Nutrition Science and Everyday Application - beta v 0.1

VITAMINS AND MINERALS AS ANTIOXIDANTS 481
Scurvy is prevented by even a low intake of fruits and vegetables, and it takes at least
a month of consuming very little or no vitamin C for scurvy symptoms to develop. Thus,
scurvy is rare in developed countries today. Diet surveys show that most Americans meet
the RDA for vitamin C. When vitamin C deficiency occurs today, it is in people who consume
very limited food variety, such as those with mental illness, people who abuse alcohol
or drugs, people on very restrictive diets, and impoverished people with limited fruit and
vegetable access. People who smoke also require more vitamin C to counter the free radicals
generated by smoking.
The risk of vitamin C toxicity from foods is essentially nonexistent, because the body can
adjust intestinal absorption and urinary excretion to maintain a healthy vitamin C level.
However, high doses of vitamin C from supplements have been reported to cause numerous
problems, including gastrointestinal upset and diarrhea. To prevent these discomforts, the
UL for vitamin C is set at 2,000 milligrams per day for adults, more than twenty times the
RDA.
At very high doses in combination with iron, vitamin C has sometimes been found to
increase oxidative stress, reaffirming that getting your antioxidants from foods is better
than getting them from supplements. There is also some evidence that taking vitamin C
supplements at high doses increases the likelihood of developing kidney stones; however,
this effect is most often observed in people that already have multiple risk factors for kidney
stones.
Can Vitamin C Supplements Prevent the Common Cold?
Many people believe that taking a vitamin C supplement can prevent the common cold
or decrease its symptoms. This idea was popularized by Linus Pauling in the 1970s, and
it’s continuously promoted today in the form of over-the-counter supplements such as
Emergen-C and Airborne. These typically contain doses in the range of 1000 mg of vitamin C,
far higher than normal levels of vitamin C in the diet and enough to reach the UL of 2000 mg
if a person takes two doses per day.