If you’re familiar with this blog, you probably know that before eating something I want to know exactly what it is, where it comes from, and, above all, if it’s good or bad for my health. Basically, I need to know everything about it.
I did my fair share of research, and this is what I discovered. Hoping that you’ll find it useful too.
What is stevia?
Stevia (Stevia Rebaudiana) is an herb that grows wild as a small bush in Paraguay and Brazil. Its leaves are rich in glycosides, which account for its incredible sweetness.
Stevia’s extracts (the ones we can find at the grocery store) are manufactured in several different ways (some of which have also been patented). Generally, the most common process consists of water extraction, decoloration, and purification.
How long has it been used?
The leaves have been traditionally used for hundreds years in Paraguay and Brazil to sweeten local teas, medicines, but also as a sweet treat.
Since the 1970s, Japanese have cultivated stevia as an alternative to artificial sweeteners (that have long been suspected of being carcinogens). They have been using stevia in food products, soft drinks, and for table use. As of today, Japan consumes more stevia than any other country in the world.
Stevia is cultivated (and consumed) also in other countries, including China, Korea, Taiwan, Thailand, Malaysia, Colombia, Peru. Paraguay, Brazil, and Uruguay.
Why is it good?
First and foremost stevia has almost no effect on blood glucose. This particular feature makes it very attractive for people on carb-controlled diets.
According to some studies, stevia may actually lower blood sugar levels. These findings, however, have yet to be confirmed, and contradictory results make any conclusion premature.
There is also some evidence that stevia may help individuals improve insulin production and might be helpful with hypertension. These findings are yet to be confirmed by more extensive studies; it does sound promising though.
Stevia is also pretty safe when it comes to tooth decay. Two tests conducted at Purdue University not only have assessed that stevia is fluoride compatible, but that it may also prevent the development of plaque.
Stevia is extremely heat stable, hence can be used in everyday cooking and baking.
Furthermore, raw herbal stevia contains a whole array of phytonutrients. Unfortunately, in the quantities typically consumed, the nutritive benefits will be negligible. On top of that, stevia’s extracts, being more refined, will contain far fewer of these phytonutriens and volatile oils.
Controversy on stevia
This is where it gets kind of complicated. Several studies on stevia have raised some concerns over its consumption by humans. All these researches, however, were pretty limited in size, and lacked support of extensive data. They also focused on different types of stevia, different extraction methods, and different parts of the plants. This makes it difficult to compare data across studies. Nonetheless, all of them are worth mentioning:
- A 1985 study reported that steviol (a breakdown product from stevioside and rebaudioside) is a mutagen (i.e., an agent that causes genetic mutation). Meaning that the use of stevia could trigger degenerative diseases in humans such as cancer.
However, the findings of this study were criticized on procedural grounds that the data were mishandled in a way that even water would have appeared to be mutagenic.
- Other studies conducted over the following years have showed mixed results on the mutagenic effects of stevia, and its toxicology. Some reported that steviol and stevioside were scarce mutagens while others did not find any harmful effect.
- In 2008, an extesive review of all said studies was carried out. The outcome was that 14 out of 16 studies showed no health hazard for sevioside, while 11 out of 15 showed no genotoxicity activity for steviol. No evidence for stevia's constituants causing cancer or birth defects was found.
- In 2006 the WHO (World Health Organization) conducted a thorough evaluation of studies of stevioside and steviols and concluded that “stevioside and rebaudioside A are not genotoxic in vitro or in vivo [...] the genotoxicity of steviol and some of its oxidative derivatives in vitro is not expressed in vitro”. The report also found no evidence of carcinogenic activity.
- In 2009 the FDA - after banning stevia use for years based on the 1985 study - claimed “Rebiana (rebaudioside A) to be Generally Recognized As Safe (GRAS)”
The bottom line is that there is yet not enough data to conclude whether stevia is healthy or not. Personally, I do not believe it’s toxic, and I intend to use the product with confidence, but also in moderation. In the hope that soon a new study with more conclusive evidence on the effects of stevia on human health will be published.
If I have to point to something that I really don’t like about stevia extract is that it’s ultra-processed.The extraction method is quite complicated, and entails several stages.
I like to consume things that are as close as possible to their raw form, and stevia extract seems a bit too “manufactured”. However, next time I’ll be in Brazil (or Paraguay) I’m gonna look for stevia raw leaves, and try them to sweeten my green tea!
The Iron You