Sucralose, an artificial sweetener sold under the brand name Splenda, is the most popular sugar substitute on the planet[*].
Cancer risk, weight gain, altered gut bacteria — all these problems have been linked, by one source or another, to sucralose consumption.
But is Splenda as bad as it seems? This article will cover whether the world’s most popular low-calorie sweetener is keto, as well as how Splenda affects your risk of cancer, weight gain, and more.
You’ve seen Splenda at your local diner, coffee shop, and supermarket. The signature yellow sachets contain the artificial sweetener sucralose — a sugar substitute about 400 times sweeter than sucrose (table sugar)[*].
Sucralose is known as an organochlorine sweetener because it’s formed through the chlorination of sucrose. When you eat this chlorinated sugar derivative, it interacts with chemical sensors in your mouth to create a powerfully sweet taste, without the caloric load of real sugar[*].
Pure sucralose, as advertised, contains zero calories. Splenda, however, cannot claim to be calorie-free. That’s because Splenda powder also contains the bulking agents maltodextrin and dextrose (the corn-derived form of glucose). These added sweeteners account for the full caloric load of 3.75 calories per one packet of Splenda.
Because Splenda contains added sugars, this sweetening blend impacts your blood sugar levels. It’s good to know that up front, and you’ll learn more about it in a moment.
Besides its low-calorie count, Splenda is probably best known for a widespread (albeit questionable) claim: that it causes cancer.
Many people claim that artificial sweeteners increase cancer risk.
While there are legitimate reasons to avoid artificial sweeteners, increased cancer risk doesn’t seem to be one of them.
In these studies, researchers gave rats the equivalent of several hundred cans of diet soda, every day, from birth. Their research has no relevance to actual human sucralose consumption.
The current science shows that:
- Consuming artificial sweeteners (including aspartame, saccharin, and sucralose) poses little to no cancer risk[*]
- Aspartame (the sweetener used in Nutrasweet and Equal) does not increase human risk of cancer, preterm delivery, or vascular events — and appears to be safe for rodents too[*][*]
At very heavy doses (above 1.7 grams per day), artificial sweetener consumption appears to increase your relative risk of cancer by about 30%[*].
But a packet of Splenda only contains 12 milligrams of sucralose[*]. You’d need to eat 142 packets per day to boost your relative cancer risk.
Sucralose-related cancer fears are overblown. There are, however, other reasons to avoid Splenda.
Here are four legitimate reasons to leave Splenda out of your diet.
#1: Splenda Raises Blood Sugar and Insulin
In theory, sucralose passes through your system unabsorbed. However, studies in both mice and humans have shown that sucralose alters blood levels of glucose, insulin, and an insulin-releasing compound called glucagon-like-peptide 1 (GLP-1)[*].
For instance, one study on 17 obese women showed that sucralose increased glucose and insulin levels following an oral glucose test[*]. Other researchers, however, have not found these glycemic or insulinogenic effects[*].
Why this difference? Possibly because the women from the first study were not regular sucralose consumers, while the populations from the other studies were. There may be a habituation effect.
Either way, Splenda is not just sucralose, but also maltodextrin and dextrose. And eating maltodextrin and dextrose will definitely increase blood sugar and insulin levels.
It’s good to know that Splenda is not calorie-free and that it registers on the glycemic index, especially if you’re on a ketogenic diet where every gram of sugar matters.
Bottom line: Splenda will impact your blood sugar and insulin levels.
#2: Splenda May Cause Weight Gain
Splenda may also cause weight gain. Sucralose triggers a few different things that can contribute to fat storage[*]:
- Increasing the rate of intestinal glucose absorption
- Signaling beta cells in the pancreas to produce insulin
- Altering sweet taste receptors in the brain, which can affect appetite and satiety
The clinical data has gone both ways. One meta-analysis found no effect of low-calorie sweeteners on body weight[*]. Other studies have found that sugar substitutes increase appetite and cause compensatory overeating[*].
Bottom line: Splenda may cause weight gain, or it may not. But considering that there are better sweeteners out there, your best bet is to use one of them instead of Splenda.
#3: Splenda Affects Gut Bacteria
A healthy gut microbiome improves digestion, reduces inflammation, and enhances immune function[*]. Ideally, you want a diverse collection of beneficial gut bacteria living in your colon.
But Splenda may disrupt your gut bacteria and encourage pathogenic species to colonize your gut.
In one study, researchers fed rats sucralose for six months at a dose equal to the human acceptable daily intake. The results were disconcerting. Sucralose-fed rats not only had altered microbiomes but also showed signs of chronic liver inflammation[*].
In another rat study, 12 weeks of Splenda lowered levels of lactic acid bacteria and bifidobacteria (known to be beneficial) in the rodent gut[*]. Sucralose is bacteriostatic, meaning it inhibits the growth of certain bacteria[*].
Bottom line: Splenda disrupts good gut bacteria in animals, although there hasn’t yet been any human research on the topic.
#4: Cooking with Splenda is Dangerous
Many low-carb or sugar-free recipes call for Splenda, Equal, or Sweet’N Low. Putting sucralose in your keto brownie batter, however, might be a bad idea.
Sucralose breaks down at high temperatures, turning into compounds with unknown effects on human health[*].
Worse still, when you heat sucralose with glycerol (the molecule that binds fat together), the resulting reaction generates cancer-promoting compounds called chloropropanols[*].
Bottom line: Don’t use Splenda, but if you do — at least avoid cooking with it.
Sucralose and Splenda are common in diet soda and sugar-free packaged products like protein bars and candy. You can also find packets in nearly every cafe and restaurant in America. Read labels carefully.
Splenda comes in powder and dissolved tablet form. If you want pure sucralose, without the added maltodextrin and glucose, you can buy it as liquid or powder[*].
The FDA has set the acceptable daily intake for sucralose at 5 milligrams per kilogram body weight[*]. For a 150 pound person, this equates to about 28 packets of Splenda per day. Unless you’re pouring three sachets into each of your 10 cups of coffee, you’ll be under this threshold.
However, there are reasons to avoid Splenda in general, even at lower doses. Splenda:
- Can raise blood sugar and insulin levels in some individuals
- May cause weight gain
- Disrupts gut bacteria (in rats)
- Alters drug metabolism (in rats)
- Becomes toxic at high temperatures, especially if you heat it with fat
Splenda may not measurably increase cancer risk, but it certainly has physiological effects on the human body. You’re better off using another low-carb sweetener in your coffee, tea, or keto-friendly treats.
Because of their glycemic effects, all forms of sugar — sucrose, fructose, high-fructose corn syrup, honey, maple syrup, brown sugar, etc. — are not keto-friendly.
Because it contains both simple sugars and sucralose, Splenda may spike blood sugar too.
Here are two natural sweeteners that are keto:
This plant-based sweetener, derived from the Stevia rebaudiana plant, is not only tasty — it’s also been shown, in multiple studies, to lower both blood sugar and insulin levels[*]. In fact, researchers consider stevia to be a promising adjunct treatment for diabetes and metabolic syndrome[*].
- Lowers inflammation by blocking an inflammatory particle called TNFα[*]
- Decreases oxidative stress through antioxidant phenols[*]
- Improves dental health[*]
- Decreases liver peroxidation (in rats)[*]
Stevia is widely available. You can buy pure stevia in powdered, granulated, or liquid form (one brand is Truvia) — or look for stevia on the label of your favorite keto snacks, like Perfect Keto Bars.
Some people find that stevia has a bitter aftertaste. If you’re one of them, consider monk fruit extract instead.
#2: Monk Fruit
Monk fruit, used for hundreds of years in China, isn’t so different from stevia. Like stevia extract, monk fruit extract is[*]:
- Hundreds of times sweeter than sugar
- A powerful antioxidant
- Non-glycemic (no blood sugar impact)
Monk fruit is safe and has no side effects — in fact, its antioxidant effects make it quite good for you[*]. A lot of people find monk fruit to taste the most like real sugar, too.
The Takeaway: Is Splenda Keto?
Splenda probably doesn’t cause cancer, and a little Splenda here and there is likely fine.
However, Splenda does spike your blood sugar, and there are enough unknowns that you’re probably best off avoiding it — especially since there are better keto sweeteners out there.
If you want something sweet, stick to stevia and monk fruit. They’re actively good for you, with no side effects and no uncertainties when it comes to your health.