What it is
Vitamin C is a water-soluble antioxidant with two headline jobs: building collagen (skin, tendons, blood vessels — the body's scaffolding) and boosting iron absorption from plant foods. Your body doesn't store much and can't make any, so it wants a steady supply.
How much
Around 75–90 mg a day for adults covers the reference intake — a single bell pepper or a couple of kiwis. Smokers need meaningfully more. True deficiency (scurvy) is rare and takes months of near-zero intake; the megadose habit, meanwhile, mostly produces expensive urine — excess is excreted, and the cold-prevention evidence is thin.
How well it's tracked
Moderately. Vitamin C left many modern labels, but the produce that carries it is well covered in generic food data — your number will be most accurate on whole-food days.
Food sources
Bell peppers (the quiet champion), citrus, kiwi, strawberries, broccoli, tomatoes, and potatoes — which, eaten daily, have prevented more scurvy than oranges ever did.
In the app
Vitamin C has its Insights card with contributors and history. Plant-based and iron-conscious? Pairing C-rich foods with iron-rich meals is the practical trick worth stealing.