When you hear "vitamin C," you probably envision fighting a cold with a big glass of OJ. This important nutrient, however, performs many other functions and is found in a wide variety of foods.
Among adults, the recommended dietary allowance (RDA) for vitamin C is 90 mg for men, 75 mg for non-pregnant women, 80–85 mg during pregnancy and 115–120 mg if breastfeeding. Smokers are advised to up their intake by an additional 35 mg a day. Research conducted by Oregon State University found the average intake of vitamin C in the United States is 84 mg. So while true deficiency is rare, nearly 40 percent of Americans still don’t meet the estimated average requirement for vitamin C.
Wondering if consume too much of the stuff? The Mayo Clinic noted that vitamin C is a water-soluble vitamin, which means that any excess your body doesn’t need will be excreted in your urine. Although an upper limit has been set at 2,000 mg a day, dietary vitamin C above that level likely won’t cause any harm. "Megadose" vitamin C tablets, however, which contain far more vitamin C than you could ever realistically eat, may cause unpleasant symptoms such as diarrhea and headache.
Since childhood, many of us have doubled down on the orange juice when we’re sick. Citrus fruits are certainly a rich source of vitamin C, but the claim that they can defeat viruses like the common cold is largely exaggerated.
One cup of OJ has 124 mg of vitamin C while one large orange has 97.5 mg. Similarly, a cup of pink grapefruit juice has 93.9 mg whereas a white grapefruit has 79 mg. Lemons and limes also contain a good amount of vitamin C. It’s easy to meet the RDA for vitamin C with just a bit of citrus, but, according to Dr. Bruce Bistrian, chief of clinical nutrition at Beth Israel Deaconess Medical Center, that’s no magic bullet for conquering a cold.
The expert told Harvard Health, "The data show that vitamin C is only marginally beneficial when it comes to the common cold." Research suggests that large doses of vitamin C may help extremely active people avoid getting sick, but it didn’t help the general population dodge a cold. Getting more than 200 mg a day did, however, shorten colds by 14 percent among children and 8 percent among adults.
Some people may not find it as appealing as a tall glass of OJ, but a single cup of canned tomato juice has 170 mg of vitamin C — about 50 percent more than an equivalent serving of orange juice. All that vitamin C may not be able to cure the common cold, but it’s still doing a lot for your immune system.
According to a 2017 article published in the journal Nutrients, vitamin C helps give skin its structure, creating a first-line defense against invading germs. It also accumulates in phagocytes (a group of white blood cells designed to destroy germs by essentially "eating" them) and makes them more active. The vitamin is also needed for apoptosis, the destruction and recycling of old or damaged cells.
Additionally, Vitamin C helps lymphocytes, another type of immune cell, differentiate into specialized B- and T-cells, designed to target specific invaders the body has encountered in the past. The article’s authors pointed out that vitamin C deficiency "results in impaired immunity and higher susceptibility to infections." So, when it comes to your immune system, vitamin C may be more of a prerequisite for proper functioning rather than a secret weapon that boosts performance.
When it comes to vitamin C, nothing packs more punch than guava. This delicious tropical fruit boasts 377 mg of vitamin C — a staggering 419 percent of your RDA — in just one cup.
Although Vitamin C deficiency is rare in modern times, 15th to 18th-century sailors on long sea voyages often didn’t have access to fresh produce, leading to a severe form of vitamin C deficiency known as scurvy. The condition can cause a number of symptoms, including anemia, bleeding gums, tooth loss, bone pain, swelling, and depression. If untreated, scurvy can even be fatal. Those most at risk are older adults, people who heavily use alcohol or illegal drugs, and individuals who have a poor or restrictive diet (such as extremely picky eaters, those with certain eating disorders, or individuals living in poverty).
Treatment is thankfully as simple as vitamin C supplementation, and in three months patients with scurvy can expect to make a full recovery. Luckily, you don’t need to eat a daily serving of guava to stave off scurvy. According to Healthline, just 10 mg a day is enough — far below the recommended daily intake.
If you’ve got achy knees or hips, you may want to try eating more papaya. One small fruit contains 95.6 mg of vitamin C, and that may be just what you need to soothe your unhappy joints.
In a 2019 study published in the journal Medical Archives, researchers divided patients with knee osteoarthritis into two groups, one of which received vitamin C supplements. The study authors found that those who took the vitamin C had lower levels of pain and rated their quality of life higher than those in the control group. The researchers concluded that "getting the right amount of vitamin C is key for both preventing inflammatory arthritis and maintaining healthy joints with OA [osteoarthritis]"
Yes, the "right amount" is indeed key, considering too much vitamin C may actually worsen arthritis symptoms. WebMD cited a study published in the journal Arthritis & Rheumatism which found that high-dose vitamin C supplements actually worsened knee osteoarthritis in guinea pigs. Lead author Dr. Virginia Kraus explained, "Our findings suggest that dietary intake should not be supplemented above the currently recommended dietary allowance." It’s important to note, however, that the study used high doses of supplemental, rather than food-derived, vitamin C and used animal subjects rather than humans.
With their sensual red color and heart shape, it’s no wonder that strawberries have been considered a symbol of love and desire for centuries. And it’s likely their high vitamin C content (97.6 mg per one-cup serving) that’s earned them their reputation as a potent aphrodisiac.
Penn Medicine noted that vitamin C may boost libido. In a 2002 study published in Biological Psychiatry, researchers gave participants either high-dose ascorbic acid (vitamin C) or a placebo for 14 days and found that individuals who received the ascorbic acid reported increased frequency of sexual intercourse compared to those given the placebo. It’s important to note, however, that the study used synthetic vitamin C rather than dietary forms and at a dosage too high (3,000 mg) to realistically attain from food sources alone.
In addition to putting you in the mood, vitamin C may also be necessary for fertility. Research published in the Urology Journal demonstrated that vitamin C "significantly improves sperm concentration and mobility." And in a study published in the journal Biology of Reproduction, researchers noted that vitamin C is necessary for an ovarian follicle to release a viable egg. Insufficient levels of vitamin C could therefore contribute to female infertility.
If you’ve got the spice tolerance, you should chow down on some chili peppers. One raw hot green chili pepper contains 109 mg of vitamin C, which can seriously benefit your skin.
A 2017 paper published in the journal Nutrients noted that vitamin C concentration is particularly high in the skin. The epidermis (the topmost layer of skin) contains 6–64 mg per 100 g of wet weight, while the dermis (the thicker layer of skin below the epidermis) contains 3-13 mg. In contrast, muscles contain 3-4 mg, while the heart contains 5-15 mg.
Vitamin C is required for the creation of collagen, the protein that gives skin its structure. It’s also necessary for maintaining the proper balance between collagen and elastin (a protein that gives skin its stretch) in the dermis. As a powerful antioxidant, vitamin C also protects against cellular skin damage caused by UV radiation. Signs of aging, like wrinkles, can be postponed with vitamin C, which explains why so many serums and lotions contain the vitamin. The researchers concluded, however, that delivering vitamin C topically can be challenging and that ingesting vitamin C through food or supplements is likely to produce better results for your complexion.
Bell peppers are one of the richest sources of vitamin C available. One cup of raw red bell pepper contains 190 mg, while the same serving size of green bell pepper contains 120 mg. Vitamin C is essentially nature’s Band-Aid, helping to promote speedy wound healing, so you may want to reach for a colorful bell pepper the next time you have a cut.
In a 2013 paper published in the British Journal of Community Nursing, Dr. Jane Moores noted that vitamin C plays an important role in all phases of wound healing. During the initial inflammatory phase, vitamin C is required to clear away white blood cells after they’ve performed their function, preventing inflammation from getting out of control. In the proliferative phase, when new tissue is being created, vitamin C contributes to "synthesis, maturation, secretion and degradation of collagen." Lastly, during the maturation phase of healing, when collagen (the protein that gives skin its structure) is remodeled and realigned into an orderly network of fibers and the wound fully closes, insufficient vitamin C may lead to altered collagen production and scar formation. Moores cautioned that healing a wound requires a lot of vitamin C, so higher dietary intake or supplements may be necessary.
Raw broccoli is a great source of vitamin C; one cup contains 81.2 mg. But if you prefer your broccoli cooked, or if you tend to let it languish in your fridge for weeks before eating it, you’ll be getting much less. That’s because vitamin C is fragile and breaks down when foods are heated or stored for long periods of time. In fact, the vitamin C in produce begins to degrade as soon as the fruit or vegetable is picked. After seven days at 68 degrees Fahrenheit, broccoli’s vitamin C content will have diminished by 56 percent. Refrigeration slows this process, and freezing completely stops vitamin C depletion.
In a 2013 study published in the journal Nutrition & Food Science investigated how microwaving, steaming, and boiling affected the vitamin C content of broccoli as well as spinach and lettuce. Broccoli lost 14.3 percent of its vitamin C content after steaming, 28.1 percent after microwaving, and a whopping 54.6 percent after boiling. The study concluded that "eating raw vegetables is the best way to obtain vitamin C." But if you don’t like the taste of raw broccoli or it’s hard on your digestion, opt for quick steaming over other cooking methods.
Dark leafy greens
You can add "packed with vitamin C" to dark leafy greens’ already long list of health benefits. A 100-gram serving of spinach, for instance, has 28.1 mg of vitamin C. A serving of kale provides 80 percent of the recommended daily allowance of vitamin C whereas mustard greens, collard greens, and Swiss chard provide 59 percent, 58 percent, and 43 percent, respectively.
Interestingly, vitamin C improves absorption of iron from plant-based sources. There are two types of iron: heme (from animals) and non-heme (from plants). While heme iron is easily absorbed by the body, non-heme iron is much less bioavailable. In addition to improving absorption in the digestive tract, vitamin C plays a number of other roles when it comes to both kinds of iron. These include influencing cells’ uptake of iron from the blood and regulating how much iron is stored in the body.
The good news is that, in addition to being packed with vitamin C, dark leafy greens are also one of the best sources of plant-based iron. A serving of Swiss chard, for example, provides 22 percent of your daily iron needs, while collard greens provide 12 percent.
One cup of raw Brussels sprouts contains 74.8 mg of vitamin C, making them one of the best vegetable sources of this key nutrient. You know vitamin C is a powerful antioxidant, but what exactly does that mean?
Antioxidants are chemicals that protect the body against damage from free radicals. Free radicals are highly unstable atoms of oxygen that try to "steal" electrons from other molecules in the body. This destabilizes the molecules and creates a chain reaction that leads to damage throughout the body, a process known as oxidative damage or oxidative stress. Substances that produce free radicals can be found in food and in our environment, and free radicals are also created as the byproduct of natural chemical processes in the body. Antioxidants are able to give free radicals the electrons they want without becoming destabilized themselves.
Although vitamin C is well known for its antioxidant properties, it can also actually encourage free radical damage in certain situations. A 2017 peer-reviewed paper noted that vitamin C can "act as a prooxidant, especially in the presence of transition metals, such as iron and copper, starting different hazardous radical reactions."
Even the little garnishes you add to your meals can boost your vitamin C intake. Two tablespoons of parsley contain 10 mg, which adds up quickly when you’re dressing up pasta, potatoes, or other items.
Parsley has even been cited as having "anti-cancer powers," and vitamin C has also been looked at as a potential cancer treatment. According to Dr. Karthik Giridhar at the Mayo Clinic, however, there’s no evidence to suggest that vitamin C can cure cancer on its own. Initial studies conducted in the 1970s appeared promising, as vitamin C was toxic to isolated cancer cells, but these studies were flawed and later discredited. More recently, researchers discovered that intravenous vitamin C has different properties than ingested vitamin C, rekindling interest in the vitamin’s use for cancer treatment. Researchers have since begun investigating whether vitamin C can boost the effectiveness of first-line cancer treatments such as chemotherapy.
It’s important to note, however, that even if vitamin C can give cancer patients an extra advantage while undergoing treatment, this is likely only at extremely high doses delivered intravenously. This is very different than simply upping your intake of dietary vitamin C.
When you think about foods that are good for your heart, the humble potato probably doesn’t cross your mind. But the vitamin C in spuds could have a big impact on your cardiovascular health. One large potato contains 72.7 mg of vitamin C — a little more than 80 percent of the recommended daily allowance.
A review published in 2016 in the International Journal of Molecular Sciences explored the link between vitamin C and cardiovascular disease, the leading cause of death in the United States. The authors noted that although "classical vitamin C deficiency, marked by scurvy, is rare in most parts of the world, some research has shown variable heart disease risks depending on plasma vitamin C concentration, even within the normal range."
The researchers found that lower levels of vitamin C were associated with greater risk of dying from cardiovascular disease and that increasing vitamin C intake may "slightly improve" cholesterol and heart function in those with low vitamin C levels. But the researchers found little evidence to suggest that vitamin C provided additional cardiovascular benefits among those who weren’t deficient.
Although fruits and vegetables are the primary sources of vitamin C, a few animal foods do contain this important micronutrient. A 3-ounce serving of cooked chicken liver, for instance, contains 2.3 mg of vitamin C, while the same size portion of cooked lamb liver contains nearly five times that amount: 11 mg. The taste of liver isn’t for everyone, but if you can stomach it, you’ll get a lot more than just vitamin C. Liver is packed with vitamin A, B vitamins, iron, copper, choline, and high-quality protein.
For indigenous peoples living in the harsh arctic environment, fresh fruits and vegetables aren’t exactly easy to come by. The Inuit people of Alaska get their vitamin C mainly from liver and other animal sources. A 100-gram portion of raw caribou liver, for example, contains nearly 24 mg. Other major animal sources of vitamin C in the Inuit diet include seal brain (approximately 15 mg per 100-gram serving) and raw whale skin (38 mg per 100-gram serving).
All those animal sources add up. According to a study published in the Journal of Food Composition and Analysis, the average Inuit women aged 20 to 40 consumes 68 mg of vitamin C each day.
If you’re a sushi fan and love your rolls topped with bright orange roe (fish eggs), you may be getting an additional shot of vitamin C with your meal. While exact vitamin C content varies depending on the species of fish, an ounce of roe contains, on average, about 7 percent of the recommended daily allowance of vitamin C.
If the idea of eating fish eggs makes you queasy and you don’t get enough vitamin C elsewhere in your diet, you can always opt to take a supplement. Synthetic vitamin C is considered one of the safest and most effective supplements.
A 2013 paper published in the journal Nutrients noted that vitamin C was first synthesized in the early 1930s and has been in wide use ever since. The authors pointed out, "Although synthetic and food-derived vitamin C is chemically identical, fruit and vegetables are rich in numerous nutrients and phytochemicals which may influence its bioavailability." However, in the research they reviewed, they found that "all steady state comparative bioavailability studies in humans have shown no differences between synthetic and natural vitamin C."