It depends on the case; there is no single guideline.
Randomized trial: taking a broccoli sprout homogenate (rich in sulforaphane) modulated NK cells in blood after inoculation with the live influenza vaccine, and it had previously been shown to reduce viral load in the nose. A signal of immune support; small study with indirect markers.
View the study (study) →Diet · Highest evidence: Low · 1 finding
Information, not medical advice. Prescription drugs require a doctor.
Information, not medical advice. Scientific evidence reflects the quality of the studies.