The Claim:
A video claims that taking massive amounts of Vitamin C, Zinc, and other supplements can boost your immune system and eliminate the need for a flu vaccine.
The Facts:
Supplements are not necessarily useless. Oral zinc may help with cold treatment if taken within 24 hours of symptom onset, but it can have side effects and interactions with medicines. Intranasal zinc should be avoided due to the risk of irreversible loss of smell.
While Vitamin C may have some minor protective effects against colds and may slightly reduce their duration and severity, high doses of Vitamin C, like suggested in the video, can cause digestive issues and in some populations, increase the risk of kidney stones.
Vitamin D may help prevent colds and the flu in those who are deficient in Vitamin D, but has little benefit for those who are not.
Studies suggest quercetin may reduce the severity of influenza, but this assumes you already get sick.
None of these home remedies will prime your immune cells to fight influenza before you are exposed, though. The most effective defense against the flu, however, is vaccination, which is recommended for all individuals aged six months and older.