Every time you pour yourself a cup of diner coffee, it may seem you have more and more options for sweeteners to put in it — yellow, blue, and pink packets of artificial sweeteners; caramel-colored raw sugar; the good old-fashioned granulated, white stuff; and, more recently, sugar alternatives like stevia and monkfruit, billed as “all natural,” healthy options.
Stevia, in particular, has gained popularity among fitness devotees and dieters thanks to its calorie count (zero) and its plant-based origins. Over the past few years, major companies like Coca-Cola and PepsiCo have caught on, releasing products that use it as a sweetener. But for all the hype, scientists say stevia falls short of the reputation it’s gained as a natural, healthy sugar alternative. We asked some experts to explain what you need to know about stevia, and some things you ought to know about sugar and all its stand-ins.
So what is stevia, anyway?
Stevia is derived from Stevia rebaudiana Bertoni, an herb native to Paraguay. It was first described in the early 20th century by an Italian botanist who saw indigenous South American tribes using the plant’s crushed leaves to sweeten teas and other drinks.
The stevia you can buy in stores today starts out as that same plant, which now goes through a multistep refinement process where it’s filtered and chemically altered, then dried and ground to create a powder. The herb, a member of the Chrysanthemum family, contains two types of glycoside compounds, stevioside and rebaudioside A, that provide the sweet taste. During this process, one or both of these compounds are extracted from the leaves by boiling them, then filtering the water through a material that traps the glycosides. An alcohol wash frees the glycosides, which can then be made into a syrup or recrystallized and ground.
Does this mean stevia is a natural sweetener?
If you consider the result “all natural,” then you should lump table sugar into that definition, too, says Nicole Avena, a professor of neuroscience at Mount Sinai School of Medicine who’s studied the effects of sweet things on the brain.
“Since stevia came on the market it’s been billed as a natural sweetener that comes from the earth,” she says. “Well, table sugar is from the earth — it starts out as sugar cane and then it’s highly processed. If you were to grow a stevia plant and chew the leaves, it tastes nothing like what you buy. So by that definition, sure, stevia is derived from nature, but so are cocaine and heroin.”
And what you’re buying is almost definitely not 100 percent stevia. The sweetener’s popularity is bolstered by the fact that it can be used as a 1:1 replacement for sugar in recipes — but that makes less sense when you consider that stevia is at least 200 times sweeter than granulated table sugar. To make it work as a substitute, and to tone down the potent sweetness, some brands mix the dried and ground stevia with a filler (or “bulking agent”) like cornstarch or maltodextrin.
Does it have side effects?
When you put something sweet in your mouth, the taste buds on your tongue recognize that sugar is present. Your body responds by secreting digestive enzymes to break down the disaccharide molecule sucrose (or table sugar) into the monosaccharide glucose. The glucose is quickly absorbed into your blood stream — this is when you get a “sugar rush” — and the hormone insulin is released to retrieve the glucose and distribute it throughout the body for use as energy.
According to registered dietician Ryan D. Andrews, author of A Guide to Plant-Based Eating, the body seems to respond differently to a calorie-free alternative like stevia.
“There’s a substantial difference,” he says. “There’s a whole physiological cascade of things that take place with sugar that doesn’t seem to happen with stevia. It doesn’t provide glucose, it doesn’t provide calories. It’s just consumed and then eliminated in the body.”
If you’re counting calories, that makes stevia a good substitute for table sugar, which contains about 20 calories per teaspoon. But your tongue isn’t the only part of your body that’s sensitive to taste, and some research indicates that sweetness alone might encourage your cells to store more fat.
Sabyasachi Sen, an associate professor of medicine and endocrinology at George Washington University, says taste receptors in the intestinal wall recognize sweetness and open up cells to absorb glucose — even when you’re using a low- or no-calorie sugar substitute. “The taste receptors in the gut are similar to those in the tongue,” Sen says. “They act like transporters that take glucose from outside the cell to inside the cell. When you eat something sweet, the receptors basically open the gates.”
Sen’s research on the effect of sucralose — commonly marketed as Splenda — on stem cells taken from human fat tissue found that the artificial sweetener actually caused an increased accumulation of fat droplets inside cells.
The accumulation of fat Sen observed was more common in cells taken from people who are already overweight, which means trying to lose weight by replacing sugar with an artificial sweetener or a zero-calorie natural alternative, like stevia, could have the opposite effect.
There’s a lot of conflicting research out there about stevia. Some studies show it has anti-inflammatory properties, or can lower blood pressure. Other, slightly more alarming studies show that in significant quantities, it might actually be able to damage our DNA.
“We’re so hyper-focused on calories,” Andrews says. “If something doesn’t have calories, we automatically think it’s this thing with no consequence. But it can have all sort of effects in the body, and they’re not necessarily benign.”
That doesn’t mean you need to panic about the stevia you’ve been stirring into your coffee. It’s still relatively new to the scene, and long-term studies could have completely different results. All we can do, Andrews says, is wait and see.
Is stevia healthier than regular sugar, though?
A lot of sweet foods aren’t bad for you because of the sugar they contain. Usually, the other ingredients are the real problem.
“If they put stevia in Twinkies, Twinkies are still going to be packed with fat and really bad for you,” Avena says. “It’s not just the sugar adding the calories. In fact, the amount of calories the sugar adds is really negligible in the wider scope. It’s not that sugar is unhealthy — in appropriate amounts, it’s fine to consume some sugar. It’s just that we eat too much of it.”
Andrews agrees, and while he uses a small amount of stevia to sweeten his morning tea (he tries to avoid table sugar mainly to prevent dental issues), he doesn’t recommend using it — or any sweetener — in excess.
“I believe that as a culture, we are looking for a way to have consumption without consequence,” he says. “We do it with a lot of things in life, but I think we’re looking to have the same enjoyment with foods and beverages without any type of negative result. A nutritious, health-promoting diet is going to be low in any sweetener. If somebody is eating a fair amount of sweet foods, no matter if they’re using sugar, aspartame, sucralose, or stevia, that’s not the ideal way of eating for general health. If you switch from eating a lot of sweet foods with sugar to a lot of sweet foods with stevia, it’s not necessarily going to be better.”
If you’re really looking for a completely “natural” way to sweeten foods, then, your best bet is to pick something unprocessed, like honey, maple syrup, or pureed fruit. But the best thing you could do for your long-term health, Avena says, is to “unsweeten your diet.”
“I don’t care what kind of sugar or sweetener or substitute or alternative you use,” she says. “You just have to use less of it.” It’s all about quantity. It’s fine to indulge in the occasional treat — and if you go for the full-sugar, full-calorie version, Andrews says, you may actually be less likely to go back for more.
“If you want a bowl of ice cream, and instead you have something that’s low fat, or made with a substitute sweetener, the first problem is you could develop a mindset of, ‘I can eat more of this,’” he says. “The other thing is it’s just not as satisfying. So just have the treat. Eat the occasional rich dessert, be satisfied, and move on.”