Stevia vs. Splenda: Which Sugar Substitute Is Healthier?

Good news for those who are committed to reducing their sugar intake but can’t stomach the taste of unsweetened coffee: Sugar isn’t the only way to satisfy a sweet tooth. The only bad news is that the sugar substitute scene is a tad complicated. Take stevia vs. Splenda, for example—what’s the difference? And is one better for you than the other? If you want the TL;DR, look no further: Stevia is a plant-derived sweetener while Splenda is created by changing the molecular structure of sugar. While both sweeteners contain zero calories and are considered safe to consume by the U.S. Food and Drug Administration (FDA), there are some unanswered questions about the way Splenda affects the body (more on that below). Plus, stevia may be more stable in high temperatures, making it better for cooking and baking. Read on for the full scoop on these alternative sweeteners, including how to use them and which one is healthier.

Stevia is a natural sweetener that’s derived from Stevia rebaudiana, a plant native to Brazil and Paraguay. The key thing to know about the stevia plant is that it contains several intensely sweet compounds called glycosides. These compounds can be extracted from the leaves and purified through a process that involves steeping the dried leaves in water, filtering organic material out of the steeping liquid, and then isolating the glycosides to turn them into a concentrated resin. The result of this process is a popular natural sweetener that is 200 to 300 times sweeter than table sugar and contains zero calories. 

Splenda is an artificial sweetener and a popular alternative to sugar. However, unlike stevia, Splenda does not occur naturally: This additive is created through a chemical process that involves changing the molecular structure of table sugar by replacing three hydrogen-oxygen groups with chlorine atoms. What you get after this tweaking process is sucralose—the substance that’s responsible for giving Splenda (along with many other sugar-free products, such as chewing gum, soda and ice cream) its sweetness. Splenda is the brand name and the most common variety of a sucralose-based artificial sweetener.

In addition to sucralose (which is an indigestible substance), Splenda also contains dextrose and maltodextrin—two readily digestible carbohydrates that contribute a tiny number of calories to the sweetener. How many, you ask? One teaspoon of the stuff contains just 2 calories. (Note: Splenda can still be advertised as a “no-calorie” sweetener since it meets the FDA requirements for no-calorie foods, which is less than 5 calories per serving.) The calories in Splenda are ultimately negligible, however, considering how little one needs to use to accomplish the desired effect: This sweetener is 400 to 700 times sweeter than regular sugar—making it undeniably effective at giving a saccharine quality to foods and beverages.

Splenda is much sweeter than stevia

You might think of pure table sugar as existing at the top of the sweetness chart, but that’s not the case. Both Splenda and stevia are sweeter than sugar, and the former is the sweetest of all. Splenda is a whopping 700 times sweeter than sugar, while stevia is 300 times sweeter than sugar. Still, it’s safe to say that, for all intents and purposes, both these products are plenty sweet.

Stevia may be better for cooking

The plant compounds behind stevia are known to be heat-stable, meaning they aren’t altered or destroyed when subjected to high temperatures. Ostensibly, the same is said to be true of sucralose (i.e., Splenda) and that remains the official stance of the FDA. However, emerging research has contested the heat stability of sucralose—including this 2009 study and this 2015 scientific report, which conclude that the substance does indeed begin to degrade at temperatures above 247 degrees Fahrenheit, resulting in potentially harmful byproducts. Yet another study from 2013 yielded similar results, particularly when sucralose was heated in the presence of metal oxides—like the kind that naturally occur when cookware is heated. More research is needed to prove or disprove the assertion that sucralose and high-heat don’t mix, though—so for the time being there’s no formal contraindication there. Still, given the possibility that Splenda isn’t as heat-stable as was originally believed, some folks are opting to play it safe and avoid baking and cooking with the artificial sweetener. (And since there’s no question as to the safety of stevia that has been exposed to high temperatures, it’s a distinction worth noting.)

Both stevia and Splenda boast the benefit of being calorie-free sweeteners; while this might sound like a boon to weight loss goals, it may not be quite so simple. Here are some of the risks and benefits worth consideration when it comes to determining which one is healthier.

Zero-calorie sweeteners may cause weight gain

Before we look at the potential benefits of each sweetener, it's worth noting that some research has shown that zero-calorie sweeteners may actually cause you to eat more and could be linked to weight gain. Per a 2017 report published in the Canadian Medical Association Journal, “evidence from RCTs [randomized controlled trials] does not clearly support the intended benefits of nonnutritive sweeteners for weight management, and observational data suggest that routine intake of nonnutritive sweeteners may be associated with increased BMI and cardiometabolic risk.”

Both sweeteners interfere with gut bacteria

In case you missed it, the function and balance of gut flora is a pretty big deal for general health, both physical and mental. And unfortunately, there’s research to suggest that both stevia and Splenda may adversely affect healthy gut bacteria. That said, excessive sugar consumption is also widely known to create imbalances in the delicate gut microbiome, and both these sweeteners are thought to be safe in this regard, provided they are used sparingly enough that the various forms of bacteria in your gut can cope. In terms of deciding whether stevia or Splenda is better for your gut, we’ll call this one a tie.

Maltodextrin can cause spikes in blood sugar

The science suggests that neither stevia nor sucralose disrupt blood-glucose levels in the same way that sugar does. As such, both are relatively safe options for individuals who have or are at risk for developing diabetes. That said, the carbohydrates in Splenda—maltodextrin in particular—have been shown to cause spikes in blood-glucose levels. To complicate matters, many brands of stevia contain such ingredients as well. That said, the original Splenda product is guaranteed to contain maltodextrin; whereas it is possible to steer clear of these questionable stevia blends in favor of a purer product that won’t mess with your blood sugar.

Cooking with sucralose might result in toxic compounds

Again, some available studies suggest that harmful (possibly carcinogenic) byproducts are present when Splenda is heated to temperatures above roughly 250 degrees Fahrenheit; however, the science on the subject is still quite limited and most of the available research has been conducted on mice and rats. The takeaway? For now, sucralose is considered safe, but we still have a lot to learn about the way in which sucralose affects the body—particularly in terms of its potential toxicity after exposure to high-heat conditions.

Stevia and Splenda are both FDA-approved sweeteners that are generally deemed to be safe, calorie-free substitutes for sugar. Also, because they are so intensely sweet that they only need to be used in tiny amounts, stevia and Splenda are both less likely to be consumed in a way that would mess with your blood-glucose levels, when compared to regular table sugar. When choosing between the two, you may want to consider the ongoing concerns surrounding the heat-stability and toxicity of Splenda and to avoid using it in cooking or baking. As such, stevia might be the healthier choice when it comes to anything other than a hot beverage.