Food Preparations
Here's something that surprises people: how a food is prepared can change its nutrition before it ever hits your plate, sometimes for better, sometimes for worse. Same ingredient, different outcome.
Raw
Some foods keep more of certain nutrients when raw, especially heat-sensitive ones like vitamin C and some B vitamins. But raw isn't automatically "healthier." Cooking some veggies actually unlocks nutrients; for example, cooked tomatoes and carrots release more lycopene and beta-carotene than raw ones do. Raw prep also carries higher food-safety risk for certain items (meat, eggs, sprouts), which is exactly why proper handling matters.
Boiling/steaming
Steaming keeps more nutrients than boiling (boiling leaks water-soluble vitamins like C and some B's into the water, callback to your vitamins section).
Roasting/baking
Uses little or no added fat, brings out flavor; a solid everyday default.
Sautéing/stir-frying
Quick, uses a little oil (ideally an unsaturated one); actually helps you absorb fat-soluble vitamins from veggies.
Grilling
Flavorful and low-fat, with a quick note that charring meat heavily can create some not-great compounds, so don't burn it to a crisp.
Frying (deep/pan)
Tastes great but adds a lot of fat and calories, and if the oil's been reused/overheated it's worse; an "enjoy sometimes" method.
Canned
Canning preserves food for ages without refrigeration, making it affordable, accessible, and low-waste. Canned beans, veggies, and fruit are legit nutrition staples, not a lesser choice. Produce is usually canned at peak ripeness, so it can be just as nutritious as fresh--sometimes more so than "fresh" produce that spent a week traveling. Just watch for added sodium (in canned veggies and soups) and added syrup (in canned fruit). Pro tip: rinse canned beans and veggies to cut sodium significantly, and pick fruit canned "in its own juice" to skip added sugar.
Frozen
Frozen produce is also flash-frozen at peak ripeness and is nutritionally right up there with fresh, often at a friendlier price. It's a genuinely underrated hero of the grocery store.
Irradiated
Food irradiation uses controlled doses of radiation to kill bacteria, insects, and pathogens, extending shelf life and improving safety. It does not make your food radioactive (a super common myth), and it's regulated and used on things like spices, some meats, and produce. It causes minimal nutrient loss, on par with other preservation methods like canning or pasteurization.
Fermented
Fermentation uses bacteria or yeast to break food down, which can boost certain nutrients and add beneficial probiotics: how you doin (Friends reference) yogurt, kimchi, and sauerkraut. Great news for your gut microbiome (see digestion topic for more information on the gut microbiome).
Dried
Drying pulls the water out to preserve food (think dried fruit or jerky). Just know it concentrates everything, nutrients and sugar/calories, so portion size matters more than with the fresh version. A handful of raisins packs a lot more sugar than the same handful of grapes.