Nov 12, 2002 5 min read

When the recommended dietary allowance (RDA) of 60 mg daily for vitamin C was originally set, the basis of need was to prevent the deficiency disease scurvy. Since that time, the Food and Nutrition Board of the National Academy of Sciences raised the recommended level to 90 mg for men and 75 mg for women. But scientists, whose work influenced the last increase, believe 75 mg for women is still not enough.

Dr. Mark A. Levine, researcher at the National Institutes of Health, headed up a study in which a group of healthy women were put on a carefully controlled diet to deplete their vitamin C. Supplements were gradually added back to their diets while blood levels of vitamin C were measured to determine the optimal level necessary. What they found was that women should also be on a daily regiment of at least 90 mg.

Vitamin C is essential for the formation of collagen – a protein that gives structure to bones, cartilage, muscle and blood vessels.

It also aids in maintaining healthy capillaries, bones and teeth and in the body’s absorption of iron.

Recent studies have uncovered a whole new host of possible benefits:

– Women who consume higher-than-recommended doses of vitamin C may lower their risk of cataracts.

– Higher levels of vitamin C have been associated with lower instances of symptomatic gallbladder disease in women.

– Diets high in vitamins C and E may lower the risk of Alzheimer’s and other dementias.

– Vitamins C and E tend to prevent artery inflammation caused by a heavy, caloric-dense meal.

– Two glasses of orange juice a day lowers blood pressure – while stopping the orange juice routine allows the pressure to creep back up.

– A diet rich in phytochemicals and vitamin C helps to reduce the risk of cancer.

– Vitamin C may help your body manage stress and boost your immune system.

– Vitamin C may help older adults offset age-related weight gain and other ailments by increasing their resting metabolisms.

In another gender-related study, women may experience more oxidation in their cells than men. (Oxidation is the accumulation of cell-damaging substances known as free radicals.) It seems women in general may need more antioxidants, and vitamin C is a strong antioxidant.

Pregnant women may have additional worries – low levels of vitamin C may contribute to preeclampsia, a toxic condition that sometimes develops in late pregnancy and is characterized by a sudden rise in blood pressure and weight gain, severe headaches, visual disturbances and fluid retention. Preeclampsia puts both mother and baby at risk.

Low levels of maternal vitamin C can also be devastating for premature babies. One study at the National Human Genome Research Institute of the National Institutes of Health rediscovered reduced vitamin C availability during pregnancy may be responsible for respiratory failure and massive brain bleeding in preemies shortly after birth.

The good news – these conditions are largely preventable simply by increasing your intake of vitamin C. But how much is enough and how much is too much?

The recommendations from Levine’s study are that 100 to 200 mg daily will best serve most adult needs. However, a few experts recommend even higher doses, such as those amounts used in many of these clinical trails – the cataract study suggests 500 mg a day unless you are prone to kidney stones.

Almost all experts agree that the maximum amount anyone should ever consider is 1,000 mg daily. Blood levels are thought to reach a plateau at this amount. Anything beyond is not absorbed.

Overdosing can actually be as harmful as underdosing and can result in a thickening of arteries at twice the normal rate. (These studies were based on 500 mg daily during a period of 18 months. These researchers also believe vitamin C reaches plasma and tissue saturation at 100 mg per day).

What are our best dietary sources of vitamin C? Though a large variety of foods contribute vitamin C, Ohio State University Extension lists the following as the best overall: cantaloupe; grapefruit and grapefruit juice; honeydew melon; kiwifruit; oranges, including mandarin; orange juice; papaya; strawberries; tangelos and tangerines; watermelon; asparagus; broccoli; brussel sprouts; red cabbage; cauliflower; kale; kohlrabi; sweet green and red peppers; plantain; snow peas; sweet potatoes; and tomatoes.

Ready-to-eat cereals are often fortified to include vitamin C – check the nutrition labels, but remember the percentages listed are based on the current RDA.

Since vitamin C is water soluble, OSU Extension recommends you eat fruits and vegetables raw whenever possible. If you do choose to cook them, steam, boil or simmer in a minimal amount of water for the shortest time possible. Some vegetables can be cooked in their skins to protect their vitamin C, such as potatoes.

Prepared juices should be refrigerated and used within two to three days. Refrigerate cut raw fruits and vegetables in an airtight container with no water.

Jan Hawkins is a freelance health care journalist residing in Kentucky.