Whether you’re just wanting to lose a few pounds, get your blood glucose levels down, or you’ve embarked on a New You Lifestyle Overhaul, we’ve all played around with ways to have our sweets without suffering the consequences at one time or another. The food industry has been there to answer that desire with “diet” artificially sweetened drinks of all kinds and we are taking them up on it. According to the Calorie Control Council, American adults consuming sugar-free foods and drinks increased from 78 million in 1986 to 187 million in 2010. Diet sodas are the most popular sugar-free products, followed by non-carbonated drinks, gum, and sugar substitutes, according to the organization.
And yet… Obesity and its complication Type 2 Diabetes are on the rise too. So scientists have been asking what the connection is, if any. And fortunately, when scientists have questions, they do studies…
Could diet sodas, with essentially no carbohydrates and no calories, raise blood glucose and weight? Or is the whole thing an illusion in the data?
Four studies in the last decade have investigated concerns about diet soda and blood sugar and weight gain.
** WARNING: SCIENCE CONTENT! **
In 2005, University of Texas researchers reported that people who drank diet soda were more likely to gain weight than people drinking regular soda.
In 2006, scientists at Dartmouth found that people with diabetes who drank one or more cans of diet soda daily had A1C levels on average 0.7% higher than those who didn’t.
In 2007, the American Heart Association found that those who drank either regular or diet soda were at a higher risk of “metabolic syndrome,” including diabetes, high blood pressure, high levels of LDL (“bad”) cholesterol, and obesity, as compared to people who drank no soda at all.
In the January 16, 2009 issue of Diabetes Care, a group of analysts reviewing the Multi-Ethnic Study of Atherosclerosis found that “Daily consumption of diet soda was associated with… a 67% greater relative risk of… Type 2 diabetes compared to non-consumption.” The study reported that increased diabetes was not caused by an increase in weight, although weight did also increase.
You can also find tons of anecdotes on people who say they lost weight after quitting diet soda habits, but that of course, isn’t scientifically studied.
So, what is actually happening? Are people who buy diet soda doing so because they are already overweight and therefore already at higher risk for diabetes and weight-related complications?
Or maybe artificial sweeteners confuse the body about how much energy it is taking in, tricking the liver into thinking glucose levels are low, causing it to release sugar to keep us from going low, which raises blood sugar levels and consequently, insulin levels?
Most artificial sweeteners are much sweeter-tasting than sugar so perhaps in comparison to them, “real” food doesn’t taste sweet, so we tend to eat more to meet the caloric needs our inaccurate “readings” are giving us.
Additionally, some sweeteners used for diet drinks can also lead to or aggravate other health problems. Diabetes Self-Management has a long article on that here.
More recent research, done in 2014, actually suggests that artificial sweeteners could raise your blood sugar levels more than plain old sugar-sweetened sodas and desserts, not because of existing lifestyle choices, or chemical to brain chicanery, but because of the effects that artificial sweeteners have on your gut bacteria.
Recently, there has been a trend of scientists looking far more closely at the link between gut microorganisms and health.
Eran Elinav, MD and a collaborator, Eran Segal, PhD, published their team’s findings in the journal Nature. Both scientists are on the faculty of the Weizmann Institute of Science in Israel.
“Initially, we were surprised by the results, which is why we also repeated them multiple times,” Segal said.
Their study — done with mice and humans — found that saccharin (Sweet‘N Low), sucralose (Splenda) and aspartame (NutraSweet and Equal) raised blood sugar levels by dramatically changing the gut microorganisms, mainly bacteria, in the intestines that help with nutrition and the immune system. There are trillions of them — many times more than the cells of the entire body — and they account for roughly 4 pounds of your body weight.
Industry groups (predictably) said the small number of mice and people studied make the findings hard to apply to larger populations, and this is somewhat true, as larger sample studies would yield more data and findings. But you can hardly throw out the findings of a small study simply because it is small — time to move on to larger groups.
Segal and Elinav added artificial sweeteners (a daily amount equivalent to what humans get in about four cans of diet soda) to the drinking water of their mice and found that their blood sugar levels became higher than those of mice who drank straight up sugar water — this was consistent whether the animals were on a normal diet or a high-fat diet.
Although saccharin, sucralose, and aspartame are three different compounds, “the effects were quite similar to each other,” Segal said. More research would be needed to see whether other sweeteners, such as stevia, can also change the collection of microorganisms in the gut.
When the sweetener-fed mice were given antibiotics to clear their gut of bacteria, their blood sugar levels dropped back to normal.
But maybe the effect was only on mice? No. The scientists also studied nearly 400 people and found the gut bacteria of those who consumed artificial sweeteners were different from those who did not. People who used artificial sweeteners also tended to have higher fasting blood sugar levels and a forerunner of type 2 diabetes called impaired blood-sugar tolerance.
Finally, the researchers recruited seven volunteers, five men and two women, who didn’t usually consume artificial sweeteners and tracked their blood sugar levels for a week. The volunteers were given the FDA’s maximum acceptable daily intake of saccharin from day two through day seven. At the end of the week, blood sugar levels had risen in four of the seven people. Analysis of feces from people whose blood sugar rose provided evidence that the artificial sweetener had changed their gut bacteria.
“It’s small,” Obin said of the seven-person study, “but it’s very, very profound.”
Obin said the new research might provide an explanation for mixed findings in previous studies. Just as in the people studied, drinking artificial sweeteners did not affect blood sugar levels in all of the mice. Every person and animal has a unique configuration of gut bacteria and some of them were not adversely affected by the artificial sweeteners — diet, genetics, health status, and sex all contribute to these differences. “Perhaps not all of the (individual) microbial compositions would indeed be susceptible to the action of the sweeteners,” Segal said.
While it would be best for your health to stop drinking sodas altogether, as long as you aren’t Type 1 Diabetic small servings of sugary, non-diet soda is probably safer than artificially sweetened ones. I will be sticking to iced tea, sparkling water, or fruit juice diluted with water.
And my daily dose of Paula’s Purple Rice, of course :).