# Guinness and mosquitos? **URL:** \ **Category:** Factual Questions\ **Created:** [March 3, 2006, 6:04pm UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930 "2006-03-03T18:04:46Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![tdn](https://avatars.discourse-cdn.com/v4/letter/t/94ad74/32.png) [@tdn](https://boards.straightdope.com/u/tdn)\ **Post date:** [March 3, 2006, 6:04pm UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930/1 "2006-03-03T18:04:46Z")
I just overheard this bit of lore that pinged my BS meter: In the summer, drink Guinness Extra Stout. It will make your blood bitter and mosquitos will leave you alone. The person who said admitted to not ever having tried it. Well? ---
**Author:** ![irishgirl](https://avatars.discourse-cdn.com/v4/letter/i/8edcca/32.png) [@irishgirl](https://boards.straightdope.com/u/irishgirl)\ **Post date:** [March 3, 2006, 6:16pm UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930/2 "2006-03-03T18:16:27Z")
Well, Guinness has various B vitamins, and my local health food shops suggest taking vitamin B complex to ward off insects, but I have no idea if it works. ---
**Author:** ![tdn](https://avatars.discourse-cdn.com/v4/letter/t/94ad74/32.png) [@tdn](https://boards.straightdope.com/u/tdn)\ **Post date:** [March 3, 2006, 8:47pm UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930/3 "2006-03-03T20:47:27Z")
> [@irishgirl](#): > > Well, Guinness has various B vitamins, and my local health food shops suggest taking vitamin B complex to ward off insects, but I have no idea if it works. Why would Guinness have vitamins not found in other beers? AFAIK, the only _real_ difference is the addition of nitrogen. ---
**Author:** ![Left\_Hand\_of\_Dorkness](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/left_hand_of_dorkness/32/7156_2.png) [@Left\_Hand\_of\_Dorkness](https://boards.straightdope.com/u/Left_Hand_of_Dorkness)\ **Post date:** [March 3, 2006, 9:15pm UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930/4 "2006-03-03T21:15:57Z")
> [@tdn](#): > > Why would Guinness have vitamins not found in other beers? AFAIK, the only _real_ difference is the addition of nitrogen. Unfiltered beer still contains yeast cells, which are rich in B vitamins. [cite](http://www.dtphoto.com/brewing/blog.html) (not a very good one, but I’m virtually certain this is true). Guinness won’t contain more B than other unfiltered beers necessarily, but it’ll contain more than filtered beers. Daniel ---
**Author:** ![ExTank](https://avatars.discourse-cdn.com/v4/letter/e/35a633/32.png) [@ExTank](https://boards.straightdope.com/u/ExTank)\ **Post date:** [March 3, 2006, 9:20pm UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930/5 "2006-03-03T21:20:50Z")
Will the miracles of beer never cease? ---
**Author:** ![silenus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/silenus/32/166_2.png) [@silenus](https://boards.straightdope.com/u/silenus)\ **Post date:** [March 3, 2006, 9:22pm UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930/6 "2006-03-03T21:22:00Z")
Brilliant! ---
**Author:** ![Freddy\_the\_Pig](https://avatars.discourse-cdn.com/v4/letter/f/a587f6/32.png) [@Freddy\_the\_Pig](https://boards.straightdope.com/u/Freddy_the_Pig)\ **Post date:** [March 3, 2006, 9:26pm UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930/7 "2006-03-03T21:26:57Z")
But . . . but . . . even assuming that they care, how do mosquitos know how much Vitamin B you have in your blood without biting? 😕 And once they’ve bitten, what’s the use? ---
**Author:** ![tdn](https://avatars.discourse-cdn.com/v4/letter/t/94ad74/32.png) [@tdn](https://boards.straightdope.com/u/tdn)\ **Post date:** [March 3, 2006, 9:28pm UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930/8 "2006-03-03T21:28:45Z")
> [@Left Hand of Dorkness](#): > > Guinness won’t contain more B than other unfiltered beers necessarily, but it’ll contain more than filtered beers. So why Guinness specifically, then? Unless the people saying this think that most quality brews are Heineken, Molson, and Colt. Maybe they don’t know of any other unfiltered beers. ---
**Author:** ![Left\_Hand\_of\_Dorkness](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/left_hand_of_dorkness/32/7156_2.png) [@Left\_Hand\_of\_Dorkness](https://boards.straightdope.com/u/Left_Hand_of_Dorkness)\ **Post date:** [March 3, 2006, 9:48pm UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930/9 "2006-03-03T21:48:37Z")
> [@tdn](#): > > So why Guinness specifically, then? > > Unless the people saying this think that most quality brews are Heineken, Molson, and Colt. Maybe they don’t know of any other unfiltered beers. I think you’ve got it. Guinness is, and this is a total WAG, the bestselling unfiltered beer in the US (and probably in the English-speaking world). Daniel ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 3, 2006, 9:49pm UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930/10 "2006-03-03T21:49:54Z")
If you have the beer sitting out in front of you, it’s conceivable that Guiness would be better than most. One of the things mosquitoes home in on is carbon dioxide, since many sources of carbon dioxide contain blood. The bubbles in a regular beer will be CO[sub]2[/sub], and so might conceivably attract mosquitoes, but the nitrogen bubbles in Guiness would not (I presume that Guiness still contains some CO[sub]2[/sub], but not as much as other beers). On the other hand, if this is the mechanism, you’d be better yet with flat beer of any variety, or no beer at all. ---
**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://boards.straightdope.com/u/matt)\ **Post date:** [March 3, 2006, 10:52pm UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930/11 "2006-03-03T22:52:08Z")
> [@Freddy the Pig](#): > > But . . . but . . . even assuming that they care, how do mosquitos know how much Vitamin B you have in your blood without biting? 😕 And once they’ve bitten, what’s the use? In my experience, people who take large doses of B vitamins smell of B vitamins. I guess the smell is supposed to put the mozzies off. Similar claims have been made for [marmite](http://www.ihatemarmite.com/marmite/marmite.asp?section=marmite&id=79) on the same basis. Trouble is, vitamin B doesn’t seem to do anything against mosquitoes in controlled trials. Although Google “vitamin B” with “mosquitoes” and you’ll find no end of people claiming their B supplements stopped them getting bitten. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [March 4, 2006, 12:23am UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930/12 "2006-03-04T00:23:52Z")
> [@Chronos](#): > > If you have the beer sitting out in front of you, it’s conceivable that Guiness would be better than most. One of the things mosquitoes home in on is carbon dioxide, since many sources of carbon dioxide contain blood. The bubbles in a regular beer will be CO[sub]2[/sub], and so might conceivably attract mosquitoes, but the nitrogen bubbles in Guiness would not (I presume that Guiness still contains some CO[sub]2[/sub], but not as much as other beers). > > On the other hand, if this is the mechanism, you’d be better yet with flat beer of any variety, or no beer at all. No, no. You need a Guiness in your hand and a bucket of dry ice way over yonder at the other end of the yard! ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [March 4, 2006, 1:11am UTC](https://boards.straightdope.com/t/guinness-and-mosquitos/346930/13 "2006-03-04T01:11:17Z")
> [@Chronos](#): > > If you have the beer sitting out in front of you, it’s conceivable that Guiness would be better than most. One of the things mosquitoes home in on is carbon dioxide, since many sources of carbon dioxide contain blood. The bubbles in a regular beer will be CO[sub]2[/sub], and so might conceivably attract mosquitoes, but the nitrogen bubbles in Guiness would not (I presume that Guiness still contains some CO[sub]2[/sub], but not as much as other beers). > > On the other hand, if this is the mechanism, you’d be better yet with flat beer of any variety, or no beer at all. Correct me if I’m wrong, but isn’t Guinness Extra Stout only available in CO2 carbonated bottles? All the ones I’ve seen with widgets and at the pub are not extra stout.