When a female mosquito bites you, she extracts up to 0.01 milliliters of blood in order to help her eggs mature before they hatch. Unfortunately, she leaves behind a red, itchy bump, a result of an allergic reaction to her saliva. And that's not the worst part: mosquitoes can also transmit deadly diseases, such as malaria and yellow fever. There are steps you can take to help avoid being bitten by a mosquito, but they do not include taking vitamins.
Vitamin B Research
Vitamin B is the only vitamin that has been tested to repel mosquitos. A study published in 2005 in the "Journal of the American Mosquito Control Association" tested various regimens of vitamin B administration and found no effect. Similarly, the use of a transdermal vitamin B-1 patch did not provide significant protection against mosquitoes in a study published in "Acta Tropica" in 2012. No ingested compound, including vitamins, has been shown to be effective in repelling mosquitoes, note the authors. The American Mosquito Control Association affirms that B vitamins have no impact on mosquito bites.
Clip-on personal diffuser devices containing metofluthrin or a mixture of cinnamon oil, geranium oil, eugenol and peppermint oil may be an effective defense against mosquito attacks, states the "Acta Tropica" study. Clip one onto your clothing before going outside when mosquitoes are a concern. You can also apply a topical solution directly to your skin that contains N, N-diethyl-3-methylbenzamide -- DEET -- which, according to the American Mosquito Control Association, is the standard by which all other insect repellents are measured. Citronella candles are somewhat useful for keeping mosquitoes at bay, although other smoke-producing candles may be just effective.