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Does Vitamin C Really Help With Colds? What Science Says
- Dr Joseph Nightingale
- 3 days ago
- 6 min read
You’ve got a cold. Your nose is running, you’re coughing, and you’re feeling run-down. Along with the paracetamol and cough drops, one of the top things people recommend is vitamin C. That could be a big glass of orange juice or a vitamin C supplement.
But does vitamin C really help with colds? Can it boost your immune system and help you fight back? Or does it make any difference at all? Find out below.
What is Vitamin C? And What Does It Do?
Vitamin C, also known as ascorbic acid, is a water-soluble vitamin and antioxidant used by the body for the maintenance of muscles, bones, and blood vessels. Unlike some nutrients, your body cannot produce or store vitamin C in significant amounts, which means you need a steady supply from food or supplements.
Vitamin C plays a crucial role in the immune system. It stimulates the production and function of white blood cells. As an antioxidant, it helps protect cells from everyday damage that can lead to inflammation, a weaker immune system, and long-term health problems.
The Benefits of Vitamin C
Vitamin C’s benefits go far beyond cold prevention. It helps with everything from collagen production and wound healing to heart and blood vessel protection. Here’s an overview:
Gives your immune system a helping hand. Vitamin C supports your body’s natural defences, helping you fight off bugs and potentially get over colds a little faster.
Helps keep your skin looking healthy. It’s essential for making collagen, which keeps your skin firm and helps cuts and wounds heal properly.
Looks after your heart and blood vessels. Vitamin C helps keep blood vessels in good shape and may contribute to healthy blood pressure.
Helps your body use iron properly. If you eat a lot of plant-based foods, vitamin C helps your body absorb iron more effectively.
Protects your cells behind the scenes. As an antioxidant, it helps mop up cell-damaging free radicals that build up as we age.
How Much Vitamin C Do I Need?
In the UK, the NHS recommends a daily intake of vitamin C for adults of 40mg per day. That’s roughly the amount you’d get from one medium orange, or a small handful of broccoli florets. Most people easily meet this requirement through a balanced diet that includes fruit and vegetables.
However, if you’re a smoker, recovering from illness or surgery, or are under high physical or emotional stress, you might need a little more vitamin C.
Because vitamin C is water-soluble, it isn’t stored in the body — it’s excreted in the urine. That means it’s more important to get a regular daily intake than worrying about occasional high doses.
Symptoms of Vitamin C Deficiency
True vitamin C deficiency is rare in the UK. It usually only occurs in people with very restricted diets. Early symptoms may include:
Persistent fatigue and low energy
Frequent infections or slow recovery from illness
Easy bruising
Bleeding gums
Dry, rough skin
Prolonged deficiency is known as scurvy, a condition marked by joint pain, muscle weakness, gum recession, and poor wound healing.
Always feeling run-down? It’s not always down to vitamin C. A simple fatigue blood test can help identify what’s really going on.
Does Vitamin C Help with Colds?
Vitamin C can help with colds. It’s not clear if it can prevent them, although people with a vitamin C deficiency are at increased risk of infections.
The original theory about vitamin C and colds was popularised by Nobel prize winner Linus Pauling in 1970. At the time, there were no reliable studies proving the point. Now, that’s changed. An analysis of 29 studies found that supplementing with 20 mg or more of vitamin C did not reduce the risk of catching a cold.
Some studies show that taking vitamin C in the weeks before very intense physical stress (like running a marathon) may reduce the risk of developing a cold by half — but that effect hasn’t been seen in the general population.
However, high-dose vitamin C (6–8 grams per day) in controlled studies shortened the duration of colds in children and showed a modest reduction in cold duration in adults. This is far above the recommended daily amount, and such high doses are not suitable for everyone.
“Vitamin C probably won’t stop you catching a cold, but if you’re low in it or you take it early when symptoms start, it can help reduce how bad the illness feels and how long it lasts.” Dr Ravi Gowda
Other Ways to Treat a Cold
Generally speaking, your body has to fight the cold itself. There’s no shortcut. But you can support your body, shortening the duration of the cold by:
Getting plenty of rest
Staying well hydrated with water, herbal teas, and clear broths
Using paracetamol or ibuprofen
Trying steam inhalation to relieve congestion
Drinking warm drinks (hot, ginger, and lemon work well)
Eating light, nourishing foods
Don’t push yourself. Overexertion during a cold can prolong recovery and make symptoms feel worse.
How to Prevent a Cold
When a cold goes around, it seems like everyone gets it. But some people seem to get struck down harder than others. How do you prevent a cold?
Good basic hygiene does a lot of the heavy lifting: wash your hands, avoid touching your face, and keep your distance from people who are actively unwell.
Looking after your immune system matters too. A lack of sleep, high stress, no exercise, and poor-quality foods all degrade your immune system, leaving you wide open to a cold. Focus on foods rich in vitamin C, zinc, and protein to give your immune system the building blocks it needs.
And finally, garlic. It contains natural compounds like allicin, and some studies suggest regular garlic consumption may reduce how often you catch colds.
Read More: 5 Expert Tips to Prevent Flu
Sources of Vitamin C
Vitamin C Rich Foods
Most people don’t need a vitamin C supplement; they need a balanced diet. If you’re eating plenty of fruits and vegetables, you’re almost certainly getting your daily intake of vitamin C.
Some of the best natural sources of vitamin C include:
Citrus fruits like oranges, lemons, and grapefruits
Strawberries, blackcurrants, and kiwi
Red and green peppers
Broccoli, Brussels sprouts, and spinach
Tomatoes and potatoes
Vitamin C Supplements
When a cold hits, vitamin C supplementation is smart. Your diet is likely to take a hit. Supplementing helps you to reach your daily target.
Vitamin C supplements come in many forms, including tablets, capsules, powders, chewables, and effervescent drinks. While vitamin C is generally safe, very high doses can cause stomach upset and diarrhoea in some people.
Vitamin C Supplements: What to Know
Who Should Take Vitamin C Supplements
Most people don’t need vitamin C supplements. If you eat plenty of fruits and vegetables (especially citrus fruits), you’re getting your daily intake. Even a glass of orange juice is enough.
That being said, if you don’t eat fruit and vegetables, smoke, are recovering from illness or injury, or are under high physical and mental stress, supplementation is sensible.
What Types of Supplements are Available?
Vitamin C is available in several forms, including:
Tablets and capsules – the most common and convenient option
Chewables – useful for people who dislike swallowing tablets
Powders – can be mixed into water or smoothies
Effervescent tablets – dissolve into a fizzy drink
Some vitamin C tablets add other immune-supporting ingredients such as zinc, vitamin D, or bioflavonoids.
When Is the Best Time to Take Vitamin C?
Vitamin C is fine at any time of day. Because it’s water-soluble, it’s more about consistency than timing. Your body doesn’t store it, so if it’s not being used, it’s excreted.
What Happens If I Take Too Much Vitamin C?
In most cases, nothing.
Your kidneys will simply filter out the excess vitamin C. However, if you reach very high doses, you might notice stomach cramps, diarrhoea, nausea, or bloating. Extremely high doses over prolonged periods increase the risk of kidney stones. It’s not advised to exceed the recommended dosage.
Keeping Well During Cold and Flu Season
Colds are common, but flu can be far more serious. In older adults and people with underlying health conditions, it’s a major concern. If you’re eligible, a seasonal flu jab is one of the most effective ways to protect yourself and those around you.
Regular health checks are also crucial to identifying underlying issues. Our comprehensive Well Woman Check and Well Man Check assess key markers linked to fatigue, immunity, hormones, and overall health. We offer personalised advice based on the results, keeping you fit and well throughout the cold and flu season.
References
Vitamin C: Benefits and How Much You Need | Cleveland Clinic
Vitamin C for preventing and treating the common cold | Cochrane Database Syst Rev.
20 Foods That Are High in Vitamin C | Healthline
Common colds: Research summaries – Does vitamin C prevent colds? | NIH
Written by:
Dr Joseph Nightingale, MBBS, MSc
Approved by:
Consultant Physician in General Internal Medicine
MBBS, MRCP(UK), DTM&H, MRCGP, DCH, DRCOG, DFFP