Zinc has cold-fighting abilities

Zinc - How Foods Fight Cancer

Good food sources of zinc

The mineral zinc has been promoted for its cold-fighting abilities, and,
indeed, it works. However, when it comes to zinc or any other mineral,
you want neither too little nor too much, just as we saw with vitamin
E.17 Researchers in New Jersey discovered this fact accidentally.18 They
tested zinc’s effects in a group of older men and women. Some were
given zinc tablets, while others got placebo tablets that looked and
tasted just like zinc. And to make sure that everyone was generally wellnourished,
the researchers also asked the participants to take a daily
multiple vitamin.

When the researchers later checked the group’s immune function, they
found, to their surprise, that everyone had an immune boost. You can guess
why. The multiple vitamin apparently counteracted a variety of mild
nutritional deficiencies, and that improved their immunity. However, the
researchers had a second, more surprising, finding: The volunteers who
were taking as little as 15 milligrams of zinc actually had worse immune
function than those who got placebos. In other words, zinc is an essential
nutrient and a helpful immune booster when ingested in minute quantities.
But it is easy to go overboard, and excess zinc interferes with immune function.
The recommended amount of zinc in the daily diet is 8 milligrams for
adult women and 11 milligrams for adult men. Table 16 lists some good
foods that will keep your zinc intake up where it should be, without going
too high.