Is Stevia the Healthiest Sweetener?

~10 minute read. Cliff Notes:

• For Stevia to be the healthiest sweetener, it would need to be beneficial or it would need to avoid the negative health consequences that the other sweeteners are responsible for
• There is no evidence that Stevia is uniquely good for you
• There is no good human evidence that any artificial sweetener does anything bad to your health by any metric
• In terms of gut health, if anything, Stevia may be the worst option

We’re often asked why it is we don’t use Stevia, or if Stevia would not have been a better choice for including in our products. This is a perfectly reasonable, understandable, and an overall great question! If there is a better option, we believe we have a duty to use it, but is Stevia the better option? This short blog seeks to answer that question as fully as possible.

Is stevia better than other sweeteners?

First of all we need to frame the discussion. If we’re asking whether or not Stevia is better, the honest place to start out is by asking ‘better than what?’ There are a host of different options if you want to include a substance that increases the sweetness of a given product, with the primary choices being: 

1. Nutritive Sweeteners: sugar, sugar alcohols, modified sugars and natural syrups like honey
2. Non Nutritive Sweeteners (NNS) like sucralose and highly refined stevia extract

Now of course if you wanted to create a product that is as close to nature as possible you would sweeten it with a natural substance like honey, agave nectar, maple syrup or table sugar from cane or beets. This is a fine suggestion – indeed these are included in a many of the products you find on supermarket shelves, but of course they also contain calories; lots of them if you want to make a product taste sweet and dessert-y. There are arguments to be made that we active folks don’t need to worry so much about sugar as people think we do, but it’s easy to see why a protein powder flavoured with 30g sugar per serving, or a 400kcal protein bar with 150kcal from maple syrup probably wouldn’t be so successful in the health and fitness space.

As such, we’re going to pretty much ignore nutritive sweeteners for the time being and focus on what we feel is the most fair comparison – NNS.

If you’re looking to sweeten something with NNS you have a large number of options, with the most famous being Aspartame, Sucralose (which we use at Awesome Supplements), Saccharine and Stevia. As such, if we’re asking if Stevia is the best NNS, or better than the other NNS, we would need to define how ‘good’ the other options are. It’s very difficult to do this via taste profile because taste preferences are subjective, so instead we’re going to compare Stevia to the other NNS along the axis that comes up the most – health.

So how good or bad are artificial sweeteners (NNS) in general?

Ask that question online and you will, without doubt, receive a confident answer that NNS aren’t good for you. They’re implicated in various cancers, in neurological issues, in increased weight and impaired insulin sensitivity and more…but is that true?

Do artificial sweeteners actually cause cancer?

A big issue in this area is that the preponderance of the research is done in rodent models. This research is important, but it’s self-evidently difficult if not impossible to extrapolate the results seen in a rodent trial directly to human beings, and that’s before you ask about the extremely high doses used in rodent trials (indeed the entire point in many studies is to give a rodent an unrealistically high dosage to see what happens, before using this to determine if this response would also occur at lower doses) and the unbalanced diets/unhealthy lifestyles the rodents endure which increases their risk of encountering problems. As such, we would benefit greatly from focusing on human trials, which is exactly what a 2019 study did.

The paper Association between intake of non-sugar sweeteners and health outcomes: systematic review and meta-analyses of randomised and non-randomised controlled trials and observational studies by Toews and colleagues published in the British Medical Journal (1) sought to assess the association between intake of non-sugar sweeteners (NSS) and important health outcomes in generally healthy or overweight/obese adults and children. It did this by looking at every paper ever published which met the following criteria:

• Generally healthy or overweight adults and children
• They clearly stated which NSS was used, and that the NSS was compared to no intake of NSS or that a higher intake was compared to a lower one
• Used a dose that would actually be consumed in the real world
• Studied people for at least 7 days

Basically it included all of the papers that are actually able to answer the question “are NSS bad for you?” with the principle focus being on body weight or body mass index, glycaemic control, oral health, eating behaviour, preference for sweet taste, cancer, cardiovascular disease, kidney disease, mood, behaviour, neurocognition, and general adverse effects.

And their findings when they combined all of these data? The below is taken from the section focusing on adults simply for the sake of keeping this to a reasonable length, but the data are basically the same in children. Feel free to read the paper itself (link in the references) if you’re particularly interested in seeing that information. If you want to skip the technical and zoom right to a summary just scroll to the text at the bottom.Note that where the ‘certainty of evidence’ is mentioned, this is a measure of how much trust you should put on the idea that something is causal.

For example, it’s true that ice cream sales increase at the same time as murder rates increase, so there is a correlation between ice cream sales and murder, but the certainty of that evidence is pretty damn low! Correlation is not causation. On to the findings…

NSS had no real effect on body weight on average, though including them may lead to a modest loss in overweight people who weren’t actively trying to lose weight (likely because NSS replaced calories). One randomised controlled trial found a slightly smaller difference in BMI changes between people using NSS and not using NSS but the evidence quality was ‘low’, and one cohort study found that people gained 90g less bodyweight when using a smaller amount of Saccharine vs a larger amount of Saccharine, but who really cares about 90g of weight especially when the certainty of evidence was ‘very low’. Interestingly no consistent difference was seen between the different kinds of NNS used, including Stevia.

What about sweeteners for those with diabetes?

When looking at those with diabetes, NSS use coincided with a slightly reduced blood sugar concentration but no difference in insulin levels, sensitivity, or beta cell function (the cells that make insulin), with a ‘low’ certainty of evidence.

When looking at energy intake, NSS seemed to reduce energy intake (again probably because people swapped energy-containing things out) by a reasonable degree on average, though most of the difference was accounted for by one study that found a far higher reduction than the others, meaning that the overall body of evidence suggests a small, rather than larger decrease. Interestingly two randomised controlled trials found that Stevia performed no better than placebo in this regard. When looking at energy intake specifically in overweight people trying to lose weight, researchers found that NSS were associated with a far greater reduction, but no difference in terms of self-control or hunger measures, implying a significant benefit for this subgroup. Finally, when looking at sugar specifically, NSS seem to either reduce sugar intake or make no difference.

NSS were not associated with an increased risk of almost any kind of cancer when NSS consumption vs no NSS consumption were compared, though there was a small increase in risk found in one observational study on pancreatic cancer, and one observational study on ovarian cancer, though the certainty of evidence was ‘very low’. There was also no difference found when high and low intakes were compared.

There was no good quality evidence that NSS use when compared to either nutritive sweeteners of other NSS reduced blood pressure, though there was some ‘very low certainty’ correlation.

When looking at mental wellbeing the picture is complicated. One study with a very low certainty of evidence found an increased risk of depression with NSS vs nothing, and another with the same low certainty found the same result when comparing high to low intakes of aspartame, but then there was no effect on mood in another study with a moderate certainty of evidence. In terms of neurocognition, no effect was found in one study comparing NSS to nothing and another found no effect with a low dose but a negative effect with a high dose.

And then in other studies with a low certainty there was no effect on kidney disease, skin reactions, loss of appetite, headaches, behaviour, or neurocognition.

The findings, a summary

Overall, when looking at human data from studies representative of normal intake and long enough to find an effect, basically no effect is seen on and health outcomes from the use of NSS. Where an effect is seen, the certainty of evidence is either low or very low indicating that it’s not clear that the difference was made by the substance or not. This is of course not proof that NSS are harmless, but it does raise the question “if they are harmful, why has this not been found in human trials using representative intakes?”

It is with that backdrop that we need to frame the conversation around Stevia, because it’s only with that framing that we can objectively answer the question implicit in the title of this blog. To be the healthiest sweetener, Stevia would either have to be directly beneficial or it would have to avoid the negative health outcomes associated with the other options, and given that there is no good evidence in human trials (as of 2019 at least) that the other options are harmful in literally any way, that leaves Stevia with a large hill to climb. Stevia cannot be the healthiest sweetener if it’s not beneficial on its own, and the other sweeteners don’t pose a health risk.

As yet, we were unable to find any studies showing a health benefit of Stevia, beyond that noted above for NSS in general – they can help people reduce their sugar intake, and so their calorie intake. 

As a final note in this section it’s important we discuss the effect of sweeteners on the gut microbiome, because that wasn’t addressed in the above. This is indeed one area of discussion that is very much worth having, though conclusive findings in any area have yet to be found. It’s also worth keeping in mind that an alteration in the gut microbiome isn’t necessarily a problem, though it may lead to one. If NNS have not been found to lead to weight gain, impairments in glucose tolerance or insulin sensitivity, headaches, cancer risk, and so on, whether any effects do or do not matter is a genuine question to ask. With that being said, a 2019 Review of Experimental Studies and Clinical Trials evaluating the effects of NNS on the gut microbiome (2) concluded the following:

“…The effects of sweeteners on gut microbiota have not been completely elucidated. Within NNSs, only saccharin and sucralose shift the populations of gut microbiota. The ingestion of saccharin by animals and humans showed alterations in metabolic pathways linked to glucose tolerance and dysbiosis in humans. However, more human studies are needed to clarify these preliminary observations. Within nutritive sweeteners, only stevia extracts may affect gut microbiota composition….

…Further studies are needed to elucidate whether the changes observed in the intestinal microbiota in animals are present in humans and to study the effects of sweeteners for which evidence is not available so far. In this regard, there is an actual need to perform well-designed, long-term, double-blind, placebo-controlled, randomized clinical trials with appropriated doses and adequate subject sizes to evaluate the potential impact of both NNSs and LCSs on intestinal microbiota and how they could affect major outcomes and risk biomarkers related to chronic diseases.”

In short, so far it is not possible to say whether these substances are or are not bad for our gut health, though what little evidence does exist doesn’t really support the idea that Stevia is uniquely unlikely to cause harm. Indeed, it may be one of the problematic ones…

Generally speaking, Stevia seems to be promoted primarily using the naturalistic fallacy – the assumption we all make that things that are more close to nature are inherently either good or at least better than the manmade alternative, but as you have seen this is not necessarily the case. Indeed, to finish this piece I’ll point you to the table below which compares the ADI for all of the most commonly used sweeteners, taken from the European Food Safety Authority. The ADI or Acceptable Daily Intake is the dose assumed to be harmless – and as you can see, if anything, Stevia should be viewed more cautiously than the others.