The Science Behind Truvia and PureVia Sweeteners (Rebiana)

The FDA recently announced that they have cleared a new, zero calorie sweetener called rebaudioside A (rebiana) for sale in the US, calling it ‘safe for use in foods and beverages‘.

NOTE: This article is the 2nd part of a series about Truvia and PureVia. You may want to read the first part to better understand this article:

Part 1: Truvia and PureVia – A Window to the Past or the Future?

As a result of this decision, two products featuring the new sweetener are coming to market – Truvia and PureVia.  Truvia was jointly developed between the soft drink maker Coca-Cola and agribusiness giant Cargill while PureVia was developed by PepsiCo in partnership with artificial sweetener industry veteran Merisant (under the proxy Whole Earth Sweetener Company).

The Coca-Cola Company has already announced products, including Sprite Green and Odwalla Mojito Mambo and Pomegranate Strawberry Juices, that will be for sale in 2009 containing the additive Truvia.  Not to be outdone, PepsiCo will put PureVia in Sobe Zero Calorie Life Water and Trop50 – a new low calorie orange juice slated for March 2009 release.

The idea of a real, zero calorie sweetener has been a goal of many agribusiness giants for some time but have Truvia and PureVia been adequately tested?   Nutrition Wonderland has gone through the science surrounding these new sweeteners and spoken with some major industry players to get the scoop.  We have found some positives and some serious negatives, which we will review here.

Starting From the Beginning

Truvia and PureVia contain mostly the same chemical formula, as you can see in our chart below.  Both are mostly made of two sweeteners, erythritol and rebiana (called Reb A in PureVia).  Erythritol is a substitute low calorie sugar-alcohol sweetener developed by the French company Cerestar who was later purchased by CargillSugar-alcohols are not really sugars; they require adding hydrogen to sugar molecules so the body ignores them.  Erythritol is a favorite because it supposedly does not cause as many stomach aches as other similar sweeteners.

It was FDA approved back in 2001 based on contract science, some of which was sponsored by Cerestar itself [1,2].  The World Health Organization also reviewed erythritol and found it to be safe.  Little other science exists on the subject.

We could spend more time on erythritol but there is not much new to report about it.  It has not been extensively used (up until now), it has not been extensively studied and it was approved quite awhile ago now.  It is a bit of a sweetener dark horse, if you will.

PureVia vs. Truvia - Fight!

PureVia, but not Truvia, adds in another sweetener called isomaltulose – another supposedly safe sweetener with just a little contract science behind it.  It is derived from regular sucrose to create a sweetener with a longer sustained energy release in the body.  The FDA gave this one a green light back in 2006 at the behest of German sugar giant Sudzucker AG.  Again, it has seen very little use in the American food supply and we just don’t know very much about it scientifically beyond the fact that it does not harm teeth and does not cause stomach aches.

The Stevia Flower, photo by Ethel Aardvark

The other major component of Truvia/PureVia, rebiana, comes from a small herb plant called stevia.  Stevia originally comes to us from South America – where it has been used medicinally for centuries by indigenous people.  Rebiana sweeteners represent the first commercial applications of stevia in the United States but not the first in the world.  Another sweetener derived from stevia – called stevioside – was developed by the Japanese in the late 1970s and now controls 40% of the sweetener market in Japan.  Consequently, what we scientifically know about stevia is mostly based on stevioside, not rebiana – a problem we will see throughout this discussion.

The Concensus on Stevioside

The science we do have about stevia has only come about recently – in the last 20 years or so.  Despite very few (if any) reports of adverse reactions in the Japanese population from stevioside, some studies found that it was mutagenic, that is it could mutate the DNA of rats.  These findings were later dismissed in scientific literature multiple times when it was shown only extremely large amounts – far larger than anyone could consume – created the mutation.

Subsequent study of stevioside’s medical effects have found it confers significant health benefits to those who use it medicinally.  Improved immune system regulation [1,2,3] and improve glucose absorption in the body [1,2],  have led some researchers to suggest stevioside:

“may have the potential of becoming a new antidiabetic drug for use in type 2 diabetes”

Even further, stevioside helps regulate cholesterol and triglycerides [1,2], which means it may treat metabolic syndrome (also known as syndrome X).

On the whole, these findings suggest stevioside has major benefits but what about rebiana?

The Rouge Rebiana

If you follow any of those study links above, they will dump you into the PubMed scientific database.  The US National Institute of Health (NIH) requires all studies they fund (which is a considerable number) to publish their studies into this database.  Logically, we first looked for Truvia and PureVia here.

Pubmed, an amazing resource

A search for either sweetener nets zero search results, as of February 2009 (feel free to try it yourself, click here) – despite all the stevioside research.  However, searching for rebiana nets us 49 very recent results, presumably the ones the FDA used to clear this product (compared to 181 for stevioside).

Diving through the search results leads us to a special supplementary release in July 2008 by The Food and Chemical Toxicology Journal called “Rebaudioside A: An Assessment of Safety”.  As an aside, it should be noted this release perfectly coincided with Coca-Cola’s first PR campaign that released Truvia to the public with a lavish promotion at Rockefeller Center in New York City last summer.  Below is some footage of the event:

As for the science in this tome, we find a total of 11 research articles published about rebiana.  One of them [#12] is a review of the toxicity of stevioside , which, as we covered above, we declared safe by a decent battery of tests.  Two others [#2, #11]  deal with the development of rebiana from the stevia plant, both casually suggesting the toxicology information of stevioside should equally apply to rebiana – a dubious claim at best considering how little research has been done on the later.

However, another study in this group [#5] actually demonstrates that the two sweeteners are relatively similar.  They based this statement on how quickly they are absorbed by the body as you can see in this chart:

Results from study #5 in the rebiana review

While it seems convincing, this report did not use a control group or use any kind of statistical analysis to determine if the slight difference in absorption between the two sweeteners was statistically significant.  Further, the study used about 20% (.8 mg/kg) more rebiana than stevioside in its test, a factor that is sure to skew results.  Their observations also omitted an important data point when observing stevioside at the critical 1 hour mark.  Not to mention, the time schedule on the main graph in the report is misleadingly constructed to show each observation as having occurred in hourly succession (when in fact no observations were made in hours 2 or 3).  This science is very poor in quality and, not surprisingly, funded by Cargill.

Another one of the studies [#4] dealt directly with the toxicity of rebiana by super-dosing rats and observing them.  Most rats ended up eating significantly less food and consequently attaining lower body weight as they aged, consistent with other megadose sweetener studies.  But, most importantly, the rats did not die from rebiana so we could count that as a good thing.  Methodology in this study was far more convincing than the previous study – controls were used and statistical significance was achieved.  Still, the result of this study – that rebiana produces appetite suppression, should be followed up with additional study, something the authors do not call for.  Again, you should note that this study was funded by Cargill which may have influenced the lack of a call for additional study, though this is a minor critique.

Follow the money - its not hard

Rebiana: The Human Studies

Two of the remaining studies deal with people instead of mice, so they should carry the most weight in your mind.  The first, [#6 in rebiana study supplement] tested rebiana against blood pressure and found high dosed patients maintain the same blood pressure in a randomized, double-blind placebo trial, the best type to use.  We can say a few bad things about this study but nothing ridiculously major; it was only 4 weeks long, it did not test against people who already have high blood pressure (a substantial portion of the population), and, again, Cargill funded the study.  Overall, this is encouraging but it is only the first study of its kind so its hard to draw too much from it.

Controversial little shrub, eh?

The other human study deals with rebiana and how it effects people with type II diabetes..  The study uses a megadose, 7X what a heavy user would probably ingest, and followed a little more than 100 patients for about 4 months.  Results of this placebo study show no severe effects on blood pressure or blood sugar.  However, there was one case of hyperglycemia – that is too much glucose in the blood stream – but in a group of diabetics, something like this seems likely to happen during a 4 month period of time.  And let’s not forget to mention that some Cargill money managed to squeeze its way into the study.

In a way, this particular finding was a bit of a disappointment.  There was hope that rebiana would treat diabetes much like it is suspected stevioside can but this is the second study to disprove that.  The first study on this topic showed that rebiana was not able to deliver any of the metabolic syndrome reducing effects of stevioside, so a consensus is forming.  A few others studies show rebiana helps regulate glucose, but there is still much more investigation necessary.

First Thoughts

The studies we have about rebiana – and consequently Truvia and PureVia – are a mixed bag.  As we showed, some demonstrate safety, some show risk.  None really deal with potential side effects, an issue with a product that will find its way deep into the food supply.  Most surprisingly though, absolutely no published studies have actually tested Truvia or PureVia themselves.  This is probably because the sweeteners themselves were not ready in advance to be tested but we must ask why the American public is being silently asked to bear that burden.

It would appear rebiana (along with erythiritol and isomaltulose) present little risk to people with high blood pressure and type II diabetes but in the world of science, your opinions are an extension of the crowd.  In a sense, you are only as good as those that have come before you.  With rebiana, there is no concensus, no crowd – so there is no way we can give any type of authoritative opinion on it yet.  The crowds surrounding erythiritol and isomaltulose are even more sparse.

That’s all a problem with a new product and one the makers of Truvia and PureVia have done very little to assuage.  While most of these studies appear to verify that rebiana et al., do not have toxic effects, they are all very short term and funded exclusively by industry.  It is beyond unlikely that any study funded by Cargill is going to show rebiana and Truvia to be anything but the safest sweetener ever to arrive on planet earth.  Having said that, some of their studies do appear to demonstrate safety of rebiana but it so hard for us to believe these results with so much of their own money on the table.

Now, lets give Truvia and PureVia a little credit here.  This is the first sweetener product(s) developed by an agribusiness interest that is not purely a chemical.  A real plant is involved here and that is the first time that has ever happened.  Not only that, the stevia plant shows some rather amazing medical benefits.  So, for a brief moment, let us congratulate Cargill and Merisant for at least starting with something very beneficial found in nature.  That is a MAJOR step in the right direction.

Still, major questions persist.  When will Truvia or PureVia actually be tested?  How can we trust science sponsored by the same people who will gain from its results? What makes this better than just using regular old stevia?

In our next and final view of Truvia and PureVia, we will talk about how all of this science relates to stevia’s controversial past, discuss some of our conversations (and lack thereof) with government/NGO players and finally present our view on the best way forward with these sweeteners.

Please read Part 3 of the Truvia/PureVia series:
Part 3: Truvia and PureVia – The Controversy of Stevia
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