;498(7452):99-103).
However, the literature is confusing. Several studies show that artificial sweeteners do not raise blood sugar or insulin levels, but sucralose can raise blood sugar and insulin levels (Diabetes Care, Sept 2013;36(9):2530-5), aspartame can raise blood sugar levels (Appetite, Aug 2010;55(1):37-43), and saccharin can raise blood insulin levels (Appetite, Nov 2008;51(3):622-7).
In addition to the possible effects on gut bacteria, it appears that sweetness from any source may affect the way that your brain tells you when to stop eating. Anything that leaves a sweet taste in your mouth may encourage you to take in more calories.
Artificial Sweeteners Timeline Saccharin was first used widely in 1917 when sugar was rationed during World War I, but it wasn't until the 1940s and the sugar rationing of World War II that saccharin use increased markedly. Then an unfounded scare about saccharin causing cancer in the 1960s reduced its use. Aspartame was discovered in 1965, but it was not used on a large scale until 1981. In 1967, acesulfame was discovered. It was approved by the FDA in 1992 and by 1998 was used extensively in many sugarless and even sugared soft drinks.
So far, the FDA has approved six artificial sweeteners:
• Aspartame (Equal®, NutraSweet®, others) - 180 times sweeter than sugar
• Acesulfame-K (Sunett®, Sweet One®) - 200 times sweeter than sugar
• Saccharin (Sweet’N Low®, Necta Sweet®, others) - 300 times sweeter than sugar
• Sucralose (Splenda®) - 600 times sweeter than sugar
• Neotame - 7,000 to 13,000 times sweeter than sugar
• Advantame - 20,000 times sweeter than sugar
Stevia, 300 times sweeter than sugar, comes from the leaves of a plant and has not yet been evaluated by the FDA. I know of no long-term studies of the health effects of stevia.
Erythritol, sorbitol and xylitol are sugar alcohols, a class of compounds that have been used for decades to sweeten chewing gum, candy, fruit spreads, toothpaste, cough syrup, and other products. They appear to be safe, but do not eat large quantities of foods with sugar alcohols at one time because they can cause horrendous intestinal gas.
My Recommendations It is fairly well established that sugared drinks and sugar-added foods can increase weight gain and risk of diabetes. It has been suggested, but not proven, that artificial sweeteners also contribute in some way to weight gain and diabetes. Until cause-and-effect is established, I recommend using any type of sweetened foods or drinks only occasionally, not as a regular habit. Quench your thirst with plain water or unsweetened beverages such as tea or coffee.
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