Although most animals can make vitamin C from scratch, humans have lost the ability over the course of evolution. We must get it from food, chiefly fresh fruits and vegetables. One of this vitamin's main functions is helping the body manufacture collagen, a key protein in our connective tissues, cartilage, and tendons.

From ancient times through the early nineteenth century, sailors and others deprived of fresh fruits and vegetables developed a disease called scurvy. Scurvy involves so-called scorbutic symptoms, which include nonhealing wounds, bleeding gums, bruising, and overall weakness. Now we know that scurvy is nothing more than vitamin C deficiency.

Scurvy was successfully treated with citrus fruit during the mid-1700s. In 1928, when Albert Szent-Gyorgyi isolated the active ingredient, he called it the anti-scorbutic principle, or ascorbic acid. This, of course, is vitamin C.

Vitamin C is a powerful antioxidant that neutralizes damaging natural substances called free radicals. It works in water, both inside and outside of cells. Vitamin C complements another antioxidant vitamin, vitamin E, which works in lipid (fatty) parts of the body.

Vitamin C is the single most popular vitamin supplement in the United States and perhaps the most controversial, as well. In the 1960s, two-time Nobel Prize winner Dr. Linus Pauling claimed that vitamin C could effectively treat both cancer and the common cold. Subsequent research has mostly discounted these claims, but hasn't dampened enthusiasm for this essential nutrient. The vitamin C movement has led to hundreds of clinical studies testing the vitamin on dozens of illnesses; at present, however, no dramatic benefits have been discerned.

Requirements

Vitamin C is an essential nutrient that must be obtained from food or supplements; the body cannot manufacture it. The official US and Canadian recommendations for daily intake are as follows:

  • Infants
    • 0-6 months: 40 mg
    • 7-12 months: 50 mg
  • Children
    • 1-3 years: 15 mg
    • 4-8 years: 25 mg
    • 9-13 years: 45 mg
  • Males
    • 14-18 years: 75 mg
    • 19 years and older: 90 mg
  • Females
    • 14-18 years: 65 mg
    • 19 years and older: 75 mg
  • Pregnant Women
    • 18 years old or younger: 80 mg
    • 19 years and older: 85 mg
  • Nursing Women
    • 18 years old or younger: 115 mg
    • 19 years and older: 120 mg

Note: Smoking cigarettessignificantly reduces levels of vitamin C in the body.1 The recommended daily intake for smokers is 35 mg higher across all age groups.

Vitamin C supplements are available in two forms: ascorbic acid and ascorbate. The latter is less intensely sour.

Sources

Most of us think of orange juice as the quintessential source of vitamin C, but many vegetables contain as much or even more. The National Institutes of Health's Office of Dietary Supplements offers this list of foods that are high in vitamin C:188

Food Serving size Vitamin C content
(milligrams [mg])
% Daily Value
Sweet red pepper, raw ½ cup 95 158
Orange juice ¾ cup 93 155
Orange 1 medium 70 117
Grapefruit juice ¾ cup 70 117
Kiwifruit 1 medium 64 107
Green pepper, raw ½ cup 60 100
Broccoli, cooked ½ cup 51 85
Strawberries, fresh ½ cup 49 82
Brussels sprouts, cooked ½ cup 48 80
Grapefruit ½ medium 39 65
Broccoli, raw ½ cup 39 65
Tomato juice ¾ cup 33 55
Cantaloupe ½ cup 29 48
Cabbage, cooked ½ cup 28 47
Cauliflower, raw ½ cup 26 43
Potato, baked 1 medium 17 28
Tomato, raw 1 medium 17 28
Spinach, cooked ½ cup 9 15
Green beans, cooked ½ cup 8 13

One great advantage of getting vitamin C from foods rather than from supplements is that you will get many other potentially healthful nutrients at the same time, such as bioflavonoids and carotenes. However, vitamin C in food is partially destroyed by cooking and exposure to air, so for maximum nutritional benefit you might want to try freshly made salads rather than dishes that require a lot of cooking.

Vitamin C Deficiency

Scurvy, the classic vitamin C deficiency disease, is now a rarity in the developed world, although a more subtle deficiency of vitamin C is fairly common.2-6According to one study, 40% of Americans do not get enough vitamin C.7In fact, vitamin C deficiency sufficient to cause bleeding problems during surgery turns out to be more common than previously thought.141

Aspirinand other anti-inflammatory drugs might lower body levels of vitamin C,8-10 as might oral contraceptives.11-15 Supplementation may be helpful if you are taking any of these medications.