Vitamin C strengthens your immune system, bones, blood vessels, and cells.
The Hungarian biochemist Albert Szent-Györgyi discovered vitamin C in the 1930s — hundreds of years after more than two million sailors died of a gruesome disease they likely could have staved off with more fruits and veggies aboard ship. That disease was scurvy, which for centuries was not known to be caused by a deficiency in ascorbic acid, or vitamin C, according to the American Chemical Society. Most produce contains vitamin C in amounts sufficient to keep such extreme deficiencies at bay.
Why is vitamin C so important? Marisa Moore, RDN, who’s based in Atlanta, says the vitamin plays a critical role in maintaining tissues, keeping bones healthy, and protecting cells and blood vessels from damage.
“Vitamin C is a nutrient we need for so many processes in the body,” she says. “And it’s one of those essential vitamins we can’t make in our bodies.”
Because of its powerful antioxidant properties, vitamin C can help regenerate cells, support the immune system, and help the body absorb iron, according to the National Institutes of Health (NIH) Office of Dietary Supplements. Other touted benefits of vitamin C may include reducing the risk of heart disease and memory conditions like dementia, and protecting against eye diseases such as macular degeneration.
Without vitamin C, your body literally falls apart. Back when vitamin C deficiency was more prevalent, says the Science History Institute, it caused people’s gums to bleed and teeth to fall out. The deficiency could even lead to death from internal hemorrhaging. When physicians realized citrus fruits had a role in preventing scurvy, ships were stocked with limes. (This is how the term “limey,” used to refer to sailors, was coined.)
Don’t worry — your chances of getting scurvy today are slim to none. It’s something, at least in developed nations, that we really don’t think about, because vitamin C is in so many of the foods we eat daily. There are also plenty of vitamin C supplements and multivitamins containing vitamin C out there, but Moore recommends getting nutrients from whole foods. The U.S. Food and Drug Administration (FDA) does not regulate dietary supplements, and the agency notes they’re different from drugs in that they aren’t “intended to treat, diagnose, prevent, or cure diseases.”
Studies on vitamin C supplements are limited, but research has not found that any one supplement is better than other forms, according to the Office of Dietary Supplements. If you’re already getting vitamin C from food, taking supplements may or may not be beneficial — excess vitamin C will mostly be excreted from the body in the urine.
What Is the Recommended Daily Allowance (RDA) of Vitamin C?
It’s extremely difficult to overdose on vitamin C through food alone, but it is possible to experience side effects if you somehow overdo it on supplements. The NIH recommends that adults get no more than 2,000 milligrams (mg) a day. It’s equally difficult to be vitamin C deficient, unless you live somewhere with little access to fruits and vegetables. Moore says at the very minimum your body needs 10 mg of vitamin C per day, but the recommended daily allowance (RDA) varies depending on age, gender, life stage, and lifestyle choices like smoking.
According to research published by the U.S. Food and Nutrition Board, among people age 19 and older, the RDA is 90 mg for men and 75 mg for women. Anyone who smokes regularly needs extra vitamin C, and should get an additional 35 mg per day. Pregnant women need 85 mg, and lactating women require 120 mg of vitamin C.
The Office of Dietary Supplements lists certain groups of people who have a higher risk of vitamin C deficiency. Research, such as a study published in July 2020 in the journal Nutrients, has shown smokers have lower vitamin C levels than nonsmokers, and thus they need a little extra in their diet. Infants who are fed evaporated or boiled milk, both of which are deficient in vitamin C, may not be getting enough of the nutrients they need. Medical conditions that cause malabsorption and certain chronic diseases may reduce the body’s ability to absorb vitamin C, increasing the amount the body needs, according to the International Foundation for Gastrointestinal Disorders.
Michael Wald, MD, ND, PhD, a registered dietitian in Chappaqua, New York, and the host of the podcast Ask the Blood Detective, says the RDA is the minimum amount needed to prevent vitamin C deficiency, and it isn’t necessarily representative of the ideal vitamin C value each person needs.
What Foods Are the Highest in Vitamin C?
Because, per the NIH, the FDA does not require food labels to list the vitamin C that naturally occurs in foods, only the amount of vitamin C that has been added, it can be difficult to know which packaged foods are good sources. Luckily, plenty of whole foods such as fruits and vegetables are chock-full of C. Some, like red bell peppers, can provide more than 100 percent of the DV of the vitamin in one or two servings, as USDA data demonstrates.
“People should always begin with a diet high in fruits and vegetables,” says Dr. Wald. “Age, genetics, absorption, disease, exercise, stress, sleep, alcohol, and various other lifestyle factors all play a role in the amount of vitamin C one needs.”
Note that cooking affects the nutrient content of foods. Because vitamin C is heat sensitive and water soluble, the longer you cook a food with vitamin C, the more C it loses, notes an article published in April 2018 in the journal Food Science and Biotechnology. The authors wrote that microwaving a food with vitamin C led to better retention of the nutrient than boiling. It’s even better if you can eat high–vitamin C foods raw.
Vegetables That Are High in Vitamin C
Here are some of the foods recommended by the NIH that contain vitamin C, as well as flavonoids and bioflavonoids (powerful antioxidants found in fruits and veggies) that work with vitamin C. The following vegetables are excellent sources of vitamin C, according to USDA data.
- Bell peppers A 1 cup portion of chopped red bell peppers has 191 mg of vitamin C.
- Red and green chili peppers One red chili pepper contains 64.8 mg of vitamin C.
- Dark green leafy vegetables This includes garden cress, kale, mustard greens, Brussels sprouts, cauliflower, and broccoli. For example, 1 cup of chopped broccoli has 81.2 mg of vitamin C.
- Potatoes One medium-size potato contains 17.7 mg of vitamin C.
Fruits That Are High in Vitamin C
Citrus fruits and fruit juices are famous for being high in vitamin C, but they aren’t alone — or even the best source. The following fruits are considered excellent sources of vitamin C, according to USDA data.
- Guava Just one of these tropical pink-fleshed fruits delivers 125 mg of vitamin C.
- Strawberries Berries are brimming with antioxidants, and 1 cup of sliced strawberries has 97.6 mg of vitamin C.
- Papaya Another tropical pick, 1 cup of this orange-hued fruit’s cubed flesh yields 88.3 mg of C.
- Oranges Practically synonymous with vitamin C, one whole navel orange offers a hefty 82.7 mg of vitamin C.
- Kiwi Small but powerful, one kiwifruit has 64 mg of vitamin C.
- Blackberries 1 cup of blackberries has 30 mg of vitamin C.
- Lemons and limes A lemon contains 34.4 mg of C, while a smaller lime has 19.5 mg of vitamin C. It’s unlikely you’ll eat either of these fruits whole, but the juice delivers most of that amount.
What Does Science Say About Vitamin C for Specific Health Conditions?
There’s no disputing vitamin C is a vital compound needed for the healthy functioning of our bodies. The list of afflictions and conditions vitamin C is suggested to improve or prevent is ever growing, but not all claims are backed by science.
- Neurodegenerative diseases These include Alzheimer’s disease, multiple sclerosis, Huntington’s disease, and Parkinson’s disease. Authors of a review published in July 2017 in the journal Nutrients looked at the literature on vitamin C and neurodegenerative diseases and found promising results for the treatment of neurological diseases in animal studies, but human studies are both limited and lacking in evidence.
- Various cancers While the National Cancer Institute notes that intravenously administered high-dose vitamin C may improve the quality of life of cancer patients, vitamin C as a cancer treatment isn’t approved by the FDA. A study published in the July 2018 International Journal of Cancer surveyed 182,000 women over 24 years and found that breast cancer risk for those who consumed more than 5.5 servings of fruits and veggies daily was lower by 11 percent. While there is an association between eating lots of fruit and veggies and having a reduced risk of cancer, there’s no direct link to vitamin C as a cancer treatment yet.
- Eye issues like cataracts and macular degeneration The eye has a high metabolic rate, which causes the production of harmful free radicals that damage cells. The prevailing theory is that because vitamin C is such an effective antioxidant — a protector of the body’s molecules — it may play a role in fighting off free radicals that lead to eye disease. But a review in the October 2020 issue of Nutrients found no connection between the incidence of cataracts and vitamin C intake in humans.
- Psychiatric disorders, including depression and anxiety Several smaller scale studies have shown an association between vitamin C and its positive effects on mood and related disorders, such as depression and anxiety. Several studies referenced in a November 2020 review in the Journal of Nutritional Biochemistry revealed lower rates of depression and anxiety among subjects (human and animal) with higher levels of vitamin C. Because vitamin C helps maintain organs like the brain, the study notes there are “biological justifications for a positive effect of vitamin C on mood,” but more research is needed to prove that vitamin C can beat the blues. Given the lack of evidence, it’s still best to consult your healthcare provider about any mental health issues you are experiencing.
- The common cold How many times have you been told to take vitamin C when you’re sick? When you feel the flu coming on, Moore says gulping down a bunch of vitamin C supplements probably won’t do much to prevent it. “Vitamin C might help to decrease the duration of a cold, but taking it preventively — the research doesn’t necessarily support that,” she says. A 2017 study by the Department of Public Health and University of Helsinki found that people who regularly take vitamin C even before getting sick didn’t contract fewer colds, but they did seem to get over them more quickly than those who didn’t supplement with the vitamin.
Moore says there is strong evidence that vitamin C helps the body absorb more iron from food, especially nonheme iron from meat-free food sources. Pairing vitamin C–rich foods with iron-rich foods — for example, spinach with orange segments, or black beans with salsa — is especially important for people who are vegan, vegetarian, or anemic, and for women of childbearing age, Moore says.
A Bonus Potential Benefit of Vitamin C? Younger, Healthier Skin
A case can be made that vitamin C will keep you looking young and vital. Per an October 9, 2020 article in Scientific Reports, vitamin C stimulates the production of collagen — a protein that helps keep your skin firm and full. Diets rich in vitamin C are likely to have other positive benefits for the skin, too. Some benefits noted in the study included reducing the formation of scars, preventing wrinkles, and maintaining skin’s overall health.
Vitamin C creams and serums have been on the market for a while now, and the review study found that topical applications of vitamin C produced better results for collagen formation, although further research is needed.
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