What Is It?
In the eighteenth century, seasoned sailors found that by sucking on lemons they could avoid scurvy, a debilitating disease that often developed during long voyages when fresh fruits and vegetables were scarce. When the lemon’s key nutrient was formally identified in 1928, it was named ascorbic acid for its anti-scurvy, or antiscorbutic, action. Today ascorbic acid is widely known as vitamin C.
The health benefits of vitamin C are abundant and varied, but it’s probably best known as a cell protector, immunity booster, and powerful antioxidant. The body’s ligaments, tendons, and collagen (a protein found in connective tissues) rely on the presence of vitamin C to stay strong and healthy. Like all antioxidants, vitamin C counters the effects of cell-damaging molecules called free radicals. As an added benefit, it even helps the body recycle other antioxidants. For certain conditions, vitamin C is best taken with other antioxidants, such as vitamin E, flavonoids, and carotenoids.
Specifically, vitamin C may help to:
Lessen the severity and duration of colds and flu. Taking vitamin C at the first sign of a cold or the flu may keep the illness from fully developing, and you’ll probably recover faster. In a 1995 review of studies investigating the effect of vitamin C on colds, researchers concluded that doses of 1,000 to 6,000 mg a day at the onset of symptoms reduced a cold’s duration by 21%, and shortened its duration by one day on average. Taking vitamin C doesn’t prevent colds, however.
Speed wound healing and minimize the effects of bruising. Vitamin C helps the body to repair and maintain itself by reinforcing cell walls and helping to strengthen tiny blood vessels called capillaries. It further accelerates healing by inhibiting inflammation.
Keep gums strong and healthy. When taken daily, vitamin C protects gum tissue against cell damage and speeds healing in this delicate area. It’s often taken with flavonoids for this purpose. Brushing the gums with vitamin C powder can also minimize inflammation and bleeding.
Increase resistance to heart disease (and angina) by improving cholesterol levels. Several studies have linked the presence of low levels of vitamin C to a greater risk of angina and heart attacks in people with existing heart disease. Research also indicates that, when taken with vitamin E, vitamin C helps protect LDL (“bad”) cholesterol from oxidation, thus preventing plaque buildup in coronary arteries. Vitamin C may also boost blood levels of HDL (“good”) cholesterol; studies are ongoing to provide definitive evidence of this action.
Prevent certain cancers. As a powerful antioxidant, vitamin C may help to fight cancer by protecting healthy cells from free-radical damage and inhibiting the proliferation of cancerous cells. Specifically, recent studies have shown that the vitamin may help stave off cancers of the stomach and esophagus by blocking the conversion of nitrates and nitrites into cancer-causing compounds. Debate over the value of vitamin C for cancer treatment and prevention is fierce, however, with some studies finding no benefit—or even drawbacks—from vitamin C supplementation, while others report prolonged survival in cancer patients, especially when it’s taken along with vitamin E.
Protect against cataracts. Vitamin C may keep the lens of the eye from being damaged by cigarette smoke and ultraviolet (UV) light, both types of exposure linked to cataract formation. One study showed that women who took vitamin C supplements for 10 years or more had a 77% lower risk of “lens opacities,” the beginning stage of cataracts, than women who didn’t use supplements.
Relieve allergies, eczema, sinusitis, and asthma. Vitamin C is a natural antihistamine capable of blocking the effect of inflammatory substances some people produce in response to allergens such as pollen and pet dander. Allergies are often an underlying cause of sinusitis and may also trigger the intensely itchy rashes associated with eczema. Vitamin C is frequently recommended with other antioxidants such as flavonoids for sinusitis. Numerous studies have shown that vitamin C helps prevent or improve asthmatic symptoms as well; asthma sufferers are often deficient in this and other vitamins. Vitamin C has also been shown to help exercise-induced asthma attacks, in some cases thwarting an attack if taken in an adequate dose right before a workout. Adults with exercise-induced asthma may want to experiment with doses from 500 mg to 5000 mg.
Prevent migraines. Taken along with pantothenic acid, vitamin C boosts the production of hormones that help the body deal with the adverse effects of stress-induced migraines.
Improve memory. As an antioxidant, vitamin C plays a key role in maintaining healthy nerve cells, and is often taken in combination with vitamin E, mixed carotenoids, ginkgo biloba, and coenzyme Q10 to help prevent memory loss.
Fight chronic fatigue syndrome. Vitamin C taken with mixed carotenoids helps strengthen a weakened immune system, believed by many to be a factor in this disabling disorder.
Control gallstone formation. Sometimes gallstones develop when bile contains high concentrations of cholesterol. Vitamin C may help to lower the risk of this occurring by reducing bile cholesterol levels.
Combat the effects of aging and extend life. Used in combination with other antioxidants, such as vitamin E and flavonoids, vitamin C may combat the deteriorative effects of aging (such as wrinkles) caused by free-radical damage. It may also help you live longer. In one study, men who took more than 300 mg of vitamin C a day (from food and supplements) lived longer than men who consumed less than 50 mg a day.
Note: Vitamin C’s immune-boosting and antioxidant properties make it useful for many other disorders. For information on these additional ailments, see our Dosage Recommendations Chart for Vitamin C.
The RDA for vitamin C for nonsmoking men and women is 60 mg a day (for smokers it’s 100 mg). Recently experts have strongly suggested increasing the RDA to between 100 and 200 mg a day for all adults, and many recommend getting much more of this vitamin to maximize its health benefits.
If You Get Too Little
The chances of getting scurvy today are all but nonexistent, because just 10 mg of vitamin C a day prevents this disease. Less than 50 mg a day, however, can result in an increased risk of heart attack, cataracts, and a reduced life span.
If You Get Too Much
Because vitamin C is water-soluble—what the body cannot use, it eliminates in the urine and feces in about 12 hours—it’s hard to get too much. But while many people are able to tolerate high doses of vitamin C (as much as 6,000 mg a day) with no ill effects, others may suffer from mouth ulcers, diarrhea, gas, and bloating at doses above 2,000 mg; these problems subside when the dose is reduced.
General Dosage Information
Special tip: Consider taking vitamin C as part of an antioxidant formula. It works best in concert with other antioxidants, especially vitamin E and flavonoids. The flavonoids, sometimes labeled as bioflavonoids, also enhance the effectiveness of vitamin C.
For general health: Make sure you get 500 mg a day through foods and supplements.
For the treatment of various diseases: Depending on the ailment, 1,000 to 6,000 mg may be appropriate.
Be sure to check out our Dosage Recommendations Chart for Vitamin C, which lists therapeutic dosages for specific ailments at a glance.
Guidelines for Use
Your body can’t use more than 1,000 mg of vitamin C in any given dose. If you need to take a larger amount, split it into two or three doses spread throughout the day.
Vitamin C can be taken with or without food, as you prefer.
When shopping for vitamin C, don’t waste money on specialized products—esterified C, time-released C, vitamin C with rose hips. There’s no evidence that these are more efficiently absorbed than simple ascorbic acid.
Large doses of vitamin C may interfere with the body’s absorption of copper and selenium; be sure to get enough of these minerals (copper, about 3 mg; selenium, about 100 mcg) through food or supplements.
Large doses of vitamin C may cause a false positive result for glucose in the urine.
If you have hemochromatosis, a genetic tendency to store excess iron (vitamin C enhances iron absorption), don’t take more than 500 mg of vitamin C a day.
Vitamin C can distort the accuracy of medical tests for colon cancer and hemoglobin levels. Let your doctor know if you’re taking vitamin C supplements.
Alcoholism 1,000 mg 3 times a day
Allergies 500-1,000 mg twice a day. May be partially covered by your daily multivitamin/antioxidant.
Anemia 500 mg 3 times a day
Angina 1,000 mg daily in addition to your basic multivitamin and antioxidant
Asthma 500-1,000 mg twice a day. May be partially covered by your daily multivitamin/antioxidant.
Athlete’s Foot 1,000 mg twice a day
Burns 1,000 mg 3 times a day until healed; may be partially covered by daily multivitamin/antioxidant complex
Cancer 2,000 mg twice a day, in addition to the amount in your daily multivitamin and antioxidant
Cataracts 500-1,500 mg once a day; all or part may be covered by your multivitamin/antioxidant
Chronic Fatigue Syndrome 500-2,000 mg 3 times a day
Colds 2,000 mg 3 times a day for 5-7 days; then reduce dose to 1,000 mg 3 times a day for the next 5-7 days
Constipation 1,000 mg twice a day. Dose may be increased by 1,000 mg a day (up to 5,000 mg a day) until bowel movements become regular. May be partially covered by daily multivitamin and antioxidant complex.
Crohn’s Disease 500 mg twice a day; should be partially covered by your daily multivitamin and antioxidant.
Cuts and Scrapes 1,000 mg twice a day for 5 days.
Acute: 2,000 mg twice a day
Chronic: 1,000 twice a day; may be partially covered by your daily multivitamin and antioxidant complex.
Endometriosis 1,000 mg twice a day
Fatigue 1,000 mg twice a day
Flu 2,000 mg 3 times a day for 5-7 days; then reduce dose to 1,000 mg 3 times a day for the next 5-7 days
Gout Start with your multivitamin and antioxidant complex, then add 500 mg a day, every 5 days until you reach 1,000 mg twice a day.
Gum Disease Brush 1/2 tsp. powder along the gum line with a soft brush once every other day, alternating with vitamin E (below).
Heart Disease Prevention 750-2,000 mg daily; may be partially covered by your daily multivitamin
Hepatitis 500-1,000 mg twice a day in addition to a daily multivitamin and antioxidant complex
High Cholesterol 1,000 mg twice a day; may be partially covered by your daily multivitamin and antioxidant complex.
Infertility, Male 1,000 mg twice a day in addition to the amount in your daily vitamin program
Lupus 1,000 mg twice a day in addition to amount present in your daily multivitamin and antioxidant complex
Macular Degeneration 1,000 mg once a day in addition to that found in your daily multivitamin and antioxidant
Multiple Sclerosis 1,000 mg a day in addition to that found in your daily multivitamin and antioxidant
Osteoporosis 250-500 mg a day
Sore Throat 1,000 mg 3 times a day
Sunburn 1,000 mg 3 times a day until your sunburn heals; should be partially covered by daily multivitamin and antioxidant.
For hyper: 1,000 mg a day; may be partially covered by a daily multivitamin and/or antioxidant complex
Urinary Tract Infections 500 mg every other hour, as tolerated
Yeast Infection (Vaginal) 1,000 mg twice a day
David Edelberg, M.D.
Because the body doesn’t make or store vitamin C (also known as ascorbic acid), you’ll need to replenish your supply often, through the foods you eat and probably with supplements as well.
HOW IT HELPS ALLERGIES
As an antihistamine, vitamin C is a natural remedy for allergy sufferers. In fact, several clinical studies have explored the vitamin’s power to counteract histamine in the body, and by extension, its presumed ability to minimize sneezing, watery eyes, and other aggravating discomforts of allergic reactions. Interestingly, people who suffer from asthma are often deficient in vitamin C.
WHAT TO LOOK FOR
Despite the multitudes of bottles that line drugstore shelves, all vitamin C products are pretty similar.
Pills or capsules are what I usually suggest for normal use; side effects are generally minimal. Buffered vitamin C may be a better choice if you’ve got an acid-y stomach. This form combines ascorbic acid with minerals such as calcium, magnesium, sodium, or potassium. (Look for products such as calcium ascorbate or sodium ascorbate.) Just remember to account for the additional amounts of these minerals you’re getting in your daily totals.
Vitamin C combined with flavonoids can be very useful because the flavonoids enhance the body’s absorption of vitamin C. You certainly can buy these nutrients separately, and sometimes that’s convenient if you want to vary the dose of either one. On the other hand, with a combination product: You won’t need to swallow as many pills. It should cost you less than buying each of these supplements separately. The effect on the body will be the same whether you take each of these separately or in a combination product. Shopping tip: Special features–including “esterified,” rose hips, or time-release forms–are often just manufacturer’s hype. All cost more, and they’re probably no more effective than regular capsules or tablets of vitamin C.
The following are a few pointers for using vitamin C: If you need a high dose: The powdered form of vitamin C, which is also buffered, is a very convenient way to quickly get a high therapeutic dose. One teaspoon of powder can provide up to 2,500 mg of C, depending on the brand. Try mixing the powder (sometimes sold as crystals) into a glass of orange juice; it just makes the juice taste a bit tart. Take the vitamin regularly, over the long term, if you suffer from allergies, because some research indicates that vitamin C only lowers a person’s blood histamine over time. When you get too much: Some people discover that they can only tolerate so much vitamin C at a time, or during a given day, before it causes loose stools and an “urge to purge.” While this rarely occurs at doses below 8 to 10 grams per day, if it does, you’ll need to limit your doses to what the bowel can tolerate.
David Edelberg, MD