Vitamin C helps your body build and repair tissue, fight off infections, and protect cells from damage

Vitamin C is a nutrient your body cannot make on its own, so you need to get it from food or supplements. It does three main jobs: it helps form collagen (the protein that holds skin, bones, and tendons together), it strengthens your immune system by supporting white blood cells, and it acts as an antioxidant to protect your cells from damage caused by free radicals—unstable molecules that build up over time.

Most people think of vitamin C only when they have a cold, but it works in your body every day. It helps wounds heal, keeps your gums healthy, and makes it easier for your body to absorb iron from plant-based foods. Without enough vitamin C, your body cannot do these repairs and defenses well.

Key Takeaways

  • Vitamin C helps your body make collagen, which is the structural protein in skin, bones, joints, and connective tissue.
  • It supports your immune system by helping white blood cells work more effectively to fight infection.
  • As an antioxidant, vitamin C protects your cells from damage that can build up over decades.
  • Your body does not store vitamin C, so you need to eat sources of it regularly—most people get enough from food alone.

How vitamin C strengthens your immune system

Vitamin C helps your white blood cells—the cells that identify and fight infections—work more effectively. When you have enough vitamin C, these cells can move faster and respond more quickly to threats like bacteria and viruses. This does not mean vitamin C prevents you from getting sick, but it may help your body mount a faster defense.

The research on vitamin C and colds is mixed. Studies show that for most people, taking extra vitamin C does not prevent colds from happening. However, for people under extreme physical stress (like athletes training hard or people in very cold climates), getting enough vitamin C may reduce how often they catch colds. Once a cold starts, vitamin C does not seem to shorten it much, though some studies suggest it might reduce how severe symptoms feel.

Vitamin C and collagen: why your skin, bones, and joints need it

Collagen is the most common protein in your body. It gives structure to your skin, keeps your bones strong, holds your joints together, and supports your gums and blood vessels. Your body cannot make collagen without vitamin C—the nutrient is literally required for the chemical reaction that builds it.

This is why vitamin C matters for wound healing. When you cut yourself or have surgery, your body needs to build new collagen to close the wound and form scar tissue. Without enough vitamin C, this process slows down. For older adults or people recovering from injury, getting enough vitamin C is part of what helps tissue repair happen on schedule.

Vitamin C also helps keep your skin firm and may slow some signs of aging, though this happens gradually over months and years, not overnight. The connection is real but modest—vitamin C is one piece of skin health, not the whole picture.

Vitamin C as an antioxidant: protecting your cells from damage

Free radicals are molecules created when your body uses oxygen, and also from pollution, sunlight, and smoking. They are unstable and can damage your cells' DNA and proteins. Over time, this damage builds up and is linked to aging and diseases like heart disease and cancer. Antioxidants like vitamin C neutralize free radicals before they cause harm.

Your body has many antioxidant systems, and vitamin C is one tool among many. It is not a cure or prevention for disease, but getting enough of it is part of how your body defends itself against daily cellular damage. This protection happens quietly over years, not in a way you can feel day to day.

How much vitamin C you need and where to find it

The recommended daily amount is 90 milligrams for adult men and 75 milligrams for adult women. Pregnant people need 85 milligrams, and people who smoke need an extra 35 milligrams on top of the base amount because smoking uses up vitamin C faster.

Most people get enough vitamin C from food without trying. One medium orange has about 70 milligrams. One cup of raw bell peppers has about 150 milligrams. Strawberries, kiwi, broccoli, Brussels sprouts, and tomatoes are all good sources. Cooking can reduce vitamin C content, so raw or lightly cooked vegetables retain more.

If you do not eat many fruits and vegetables, a supplement can help you reach the daily amount. Vitamin C supplements come as tablets, powders, or gummies. Your body can only absorb a certain amount at once—roughly 200 milligrams—so taking a very large dose does not give you extra benefit; your body straightforward excretes the rest in urine.

Who might need to pay closer attention to vitamin C intake

Most people eating a varied diet get enough vitamin C without thinking about it. But some people have a harder time getting enough: people who smoke, people with certain digestive conditions that affect nutrient absorption, people with very limited diets, and older adults who eat less overall.

Severe vitamin C deficiency is rare in developed countries and causes a condition called scurvy, which involves bleeding gums, poor wound healing, and joint pain. You would need to eat almost no fruits or vegetables for months to reach this point. Much more common is straightforward not getting the full recommended amount, which means your body's repair and defense systems work less efficiently than they could.

Vitamin C from food versus supplements

Food sources of vitamin C come with fiber, other vitamins, and minerals that work together. A supplement gives you the vitamin C alone. Both can help you reach your daily target, and for most people, either approach works fine.

Supplements are useful if you know your diet is low in fruits and vegetables, or if you have a condition that makes absorption harder. They are also portable and do not spoil. Food sources are usually cheaper over time and give your body other nutrients at the same time. There is no strong reason to choose one over the other if both get you to your daily amount.

Frequently Asked Questions

Can too much vitamin C hurt you?

Your body excretes excess vitamin C in urine, so taking more than you need does not build up in your system. Very high doses from supplements (several grams per day) can cause diarrhea, nausea, or kidney stones in people with certain risk factors. Staying near the recommended amount is safest.

Does vitamin C prevent colds?

For most people, no. Studies show that taking vitamin C regularly does not reduce how often you catch colds. For people under extreme physical stress, it may help slightly. Once a cold starts, vitamin C does not shorten it much for most people.

Is it better to take vitamin C every day or only when sick?

Your body does not store vitamin C, so it works best when you get it regularly throughout the day. Taking it only when you feel sick does not give your immune system the ongoing support it needs. A steady intake from food or daily supplements is more effective.

Can vitamin C supplements replace eating fruits and vegetables?

A supplement can help you reach your vitamin C target, but fruits and vegetables provide fiber, other vitamins, minerals, and compounds that supplements do not. They work best together, not as a replacement for each other.

Does vitamin C help with joint pain or arthritis?

Vitamin C is needed to build and maintain collagen in joints, so getting enough matters for joint health. However, there is no strong evidence that extra vitamin C beyond the recommended amount reduces arthritis pain or slows joint damage in people who already have arthritis.