We've known for a long time that it prevents scurvy and is important for the healthy functioning of all mucus membranes in our bodies.
Now mounting evidence suggests (but doesn't prove) that vitamin C may play a role in preventing many kinds of cancers, hardening of the arteries, cataracts and birth defects, as well as reducing high blood pressure and common cold symptoms.
The Environmental Nutrition (EN) newsletter points out that on any given day, fewer than 50 percent of Americans consume 60 mg of vitamin C, the Recommended Daily Allowance (RDA) established by the National Academy of Sciences. Some researchers suggest goals should be set higher, at 150 to 200 mg per day.
Popping a supplement would seem like a good idea. But few researchers are willing to promote such an easy out. Food offers many nutrients, both known and unknown, making shortcuts risky. The recently discovered cancer-fighter sulforaphane, found in cabbage-family vegetables, is a case in point.
EN notes that only 9 percent of the population actually eats 5 serving of fruits and vegetables daily. Of those who do, 72 percent do not eat those high in vitamin C.
Fruits high in vitamin C (one serving meets the RDA) include a kiwi fruit (75 mg), a medium mango (57 mg), a navel orange (80 mg), half a papaya (94 mg), a cup of strawberries (85 mg), a cup of cranberry juice cocktail (108 mg), a cup of fresh grapefruit juice (94 mg), a cup of fresh orange juice (124 mg), a cup of frozen orange juice (97 mg) and a cup of mandarin oranges (86 mg).
Fruits with moderate amounts of vitamin C (one-fourth the RDA or more) include one-fourth of a honey dew melon (23 mg), a grapefruit half (47 mg), a cup of raspberries, blackberries or blueberries (31 mg), a cup of bottled grapefruit juice (50 mg), a cup of raw or juice-packed pineapple (24 mg), a medium tangelo or tangerine (26 mg).
Vegetables high in vitamin C include a cup of raw (163 mg) or cooked (135 mg) broccoli, six to eight medium brussels sprouts (87 mg), a cup of raw (78 mg) or cooked (60 mg) cauliflower, a cup of cooked collard greens (92 mg), a cup of cooked kale (82 mg), a cup of cooked mustard greens (96 mg), a large sweet bell pepper (128 mg), a cup of cooked turnip greens (92 mg).
Vegetables containing moderate amounts of vitamin C include a small ripe tomato (23 mg), a large baked sweet potato (40 mg), a cup baked winter squash (26 mg), half a baked acorn squash (20 mg), half a raw chayote (19 mg), 3 1/2 ounces raw or one cup cooked (50 mg) spinach, a cup of canned tomatoes (24 mg), a cup cooked wax beans (26 mg), a medium baked potato (20 mg), a medium boiled potato (16 mg), 3 1/2 ounces romaine lettuce (18 mg), a cup of raw or cooked cabbage (47 mg), a cup of cooked asparagus (34 mg), 3 1/2 ounces raw alfalfa sprouts.
Colleen Pierre, a registered dietitian, is the nutrition consultant to the Union Memorial Sports Medicine Center in Baltimore.