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Health Benefits of Vitamin C: Diet, Supplements and Deficiencies

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Vitamin C: The Discovery

Scurvy, a clinical syndrome that results from vitamin C deficiencies, was first reported in 1550 BC.

The description from Hippocrates sounds grim: “The mouth feels bad; the gums are detached from the teeth; blood runs from the nostrils…ulcerations on the legs; some of these heal… skin is thin.”

In the 18th century, James Lind, of the British Royal Navy, found eating lemons and oranges could bring scurvy into remission. By the early 20th century, researchers had discovered the structure and synthesis of ascorbic acid, more commonly called vitamin C.

Most animals make their own vitamin C, but for humans, it is an essential vitamin. Your body can store very little vitamin C, and clinical deficiencies occur when levels drop to less than 350 milligrams (mg).

Vitamin C Deficiency

Vitamin C is naturally found in fresh fruits and vegetables. In fact, that’s how we consume about 90 percent of vitamin C. Not regularly eating these foods most often creates vitamin C deficiencies.

Even then, it isn’t so easy. Vitamin C is heat sensitive and boiling or cooking can remove a food’s nutritional value. Food transit time and other factors could decrease vitamin C levels.

Overt deficiencies create scurvy because of vitamin C’s role in the synthesis of specific types of collagen in the skin, blood vessels, and specific tissues. While rare, scurvy still occurs today.

Much more common are what researchers call subclinical (or more subtle and not always recognizable) vitamin C deficiencies. The first symptom of vitamin C deficiency is fatigue, which is non-specific, but quite common.

“Vitamin C deficiency is relatively rare in developed countries but still affects more than 1 in 20 people,” says Erica Julson, MS, RDN, CLT.

Smokers and low-income people are among those most at risk for deficiencies. Alcohol abuse can also create vitamin C deficiencies. People with limited food variety, people with malabsorption issues, and those with certain chronic diseases, including some cancer patients, may all experience vitamin C deficiencies.

More subtle symptoms of vitamin C deficiencies that can take months to develop include:

  • Rough, bumpy skin

  • Easy bruising

  • Slow-healing wounds

  • Painful, swollen joints

  • Weak bones

  • Bleeding gums

  • Immune deficiencies

  • Poor mood

  • Fatigue

  • Unexplained weight gain

  • Inflammation and oxidative stress

Health Benefits of Vitamin C

Vitamin C’s immuno-protective, anti-inflammatory, antiviral, and antibacterial roles are well-known. It works as the co-factor for a number of enzymes (including collagen synthesis) and as a water-soluble antioxidant. Researchers prize vitamin C because it benefits numerous conditions including cancer and neurodegenerative diseases.

These are several of the reasons you want an optimal dose of vitamin C. Vitamin C plays multiple roles to support and maintain health.


You’re heading home from work, start to feel a little achy, and reluctantly acknowledge that a cold is coming on. Will swallowing a few vitamin C capsules help?

That’s what the American scientist and Nobel Prize-winning, Linus Pauling claimed in the 1970s: That vitamin C could successfully treat or prevent the common cold. Subsequent studies have yielded mixed conclusions, and today many critics regard Pauling as either brilliant or controversial.

Can vitamin C fight the common cold? Possibly. Several cells within the immune system, such as phagocytes and T cells, can accumulate vitamin C. Conversely, vitamin C deficiencies result in a reduced resistance against certain pathogens; more of this vitamin can support the immune system.

One review of 29 studies (with over 11,000 children and adults total) looked at whether using at least 200 milligrams (mg) of vitamin C could prevent colds. Most studies used 1,000 or more mg of vitamin C daily, and some studies followed participants who took vitamin C over several years.

Researchers concluded that you couldn’t prevent colds by taking vitamin C regularly, but you could shorten a cold’s duration by about 10 percent. So if you had a cold 10 days, regularly taking vitamin C could shorten it by one day.

Symptoms of a cold were also milder among regular vitamin C users, but once they became ill, vitamin C didn’t shorten the length of colds.

Meta-analyses show vitamin C can slightly reduce the duration of the illness in healthy persons but does not affect its incidence and severity. In other words, don’t expect to mega-dose on vitamin C supplements while you’re ill and feel amazing the next morning. Though, it may help a little.

Oxidative stress (when free radicals overpower your body’s antioxidant defenses) and inflammation are drivers in many illnesses including the common cold. Vitamin C can help reduce both.

As a powerful antioxidant, vitamin C contributes to immune defense by supporting the immune system. Vitamin C deficiencies result in impaired immunity and higher susceptibility to infections, including respiratory infections and whole-body infections. In turn, infections significantly impact vitamin C levels due to increased inflammation.


Over 80,000 chemicals exist in furniture, cosmetics, cleaners, and food. Most haven’t been adequately tested for their impact on human health.

Detoxification isn’t something that happens a few times a year (although a professionally designed plan can help elevate your body’s ability to detoxify). Your cells constantly detoxify so providing them optimal amounts of nutrients becomes crucial.

Among them includes vitamin C. One animal study found that high doses accelerated the excretion of lead, one of the most toxic heavy metals, compared with low doses of vitamin C.

As an antioxidant, vitamin C can neutralize and remove environmental pollutants, the damage that occurs due to ultraviolet (UV) radiation and other pollutants. One study found healthy young adults low in vitamin C had significantly increased levels of oxidative stress and reduced antioxidant capacity.

Vitamin C is only one player in the antioxidant arsenal. Others include vitamin E, glutathione, and carotenoids (vitamin A). For instance, vitamin C can help reduce oxidative damage to the skin combined with vitamin E.


Vitamin C also has the power to reduce chronic inflammation, which can increase with high levels of toxicity in some people. One study found that supplementing with 500 mg of vitamin C twice daily could alleviate inflammatory markers in hypertensive and/or diabetic obese patients.

Vitamin C also plays a role in glutathione. This master antioxidant protects against oxidative stress, mercury, other toxic metals, alcohol, and persistent organic pollutants (POPs). The amount of glutathione within your cells is highly associated with health and longevity.

Glutathione helps detoxify potentially dangerous compounds, excreting them or directly neutralizing them. Researchers associate low levels of glutathione with numerous complications including macular degeneration, Parkinson’s disease, and other neurodegenerative disorders.

Glutathione and vitamin C work as a team. Glutathione recycles vitamins C and E. In turn, vitamin C’s free radical-fighting abilities can spare glutathione levels, thereby increasing glutathione levels and leaving this master antioxidant to protect against other free radicals.

Vitamin C can also perform as an antioxidant in its own right, even with sufficient amounts of glutathione. One study found just a 500-mg vitamin C supplement daily maintains glutathione concentrations and improves overall antioxidant protection.

Collagen Production

Collagen is an abundant structural protein, comprising of about one-third of the total protein in humans. If you want glowing skin, healthy hair and nails, supple joints, and strong bones and muscles, you want optimal amounts of this ubiquitous protein.

To support collagen production, you need optimal vitamin C, which contributes to two key enzymes in collagen synthesis. Vitamin C interacts with amino acids within collagen cells to provide hydrogen and oxygen so those amino acids can make collagen.

Without optimal vitamin C levels, collagen production slows down making your skin more susceptible to wrinkles and bruising. Several reports find lower vitamin C levels in aged or photodamaged skin.

Skin-related aging occurs from many factors, including excessive sun exposure, smoking, and environmental stress. Some research shows that consuming significant amounts of vitamin C can improve elasticity, wrinkling, and other skin benefits. These studies included a high intake of fruit and vegetables, which contribute vitamin C, as well as other nutrients.

Vitamin C also plays a role in joint health. After controlling for confounding variables, researchers found that vitamin C supplementation could help prevent knee osteoarthritis, the most common form of arthritis that includes joint pain and swelling.

Vitamin C can also benefit rheumatoid arthritis and provide joint protection due to its antioxidant potential, its role as a cofactor in collagen synthesis, and its ability to fight infection via its anti-inflammatory protection.

Vitamin C from Your Diet

Immune health, detoxification, and collagen production are three of many roles vitamin C plays in your body. To get these and other benefits, you’ll want to ensure you’re getting sufficient amounts of this workhorse vitamin.

Start with whole foods. While many colorful fruits and vegetables contain good amounts, some of the best foods that are rich in vitamin C include:

  • Peppers (including yellow, green chili, and red chili peppers)

  • Kiwi

  • Kale

  • Spinach

  • Broccoli

  • Brussels sprouts

  • Strawberries

If you want therapeutic amounts of this vitamin, you’ll probably need to supplement. While they have been revised, the Recommended Daily Allowance for vitamin C exceeds the amount necessary to prevent scurvy but is still paltry: 90 mg a day for adult men and 75 mg a day for adult women. Smokers have higher requirements: 125 mg a day for men and 110 mg a day for women.

Eating a colorful array of fruits and vegetables and taking a multivitamin will easily help you get those amounts. But remember, these are the minimum-wage amounts of vitamin C to prevent disease. To thrive and provide your body with all the benefits of this vitamin, you’ll probably want to supplement.

Scientists find no evidence that large amounts of vitamin C (up to 10 grams daily for adults) create any adverse or toxic effects. At the same time, higher doses of vitamin C can have adverse effects in some people. Talk with your healthcare professional before you increase doses about optimal, safe levels for you.

Vitamin C from Supplements

Should you need to consume higher doses of Vitamin C, one way to determine your optimal dose is through titration, where you gradually increase vitamin C intake to bowel tolerance. Specific amounts will vary among individuals, but you might start with one to two grams of vitamin C and gradually increase to tolerance. Again, discuss this and other options with your healthcare professional.

The vitamin C you get in your food is very similar to what you get in a supplement, although better supplements combine vitamin C with other nutrients to mimic the nutrient profile you consume in food.

Among them include bioflavonoids (alternately called flavonoids), the over 6,000 plant chemicals that give fruits and vegetables their unique color. Bioflavonoids work synergistically to support the absorption of vitamin C while providing additional nutrient support.

One specific bioflavonoid quercetin, found in apples and other foods, can provide additional anti-inflammatory and antioxidant benefits combined with vitamin C.

Your body tightly regulates vitamin C. Researchers find you absorb about 70 to 90 percent of vitamin C when you take 30–180 mg a day. At higher doses (above one gram a day), absorption falls to less than 50 percent. The rest gets excreted in your urine. That doesn’t mean you shouldn’t use higher doses, especially because vitamin C is inexpensive and performs so many roles.

As a water-soluble nutrient, you can take vitamin C supplements with or without food, although some people may feel stomach upset taking it on an empty stomach.

If you’re not eating a healthy diet and maintaining good lifestyle habits like optimal sleep, stress management, and consistent exercise, vitamin C supplements probably won’t do much.

Vitamin C also isn’t a cure-all nutrient; it works as a team with other vitamins and minerals to support immunity and everything else. Research shows, for instance, that vitamin C works better with vitamin D and zinc for the common cold.

Overall, vitamin C’s therapeutic benefits warrant supplementing, but even then, you’ll want to eat plenty of vitamin C-rich foods to optimize levels of this multitasking vitamin.

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