Stevia was first marketed as a sweetener a few years ago and has since become the in thing. However, there is some debate about its health benefits.
A plant with very strong sweetening properties. ©Shutterstock/Linda Hall
One sweetener’s loss is another sweetener’s gain. Stevia extract was first sold in Europe at the turn of the millennium, a time when aspartame, the undisputed leader among sweeteners since the 1960s, was being undermined by claims that it was carcinogenic. On the other hand, steviol glycoside (aka stevioside or rebaudioside A) was praised as a perfectly natural product. It is extracted from Stevia ribaudiana, a plant found in Paraguayan and Brazilian forests. The indigenous populations of these regions have always used this plant to sweeten their maté infusions. Compared to white sugar, stevia extract sweetens 300 times more, plus it’s calorie free.1 In just three years, between 2009 and 2012, the supposed miraculous properties of stevia increased its share of the sweeteners market to 36%.2
However, some experts in the field of health risks claim that this substance is not entirely risk-free. Marie-Louise Scippo, a professor who researches food-related chemical risks at the Université de Liège, explains, “What we call a natural sweetener comes from highly concentrated plant extracts.” In 2008, the Joint Expert Committee on Food Additives (JECFA), composed of members of the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO), assessed the toxicity of steviol glycoside. As a result, the WHO recommends limiting the acceptable daily intake (ADI) of steviol glycoside to 4 mg/kg of body weight.3 This safety measure is currently applied throughout Europe and the United States.
As Zoie Jones, Communications Officer at the FAO explains, “This joint committee was established to protect consumer health and promote fair practices in food.” She goes on to say, “The Codex Alimentarius or ‘Food Code’ is a collection of standards, guidelines and codes of practice adopted by the Codex Alimentarius Commission. […] Codex texts are non-binding recommendations that only become mandatory if and when they are accepted into national legislation.”
Loïc Briand, a researcher at the Centre for Taste and Feeding Behaviour (CSGA) in Dijon points out that “Some time ago, we discovered that the sweet taste receptor causes a reaction not only on the tongue, but also in the intestines, the pancreas and adipose tissue. This raises even more questions about how sweeteners may affect our health and the risks associated with their use.”
Today, only the highly purified plant extract is authorised. The sale of fresh or dried stevia leaves is banned in Europe and the United States.4 China is the world’s biggest producer of stevia, and the plant is widely used there to combat high blood pressure. One of the good things about this plant is that it grows easily, as long as it has a little water. PureCircle, the Malaysian manufacturer and current market leader, sources the plant from some twenty countries across five continents.5
Marketing made easy
In the United States, Coca-Cola was quick to seize upon steviol glycoside and patented its use under certain conditions, notably for its life range, easily recognised by its green label to symbolise nature. It is important to point out that, while some fizzy drinks boast about their stevia content, it is usually not the only sweetener used. Sugar is also frequently added, to optimise flavour.6 Loïc Briand confirms, “The industry is looking closely at these mixes. When sweeteners are combined with sugar, they act as flavour enhancers and reinforce sweetening power even more.” The combination with real sugar does in fact reduce stevia’s bitter aftertaste. Loïc Briand goes on to explain, “Our tongues only have one sweet receptor compared to twenty-five bitterness receptors. Some sweeteners, such as stevia or saccharine, activate both types of receptor simultaneously. The sweetness initially masks the bitterness, but then we get a bitter aftertaste.” Sweeteners and sugar do not have the same sensory profile in our mouths, and their properties differ when they are used in the manufacture of processed products. Stevia also has quite a strong natural aftertaste of liquorice.
Researchers are currently working on a more concentrated, more intense product and several companies are turning to synthetic biology to overcome the constraints of the plant’s properties and the restrictions of use.7
Economics plays an important role for all ‘miracle’ products. In 2014, the global market for stevia was valued at 347 million dollars and it is expected to reach 565 million in 2020, reflecting an 8.5% growth over this period. Consumption of stevia is estimated to reach 8.5 tonnes by the end of 2020.8 In Japan, stevia has already cornered 40% of the sweetener market.
In addition to questions about the real health benefits of this plant extract, many people have spoken out against this case of biopiracy exploiting the Guarani people. Despite the fact that the Nagoya Protocol supplementary agreement to the Convention on Biological Diversity stipulates that a population must benefit from the ‘fair and equitable sharing’ of benefits arising from the resources taken from its territory9, Western industrial groups that have tapped into Stevia ribaudiana have not compensated the people who discovered its qualities.10
‘Real’ and ‘fake’ sugars
Loïc Briand states, “It's hard to replace real sugar and I would not advise a healthy person to use sweeteners because they can trick the organism. For example, when the brain detects a sweet taste, it may carry on trying to find sugar and that could have an impact on the body's metabolism. So sweeteners are not recommended for weight-loss diets.” Nevertheless, estimates show that the demand for sweeteners is likely to remain high in the near future, particularly in developing countries, due to the growing population, higher incomes and urbanisation. We should not forget that rising obesity and diabetes led to a boom in sales of sweeteners in the 1980s, and that these substances are still included in the treatment of such conditions.11