Around this time of year, a lot of us are relying heavily on vitamin C and zinc supplements to mediate the effects of a bad cold or flu which can be bacterial or viral in nature. Natural systems in the body, such as the iron withholding defense system (IWDS), are activated to protect us from these pathogens when they invade. Where the IWDS withholds iron, other metals such as copper and zinc and the transport proteins transferrin and ceruloplasmin are present to maintain iron balance.
Copper and zinc — when behaving properly — are boosters of our immune system, powerful antioxidants, and defend us against the overproduction of free radicals generated by too much iron. Transferrin and ceruloplasmin share in the task of keeping us healthy by binding and transporting iron and copper. Transferrin, when too heavily saturated with iron, makes us more susceptible to infection. When too low, ceruloplasmin allows iron and copper to accumulate, resulting in a free radical production bonanza.
Even though vitamin C is a good antioxidant, reduces inflammation, and functions as an effective antihistamine for relieving nasal congestion, supplements taken in doses greater than 500 mg will significantly increase the absorption of iron and possibly result in iron overload. Where bacteria need iron to thrive and proliferate, viruses do not, but a virus needs an iron-rich host to thrive and grow.
Zinc ions help attract cells of the immune system to viruses. Some of these immune cells do not develop normally without sufficient levels of zinc, making the body more susceptible to wintertime illnesses.
This trace element also impacts iron levels through copper. Zinc-containing enzymes work with copper to defend the body against free radicals, molecules that damage cells as they search for electrons.
Like vitamin C, copper inactivates histamine to stop a runny nose. The copper-containing protein ceruloplasmin plays a particularly important role in the transport and storage of both copper and iron. Ceruloplasmin oxidizes ferrous iron to ferric iron, allowing iron to bind to transferrin and be carried throughout the body. When transferrin is heavily saturated with iron, a person is more susceptible to infection.
Research has shown that low ceruloplasmin levels have implications for anemia (due to its role in transporting iron needed for hemoglobin formation), neurodegenerative diseases such as Parkinson’s and Alzheimer’s (because astrocytes in the brain express ceruloplasmin), and copper deficiency.
While zinc is effective and needed for taking a cold, long-term use of supplemental zinc or iron can decrease the absorption of copper. Ceruloplasmin will be low in both cases of high zinc or high iron. Keeping all three nutrients — zinc, copper, and iron — in balance is key for healthy red blood cells.
Thompson KI, Shoham S, Connor JR. “Iron and neurologic disorders.” Brain Research Bulletin 55 (2001): 155‑64.
Weinberg ED. “Roles of metallic ions in host‑parasite interactions.” Bacteriological Reviews 30 (1966).
Weinberg ED. “Iron withholding: A defense against infection and neoplasia.” Physiological Reviews 64 (1984): 65–102.
Siegenberg D, Baynes RD, Bothwell TH, et al. “Ascorbic acid prevents the dose-dependent inhibitory effects of polyphenols and phytates on nonheme-iron absorption.” American Journal of Clinical Nutrition 53 (1994): 537-41.
Porea TJ, Belmont JW, Mahoney DH Jr. “Zinc-induced anemia and neutropenia in an adolescent.” The Journal of Pediatrics. 2000, 136 (5): 688-90.