Nutrition Science and Everyday Application - beta v 0.1

482 ALICE CALLAHAN, PHD, HEATHER LEONARD, MED, RDN, AND TAMBERLY POWELL, MS, RDN
Do these high-dose vitamin C supplements do anything to prevent or treat the misery of
the common cold? A systematic review and meta-analysis published in 2013 by the Cochrane
Collaboration summarized the results of 29 studies conducted on this question. The review
concluded that for most people, these supplements don’t prevent the common cold but
can reduce the duration of symptoms by 8% in adults and 14% in children—amounting
to a day or two of relief—but only if they’re taken consistently every day and before cold
symptoms begin. If taken after the onset of symptoms, a vitamin C supplement does not
seem to reduce the duration or severity of symptoms. Some research shows that vitamin
C supplements may be more effective in cold prevention in athletes and those in extreme
physical conditions, such as marathon runners, endurance skiers, and soldiers. 5
SELENIUM
Selenium is an essential trace mineral. It is part of the structure of at least 25 proteins
in the body, with functions in reproduction, thyroid hormone metabolism, DNA synthesis,
and antioxidant and immune protection. 6 As part of antioxidant enzymes, selenium helps
to regenerate other antioxidants, including vitamin C. These enzymes also protect lipids
from free radicals, and, in doing so, spare vitamin E. This illustrates how antioxidants work
together to protect the body against free radical-induced damage.
Food Sources of Selenium
Organ meats, muscle meats, and seafood have the highest selenium content. Grains and