If you've taken a stroll down the supplement aisle of a store, you'll probably see a big hole where Zinc should be. Zinc is a bit of a hot item now, since its reputation for protecting the immune system is well-known. Zinc plays a huge role in our bodies beyond that: it helps with vitamin A absorption, detoxification, hormonal processes, and wound healing. There are even more things to add to the list, but the focus right now seems to be on its immune support and antiviral properties.
Some due diligence: Zinc tangos with a few other minerals in our bodies. Calcium and iron, in unbalanced proportions, can block Zinc absorption. Copper (a necessary trace minerals) can also block Zinc, because it competes for the same absorption points in the small intestine. Zinc can also lower the effectiveness of Selenium, but it also lowers the effectiveness of Cadmium (which we really don't want in out system - so... yay!).
One amazing source of Zinc is Pumpkin Seeds, also called Pepitas. You can get them roasted or unroasted. At Halloween, many people are doing just that. A lot of the store bought pepitas will be sans seed coat, looking green instead of white. I will also put a plug in for this being a fantastic remedy for general men's health: Cadmium stores itself in the testes. You can also get Zinc by eating a variety of meats.
Vitamin C is a healing partner with Zinc - they have a lot of common ground. You don't have to overdo Vitamin C: the more you take at once, the less it is absorbed. It's water-soluble, so it's not stored in your body for any great length of time, and should be consumed daily. Vitamin C is an antioxidant. Antioxidants are important: although we certainly need oxygen to exist, oxidation is wearing over time and promotes aging. The big immunity factor here is that Vitamin C helps with the elasticity of blood vessel and capillary walls - that's what controls the skins ability to get rid of heat and toxins, you first line of defense against disease. Vitamin C's potency is decrease with exposure to air and heat - a fever will reduce the effectiveness of Vitamin C, too.
You can eat the citrus fruits like oranges and mandarins, but don't forget about berries! Growing up, I was not a fan of oranges (too much pith, thank you very much), but I loved Strawberries. Sweet Red Peppers and leafy greens have it, too. And, because I'm an herbalist, I will mention that Pine Needles have it, too. They make an excellent tea. Pine needles are also good at drawing toxins (antiseptic) out of a body, which is one of the reasons it is used in saunas and banyas (Russian saunas). If there are kidney issues, Pine will be too stimulating.
You can certainly use a Zinc or Vitamin C supplement, but I love the fact that we can just eat well. If you can't get to the store or they shelves of supplements are low, you can eat your wellness!
John D. Kirschmann: Nutritional Almanac - Sixth Edition
The Botanist in the Kitchen: https://botanistinthekitchen.blog/2017/10/27/botany-lab-of-the-month-jack-o-lantern/
Dr. Silvia Maggini: https://journals.sagepub.com/doi/pdf/10.1177/147323001204000104
Matthew Wood: The Earthwise Herbal: New World Medicinal Plants