You may already double down on vitamin C-rich snacks when you want to give your immune system a boost, but this powerful vitamin is responsible for far more than helping you avoid a cold (and spoiler: there are better sources of it than oranges!).
Vitamin C is an antioxidant you can easily get from a variety of foods or from supplements. Because vitamin C is water-soluble, your body can't store it, and you need enough of it daily to prevent deficiency, per the National Institutes of Health (NIH).
When you get enough vitamin C, your body will be able to function better overall. This antioxidant can help reduce how long you feel sick with the common cold, boost your skin health and much more.
What Is Vitamin C?
Vitamin C is a water-soluble vitamin. Your body needs vitamin C to form collagen, which makes up the connective tissues in the body and helps heal wounds.
Vitamin C also contributes to the overall health of your bones, cartilage and teeth.
It also plays a role in your body's absorption of non-heme iron, which comes from plant sources. That's why it's best to eat iron-rich foods like spinach with a vitamin C-rich foods, like tomatoes or peppers.
Because it's an antioxidant, vitamin C supports your overall immune function, according to a November 2017 review in Nutrients.
Antioxidants like vitamin C scavenge for free radicals, those wayward molecules that can cause DNA damage in the body. And regularly eating fruits and vegetables high in vitamin C is linked to better protection against cancer and heart disease, per the NIH.
How Much Vitamin C Per Day You Need
The recommended daily allowance for vitamin C — that is, the intake sufficient to meet the body's nutrient needs — varies according to several factors, according to the NIH.
Recommended Dietary Allowances (RDAs) for Vitamin C
Require 35 mg/day more vitamin C than nonsmokers.
Vitamin C Deficiency
Deficiency of vitamin C, which leads to a condition called scurvy, is rare in developed countries but can occur in those with poor diets.
Signs of deficiency can appear within a month of consistently low intake of this vitamin. Scurvy symptoms include fatigue, swelling of the gums and tooth loss, per the NIH.
Some people may need more vitamin C than others. Due to their higher levels of oxidative stress, smokers need 35 milligrams more vitamin C per day than nonsmokers (and those exposed to secondhand smoke should also ensure they meet the RDA for vitamin C).
Individuals with certain medical conditions like severe intestinal malabsorption or cachexia (wasting of the body due to severe chronic illness) may be at a higher risk of vitamin C inadequacy.
Those who have a limited food variety (such as some older people and, occasionally, children) may also not obtain enough vitamin C.
What Happens if You Get Too Much Vitamin C?
The tolerable upper intake level for vitamin C in those 19 years of age and older is 2,000 milligrams.
While too much vitamin C is unlikely to be harmful, a megadose may result in gastrointestinal issues, such as diarrhea, nausea and cramps, as well as headaches and insomnia, according to the Mayo Clinic.
The body absorbs less than 50 percent of a vitamin C dosage over 1,000 milligrams a day, per the NIH. What your body doesn't need it excretes via your urine, so you flush away those excess milligrams.
In contrast, at a more modest vitamin C dosage of 180 milligrams or less, the body will absorb 70 to 90 percent of the antioxidant.
Getting C From Food vs. Supplements
Natural vitamin C from food and synthetic vitamin C in supplements show the same bioavailability — meaning, the body seems to absorb both forms of the nutrient equally well, per the Oregon State University.
However, it's better to get vitamin C from food than to follow a nutrient-poor diet and then take supplements to make up for vitamin shortfalls. Through a healthy, well-rounded diet, you get the benefits of other nutrients working in conjunction with vitamin C, per Harvard Health Publishing.
Research on the benefits of multivitamins has mixed findings, and, as a result, the U.S. Preventive Services Task Force does not recommend vitamin supplements to prevent diseases like cardiovascular disease or cancer.
By including more fresh fruits and vegetables in your diet, you'll get all the nutrients you need on a daily basis, which leads to overall good health and disease prevention.
Top Vitamin C Foods
Getting vitamin C from foods is easy, as long as you eat plenty of produce.
You should aim to fill half of your plate at each meal with fruits and vegetables, per the USDA. Opt for whole fruits instead of juices, and vary the kinds of fruits and veggies you select each day.
You may automatically think of oranges and other citrus as the fruits highest in vitamin C, but in fact, guavas, kiwis and strawberries all contain more of the nutrient than oranges, per the USDA.
Among vegetables, broccoli, cauliflower, Brussels sprouts and cabbage are all rich sources of vitamin C. Tomatoes and bell peppers also supply vitamin C, as do leafy greens such as kale, Swiss chard and spinach.
Eat vitamin C-rich foods at every meal to get the milligrams you need daily and to replenish your stores of this nutrient. For instance, try any of the below meals to up your levels of vitamin C.
- Slice a half-cup of strawberries onto your morning oatmeal.
- Add half a medium-sized grapefruit alongside your eggs and toast.
- Sweeten up your Greek yogurt with a half-cup of blackberries or a half-cup of pineapple chunks.
- Construct a salad from a base of leafy greens; choose one cup of baby kale or Swiss chard.
- Along with your protein of choice, top your greens with a half-cup of cherry tomatoes and the same amount of sweet bell peppers.
- Add a small orange on the side.
- Have a half-cup of steamed broccoli with a clove of garlic.
- Enjoy a medium baked sweet potato.
Considering a Vitamin C Supplement? Here's What to Shop For
If you do decide to take supplements to help you reach your daily dose of vitamin C, be aware that there are many varieties and not all of them are created equal.
Three different kinds of vitamin C pills — liquid, tablets and chewable tablets — all appear to have equally good absorption, per Oregon State University.
However, studies present conflicting evidence on the efficacy of timed-release vitamin C, and only one showed a positive effect on nutrient absorption from bioflavonoids.
If you're looking for the best vitamin C for adults and kids, check out the reputable brands according to Consumer Lab:
Benefits of Vitamin C
In the midst of cold and flu season, you may start popping vitamin C pills in an attempt to ward off respiratory illness. However, vitamin C does not appear to prevent the common cold, per a July 2018 review of 45 studies published by Medwave.
That said, the nutrient may help some people reduce their symptoms. In fact, 480 milligrams of vitamin C taken with 800 milligrams of aspirin did reduce early symptoms of a cold compared to placebo in a 2017 study in the Journal of Health Care and Prevention.
A higher dosage of vitamin C, taken at the onset of a cold, was also found to reduce the duration of the illness and lessen its symptoms in a July 2018 meta-analysis of nine clinical trials published in BioMed Research International.
The extra amount, though, only benefited people who had already been taking vitamin C supplements on a daily basis.
Vitamin C also benefits your skin health: The collagen that vitamin C helps to form is a major component of your tissues. Beyond aging, too little collagen in the body is most often caused by an unhealthy diet, and it can lead to wrinkles and crepey skin.
Low levels of collagen can also cause health concerns like joint pain, weakening muscles, osteoarthritis or gastrointestinal problems due to the thinning of your digestive tract lining, per the Cleveland Clinic.
Other potential benefits of vitamin C may be:
- Wound healing: Vitamin C helps to repair wounds thanks to its important role in collagen synthesis. It can also help increase UV light photoprotection for your skin when combined with vitamin E (though it's not a replacement for sunscreen!).
- Dry skin: Although more research is needed, vitamin C might decrease dryness in skin and improve the appearance of skin roughness.
- Heart health: Some research shows that vitamin C is linked to benefits for your heart, including protection against atrial fibrillation, high cholesterol and high blood pressure.
- Blood sugar control: Vitamin C may help lower blood glucose spikes after meals in those with type 2 diabetes, but more research is needed.
- Iron absorption: Vitamin C helps you absorb more iron from plant-based foods.
- Potential for cancer treatment: Some studies have shown that vitamin C may help kill cancer cells in large doses. It has also been linked to lower risk of certain cancers like lung, breast and colon cancer.
- Eye health: Vitamin C may be part of a supplement formulation that's linked to reducing the risk of advanced age-related macular degeneration. Though evidence has been mixed, some studies also associate high dietary intakes of vitamin C with lower risk of cataract formation.
- Gout prevention: Vitamin C may help prevent gout, a type of inflammatory arthritis that is very painful.
- Cognitive function: Vitamin C is linked to helping protect against age-related cognitive decline and Alzheimer's disease.
- Bone and muscle health: Because it plays a crucial role in the production of the structural protein collagen, vitamin C is an important nutrient for your bones. What's more, an August 2020 study in The Journal of Nutrition looked at data from over 13,000 older men and women and found a link between low vitamin C levels and lower skeletal muscle mass as we age, suggesting that C can help preserve muscle mass.
- Sea sickness: Young people who get queasy at sea may benefit from taking vitamin C beforehand, some research shows.
- Inflammation fighter: As an antioxidant, vitamin C may lower levels of inflammation in your body.
Drug Interactions and Risks
Always speak to your doctor before starting a new supplement, including vitamin C. There are several interactions that could take place when you take vitamin C, per the Mayo Clinic:
• Aluminum: Vitamin C supplements can increase your absorption of aluminum from medications containing it, like phosphate binders, which may be harmful for people with kidney problems.
• Estrogen: Taking oral contraceptives or hormone replacement therapy with vitamin C may increase your estrogen levels.
• Protease inhibitors: These antiviral drugs may be less effective when taken with vitamin C.
• Warfarin (Coumadin, Jantoven): High doses of vitamin C may lower your response to this anticoagulant.
• Statins and niacin: Taking vitamin C along with niacin, which could benefit those with high cholesterol, might reduce niacin's effects.
• Chemotherapy: Using antioxidants like vitamin C during chemotherapy might reduce the drug's effect.
You should also take caution with vitamin C if you have hemochromatosis, a condition that causes the body to store too much iron. Large amounts of vitamin C could worsen the overload of iron in your body and damage body tissues, per the NIH.
- National Institutes of Health Office of Dietary Supplements: "Vitamin C"
- Nutrients: "Vitamin C and Immune Function"
- Mayo Clinic: "Is it possible to take too much vitamin C?"
- Oregon State University Linus Pauling Institute Micronutrient Information Center: "Supplement Forms"
- Harvard Medical School: "Should you get your nutrients from food or from supplements?"
- U.S. Preventive Services Task Force: "Vitamin Supplementation to Prevent Cancer and CVD: Preventive Medication"
- U.S. Department of Agriculture: "Start Simple with MyPlate"
- MyFoodData: "Top 10 Foods Highest in Vitamin C"
- Medwave: "Does vitamin C prevent the common cold?"
- Journal of Health Care and Prevention: "Aspirin plus vitamin C provides better relief tha placebo in managing the symptoms of the common cold"
- BioMed Research International: "Extra Dose of Vitamin C Based on a Daily Supplementation Shortens the Common Cold: A Meta-Analysis of 9 Randomized Controlled Trials"
- Cleveland Clinic: "The Best Way You Can Get More Collagen"
- The Journal of Nutrition: "Lower Dietary and Circulating Vitamin C in Middle- and Older-Aged Men and Women Are Associated with Lower Estimated Skeletal Muscle Mass "