Sweeteners: Time to rethink your choices?

Robert H. Shmerling, MD

Senior Faculty Editor, Harvard Health Publishing

When it comes to low-calorie sweeteners, you have a lot of choices. There’s the blue one, the pink one, the yellow one, or the green one. Whichever one you choose, know that scientists have probably studied it extensively. What they’ve found may surprise you.

Artificial and other non-caloric sweeteners: The major players

The marketers for artificial sweeteners have color-coded their products, but they differ in some important ways beyond their packaging. In the US, the most popular FDA-approved non-sugar sweeteners (NSSs) and their most common packaging color are:

  • aspartame (blue): examples include Nutrasweet and Equal
  • saccharin (pink), as in Sweet’N Low
  • stevia-derived (green), including Truvia
  • sucralose (yellow), as in Splenda.

How are they different? Stevia is considered a “natural non-caloric sweetener.” Saccharin and sucralose are considered “non-nutritive sweeteners” (few or no calories). Aspartame is a “nutritive sweetener” (adds some calories but far less than sugar).

Aspartame comes with a warning to be used cautiously (or not at all) by people with a rare genetic disease (called phenylketonuria, or PKU) because they have trouble metabolizing it; that’s not true for the other sweeteners. And all four vary on their level of sweetness and aftertaste, which is likely why people often prefer one over another.

Researchers take on artificial sweeteners

The reason these sweeteners exist is that people want to eat or drink sweet foods and drinks without the calories of sugar. We assume that over time, fewer calories will translate to less weight gain, more loss of excess weight, and lower risk of weight-related problems such as diabetes and high blood pressure. Although unproven, such assumptions seem reasonable: a 12-ounce can of Coca-Cola contains nearly 10 teaspoons of sugar totaling 140 calories. Over time, such empty calories can add up to many pounds of weight gain. As a result, non-caloric sweeteners long been a mainstay of dieters or anyone trying to limit caloric or sugar intake.

Are there downsides to non-sugar sweeteners?

Despite the rationale above, the effectiveness of using NSSs to lose weight, avoid weight gain, or achieve other health benefits is unproven. In fact, some studies (such as this one) found that people who often drank diet soda actually became obese more often than those who drank less diet soda or none. Another study found higher rates of metabolic syndrome and type 2 diabetes among the highest consumers of diet soda. How can this be? Researchers speculate that using NSSs may cause cravings for sweet foods, alter taste perception, or change how nutrients are absorbed. And of course, it’s possible that people simply justify eating more high-calorie (and potentially less nutritious) foods because they’ve chosen diet sodas.

In addition, research has raised questions regarding safety over the years. For example, cyclamate (which was often combined with saccharin) was banned from all US food and drink products due to concerns regarding cancer risk. Saccharin’s possible link to cancer led to a warning label; as additional research suggested no increased cancer risk in humans, this warning was dropped in 2000.

There have been reports of headaches, learning difficulties, changes in the balance of bacteria in the intestinal tract, and other problems associated with NSS consumption.

Can a new study lay safety concerns to rest?

Given all of these concerns, researchers in Europe took on the task of trying to assess the risks and benefits of various NSSs with an analysis of the best research available, including 56 previously published studies. They sought to determine the effect of various NSSs on the health of adults and kids, including those who were overweight, obese, or at a healthy weight. The effects they studied included:

  • body weight
  • oral health
  • blood sugar
  • eating behavior
  • cancer risk
  • cardiovascular disease risk
  • kidney disease risk
  • mood and brain function.

Spoiler alert: More research is needed

After an exhaustive examination of the most relevant studies, researchers concluded that:

  • There were no clear differences in health outcomes between people who used NSSs often or not at all.
  • No clear health benefits were observed with NSS use, but “potential harms could not be excluded.”
  • The quality of the research to date wasn’t very good, and no definitive conclusions could be made regarding NSS use and these important health effects.

Disappointed? I am. Then again, at least no dramatic or severe harms were detected. And I was glad they didn’t find that my favorite (stevia) was the worst of the bunch. Until we know more, it seems reasonable to suggest the usual: “all things in moderation.” Read nutrition labels and try not to consume more than a few servings per day of any NSS.

Or, do the unthinkable: do without them.


  1. Andi

    Three statements in the interpretation of The BMJ review leap out:
    “…confidence in the reported results is limited.”
    “So far, several studies on the effects of NSSs on different health outcomes have been conducted. However, their methodological or reporting quality is mostly limited and often not sufficiently detailed to include their results in meta-analyses.”
    “Most of the studies identified for this review used single sweeteners and the use patterns of sweeteners in the studies might differ from that in real life practice.”
    Also, stevia should not be thrown in with artificial NSS. Just saying. Cheers.

  2. Joan Hill

    What websites are there to find out whether the website is on the up and up?
    We are looking for hearing aids.

  3. jon jennings

    As a society do we always need to be in such a rush that we need manufactured food? Does it make sense to use artificial sweetener when raw sugars or lightly processed sugars actually provide some nutrition. Blackstrap molasses, honey, maple syrup, coconut palm sugar actually contribute to our well being, rather than just contribute to our cravings.

  4. David L.

    You forgot to mention three things.

    1. Self selection. People who take the effort to use low calorie sweeteners are people who need to, and thus have a different health conditions. Or are dieters who are failing (pretty much everyone who diets fails).

    2. Teeth. Sugar is horrifically bad for teeth, and really shouldn’t be put in drinks at all, ever.

    3. Funding. The recent increase in articles attacking low-cal sweeteners reeks of a sugar industry attack

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