# peanut butter and cancer
**URL:** https://boards.straightdope.com/t/peanut-butter-and-cancer/364185
**Category:** Factual Questions
**Created:** [July 12, 2006, 3:13pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185 "2006-07-12T15:13:42Z")
**Posts on this page:** 19
**Page:** 1
### Author:  [@rhiannon777](https://boards.straightdope.com/u/rhiannon777)
#### Post date: [July 12, 2006, 3:13pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/1 "2006-07-12T15:13:42Z")
My hometown conspiracy theorist has recently begun claiming that unrefrigerated, opened peanut butter can accumulate spores that cause cancer (I think he noted kidney and brain cancer in particular). He says that there have been multiple studies proving this, one of which just came out recently. Anyone know anything about this?
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### Author:  [@daffyduck](https://boards.straightdope.com/u/daffyduck)
#### Post date: [July 12, 2006, 3:39pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/2 "2006-07-12T15:39:06Z")
> [@rhiannon777](#):
>
> My hometown conspiracy theorist has recently begun claiming that unrefrigerated, opened peanut butter can accumulate spores that cause cancer (I think he noted kidney and brain cancer in particular). He says that there have been multiple studies proving this, one of which just came out recently. Anyone know anything about this?
From [InsideCancer.org](http://www.insidecancer.org/)
“Food crops such as peanuts, corn, and wheat are susceptible to contamination by molds – Aspergillus flavus and Aspergillus parasiticus. Aflatoxin, a byproduct of these molds, is a potent cancer-causing agent. Long-term exposure to aflatoxin has been linked to increased incidence of liver cancer.”
I doubt if the spores themselves are a real problem, I would think it would require them to grow into actual mold for the Aflatoxin to be produced, but he may be on the right track if not technically correct as is.
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### Author:  [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)
#### Post date: [July 12, 2006, 4:02pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/3 "2006-07-12T16:02:24Z")
Never trust one paragraph summaries on the Internet without doing some extra research.
Aflatoxin contamination of peanut crops and peanut butter is real. Whether it is present is sufficient quantities in modern commercial peanut butter is questionable. That it exists in commercial peanut butter in the United States is highly doubtful.
[This site](http://www.scienceinafrica.co.za/2001/august/peanut.htm) reprints a report from the South African Medical Council. It states that no real danger exists with good monitoring despite a scare in the 1990s concerning higher than legal levels of alfatoxin in school food programs (PSNP):
> [@](#):
>
> Although aflatoxins have been implicated in several episodes of acute human aflatoxicosis in various areas of the world, these have been reported at contamination levels in the milligrams per kilogram (parts per million) range, i.e. 1000 times higher than the legal tolerance levels.
>
> …
>
> We would like to point out that the peanut butter used in the PSNP is quite different from commercially available peanut butter, most of which is regularly monitored for aflatoxin levels in South Africa.
And as for the U.S., a [University of Maryland site](http://www.agnr.umd.edu/MCE/Publications/Publication.cfm?ID=174) reports that:
> [@](#):
>
> Moldy foods may contain aflatoxin, a carcinogen produced by a mold. Consumption of aflatoxin may increase the risks of cancers of the stomach, liver, and kidney. You can reduce your exposure to aflatoxin by storing nuts, grains, and seeds in dry, sealed containers. Throw away moldy or shriveled seeds, nuts, and grains, and spit out any that taste moldy. The Food and Drug Administration and food manufacturers routinely test food products for the presence of aflatoxin. Aflatoxin contamination of commercially processed foods, such as peanut butter, is not believed to be a problem in the United States.
Unless your conspiracy theorist imports his peanut butter from unrefrigerated sources in the Sudan, he can relax. He won’t, of course, since conspiracy theorists never do, but you certainly can ignore him.
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### Author:  [@vetbridge](https://boards.straightdope.com/u/vetbridge)
#### Post date: [July 12, 2006, 5:49pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/4 "2006-07-12T17:49:15Z")
> [@Exapno Mapcase](#):
>
> Unless your conspiracy theorist imports his peanut butter from unrefrigerated sources in the Sudan, he can relax. He won’t, of course, since conspiracy theorists never do, but you certainly can ignore him.
How do you explain the fact that of the people I know who have/have had cancer, **every last one of them have eaten peanut butter at some time in their lives**?!?
😉
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### Author:  [@tremorviolet](https://boards.straightdope.com/u/tremorviolet)
#### Post date: [July 12, 2006, 6:01pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/5 "2006-07-12T18:01:16Z")
> [@vetbridge](#):
>
> How do you explain the fact that of the people I know who have/have had cancer, **every last one of them have eaten peanut butter at some time in their lives**?!?
> 😉
You might be on to something. I have never, ever eaten peanut butter (beyond a cursury taste to establish that it’s icky) and **I _don’t_ have cancer**! 😉
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### Author:  [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)
#### Post date: [July 12, 2006, 8:49pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/6 "2006-07-12T20:49:23Z")
At the risk of looking like I’m wearing a tin-foil hat, there is _some_ evidence, from _some_ countries, that peanut butter consumption is directly linked to the development of liver cancer. Here are two studies from Sudan, where liver cancer is fairly common. [One](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstract&list_uids=15203373&query_hl=1&itool=pubmed_docsum). [Two](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstract&list_uids=11227922&query_hl=1&itool=pubmed_docsum).
Still, other nutritional factors, as well as local environment and storage conditions, make comparing Sudan to North America like comparing apples to oranges (or peanut butter to normal butter 🙂 )
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### Author:  [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)
#### Post date: [July 12, 2006, 9:07pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/7 "2006-07-12T21:07:37Z")
> [@KarlGauss](#):
>
> At the risk of looking like I’m wearing a tin-foil hat, there is _some_ evidence, from _some_ countries, that peanut butter consumption is directly linked to the development of liver cancer. Here are two studies from Sudan, where liver cancer is fairly common. [One](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstract&list_uids=15203373&query_hl=1&itool=pubmed_docsum). [Two](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstract&list_uids=11227922&query_hl=1&itool=pubmed_docsum).
>
> Still, other nutritional factors, as well as local environment and storage conditions, make comparing Sudan to North America like comparing apples to oranges (or peanut butter to normal butter 🙂 )
I didn’t put Sudan in my post by accident, pal. 🙂
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### Author:  [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)
#### Post date: [July 12, 2006, 9:25pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/8 "2006-07-12T21:25:01Z")
> [@Exapno Mapcase](#):
>
> I didn’t put Sudan in my post by accident, pal. 🙂
Indeed! I missed that!
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### Author:  [@robcaro](https://boards.straightdope.com/u/robcaro)
#### Post date: [July 12, 2006, 9:38pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/9 "2006-07-12T21:38:29Z")
I have eaten peanut butter all my life and I don’t have cancer! I am 77 years old now.
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### Author:  [@Excalibre](https://boards.straightdope.com/u/Excalibre)
#### Post date: [July 13, 2006, 9:54pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/10 "2006-07-13T21:54:01Z")
I’ve heard speculation that organic peanut butter is far more likely to have significant aflatoxin contamination because the peanuts aren’t treated with herbicides and so forth. I don’t know if that’s really true or not, but it makes some sense.
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### Author:  [@istara](https://boards.straightdope.com/u/istara)
#### Post date: [July 15, 2006, 6:10pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/11 "2006-07-15T18:10:18Z")
> [@Excalibre](#):
>
> I’ve heard speculation that organic peanut butter is far more likely to have significant aflatoxin contamination because the peanuts aren’t treated with herbicides and so forth. I don’t know if that’s really true or not, but it makes some sense.
Yes. I read only earlier today, when searching for pet food advice, that bird owners are advised not to use organic, “fresh” peanut butter in feeding, because of the aflatoxin risk.
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### Author:  [@Beware\_of\_Doug](https://boards.straightdope.com/u/Beware_of_Doug)
#### Post date: [July 15, 2006, 6:15pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/12 "2006-07-15T18:15:27Z")
Worst sandwich idea ever.
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### Author:  [@spingears](https://boards.straightdope.com/u/spingears)
#### Post date: [July 16, 2006, 1:42am UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/13 "2006-07-16T01:42:25Z")
> [@vetbridge](#):
>
> How do you explain the fact that of the people I know who have/have had cancer, **every last one of them have eaten peanut butter at some time in their lives**?!?😉
How many folks do you know\*\* who have eaten peanut butter at some time in their lives and DIDN"t get cancer?\*\* 😉
I understand that\*\* _some people are alergic to peanut butter._
Half the stats are meanginless. Present the WHOLE story!
How many people do you know who never or seldom ate peanut butter?
It was a pretty universal after school or such staple for kids I knew growing up.
Think I’ll go make a peanut butter and grape jelly sandwich for old times sake.
Bye! 🙂
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### Author:  [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)
#### Post date: [July 16, 2006, 2:20am UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/14 "2006-07-16T02:20:48Z")
> [@Beware of Doug](#):
>
> Worst sandwich idea ever.
Not according to Nirvana:
> [@](#):
>
> I wish I could eat your cancer when you turn black
It could only be improved by peanut butter. :eek:
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### Author:  [@Beware\_of\_Doug](https://boards.straightdope.com/u/Beware_of_Doug)
#### Post date: [July 16, 2006, 2:35am UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/15 "2006-07-16T02:35:05Z")
Evidently it could be improved even further by blowing your face off with a gun, as did the leader of said band.
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### Author:  [@Derleth](https://boards.straightdope.com/u/Derleth)
#### Post date: [July 16, 2006, 2:39am UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/16 "2006-07-16T02:39:59Z")
You got your carcinoma in my peanut butter!
You got your peanut butter on my carcinoma!
Peanut butter and cancer: The taste that grows on you.
Official snack food of the Mets.
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### Author:  [@Beware\_of\_Doug](https://boards.straightdope.com/u/Beware_of_Doug)
#### Post date: [July 16, 2006, 2:41am UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/17 "2006-07-16T02:41:14Z")
Y’know, I didn’t intend to start a full-on hijack.
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### Author:  [@Nametag](https://boards.straightdope.com/u/Nametag)
#### Post date: [July 16, 2006, 11:04am UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/18 "2006-07-16T11:04:27Z")
> [@robcaro](#):
>
> I have eaten peanut butter all my life and I don’t have cancer! I am 77 years old now.
We need your blood. Oh, and your liver.
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### Author:  [@Smeghead](https://boards.straightdope.com/u/Smeghead)
#### Post date: [July 16, 2006, 11:06pm UTC](https://boards.straightdope.com/t/peanut-butter-and-cancer/364185/19 "2006-07-16T23:06:58Z")
> [@Excalibre](#):
>
> I’ve heard speculation that organic peanut butter is far more likely to have significant aflatoxin contamination because the peanuts aren’t treated with herbicides and so forth. I don’t know if that’s really true or not, but it makes some sense.
I would be skeptical of that, personally. The molds that we’re talking about are quite common and would be likely to be found in any household. Some common bread molds produce some pretty gnarly aflatoxins. As far as I’m aware, peanut crops aren’t regularly treated with fungicides, unless perhaps there’s a specific threat like some mold that’s rampaging through the local fields, in which case it would be a specific fungicide, not one aimed at killing common household molds. The reason molds tend to come up when talking about peanut butter is because out of all microbes (molds, yeasts, bacteria, etc), they tend to be the only ones that can survive in the extremely water-poor environment peanut butter provides. The lack of competition means they have it all to themselves.
I’ve kind of lost track of my point here as I’m very hungry and rather tired right now, but I guess, like I said, I’d be skeptical of the above claim without documentation.