I received a ton of stevia products recently to sample, and one of my pals asked for my thoughts, since she considered stevia “MUCH closer to natural than the sucralose process.” I’ll admit, the NuNaturals products I have sampled taste great, clean and sweet like sugar and the liquid form I was testing was very concentrated and only needed a few drops to make a cup of coffee taste great. It’s much better than the bitter-aftertaste, licorice tasting stevia I tried ages ago. But I don’t plan to include stevia as a regular sweetener in my diet.
Below are my thoughts on stevia, which I share with caution because I know many bloggers and blog readers do choose stevia over other sweeteners.
First, natural doesn’t carry any weight as far as making me trust something. Natural does not equal benign. Manmade does not equal harmful. Nature invented some powerful toxins and carcinogens, and theoretically one could use the “it’s natural!” line to excuse tobacco and numerous other harmful drugs.
Second, everything is toxic at high enough dose. Water. Salt. Alcohol. Potassium. You name it. My concern with sweeteners is: Is the level at which I would use them (or my clients) likely to pose a health risk?
I’ve been reviewing safety data on stevia literally all week, in my spare time (haha, I know what you’re thinking! when is that?) I regularly troll the literature for aspartame, sucralose studies as well, since I do consume both of them regularly.
To start, none of the three (stevia, aspartame, or sucralose) have demonstrated carcinogenicity at any level. Not in animals, not in people. Despite what you read in your email.
When toxicity is determined for a food additive, the general idea (really simplified explanation here) is that studies are conducted in animals to determine the NOAEL. No Adverse Effects Level. This is the highest dose at which no bad things happen to the critter. Expressed in mg/kg bodyweight.
Usually, to have a margin of safety, the NOAEL is divided by 100, and that smaller number (1% of the NOAEL) is set as the ADI (Acceptable Daily Intake) for humans. This is the maximum amount that a person is advised to consume (on a daily basis). So if 100 mg/kg bodyweight was the lowest dose at which something harmful was witnessed in an animal, the ADI for humans would likely be assigned at 1 mg/kg bodyweight.
With me still?
Okay, so ADI’s for common sweeteners:
Aspartame: 50 mg/kg
Sucralose: 5 mg/kg
Stevia glycosides: 4 mg/kg
One of the problems with Stevia products is that there are so many various formulations sold, each company’s product has a different amount of stevia glycosides in it. They don’t even need to disclose how much is in it accurately because stevia extracts and glucosides are usually sold as dietary supplements, not subject to FDA regulations. Some branded versions are purified Rebaudioside A (Reb A), some are a literal soup of compounds extracted from the plant. Could this make some products safer than others? Absolutely.
I did find some additional research evidence that gave me pause with stevia:
1. The metabolism of stevia may or may not create an epoxide intermediate in the gut. One study found the presence of this epoxide, two others didn’t, but it needs to be further investigated because epoxides are reactive species that can damage DNA. Damaging DNA is generally not good.
2. In cell culture assays, stevioside was found to be mutagenic to bacterial cells – in other words, it caused an increased number of DNA mutations. Mutagenicity is suggestive of possible carcinogenesis. Needs further study. Please see pages 9 and 10 of the attached pdf at the end of this article for more detail if you’re interested, under the heading Genotoxic Effects.
3. Stevioside causes DNA breakage in blood, spleen, liver, and brain cells in rats (Nunes et al., 2007). This concerns me even more, as we’re talking mammalian cells now, not bacteria.
Now, to present a balanced argument, other studies have found NO effects when studying stevia and it’s components. A lot more studies have to be done to clarify the inconsistencies. In my opinion, there simply isn’t enough data, particularly long-term consumption data (there is none) for me to put my trust in stevia. It is simply too new, and I would trust it more if in ten or twenty years from now there is a greater library of safety research on stevia, involving multiple mammalian species, human trials and detailed metabolism of the compounds have been elucidated.
Now, should you be concerned if you are using stevia in your food or drinks? Probably not, unless you’re mainlining it. The doses at which these things are tested is quite high, so if you use it in one food item per day, I’d say the risk isn’t severe. I wouldn’t use it multiple foods per day though. Stay under 4 mg/kg.
Personally, I am most confident in the safety of aspartame, given that it has the longest clean track record of research, and every researcher and their mother has tried to find ill health effects of it. The composition of it makes biological sense to me: two amino acids and a methyl group. I can visualize the metabolism, breakdown and excretion of the components. It’s not a mystery to me, and I don’t get anywhere NEAR the ridiculously high ADI for it.
Splenda – I feel like it’s somewhere in the middle. It doesn’t have as much of a depth of safety studies as aspartame, but it’s got more than stevia. The molecular structure of sucralose ought to be minimally absorbed from the gut (since it isn’t recognized by glucose uptake mechanisms) which logically helps support that it is unlikely to cause systemic effects, since probably very little of it reaches the bloodstream, brain, etc. What does concern me (and lead me to limit my use of it) is the possible effects on gut flora and cells lining the intestine, as they are subjected to the highest concentration of the compound.
Okay this is already so long that no one else is reading I suppose……
Personally, I will continue my tasting of the free stevia samples I received just to check them all out, but I’m too cautious of it to buy it and use it long term. Just my personal choice. You do what feels (and tastes) good for you.
For more detailed research findings on what led me to my choice, see this toxicology report.
Before you send me hate mail … or an internet rumor that sucralose and aspartame cause lupus/baldness/cancer/scurvy/herpes/heart disease/ADD …. or tell me how your Aunt Sophie stopped drinking diet soda and her poodle Elvis came back to life… realize that I have no problem with you eating whatever you want and avoiding whatever you want. Respectful disagreement and discussion is welcomed, factless anecdotes or emotionally charged diatribes are not. Don’t get into a tizzy.