The 40mg target

The NHS says adults aged 19 to 64 need 40mg of vitamin C a day. That is a very small number by nutrient standards. A single medium orange delivers somewhere around 50mg. A kiwi fruit lands at roughly 60mg. A 100g portion of red pepper clears the day twice over.

"You should be able to get all the vitamin C you need from your daily diet," the NHS advises. For most adults eating a reasonable variety of fruit and vegetables across the week, that is simply true. The gap between what the target asks and what a normal meal provides is not a wide one.

"A single kiwi fruit delivers roughly 60mg. The daily target is 40mg."

Where things get more interesting is the cooking question, the iron connection, and understanding which foods punch well above their weight so you can lean on them with confidence.

What vitamin C actually does

Vitamin C is a workhorse for connective tissue. Your body uses it to produce collagen, the structural protein that holds skin, blood vessels, bones, and cartilage together, and that drives wound healing when something goes wrong. It also plays a role in keeping your immune system ticking over, though the evidence for large doses preventing colds is not as strong as the marketing tends to imply.

The function that most people do not know about is its effect on iron absorption. Vitamin C consumed alongside plant-based iron sources, what the BDA calls non-haem iron, helps your body absorb significantly more of that iron. Lentils, spinach, fortified cereals and other plant foods carry iron that your gut is naturally less efficient at extracting than haem iron from meat. Vitamin C tips the balance in your favour. More on that below.

The big-portion winners

These are the foods that do disproportionate work per normal serving. Portions are what you would actually eat in a sitting, not a laboratory weight.

Good sources from a normal shop Red bell peppers, 100g raw (roughly half a pepper): well over twice the daily target in a single portion. The highest concentration of any common supermarket vegetable. Kiwi fruit, one medium: clears the day on its own, with a bit to spare. Strawberries, a 100g serving (about seven or eight berries): a solid single-day contribution. Oranges, one medium: meets or exceeds the 40mg target. Broccoli, an 80g portion cooked (one of your five-a-day): a good contributor, with the caveat that cooking method matters.

Blackcurrants, when in season, are exceptionally high. Potatoes contribute more than most people realise, not because the concentration is dramatic but because portion sizes tend to be generous and they are eaten daily by many adults. Brussels sprouts are worth a mention for the same reason: an 80g serving at Christmas dinner is doing real nutritional work.

Cooking and storage trim it

Vitamin C is water-soluble and heat-sensitive. When broccoli boils in a large pot of water for ten minutes, a significant fraction of the vitamin C ends up in the water you pour down the drain. Brief steaming or stir-frying in a small amount of oil preserves considerably more. Microwaving is also gentler than boiling, despite its reputation.

Storage matters too. Vegetables sitting in the fridge for several days lose some of their vitamin C before you eat them. Frozen vegetables, picked and frozen quickly after harvest, often retain their vitamin C content better than fresh produce that has travelled and sat for a week.

Raw fruit is the simplest case: it retains everything. An orange eaten whole, a kiwi sliced and eaten at breakfast, a handful of strawberries with yoghurt. No cooking, no loss.

The supplement question

The body can only absorb so much vitamin C at once. Above roughly 200mg, absorption rates drop off and most of the excess is excreted in urine. Taking a 1,000mg supplement does not deliver ten times more benefit than 100mg; the biology does not work that way.

The NHS does not recommend high-dose vitamin C supplementation for healthy adults. There is no established benefit at megadose levels for most people, and the gut can complain: stomach pain, diarrhoea, and flatulence are the common side effects at doses above 1,000mg daily. The NHS note that taking less than 1,000mg a day is unlikely to cause harm, but the default recommendation remains to get vitamin C from food rather than from high-dose supplements.

For most adults, varying fruit and vegetables across the week is enough. The target is 40mg. A varied diet reaches it without counting anything.

Pair with non-haem iron

This is where vitamin C earns its place beyond the basics. The BDA notes that "eating plant-based non-haem iron with foods containing vitamin C can help your body absorb the iron." In practice, this means: a glass of orange juice with a lentil curry, a squeeze of lemon over wilted spinach, or strawberries alongside a bowl of fortified breakfast cereal. The vitamin C changes how your gut processes the iron, making the pairing more efficient than either food on its own.

Tea and coffee do the opposite. Tannins in both drinks interfere with iron absorption when you drink them close to an iron-rich meal. If you are keeping an eye on iron, a gap of an hour between the meal and your brew helps. The vitamin C, however, is working in your favour at the table.

If you want to read more about iron specifically, including the haem versus non-haem difference and which foods carry the most, our piece on foods high in iron covers the ground in detail.

A short, honest note

This page is a practical guide, not a clinical consultation. If you are concerned about your vitamin C levels or are managing a specific health condition, a GP or registered dietitian is the right person to talk to.