What is stevia and is it healthy?

From the desk of
Robb Wolf
ScienceWhat is stevia and is it healthy?

I get questions about stevia—the zero-calorie plant-based sweetener—all the time. Some people worry about hormone disruption, while others worry about toxicity. I’ll dig into these concerns and others later in this article. But in the spirit of getting to the point, the existing research suggests that you’d have to consume an astronomical amount of stevia for it to be dangerous.

In fact, I believe substituting sugar with stevia is a strong choice for most people. Added sugar is making people sick, obese, and metabolically unwell. And compared to sugar, stevia cultivation is much better for the environment. If you’ve read my latest book, Sacred Cow, you know this matters A LOT to me.

Stevia also has many potential benefits, including antioxidant effects, oral benefits, anti-diabetic effects, and more. This article is all about stevia: what it is, why it’s sweet, health benefits, safety concerns, and more.

What Is Stevia?

Centuries ago, the natives of South America satisfied their sweet tooth by chewing on the leaves of a local shrub. They didn’t know why the leaves of this plant tasted so good, but boy, did they enjoy them. Decades later, in 1905, Westerners named this plant stevia rebaudiana.

Stevia’s sweetness comes from compounds within the plant leaves called steviol glycosides, which are 50–400 times sweeter than table sugar. These glycosides are extracted to make the zero-calorie sweetener we call stevia. They include:

  • Stevioside
  • Rebaudioside A
  • Rebaudioside C
  • Dulcoside

Stevioside, in particular, has been researched extensively for its blood sugar-lowering properties. This may explain why stevia has a long history of treating diabetes among the natives in Paraguay and Brazil. Let’s double-click on this benefit now.

Health Benefits of Stevia

Stevia hasn’t yet earned “health-food” status like blueberries, but I am intrigued by the benefits. Here’s what the latest science has to say.

#1: Anti-diabetic effects

The chief characteristic of type 2 diabetes is high blood sugar. Stevia is certainly not a diabetes cure, but it may help control blood sugar by way of improved insulin function.

It should come as no shock that across multiple studies, stevia produces a lower post-meal insulin response than sugar. But in one 2010 study, stevia improved the post-meal insulin response even compared to aspartame, an artificial sweetener with zero calories.

The most interesting part: Stevioside stimulates insulin release from the pancreas at high blood sugar concentrations, which helps bring blood sugar back down. But when blood sugar is in normal ranges (below 150 mg/dl), stevia doesn’t appear to have the same insulin-stimulating effect. This in vitro data is supported by the clinical data I just mentioned.

For people with type 2 diabetes, this means that stevia may be a valuable tool in the blood sugar-management tool box. And for folks without blood sugar issues, it means that using stevia instead of sugar may help prevent the glycemic dysregulation and insulin resistance that may contribute to type 2 diabetes. Lastly, it is also the reason I believe stevia would NOT release insulin during a fast or disrupt fasting benefits.

#2: Antioxidant effects

Stevia is rich in plant compounds called phenols. These phenols may reduce oxidative stress, which drives aging and chronic disease. For instance, stevia-fed Wistar rats (a strain of rat bred to develop fatty liver) showed less signs of liver damage than rats fed a control diet. 

Some oxidative stress is normal. It’s part of living, breathing, and moving. But when too many reactive oxygen species (ROS) are produced, it’s bad news for disease risk. The trick is to find a balance. Don’t slam antioxidants like Kobayashi slams hot dogs, but don’t discount their potential benefits either.

#3: Anti-inflammatory effects

Tumor necrosis factor alpha (TNF-α) is an inflammatory particle that tends to reside in fat tissue. In diabetics, excess TNF-α decreases insulin sensitivity by reducing the activity of a protein called glucose transporter type 4 (GLUT4), which transports sugar into muscle and liver cells.

In mice, stevioside lowered TNF-α, reduced inflammation in fat tissue, thereby increasing insulin sensitivity. Stevioside also decreased circulating levels of interleukin 6 and interleukin 10—two cell-signaling proteins called cytokines linked to chronic inflammation.

Add improved insulin sensitivity and reduced chronic inflammation to the list of stevia’s potential health benefits.

#4: Oral health

A 6-month randomized controlled trial on school children found that stevia mouthwash had both antiplaque and antigingivitis effects. Conversely, sugar promotes the growth of cavity-causing bacteria like Streptococcus mutans.

#5: Overeating control 

Consuming stevia may decrease subsequent overeating. In a 2020 randomized controlled trial, people ate fewer calories if they drank a stevia-sweetened beverage (vs. water) beforehand.

This anti-hunger mechanism may involve the intestinal hormone glucagon-like peptide 1 (GLP-1). Stevia activates bitter taste receptors, stimulating this satiety hormone that slows gastric emptying, the process by which the contents of the stomach are moved into the small intestine. Theoretically, this could help with weight loss, but research hasn’t yet proven that.

One More Benefit: Sustainability

In Sacred Cow, I argue that eating properly raised meat is a net positive for the planet. I probably won’t sign a book deal for Sacred Stevia anytime soon (don’t tempt me!) but I do admire this sweetener’s sustainability.

For instance, stevia beats sugar when it comes to carbon footprint. Cane sugar production emits 64% more carbon-based pollution than it’d take to produce a comparable amount of stevia. Then there’s the water footprint. Cane sugar requires 95% more water to produce the same amount of sweetness as stevia.

I’m not saying that stevia will save the planet. But imagine if the entire sugar industry were replaced by stevia. The impacts would be considerable, on both the environment and our collective health.

The Safety of Stevia 

The Food and Drug Administration has conferred “generally recognized as safe” (GRAS) status to stevia. After reviewing over 200 human and animal studies, they set the Acceptable Daily Intake (ADI) for stevia extract at 4 milligrams per kilogram of body weight. The ADI is the daily dose of a substance one could consume over a lifetime without causing harm. For example, a 150-pound woman could safely consume up to 40 tabletop packets of stevia a day for the rest of her life.

The takeaway? Unless you’re set on consuming 41 packets in your daily morning coffee, reasonable doses of stevia seem to be very safe.

Is Stevia Bad for You? (Concerns and Side Effects)

Despite its well-documented safety profile, many folks have pinged me with concerns about stevia. Most of these concerns aren’t rooted in solid science, but rather a cursory glance at a headline, blog, or scientific abstract. But hey, why not investigate further? I’ll bite.

#1: Does stevia have side effects?

Some folks have emailed me asking if stevia could cause “nausea, bloating, and low blood pressure.” While there’s a small incidence of gastrointestinal side effects, it’s not significant enough to make a ripple. Unlike sugar, stevia is NOT fermented by gut bacteria. And there’s no evidence of blood pressure disruptions.

My guess is that these concerns are rooted in the nocebo effect. The nocebo effect is similar to the placebo effect, but with detriments rather than benefits. Nocebo occurs when you believe something (like stevia) will produce harm, and consequently that belief manifests as some adverse effect.

Is it possible that some folks can’t tolerate stevia? Of course! Each of our gut microbiomes are unique, and some people have more sensitive digestive systems than others. But much of this chatter strikes me as nocebo noise, which sounds like a great name for a band.

#2: Does stevia disrupt hormones?

This is the most common concern I hear about stevia. People worry that stevia affects reproductive hormones, decreases sperm count, and impairs fertility. The evidence they typically cite is as follows.

Some research suggests that in vitro sperm don’t respond well to bathing in a stevia solution. And some animal data suggest that WHOPPING doses of stevia decrease sperm concentrations or impair fertility in male and female rodents.

But 2 other studies found that when rats were fed stevia at a “very high dosage” it had no effect on sperm count and sperm production. The bottom line is that we have inconsistent animal data (with unreasonable doses) and ZERO clinical data supporting this concern. Personally, I see no cause for alarm.

#3: Does stevia alter the gut microbiome?

I’m also not losing sleep over stevia’s effects on the gut microbiome. True, researchers have found that stevia changes the composition of microbes in the gut in rodents. But the same study also showed that stevia “did not alter weight gain or glucose tolerance compared to [controls].” And when stevia was paired with a prebiotic, the combo reduced fat mass, food intake, and leaky gut—all very good things.

Let’s pause to remember that the gut microbiome is still essentially a mystery. When microbial shifts happen, we generally don’t know if they’re good or bad. And what’s beneficial for one person may be detrimental for another. A 2020 review in Nutrients concludes that “overall, stevia seems to modify the gut microbiota; however, further studies are needed to clarify its specific effects.”

If stevia caused negative shifts, I think we’d see adverse effects on metabolism, immunity, or other markers. Instead, we generally see metabolic benefits (or no effects) when humans consume stevia.

#4: Does stevia cause hypoglycemia?

As you’ll recall, stevia helps with glycemic control. When blood sugar is high, stevia stimulates insulin to bring it down. When blood sugar is low, stevia doesn’t do much.

There’s no evidence that stevia causes dangerously low blood sugar levels. In rats, a single large dose of stevioside didn’t cause hypoglycemia. And in humans, large daily doses of other glycosides didn’t disrupt glucose regulation. Let’s put this concern to bed.

#5: Does stevia dysregulate appetite?

Some people worry that eating stevia dysregulates appetite and drives cravings. But as we saw earlier, this concern doesn’t pan out in a clinical setting. Instead, stevia seems to decrease subsequent overeating.

A more plausible concern is that you’ll overeat stevia-sweetened foods themselves. I’ve been known to wolf down a whole stevia chocolate bar in one sitting, so I choose to buy them infrequently. I suggest you exercise similar restraint with stevia desserts. Be intentional with your intake.

Is Stevia Healthy?

Generally, yes. Most people tolerate stevia just fine, and many people benefit from it. But some super sensitive folks feel better when they eliminate stevia. It depends on your unique physiology, and it’s always best to listen to your body.

If you’re still concerned about stevia disrupting hormones, gut bacteria, or blood sugar, take a moment to review the science I cited above. Although I believe that most people’s fears about stevia are majoring in the minors, I fully support folks coming to their own conclusions.

I encourage you to try stevia if you crave sweetness on a low-carb, paleo, keto, or otherwise healthy diet. It’s an easy way to enjoy sweet tastes without the downsides of sugar.

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