When I was a kid, my grandma always told me that I should drink hot beverages on a hot day to cool myself down. I thought she was insane. Downing a steamy cup of tea sounds like the opposite of what one should do on a scorching summer day, doesn't it? Well apparently, grandma was right. One researcher at University of Ottawa's School of Human Kinetics told Smithsonian Magazine, "If you drink a hot drink, it does result in a lower amount of heat stored inside your body, provided the additional sweat that's produced when you drink the hot drink can evaporate." So if you're dying of heat (and you're not in the rainforest), go ahead and turn the kettle on.
There are plenty of other surprising examples of old wives' tales and remedies that sound like snake oil turning out to be totally legit, and this interesting Reddit thread is full of 'em. Keep scrolling.
"Infrared and Red Light Therapy is amazing. I took part in a US Air Force study on alternative medicine when I was in the Army. At the time, my left leg was in bad shape. I could barely walk because the nerves wouldn't work and the pain would be so intense that I'd collapse. I went to the study and a man with a ponytail told me to take off my shirt and lay on the table. This f-ckin guy starts dangling a crystal over parts of my body and tells me my chakras were f-cked up. This guy pulls out a single red LED and holds it next to my belly button for a minute and tells me to get up and walk down the hall. I cannot explain to you how f-cking furious I was that it worked. It didn't work because I wanted it to and he helped me trick my brain, it worked because it worked." —moon_or_crash
"I got a legitimate laugh out of the mental image of a guy in fatigues walking down the hall frowning and saying 'Oh, God damnit! I'm cured.' So thanks for that." —Paige_Railstone
"You can also use coffee filters." —ShadowWolfKane
"I tried the opposite and my coffee just tasted like yesterdays news" —BeneficialAd9435
"Helps with constipation as well. Not like a laxative that relieves constipation. But as a preventative measure. You'll sh-t like a champ if you take it daily." —EssentialFilms
"Oh this is a good one! I have BPPV and when my doctor went 'you gotta slam yourself around a little to knock the crystals out of your ears' a was like 'uuuhhhh, is this guy really an MD or did I go to a homeopath by mistake?' But it's no joke, it fixes me immediately." —Velociraptornuggets