Stevia: Natural or Artificial?

Close your eyes, and imagine yourself outside on a hot summer day, drinking a cold, zero-calorie, all-natural, healthy Coke that tastes just like the real thing without any of the guilt.  You can pinch yourself now because unfortunately, that magical Coke is still just a fantasy.  As the case against sugar consumption continues to build, food manufacturers are still hunting for the ultimate substitute to replace sugar in the foods we love.  A handful of sugar substitutes are available, but each has their own weakness, whether it’s taste, stability or health concerns.  Since being “generally regarded as safe” (GRAS) by the FDA as a food additive a decade ago, Stevia (Truvia®) has been marketed as a natural product superior to other sugar substitutes precisely because it’s natural and calorie-free.  Pressure from consumers for natural food options has companies scrambling to develop foods that are both all-natural and healthy.  But what does the word “natural” mean in an age of scientific and technological progress? The definition isn’t as clear-cut as one may think.

A Little About Sugar

When most people think about sugar they imagine sucrose, the fancy term for table sugar.  Sucrose forms when the two simple sugars fructose and glucose get together and hold hands at an ester bond, and it’s found naturally in fruits and vegetables.  Sugarcane stems and sugar beet roots are especially high in sucrose which is why they are the primary crops harvested to make table sugar.  It’s a nifty little process; basically, the juice is extracted then purified using limewater and carbonation, heated to form a syrup, and then some sugar crystals are tossed inside (called seeding) to promote crystallization.  The result is the raw brown sugar with a slight molasses flavor found in Sugar in the Raw packets at your local coffee shop.  To get from this to table sugar, it undergoes another round of purification, ion-exchange to remove the brown color, more seeding to crystallize the white sugar, and voilà, you have white table sugar.

Sugar has become ubiquitous in food and can be present in amounts that might scare you if you look closely at nutrition labels.  For decades fat was the enemy, causing U.S. sugar consumption to increase steadily until 2000 when it began to slowly decline.  Now we’re learning that eating too much sugar may not be good for us either.  Sugar is a carbohydrate that provides us with energy in the form of calories (4 kcal/g to be exact), but not much else.  We need food calories to survive, but there plenty of options much healthier than sugar.  To date, there is no evidence in humans to indicate any direct negative health effects of sugar.  And it seems the sugar industry would like to keep it that way.  Regardless, more recommendations continue to be released providing guidelines for sugar consumption.

Ideally, we replace sugar in foods altogether, but sugar is a tough act to follow.  Adding sugar to food enhances flavor, improves texture, maintains moisture and allows browning.  A worthy substitute needs to have similar taste and level of sweetness, no aftertaste, similar onset and decline of sweetness, heat tolerance, stability, and affordability.  As if that wasn’t enough, it has to be “natural,” calorie-free and safe so we can eat sweets without the guilt.  Let’s take a quick look at some of the options to see how they stand up to the challenge.

Natural Substitutes

Products like honey, maple syrup, agave, date sugar and molasses can all serve as sugar substitutes. They are all considered natural and they all taste good.  Some of them, like honey, may even have additional health benefits.  Ultimately they are all just different forms of the same sugars found in table sugar, and there isn’t solid evidence that one is any healthier than the others.

High fructose corn syrup (HFCS) also technically falls under this category.  Corn is the starting point for HFCS, which is then milled to extract cornstarch.  Enzymes are then thrown in to break down the starch to mostly fructose and some glucose.  It is highly processed, but the final product has the same components as sucrose.  HFCS has replaced sucrose in foods mainly because it is more cost-effective for manufacturers.

Artificial Sweeteners

A compound doesn’t necessarily have to be a sugar for our brains to perceive it as sweet.  Chemist James Schlatter learned this when while trying to develop an anti-ulcer medication he spilled a white powder on his hand, decided to lick it, and discovered NutraSweet.  The biggest obstacle for artificial sweeteners, aside from health concerns, is taste.  Although they initially taste sweet, they all have some degree of bitterness that can be difficult to overcome.  That’s why you often find them in different combinations with themselves or sugar to offset their flavor.  Due to the chemical structures of artificial sweeteners, the body isn’t able to absorb them and metabolize them for energy to a significant degree, which is why they are considered calorie-free.

Saccharin (Sweet ‘N Low®) is hundreds of times sweeter than sugar and is heat stable so it can be used in baked goods.  But it’s made from toluene, the compound that gives paint thinner and other industrial solvents their characteristic pungent odor, so it doesn’t taste that great.  In the 1970’s it was found to cause bladder cancer in male rats, but later it was concluded that there was no mechanism for saccharin to cause bladder cancer in humans.  It was subsequently removed from the International Agency for Research on Cancer (IARC) list of carcinogenic compounds, but skepticism remains.

Aspartame (NutraSweet® and Equal®) is made by linking together two amino acids found in our bodies: aspartic acid and phenylalanine.  It is also sweeter than sugar but has a distinct bitter aftertaste.  Baking with it will lead to disappointment because heat degrades aspartame, destroying its sweetness.  It has been rigorously tested in clinical trials, but no study to date has shown solid evidence of negative health effects in humans.  This is the sweetener to avoid for those suffering from Phenylketonuria (PKU), because they can’t metabolize phenylalanine.

Sucralose (Splenda®) appears to be the most popular.  Of all the artificial sweeteners, it’s the closest in chemical structure to sucrose- it’s sucrose with three extra chlorine atoms attached.  Despite the chlorine, Splenda seems to taste the best.  It has also been extensively studied, and like the other artificial sweeteners, there is no evidence to date of any negative health effects in humans.

Sugar Alcohols

Sugar alcohols like sorbitol, xylitol and erythritol are considered natural, but are kind of on the fence; they occur naturally as products of sucrose fermentation by bacteria, but are also synthesized.  Sugar alcohols are not as sweet as sucrose or artificial sweeteners.  They can produce a cooling sensation similar to menthol, which lends itself well to products like chewing gum, but is also a dead giveaway that they aren’t sucrose.  Unlike artificial sweeteners, sugar alcohols are metabolized so they aren’t considered calorie-free, but they typically provide fewer calories per gram than sucrose.  With the exception of erythritol, avoid binging on a product containing a sugar alcohol; in large amounts, they have the unfortunate side effects of gas and diarrhea.

Stevia

Stevia comes from the leaves of Stevia rebaudiana, a plant native to Brazil and Paraguay.  The U.S. is a little late to the Stevia party.  The indigenous people of Paraguay have been chomping on stevia leaves for their sweetness for thousands of years, and it’s been a popular sugar substitute in Japan for decades.  Stevia is much sweeter than sugar and is heat-stable allowing it to be used for baking.  It has a bitter taste and licorice-like aroma, especially in higher amounts needed for products like diet soda.  We can’t metabolize stevia, making it a calorie-free option like artificial sweeteners. Not much is known about the health effects of Stevia, but preliminary research points to potential blood pressure concerns.

Making stevia is similar to making table sugar.  Stevia leaves are harvested and then undergo chemical or enzymatic extraction, purification, decolorization, and crystallization to produce stevia crystals.  Stevia leaves have several different sweet compounds, called steviol glycosides.  Of them, rebaudioside A (Reb-A) has been found to be the best sweetener based on flavor profile, so if you consume a stevia product you are likely consuming a purified stevia extract containing mainly Reb-A.  It’s been highly processed but is still the same compound found in nature.

When purchasing a stevia product, be sure to pay attention to the label.  Truvia®, made by Cargill, is actually a blend of mostly erythritol and stevia extract (about 1%.)  Cargill says it’s made that way to balance the flavor of the stevia.  Consumers who buy Truvia because they think it’s stevia and therefore healthier should understand the product is mostly a sugar alcohol.  Stevia in the Raw® and PureVia® contain a little stevia extract and mostly dextrose (aka sugar).  Both names convey an image of simplicity and purity, but they are highly processed products with only small amounts of stevia, just like Truvia.

How Do We Define “Natural,” Anyway?

Determining whether a product is natural or artificial really depends on where it came from and how it was made.  “All-natural” is defined as being or composed of ingredients that are from nature and are not artificial.  The FDA considers something natural if it is not artificial or synthetic, and has no color additives.  It has a longstanding policy as to what it considers natural but has yet to define it or make a rule.  Based on this, it’s fair to say that table sugar, natural sugars, and Stevia can be considered natural.  They are subjected to chemical processing when they are made, but they are eventually purified and the chemical structure of the final product doesn’t differ from what is found in nature.

“Artificial” is defined as something made or produced by human beings rather than occurring naturally, typically as a copy of something natural.  Although artificial sweeteners may be derived come from compounds in nature (toluenes are found naturally in crude oil, for example) the final product has either been chemically modified in some way, making it a different compound altogether, or it’s a man-made copy.  Based on this artificial sweeteners fit the description of artificial.  Ultimately, consumers need to understand that “natural” is very much open to interpretation, allowing food manufacturers to decide how they want to define it.  That’s why it’s important for consumers to look at a product’s ingredients more closely before choosing it, because “all-natural” on a label may be more about marketing than your health.

The Bottom Line

There isn’t enough research to say whether one sugar substitute is healthier than another, or whether any of them are healthier than sugar.  If you enjoy sugar as a sweetener, use it in moderation until we know more.  If you are a fan of artificial sweeteners, choose one you like based on flavor and price, but again use it in moderation.  Although stevia is considered natural, there’s no evidence that it is healthier than any other sugar substitutes.  For me, the debate over natural ingredients in products like soda raises a bigger question: When’s the last time you saw a Pepsi tree?  My point is, even if the ingredients in a product are natural, the final product isn’t found in nature.  Most of what we consume today is man-made whether we want to admit it or not.  Just because something is natural doesn’t automatically make it healthy, and synthetic products like medications save lives every day.  I often wonder if our obsession with natural ingredients is more of a yearning for the way things used to be, rather than accepting the way things are.