Wednesday, October 23, 2013

Home Science: Does Yeast Treat Glycerin Like Sugar?

I didn't think I would be covering women's health on this blog, but a question came up among friends recently that wasn't easy to answer with a simple web search:

Do personal lubricants containing glycerin increase the chance of a yeast infection?

The all-knowing oracle Google returns mixed easy answers:

Yes, it does...

http://www.prevention.com/sex/sex-relationships/some-lubricants-may-cause-yeast-infections
http://www.shopintimateorganics.com/2011/05/my-lube-gave-me-yeast-infection.html

No, it doesn't...

http://www.idlube.com/2012/07/glycerin-is-not-a-sugar-the-sticky-situation-of-glycerin-in-lubes/
http://101.lubezilla.com/featured-stories/does-glycerin-cause-yeast-infections/

At this point, the smart thing to do is look for higher quality sources of information. Information literacy, etc. But why do that when I have such a good excuse to run an experiment in my kitchen?

The Setup

I set out two empty measuring cups and put "Sugar" and "Glycerin" paper labels next to them. In a separate glass, I prepared 112° Fahrenheit water. (From my yogurt making, I know this is a prime yeast-growing temperature.) I then poured half a cup of warm water into each measuring cup. 

In the "Sugar" cup, I stirred in one tablespoon of sugar. In the "Glycerin" cup, I stirred in one tablespoon of glycerin:

Ingredients: Glycerin 99.5% Anhydrous

Then, I stirred one teaspoon of active dry yeast into each cup. Utensils were kept separate throughout this process, of course. I soon saw clear results.

Sugar Cup


Horrifying if you think about the context of this post.

Glycerin Cup


The yeast is confused about why someone put it in warm water with nothing to eat.

Conclusions

Not all that tastes sweet is a yeast-infection inducing sugar. People are easily swayed by superstition. Kitchen science isn't as robust as journal science, so treat this like you would MythBusters.

5 comments:

  1. You are a brave crazy scientist! That was great!

    Both articles claim yeast thrives on glycerin which is a "relative" of glucose. Instead glycerin is an alcohol.

    So, though yeast don't grow in the lubricant perhaps, but the lubricant irritates area to set up for yeast AFTERWARD. Maybe it changes the pH.

    The UCLA study showed: "those who reported using oils inside the vagina had a 32% increased risk for yeast infection. "

    Does it irritate and set up for yeast? Hard to test.

    They suggested Aloe Vera and Silicone -- why not use those?



    [sniffle -- not on your blog roll]

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  2. Hi Sabio. I tracked down and read a copy of the study. It's actually decent evidence that commercial lubricants (many of which include glycerine) don't increase the chance of yeast infection, because X% of the women involved reported use of them yet no increased risk for either Candida colonization nor bacterial vaginosis were found. Oils greatly increased the chance of Candida colonization and petroleum jelly greatly increased the chance of bacterial vaginosis...but these are both categories set up in opposition to the things containing glycerine.

    Given that the reason for worrying about glycerine is false and a problem with it very likely would have shown up on the study (but didn't), I don't think it's reasonable to be worried about glycerine.

    Source: http://10.1097/AOG.0b013e31828786f8

    I'll check out your blog!

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  3. I really want to get to the bottom of this since I'don't love to use products with glycerine ... I got excited by your results only to find this study minutes later ...http://www.ncbi.nlm.nih.gov/pubmed/22342043

    What do you think?

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  4. Good find. It sounds like just under 40% of the types of yeast they tested did grow on glycerol to some extent (so 60% couldn't eat the stuff at all). It would be interesting to see results for candida albicans in particular. If you happen to find out more, I would appreciate hearing back. Thanks for commenting!

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  5. Here's an interesting blog article from a company using glycerine in their formula but they show studies where it reduces candida albicans. Its an fda 510k cleared product so its also been tested safe and cleared for sale in the US. http://www.simplyslick.com/blog/?p=23

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