Your immune system needs vitamin C to work right. But extra won't help you avoid a cold, unless maybe you're an extreme athlete, live in a very cold place, or you just need more anyway. Supplements might shorten a cold or ease its symptoms -- if you were taking them before you got sick.
Prevents Cell Damage
Vitamin C helps you get rid of chemicals that damage your cells and DNA. It's considered an antioxidant: It neutralizes "free radicals" in your body created by pollution, cigarette smoke, sunlight, radiation, and simply turning food into energy. That could help keep many parts of your body working better for longer and protect you from diseases, including Alzheimer's and cancer.
Builds Skin, Bones, Muscles, and More
Your body would fall apart without the protein collagen. Collagen fibers twist around each other to form scaffolding for your bones, cartilage, skin, and muscles (including your heart). They're also in ligaments,tendons and blood vessels. You need collagen to grow new skin and make scar tissue when you get cut and to keep your skin from getting wrinkles. And your body can't make collagen without vitamin C.
You need vitamin C to make key hormones that carry signals from your brain all over your body. These include serotonin, dopamine, epinephrine, and norepinephrine. They affect your mood, memory, motivation, and how you feel pain. For example, serotonin plays a role in keeping your daily sleep cycle on track. It's also what a common drug for depression works on.
May Preserve Sight
The vitamin A in carrots isn't the only thing that's good for your eyes. Some studies show that vitamin C might slow age-related macular degeneration (AMD) from getting worse, but it won't prevent the disease. Other studies suggest a link between vitamin C and a lower risk of cataracts.
Very high doses of vitamin C, especially through an IV, may slow the growth and spread of cancer cells. It can help chemotherapy and radiation work better. It may help you feel better and have fewer side effects, too. But it can also make treatments less effective. The FDA hasn't approved vitamin C as a cancer treatment, so check with your doctor to see if this therapy makes sense for you.
Look beyond the usual oranges, grapefruits, lemons, and limes. Berries -- strawberries, raspberries, blueberries, cranberries -- are also good sources. So are papaya, kiwi, pineapple, cantaloupe, plums, and watermelon. Even bananas, apples, and pears have some.
Fresh and raw are best because vitamin C breaks down over time and when heated.
Bell peppers are big winners. Load up on leafy greens (kale, Swiss chard, collards, and the like), cabbage, and bok choy. Crunch into broccoli, cauliflower, and Brussels sprouts. Tomatoes, sweet potatoes, and winter squash are also good sources.
It's better to steam or microwave vegetables if you're going to cook them. These methods tend to destroy less of the vitamin.
How Much Do You Need?
Adult men should get 90 milligrams every day. Women need 75 milligrams, but more when they're pregnant or breastfeeding. Your body can't make it. But most people who eat a variety of vegetables and fruits daily get more than enough vitamin C from their food.
If you want to take a supplement, look for the inexpensive ascorbic acid form. Check with your doctor about how much is right for you.
Smokers Need More
When you smoke, you'll have lower levels of vitamin C in your body. It may be because you have more free radicals to get rid of. You should aim for an extra 35 milligrams every day to make up for it.
People who are around smokers are also affected and should try to get more vitamin C, too.
Through the 1700s, sailors on long trips would die from scurvy because they had little or no vitamin C in their diet. It's uncommon today, but people who don't eat well or abuse alcohol or drugs might be low. Medical conditions, such as some cancers and kidney diseases, can also cause problems. Symptoms include being tired, swollen or bleeding gums, loose teeth, achy joints, thickened skin, bruises, and cuts that don't heal right.
Your body can't handle a lot of vitamin C, and you'll pee out what it doesn't use. More than 2,000 milligrams a day for adults can cause stomach trouble, belly cramps, and diarrhea. Big doses can also lead to kidney stones.
Partner With Other Nutrients
Put red peppers in your spinach salad. Have some broccoli with your baked beans. Or add strawberries to your oatmeal. Vitamin C helps your body use the kind of iron found in plants, which doesn't get absorbed as easily as the kind in meat and fish.
Vitamin C also teams up with other antioxidants, especially vitamin E and flavonoids. Bonus: They're often found in the same foods.