Back in my teenage years, long before I had any education or training in science, nutrition, or research, I decided to be vehemently against artificial sweeteners. I honestly have no idea where the idea came from. I probably watched a documentary or read a fad diet book (this was well before social media outlets served as a platform for biased fearmongering, although I am sure the internet played a role in some way). Aspartame was the devil and I made sure everybody knew it. I distinctly remember sitting in a diner, ripping up packets of Equal and dumping the contents onto my empty plate – my way of making a statement. That’s right, y’all, I was a victim of pseudoscience. Pseudoscience can be very, very convincing.
Flash forward to the present: I now know what a randomized, controlled trial is (plus, I have a couple degrees and stuff). But, it’s still kind of weird for me to counsel my patients that artificial sweeteners are OK, and may even help them. It’s crazy to contradict a previous version of yourself. In fact, I bet a lot of people don’t experience this very often (or don’t let themselves). But I think it’s important to reflect on our previous beliefs and actions and think critically about how we may have been… well, completely wrong.
Of course the use of artificial sweeteners in our food supply and as part of a ‘healthy’ diet is still controversial; it remains one of the most commonly discussed topics in counseling sessions with my patients (luckily, now I know what the heck I’m talking about).
When it comes to artificial sweeteners, there are two main questions we need to ask: Are they safe (do they cause diseases like cancer or diabetes, and is there risk for toxicity)? and Do they provide a health benefit in some way (i.e. do they help us lose weight, do they help diabetics with blood sugar control)?
Are artificial sweeteners safe?
Fear is born from ignorance, so let’s first define what these artificial sweeteners are. Artificial sweeteners are food additives that add a sweet taste but have little to no caloric content. Although we lump them all together into one term, they have distinctly different molecular structures and behave differently in the body when consumed. The widely known artificial sweeteners are aspartame (Equal), sucralose (Splenda), acesulfame potassium (Ace K), and saccharin (Sweet n Low – not used as commonly anymore because it once carried a warning label, which has since been dropped), stevia extracts (Truvia, PureVia)*, and sugar alcohols (xylitol, sorbitol, and other –ols). Sugar alcohols are typically less sweet than real sugar and contain a small amount of calories. They occur naturally in fruits but can also be manufactured. Artificial sweeteners are everywhere, from your toothpaste to your diet soda to your prescription medications.
Back in the 70s, there was a study done1 on male lab rats that showed that saccharin caused bladder cancer, but the results were never replicated in humans. Tons of epidemiological data have failed to show a correlation between cancer and saccharin, likely because the mechanism behind the effect was specific to rat physiology. The relationships between cancer and the other artificial sweeteners (aspartame, sucralose, etc) have also been studied extensively. No evidence has been found to show these substances cause cancer2,3. We are talking about hundreds of studies. And keep in mind, researchers doing lab animal studies with artificial sweeteners are experimenting with doses exponentially higher than any human would likely or could possibly consume – this is part of the requirement of the safety testing.**
There’s also been some reporting in the media4 recently about artificial sweeteners leading to the development of diabetes. Some of this coverage was based on a study5 done in rats and in a small human sample that didn’t control for diet (in humans) or account for weight changes (in rats) – two factors involved in one’s risk for developing insulin resistance. It was also examining only saccharin, which again, is not found in many foods anymore. So we can’t use these results and apply them to aspartame or sucralose (both of which are used in virtually all diet beverages). In fact sucralose and stevia have been studied with regards to their relationship to blood sugar and high doses (up to 3x the maximum recommended intake) of those two substances showed no effect (positive or negative) on glucose homeostasis.6-8
Are artificial sweeteners helpful?
Last year the American Journal of Clinical Nutrition published a review and meta-analysis of 15 randomized, controlled trials and 9 prospective (observational) studies in an attempt to examine the relationship between the use of artificial sweeteners and weight.9 The RCT data showed a significant reduction in weight and more favorable body composition profile when regular foods were replaced with artificially sweetened versions. In contrast, in the observational data (which remember can only suggest associations, not causations), higher use of artificial sweeteners was associated with a higher BMI. The authors suggest (as would I) this could be due to ‘reverse causality’ – those with weight issues start using a lot of artificial sweeteners to lose weight, and those without weight issues tend to ‘need’ sugar substitutes less. Further, a diet high in artificial sweeteners could also be high or low in other nutritious foods – it all depends on why someone is using the sugar sub in the first place (to lose weight, to control diabetes, or just because it tastes better to them – yes, these people exist). In my opinion there are way too many confounding variables to rely on observational data to draw conclusions about use of artificial sweeteners and weight.
We all know the running joke about the McDonald’s customer ordering a Big Mac, extra large fries, and an apple pie, and rounding the meal out with a diet Coke, right? How much truth is there to the phenomenon that diet drinks and diet food products have a halo effect, making us feel better about eating less healthy foods along with them or later in the day? Maybe you choose a diet soda at lunch because you know you’re going for ice cream after dinner. This is called energy compensation, and it too has been studied. What we see is that there is some calorie compensation when people switch out their regular foods for diet versions, but not total compensation. So someone that switches out their regular ice cream for a sugar free one (which will have artificial sweetener in it), will make up for about 30% of those calories somewhere else in their daily intake (anything under 100% is a calorie reduction, but 0% would be the ultimate goal). If you look at studies that measured ONLY diet beverages vs. regular versions (so, no diet foods), the compensation is lower, at around 15%. This suggests that switching out sugar-sweetened drinks for diet versions is pretty effective at reducing overall calorie intake. 10
It’s likely I’ll continue to discuss artificial sweeteners with clients and patients for years to come, mostly due to the unfounded fearmongering by popular food and diet personalities like Dr. Oz and the Food Babe. Their ‘warnings’ are pure sensationalism and not at all based in science. This is why it is so important to get your nutrition information from trusted sources, like registered dietitians. Don’t get me wrong, I’m not claiming that artificial sweeteners are health foods. They’re more like unhealthy-food-replacers. But when my clients and patients ask me if artificial sweeteners are safe, I say that the good, quality research available to us says yes12. For my weight loss and diabetic clients, I usually add something about how replacing regular Coke with Diet Coke can help cut calories and carbs, but that total abstinence from soda is probably best***. And I can’t emphasize enough that artificial sweeteners (or any single, specific food) won’t counteract the negative effects of an overall nutrient poor, energy-dense diet. They work best when fit into a diet full of whole, minimally processed foods – vegetables, fruits, nuts, seeds, legumes, fish, and lean poultry.
And to the manager of that diner in Pennsylvania years ago, I am sorry I wasted those 20 packets of Equal that night.
*Stevia extracts sound attractive because they’re marketed as being made from a plant, but keep in mind, the FDA-approved version of stevia for food products is the highly refined extract called rebaudioside A – not the whole leaf or crude extracts.13 The whole leaves can be sold as a supplement, however, and therefore are not regulated by the FDA. The FDA’s concerns regarding the safety of stevia as a food additive stem from the plant’s effect on blood sugar and blood pressure – it has been show to lower both in clinical studies. The FDA is concerned that large scale consumption of stevia could affect people on blood pressure- and blood sugar-lowering medications – the very population that would be interested in an artificial sweetener.
**FYI, the acceptable daily intake (ADI) of aspartame (the maximum amount that can be safely consumed on a daily basis over a person’s lifetime without negative health effects) is set at 50mg/kg/day. For a 150-lb person, this represents 18 cans of diet Coke per day. Most animal studies use 2-3 times the ADI, or even higher.
***I am not paid by Coke or artificial sweetener companies.