Vitamin C in Winter: How Much You Need and Best Sources

As the nights draw in, vitamin C is one of the first supplements people reach for. But how much do you actually need, can you get enough from food in a British winter, and is there any point in taking more if you train hard? This guide covers the official UK guidance, the best winter food sources, and when a supplement can make sense.

What vitamin C does

Vitamin C (ascorbic acid) is a water-soluble vitamin that humans cannot make, so it has to come from the diet every day. It has a long list of authorised health claims in the UK. Vitamin C contributes to:

• the normal function of the immune system;
• the protection of cells from oxidative stress;
• normal collagen formation for the normal function of blood vessels, bones, cartilage, gums, skin and teeth;
• normal energy-yielding metabolism;
• the reduction of tiredness and fatigue;
• normal psychological function and the normal functioning of the nervous system.

It also increases iron absorption, which is useful if you eat little or no red meat, because it helps your body absorb the non-haem iron found in plant foods.

How much vitamin C do you need?

The NHS says adults aged 19 to 64 need 40 mg of vitamin C a day, and that most people should be able to get this from a varied, balanced diet. That is a modest amount: a single orange or a handful of strawberries covers it.

At the other end of the scale, the NHS advises that taking large amounts (more than 1,000 mg a day) can cause stomach pain, diarrhoea and flatulence, and that these symptoms should go once you stop taking the supplements. Taking less than 1,000 mg a day from supplements is unlikely to cause harm.

Because vitamin C is water-soluble, your body does not build up big reserves. Excess is excreted, which is one reason a regular daily intake matters more than occasional large doses.

The best winter sources of vitamin C

You do not need summer berries to hit your target. Many of the best sources are in season or easy to find in UK supermarkets right now:

Food	Typical portion	Approx. vitamin C
Red pepper	Half a pepper (80 g)	100+ mg
Brussels sprouts	8 sprouts (80 g), lightly cooked	40–60 mg
Kiwi fruit	1 medium	around 50–60 mg
Orange or 2 clementines	1 medium orange	around 50–70 mg
Broccoli	80 g, steamed	around 40–50 mg
Potatoes	Medium jacket potato	10–20 mg

Values vary with variety, freshness and cooking. Vitamin C is sensitive to heat and leaches into cooking water, so steaming, microwaving or quick stir-frying keeps more of it than long boiling. Frozen vegetables are a perfectly good option and often retain vitamin C well.

Who might fall short?

Although the target is low, some people do struggle to reach it consistently, particularly in winter when fresh produce feels less appealing. Groups more likely to have low intakes include:

• people who eat very few fruits and vegetables;
• smokers, who are generally advised to consume more vitamin C;
• people on very restrictive diets;
• older adults with small appetites.

The fix starts with food: adding one vitamin C-rich fruit or vegetable to each meal is simple and effective. A supplement can then act as a back-up on busy days.

Vitamin C and training

Hard training puts the body under stress, and winter often means training in cold, dark conditions on top of work and family commitments. There is a specific authorised claim relevant to active people: vitamin C contributes to maintain the normal function of the immune system during and after intense physical exercise. This claim applies to a daily intake of 200 mg of vitamin C in addition to the recommended daily intake.

In practice, that makes a 200 mg-plus vitamin C supplement a reasonable choice during heavy blocks of training, such as a winter marathon build or an intense strength phase. It is not a substitute for sleep, sensible training loads and a good diet, which remain the foundations.

Vitastrong Vitamin C is a simple, pure vitamin C tablet with no added extras, in a 200-tablet pack.

If you want to pair it with another nutrient, zinc also contributes to the normal function of the immune system. Our Vitamin C + Zinc combines both in one daily tablet.

Common questions about timing and form

Should I take it with food?

Taking vitamin C with a meal can reduce the chance of stomach discomfort, and if that meal includes plant sources of iron, the vitamin C will also help you absorb it.

Is "buffered" or "slow-release" better?

For most people, plain ascorbic acid works well. Buffered forms may suit people with sensitive stomachs; slow-release forms are a matter of preference rather than a clear advantage.

Can vitamin C stop me catching a cold?

No supplement can promise that. Vitamin C contributes to the normal function of the immune system, but good hand hygiene, sleep, a balanced diet and staying active remain the foundations of a sensible winter routine.

For a wider look at winter nutrition, see our guide to vitamin D in the UK winter and our winter immune support stack.

Products mentioned in this article

FAQs

How much vitamin C do adults need per day?

The NHS recommends 40 mg a day for adults aged 19 to 64, which most people can get from a varied diet.

Is 1,000 mg of vitamin C too much?

The NHS says supplements below 1,000 mg a day are unlikely to cause harm. Higher amounts can cause stomach pain, diarrhoea and flatulence.

What is the best food source of vitamin C in winter?

Red peppers, Brussels sprouts, kiwi, citrus fruit and broccoli are all excellent and widely available in winter.

Do athletes need more vitamin C?

An authorised claim states that vitamin C contributes to maintain the normal function of the immune system during and after intense physical exercise, at 200 mg a day on top of normal intake.

Can I take vitamin C with vitamin D?

Yes. They do different jobs and can be taken together. In the UK, the government advises everyone to consider a daily vitamin D supplement in autumn and winter.

Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle.