Nutritive sweeteners provide calories and make our food taste sweet. Examples include table sugar, honey, high fructose corn syrup among others (there are around 61 different names for sugar!). On the other hand, non-nutritive sweeteners (also called ‘intense‘ sweeteners) are just that: they make our food taste sweet, minus the calories. The reason we perceive both sugar and sweeteners to have a sweet taste is because they both bind to the same receptors on our tongue, so they elicit a similar perception of sweetness. The EU has approved several sweeteners: aspartame, acesulfame-K, sucralose, saccharin, cyclamate, thaumatin, neohesperidin and stevia. Stevia was only approved for use in the EU in 2010 after an extensive review documented no harmful effects and declared it safe for human consumption.

Today, the market for stevia is worth £4 million and growing by 18% per year, as recent figures indicate. Why? Because sugar was very recently believed to be the evil culprit behind obesity and its related health consequences. So, in comes sexy stevia, the ‘natural’ sugar substitute which is extracted from the plant Stevia rebaudiana.  And that is what the buzz is mainly all about: while other sweeteners are man-made, stevia is the only sweetener which is not artificial, it’s merely extracted from plant leaves. All the other sweeteners are formulated (sometimes randomly) in the lab: saccharin, for instance, is a chemical compound that was accidentally discovered by a chemist who spilled some on his hand and then tasted it only to discover its intense sweetness!

Stevia is a plant that contains several sweet-tasting compounds called glycosides, the most abundant of which is stevioside. Stevioside has no calories, is 200-300 times sweeter than sucrose and is considered a natural, herbal sweetener. This has prompted the question: could stevia be the new sugar? And could it be the world’s solution to the obesity problem? This possibility has been the centre of great debate among scientists. Does replacing non-caloric sweeteners with sugar in a person’s diet help reduce overall daily caloric intake? Or does our body call our bluff and compensate by eating more to even out the caloric reduction? The theory is that our bodies are biologically set to a certain caloric intake each day, and we will eat just enough food to satisfy that limit. For instance, if I eat only 300 calories in the morning, I will most likely eat 1,200 calories worth of food during the evening to satisfy my daily requirement of 1,500 calories. However, if I eat 500 calories in the morning I will limit the rest of the day’s consumption to 1000 calories.  Some scientists suggest that this compensation happens during the course of a single day, while others believe it happens over weeks or months.

A recent review in the American Journal of Clinical Nutrition looked at the effects of sweeteners on appetite, caloric intake and BMI. The review has gathered that using sweeteners in place of sugar to reduce overall caloric intake is encouraging, but not yet conclusive. The research on short-term energy intake is still conflicting, while the long-term studies show that non-nutritive sweeteners seem to reduce overall caloric intake by about 5-15%. However, it is important to note that this review considers all sweeteners, not stevia in particular. Also, most of these studies investigate the appetite and caloric effects under controlled laboratory settings, so there is the question of whether the results are applicable to free-living conditions.  Read more on that here.

Stevia in particular was found to positively affect both glucose and insulin levels after a meal, which are both implicated in the development of type 2 diabetes. Some studies showed that stevia slightly decreases heart rate, blood pressure, cholesterol, triglycerides and LDL-cholesterol while increasing HDL-cholesterol levels. Moreover, stevia is non-cariogenic – that is, it does not cause dental caries like sugar does, which is great especially for young children and adolescents. Other health claims attributed to stevia by research include: anti-inflammatory, anti-bacterial, hypotensive, diuretic and vasodilator. These definitely help stevia win the race against other sweeteners. There are, of course, several limitations to such research. Many studies of safety and effects have been carried out in-vitro or on nonhuman species, which raises the question of applicability to humans. Even more so, many such studies that document the effects of consuming sweeteners in place of sugar are funded by industries that produce and sell sweeteners.  Nonetheless, regulatory bodies such as the European Food Safety Authority (EFSA) do review all available evidence in order to come up with safe guidelines. Moderate consumption of stevia (currently set at 4 mg/kg/day) is deemed safe. However, although the EFSA considers all health claims of stevia, it only endorses its advantage over sugar on blood glucose levels and tooth demineralisation.

As someone who enjoys my occasional dose of sweet stuff, I take all this with a grain of salt. The most important thing to remember is that both sugars and sweeteners like stevia are not recommended in large amounts as part of a healthy diet; exceptions for regular intake are made for diabetics and for those attempting weight loss who may benefit from moderate amounts of stevia as a substitute for sugar. So if you’re craving the occasional chocolate bar, there is no harm in choosing the stevia-sweetened one.

PS. Always remember to check the ingredient list of the stevia-sweetened products you’re buying, as many contain added flavours, sugar alcohols or even hidden sugars.

Laura Jabri, MSc 

Laura has a masters in Clinical and Public Health Nutrition from University College London and a bachelors degree from the American University of Beirut. Her interests include nutrition education, obesity prevention, maternal and child nutrition, undernutrition in developing countries and food sustainability solutions.  Tweet her @laurajabri

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