This is the second part of a series on all things sugar: refined, unrefined, and artificial sweeteners.
Part 1 here.
In part one I talked about how caster sugar, white sugar, coconut sugar, maple syrup, agave syrup etc. all essentially consist of the same chemical to make them sweet: sucrose. So now let’s talk about how artificial and “zero calorie” sweeteners compare.
What separates something like maple syrup from stevia is essential biochemical composition. Maple syrup consists of primarily sucrose, glucose and fructose, stevia does not.
Although stevia is marketed as a “natural” sweetener and sugar alternative, I’m inclined to include it under the branch of artificial sweeteners, for reasons which will be made clear below. So let’s talk about stevia, sucralose, and aspartame, and what makes them different from your “natural” sugars (refined or unrefined). These each ideally need a whole lengthy blog post to themselves to understand them properly, but a brief summary will suffice for now.
Stevia is a sweetener extracted from the leaves of Stevia rebaudiana, a species of plant. This process involves drying, water extraction, separation, and crystallisation using solvents such as methanol. Now I don’t know about you, but to me that doesn’t really seem to fit under the “natural” branch as well as products like maple syrup. This lengthy process, combined with the FDA not approving the crude stevia leaf, only the “highly refined Stevia preparations” , makes this seem too much like an artificial sweetener to me.
What gives stevia its sweetness are steviol glycosides, which are up to 150 times sweeter than sucrose, and have much more complex chemical structures.
Steviol glycosides are heat stable, are “zero calorie”, don’t cause dental caries or cavities, and do not raise blood sugar levels the same way sucrose does . This makes it potentially ideal for individuals with type-2 diabetes, those trying to lose weight, those looking to reduce their sugar consumption, and for children. In the past there have been scares regarding the potential carcinogenic (cancer-causing) effects of stevia, however reviews  and WHO  have determined that at levels of normal human consumption (and 100x the level above that) of no more than 4mg per kg bodyweight per day it is safe. As a result, stevia was approved in the EU in 2011.
Aspartame is an artificial sweetener and is a modified dipeptide (two amino acids joined together – aspartic acid and phenylalanine). As you can see it bears no resemblance to sucrose whatsoever, but manages to “trick” your taste buds, and as such is around 200 times sweeter than sucrose. It does produce 4kcal energy per gram (it does technically fall under the category of protein after all rather than carbohydrate) but because it’s so sweet you need such tiny amounts of it, so it’s classified as a non-calorific sweetener.
Unlike stevia, aspartame is not ideal for baking as it is heat and pH-sensitive. It was actually discovered by accident in the 1960s, and has since been rigorously tested in hundreds of studies. It’s approved in over 90 countries by all the regulatory boards, yet for some reason controversy around it still remains. Despite a ridiculous amount of fearmongering over the internet (seriously, why are people still so afraid of anything artificial when most of the population can’t even explain how their smartphone works), the general consensus has not shifted and it remains to be regarded as safe at levels of normal human consumption .
Please don’t be put off by something containing aspartame, it’s not going to do you harm (unless you have PKU in which case please avoid it).
Another artificial sweetener (I’m sure you’ve got the gist by now), which is up to 1000 times sweeter than sucrose, is pH and temperature stable (so it’s good for cooking), and despite it’s similarity to sucrose, most of it is not digested by the body and so it’s considered a non-calorific sweetener.
Over 100 studies examining risk showed it’s safe at levels of normal human consumption. You’d have to eat over 10,000 servings a day to get any kind of effect! 
Natural vs Artificial
There are of course other artificial sweeteners out there, but these are ones that are widely used and getting a lot of attention in the UK in particular. The benefits of artificial sweeteners over “natural” sugars (refined or unrefined) include: fewer calories, no promotion of dental cavities, no promotion of type-2 diabetes, and extremely rigorous testing to reach approval. Downsides include that they’re much harder to bake with as they don’t always behave in the same way as sugars, potential issues with taste for some people, and potential effects on the microbiome , although the latter has so far mainly been studied in mice so we shouldn’t draw conclusions too early.
To finish with an anecdote: I tend to use artificial sweeteners in my coffee, my tea, and even my morning oats if needed. I don’t tend to use them in baking because most of the time it just doesn’t give the right texture and consistency, especially if you’re using traditional methods of baking such as creaming butter and sugar together. I think it’s ignorant to dismiss artificial sweeteners simply because they aren’t natural; after all, I’m using an unnatural laptop to type this, after which I’m going to exit my unnatural house to get on an unnatural train and use my unnatural phone to listen to a podcast.
As always, this post is meant to inform, not tell you how to live your life. I’m just tired of seeing endless health bloggers talking about how wonderfully “healthy” and “natural” things like maple syrup are, when in fact the two words aren’t even related. Artificial sweeteners just aren’t represented in the wellness “clean eating” community out of a simple dismissal for anything not natural, which is ironic considering the majority of these “wellness gurus” are only known thanks to something completely unnatural: the internet.