This vitamin is probably better known and more widely used than any other nutritional supplement. But even if you think you're familiar with vitamin C, read on. You may be surprised to discover exactly how versatile and health-enhancing this nutrient truly is.
What Is It
As early as 1742 lemon juice was known to prevent scurvy, a debilitating disease that often plagued long-distance sailors. But not until 1928 was the healthful component in lemon juice identified as vitamin C. Its anti-scurvy, or antiscorbutic, effect is the root of this vitamin's scientific name ascorbic acid. Today, interest in vitamin C is based less on its ability to cure scurvy than on its potential to protect cells. As the body's primary water-soluble antioxidant, vitamin C helps fight damage caused by unstable oxygen molecules called free radicals, especially in those areas that are mostly water, such as the interior of cells.
What Does It Do
Vitamin C is active throughout the body. It helps strengthen the capillaries (the tiniest blood vessels) and cell walls and is crucial for the formation of collagen (a protein found in connective tissue). In these ways, vitamin C prevents bruising, promotes healing, and keeps ligaments (which connect muscle to bone), tendons (which connect bone to bone), and gums strong and healthy. It also aids in producing hemoglobin in red blood cells and assists the body in absorbing iron from foods.
• Enhances immunity.
• Minimizes cold symptoms; shortens duration of illness.
• Speeds wound healing.
• Promotes healthy gums.
• Treats asthma.
• Helps prevent cataracts.
• Protects against some forms of cancer and heart disease.
As an antioxidant, vitamin C offers protection against cancer and heart disease; several studies have shown that low levels of this vitamin are linked to heart attacks. In addition, vitamin C may actually lengthen life. In one study, men who consumed 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.
Another study found that over the long term, vitamin C supplements protect against cataracts, a clouding of the lens of the eye that interferes with vision. Women who took vitamin C for 10 years or more had a 77% lower rate of early "lens opacities," the beginning stage of cataracts, than women who didn't use supplements.
Does vitamin C prevent colds? Probably not, but it can help lessen symptoms and may shorten the duration of this illness. In a 1995 analysis of studies exploring the connection between vitamin C and colds, the researchers concluded that taking 1,000 to 6,000 mg a day at the onset of cold symptoms reduces the cold's duration by 21%, about one day. Other studies have shown that vitamin C helps elderly patients fight severe respiratory infections. Vitamin C also appears to be a natural antihistamine. High doses of the vitamin can block the effect of inflammatory substances produced by the body in response to pollen, pet dander, or other allergens.
The vitamin is an effective asthma remedy as well. Numerous studies have found that vitamin C supplements helped prevent or improve asthmatic symptoms. For people with type 1 diabetes, which interferes with the transport of vitamin C into cells, supplementing with 1,000 to 3,000 mg a day may prevent complications of the disease, such as eye problems and high cholesterol levels.
How Much You Need
The RDA for vitamin C for men and women is 60 mg a day (for smokers, it's 100 mg) However, even conservative experts think an optimal intake is at least 200 mg a day, and they recommend higher doses for the treatment of specific diseases.
If You Get Too Little: You'd have to consume less than 10 mg a day to get scurvy, but receiving less than 50 mg of vitamin C a day has been linked with an increased risk of heart attack, cataracts, and a shorter life.
If You Get Too Much: Large doses of vitamin C (more than 2,000 mg a day) can cause loose stools, diarrhea, gas, and bloating; all can be corrected by reducing your daily dose. At this level, the vitamin may interfere with the absorption of copper and selenium, so make sure you consume enough of these minerals in foods or supplements.
How To Take It
Dosage: For general health: Get 500 mg of vitamin C a day through foods and supplements. For the treatment of various diseases: Depending on the condition, 1,000 to 6,000 mg a day may be appropriate.
Guidelines For Use: Large amounts are best absorbed in 1,000 mg doses, taken with meals throughout the day. The vitamin works very well when combined with other antioxidants, such as vitamin E.
Citrus fruits and juices, broccoli, red peppers, dark greens, strawberries, and kiwifruits are all good sources of vitamin C.
• Don't take more than 500 mg a day if you have kidney stones, kidney disease, or hemochromatosis, a genetic tendency to store excess iron (vitamin C enhances iron absorption).
• Vitamin C can distort the accuracy of medical tests for diabetes, colon cancer, and hemoglobin levels. Let your doctor know if you're taking it.
Don't spend extra money on specialized vitamin C products (such as esterified C). There's no evidence that they are more efficiently absorbed than plain old ascorbic acid.
• Vitamin C may help prevent reblockage (restenosis) of arteries after angioplasty (an alternative to bypass surgery). A study of 119 angioplasty patients found that restenosis occurred in just 24% of those who took 500 mg of vitamin C a day for four months, compared with 43% of those who did not take the vitamin.
• In addition to being an antioxidant, vitamin C helps the body recycle other antioxidants. In one study, vitamin E concentrations were 18% higher in those who got more than 220 mg of vitamin C a day, compared with people who got 120 mg or less.
• Vitamin C recently came under attack when a small test-tube study found that it may cause genetic damage, potentially increasing the risk of cancer. But scientists have since identified serious flaws in the study. Many better studies show that vitamin C provides numerous benefits, including preventing certain cancers.