8 Old Wives’ Tales That Science Has Actually Backed Up

When you were sick as a child, someone put a bowl of hot chicken soup in front of you. It felt like love—and, it turns out, it was also medicine. In 2000, Dr. Stephen Rennard of the University of Nebraska Medical Center published a study in the journal Chest that tested chicken broth in a laboratory setting. His team found that the soup inhibited the movement of neutrophils—white blood cells that cause the kind of inflammation responsible for the miserable congestion and achiness you feel during a cold.

The study was modest in scope, and Rennard himself joked that he originally submitted the findings partly for their amusement value. But the result was real. The broth appeared to slow the migration of those neutrophils, meaning less swelling in the upper respiratory tract. Add to that the steam (which loosens congestion), the fluid (which keeps you hydrated), and the simple act of sitting quietly with something warm, and your grandmother’s prescription turns out to be backed by genuine biology.

The old advice to take a spoonful of honey for a cough sounds quaint—until you learn that a 2007 study from Penn State College of Medicine tested it head-to-head against dextromethorphan, the active ingredient in many over-the-counter cough syrups. The study enrolled 105 children between the ages of two and eighteen. One group got buckwheat honey before bed. Another got the cough medicine. A third got nothing.

The honey group came out on top. Parents reported that the children who got honey had less coughing and slept better than those given the medication—and the medication itself wasn’t significantly better than no treatment at all. The researchers were careful to note that infants under one year should never have honey, and that buckwheat honey was the specific variety studied. But for older children—and, by reasonable extension, adults—that sticky golden spoonful your great-aunt swore by is no longer just folklore.

The saying goes back centuries, but modern researchers have given it something previous generations lacked: a mechanism. Studies going back to 1989 have measured what happens in the body during a genuine, sustained laugh. The short answer is that stress hormones fall. Cortisol—the hormone most associated with chronic stress—drops measurably after periods of laughter, and so does epinephrine, which is essentially adrenaline.

A 2014 Loma Linda University study took this further, testing older adults who watched a funny video versus those who simply sat quietly. The laughter group showed significantly lower cortisol levels afterward and performed better on memory tests. That’s not nothing: the same stress hormones that drop when you laugh are the ones that, when chronically elevated, suppress the immune system and impair memory. Your grandmother’s insistence that you find the humor in things wasn’t just good cheer. It was, quietly, sound advice for your health.

Garlic has been used medicinally for thousands of years across dozens of cultures. Skeptics long assumed it was wishful thinking. But a 2019 meta-analysis published in Experimental and Therapeutic Medicine pooled the results of twelve randomized controlled trials and found that garlic supplements reduced systolic blood pressure by an average of around 8 mmHg in people with hypertension—a meaningful number in cardiovascular terms.

The active compound is allicin, which forms when garlic is crushed or chopped and appears to relax the walls of blood vessels. The studies examined garlic in supplement form—powder, aged extract, tablets—rather than raw cloves from a kitchen, so the amounts involved were concentrated. Still, the underlying chemistry is real. Garlic’s reputation as a health food has survived thousands of years of folk tradition and now has a stack of controlled trials to show for it—which puts it in a category that most superfoods can only dream of reaching.

This one comes with a small asterisk, but the underlying science is solid. Carrots are rich in beta-carotene, which the body converts into vitamin A. And vitamin A is essential for producing rhodopsin—the light-sensitive pigment in the rod cells of your eyes that allows you to see in low light. Severe vitamin A deficiency causes night blindness, and restoring adequate intake genuinely reverses it.

The asterisk: if your diet already supplies enough vitamin A, eating extra carrots won’t give you superhuman night vision. The claim breaks down when taken to an extreme. (The wartime British story that RAF pilots eating carrots developed remarkable night sight was propaganda designed to conceal radar technology.) But the core idea—that carrots contain something your eyes actually need—is simply true. Cooked carrots with a little fat, it turns out, are even better, since beta-carotene is fat-soluble and absorbs more readily with a bit of oil alongside.

The phrase “fish is brain food” has been repeated at dinner tables for so long that it started to feel like something people just said. Then the researchers began looking more carefully. A meta-analysis of 21 studies involving more than 180,000 people found that those who ate more seafood were significantly less likely to be diagnosed with dementia or Alzheimer’s disease. The connection appeared strongest for DHA, the omega-3 fatty acid found in high concentrations in fish—and, not coincidentally, in the human brain itself.

Brain tissue is extraordinarily rich in lipids, and researchers believe the fatty acid content of your diet influences the fatty acid composition of your brain tissue over time. The effect seems more pronounced from whole fish than from isolated supplements—a reminder that food has a way of delivering its benefits in packages that prove difficult to reassemble in a pill. Whether it’s tuna, salmon, or the sardines your grandmother insisted on, the old instinct to put fish on the table for the sake of clear thinking appears to have been right all along.

You couldn’t really test whether an apple a day keeps the doctor away until researchers at the University of Michigan tried in 2015. They analyzed data from 8,399 survey participants and compared apple eaters with everyone else. The finding was modest but genuine: people who ate an apple every day were significantly less likely to be taking prescription medications than non-apple-eaters.

Fewer visits to the doctor? The study couldn’t confirm that specifically. But the prescription result held even after controlling for other factors—and Harvard’s own nutrition researchers point to two likely reasons: quercetin, an antioxidant concentrated in apple skins, and pectin, a soluble fiber that feeds beneficial gut bacteria and helps regulate cholesterol. Neither of those is magic. Both of them are genuinely useful things for your body to have. The apple, it turns out, is a delivery vehicle for compounds your body knows exactly what to do with.

Generations of families across Europe and Latin America have taken a short walk after the evening meal as a matter of course—the Italian passeggiata, the Spanish sobremesa extending into an evening stroll. The explanation was always vague: it “helps digestion.” The actual reason is more specific and, for anyone watching their blood sugar, rather important.

A 2022 study in the journal Nutrients found that a 30-minute brisk walk after a meal substantially reduced the peak rise in blood glucose compared with sitting. Earlier trials confirmed that even a slow 15-minute walk after a carbohydrate-heavy meal made a measurable difference. The mechanism: when your muscles are moving, they pull glucose directly out of the bloodstream—reducing the spike that follows eating and easing the work the pancreas has to do. That’s not metaphorical “settling.” It’s your body handling its post-meal chemistry with a bit of help from your feet.