A long-standing medical myth suggests that taking vitamin B1, also known as thiamin, can trick your body into repelling mosquitoes.
A “systemic repellent” that makes your whole body unattractive to biting insects certainly sounds good. Even if you correctly reject the disinformation examination sure and efficient repellents As DEEToral repellents would still have the advantage that you wouldn’t have to worry about covering every inch of exposed skin or carrying containers of insecticide every time you venture outdoors.
In addition to thiamin, other suspected oral mosquito repellents include beer yeastwhich contains thiamin, and Garlicthe legendary vampire repellant. If oral repellents sound too good to be true, that’s because they are.
As a professor of entomology in Taiwan, where the mosquito-borne dengue virus is endemic, I was curious to know what the science really says about food-based repellents. After a very deep dive into the literature and reading virtually every article ever written on the subject, I have compiled this knowledge into the first Systematic review from subject.
The scientific consensus is, unequivocally, that oral repellents do not exist. Despite extensive researchNope dietary supplement, medication or condition has never been proven to make people repulsive. People who are deficient in vitamin B1 also do not attract more mosquitoes.
So where does the myth come from that mosquitoes hate vitamins, and why is it so hard to exterminate?
Making a myth
In 1943, a Minnesota pediatrician W. Ray Shannon gave 10 patients varying doses of thiamin, who had only first synthesized seven years ago. They reported that it relieved itching and prevented further mosquito bites. In 1945, a Californian pediatrician howard eder claimed that doses of 10 milligrams could protect people against fleas. In Europe in the 1950s, physician Dieter Muting claimed that daily doses of 200 milligrams kept him bite-free while vacationing in Finland, and speculated that a thiamine breakdown product was expelled through the skin.
These discoveries attracted rapid attention and almost immediate repudiation. The United States Naval Medical Research Institute tried to replicate Shannon’s findings, but failed. In 1949, Californians using thiamine to repel dog fleas reported it as “completely worthless.” Controlled studies of Swiss at Liberia repeatedly failed to find effects at any dose. The first one clinical test in 1969 concluded definitively that “Vitamin B1 is not a systemic mosquito repellent in man”, and all controlled studies since suggest the same for thiamin, beer yeast, Garlicand other alternatives.
The evidence was so overwhelming that in 1985 the The US Food and Drug Administration has declared all oral insect repellents are “are generally not recognized as safe and effective and are mislabeledmaking the labeling supplements technically fraudulent repellents.
The medical mechanisms are not there
Scientists know a lot more about mosquitoes and vitamins today than ever before.
Vitamin B1 does not break down in the body and has no known effects on the skin. The body strongly regulates it, absorbing little thiamine ingested after the first 5 milligrams and quickly excrete any excess via urine, so that it does not build. Overdose is almost impossible.
The best sources of thiamin are whole grains, beans, pork, poultry and eggs. If eating a carnitas burrito won’t repel mosquitoes, neither will a pill.
What explains the early reports, then? In addition to poor quality experimental design, many have used anecdotal reports of patients indicating fewer bite symptoms as an indicator of reduced bite, which is not a good way to get an accurate picture. of what is happening.
Mosquito bites are followed by two reactions: an immediate reaction which begins quickly and lasts for hours and a delayed reaction which lasts for days. The presence and intensity of these reactions does not depend on the mosquito, but on the familiarity of your own immune system with the saliva of that particular species. With age and continued exposure, the body goes from no reaction, to only delayed reaction, to both, to only immediate reaction, and finally to no reaction.
What Shannon and others thought was repulsion might have been desensitization: Patients were still getting bitten, they just stopped showing symptoms.
So what is the problem?
Despite scientific consensus, a 2020 survey of pharmacists in Australia found that 27% still recommended thiamine as a repellent to patients traveling abroad: an unacceptable recommendation. Besides wasting money, people who rely on vitamins for protection against mosquitoes can still get bitten, potentially putting them at risk of diseases As West Nile and malaria.
To circumvent the US ban and the widely accepted scientific consensus on oral repellents, some unscrupulous dealers manufacture thiamine patches or even injections. Unfortunately, although thiamine is safe to ingest, it box cause strict allergic reactions when taken by other routes. These products are therefore not only without valuebut also potentially dangerous.