Studies suggest possible links between low-calorie beverages and health risks, though more research is needed
Many people think of diet sodas as healthy, low-calorie alternatives to sugary drinks. Yet a small but growing body of evidence suggests that diet sodas may have health downsides and may not even provide the benefits some people turn to them for, such as weight loss. Excess sugar intake is a problem in Western society because it contributes to obesity, diabetes, and other conditions. We know that diet beverages are becoming more popular, but we don’t have a lot of research into the effects of diet beverages on different aspects of health.
According to a 2016 study published in the Journal of the Academy of Nutrition and Dietetics, nearly half of adults and a quarter of children in the U.S. consume artificial sweeteners—and the majority do so on a daily basis. Diet drinks make up the bulk of the intake. So here is what we know so far about diet sodas and their role in health, and what you can you do to make smart beverage choices in the meantime.
Not So Heart Smart?
The strongest evidence so far links regular diet soda intake with cardiovascular conditions, such as stroke and heart attack, as well as type 2 diabetes and obesity (which are also risk factors for cardiovascular disease). For example, a recent study of about 4,400 people age 45 and older found that those who drank one or more diet sodas every day were three times more likely to have a stroke than those who didn’t. This study, however, had several limitations and didn’t prove that diet sodas themselves caused people to have strokes. Although it could be that people who drink diet sodas are in poorer health than people who don’t, these findings do jibe with previous research, and thus strike a note of caution. For example, three large studies published between 2007 and 2009 found that people who drank diet sodas regularly were more likely to develop type 2 diabetes and had between 30 and 55 percent higher risk of metabolic syndrome (a constellation of health problems that could increase the risk of type 2 diabetes, heart disease, and stroke) than those who didn’t. Two other studies from 2012 further bolstered these results: Researchers linked daily diet soda consumption to about a 45 percent higher risk of heart attack, stroke, and early death in one study of about 2,600 people.
A Cautious Interpretation
The studies linking diet sodas and cardiovascular risk are intriguing, but they still need to be repeated in more rigorous settings. For example, all of these studies relied on participants self-reporting their dietary habits, which can introduce error because people don’t always remember what they ate. Additionally, those who drink diet sodas may already be at increased risk of conditions such as diabetes or obesity because they are unhealthy to begin with. For example, someone who is overweight may have switched from regular soda to diet soda to help control an already burgeoning waistline.
And not every study has shown that diet sodas negatively affect health. For example, in 2012 researchers from the Harvard School of Public Health analyzed the drinking habits of almost 43,000 men and found that those who drank sugary drinks had a higher risk of coronary heart disease, but those who drank diet sodas did not.
Another reason scientists hesitate to say definitively that diet sodas are bad for your health is that they aren’t sure how they increase disease risk. It’s possible that artificial sweeteners may damage blood vessels—possibly explaining their link to diseases such as diabetes and stroke. It’s also possible that the artificial sweeteners commonly used in diet sodas may “trick” the brain into craving rich, high-calorie foods, leading to weight gain. They may also cause changes in hormone levels or gut bacteria, both of which play a role in weight and insulin management. For example, a study published in the journal Nature in 2014 found that artificial sweeteners altered intestinal bacteria in people and mice, increasing their risk of sugar intolerance, a condition often preceding diabetes. However, these various ideas warrant larger, more rigorous studies.
What to Do
In general, your best bet is to avoid regular and diet sodas altogether. They offer little nutritional benefit, and in some cases, diet sodas may even cause headaches. For example, shortly after the artificial sweetener aspartame came onto the market in the late 1990s, one of the biggest complaints the Food and Drug Administration received about the sweetener was regarding headaches. No scientific studies have proved that aspartame or diet sodas in general cause headaches, but a review of evidence published in The Clinical Journal of Pain in 2009 suggested that large amounts of the sweetener—such as that in five or more diet soda drinks—could trigger or make headaches worse in people who are already susceptible to migraines.
In the end, an occasional soda—with sugar or artificial sweeteners—is probably fine. But your best bet is to stick with water, plain or sparkling, as much as possible. If you find unflavored water boring, add a splash of bitters with a slice of lemon or lime. Unsweetened tea is also a great choice.