By Harvard Health Letters
For weight-conscious people who love the taste and bite of carbonation of soft drinks, the advent of sugar-free soda 60 years ago seemed a blessing: If there were no calories, you didn’t have to worry about weight gain–and the diseases that go along with obesity, like diabetes and heart disease.
“But there are growing doubts about whether diet sodas really help people lose weight and avoid diabetes,” says Dr. Anthony Komaroff, editor in chief of the Harvard Health Letter.
Links to chronic conditions
As sugar-free sodas have been widely consumed, we’ve also seen an epidemic of obesity and diabetes.
“That doesn’t mean the sugar-free sodas have caused obesity and diabetes. It could be that if sugar-free sodas had not been developed, we would have seen an even worse epidemic of obesity and diabetes,” says Dr. Komaroff. He points out, however, that several excellent studies have found that sugar-free sodas are at least as likely as sugary sodas to be linked to the development of metabolic syndrome — a condition that often precedes or accompanies diabetes.
Metabolic syndrome is a cluster of conditions that may include high blood pressure, excess belly fat, high triglycerides, low levels of “good” HDL cholesterol, or high fasting blood sugar.
Diet sodas may have other adverse effects, as well. Many artificial sweeteners may increase the brain’s desire for sugar.
“They are so sweet, compared to sugar, that they stimulate a desire for sugar more than sugar does,” says Dr. Komaroff. “In other words, that calorie-free soda may lead you to crave those cookies.” Even the soda container may pose problems. Many cans are lined with a substance called bisphenol A (BPA). Several studies have found that people with higher levels of BPA in their body are more likely to have high blood pressure and heart trouble.
The latest evidence
The most recent cautionary note is from a study published in October 2014 in the prestigious scientific journal Nature. The study examined the bacteria that live in the intestines of all humans (and other animals). Gut bacteria help break down carbohydrates in food into simple sugars. It’s these simple sugars that get into the bloodstream and that add calories and weight.
After mice were given artificial sweeteners — saccharine, sucralose, and aspartame — the bacteria in their intestines changed: there were greater numbers of the type that efficiently break down carbohydrates.
“While the artificial sweeteners themselves contained no calories, they changed the bacteria in the gut in a way that led to more calories being absorbed,” explains Dr. Komaroff. In addition, mice fed the artificial sweeteners were more likely to develop high blood sugar than mice fed sugar. Several experiments showed that this increase was due to the changes in gut bacteria caused by artificial sweeteners.
What about humans? Seven healthy human volunteers in the Nature study who did not normally consume artificial sweeteners were started on a diet that included sweeteners. Within a week, four of the seven had developed changes in their gut bacteria, and higher blood sugar.
What you should do
These studies do not prove that sugar-free sodas carry health risks. Indeed, other studies have not found such risks. But a lot of people drink sugar-free sodas, so this could be important. Until the evidence is clearer, consider alternatives to all soda.
Looking for an alternative to diet sodas, but still want something low-calorie? Consider these options:
SWEET: Add frozen fruit to ice water, such as strawberries, blueberries, or pineapple, or use the juice from a slice of orange to sweeten sparkling water.
ROBUST: Drink unsweetened coffee over ice.
FLAVORFUL: Try herbal teas over ice. They come in many flavors and varieties, such as pear or raspberry.
REFRESHING: Add a few fresh mint or peppermint leaves to ice water.
POWERFUL: Drink vegetable juice blends, such as tomato, cucumber, and celery. Watch out for sodium in prepackaged vegetable juice. Make your own using a blender or juicer.
SPICY: Add a few drops of honey to hot water, then sprinkle a dash of your favorite spice, such as cinnamon or cayenne pepper, then pour over ice. Using more spices will give you extra phytonutrients. These have been linked to reductions in cancer, diabetes, and other chronic conditions.
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