Vitamin B repels mosquitoes: true or false?

Depending on who you hear it from, one or other of the B vitamins is supposed to keep mosquitoes at bay, but it doesn’t really matter which because none have ever been shown to be effective when taken as supplements.

And people have checked. For us mosquito bites are just an itchy, painful annoyance, but for great swathes of the world mosquitoes carry disease, from malaria to dengue fever. Despite a careful search, however, there are as yet no known insect repellents that can be taken as a pill.

The most effective insect repellent that we do have is the synthetic N,N-Diethyl-3-Methylbenzamide, or DEET, which is the active ingredient in most insect repellents. Like most others this is applied to the skin where it slowly vaporises, and it is the vapour — the smell — that keeps the insects away. Good insect repellents are hard to find because they must combine so many properties: distasteful to insects, safe for humans, volatile enough to evaporate off the skin but stable enough to last for a while.

It’s not easy to outwit the finely honed tracking system of a mosquito. They locate us by following our heat, our expired carbon dioxide, even our sweat. No matter what we’re doing, whether running a marathon or sleeping peacefully, they can find us. And they are persistent. When it comes to insect repellent, it isn’t enough just to waft some around yourself and hope for the best — unless all exposed skin is covered the blood suckers will happily land on the unprotected parts.

So an oral insect repellent is an alluring dream. A pill you could pop which would cause your skin to exude insect repellent would be a great convenience. Especially if it was already part of our body chemistry.

Alas it currently remains a dream. Though there is some hope that some natural component of our own biochemistry (or at least the biochemistry of those smug individuals who seem to be spared the insect onslaught) could be amplified to repel insects, that component is not vitamin B.

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