Does zinc raise testosterone?
Only if there is an actual deficiency to correct -- supplementing in men who already have adequate zinc levels does not reliably raise testosterone further.
The short answer
Zinc is a required cofactor for testosterone synthesis, and correcting a real deficiency reliably improves testosterone in men who are actually deficient. But the evidence does not support zinc as a general testosterone booster for men whose levels are already adequate. Oysters carry a long aphrodisiac folk reputation with a real, deficiency-dependent basis given their zinc content, alongside red meat, pumpkin seeds, and legumes as other food sources. Excess supplementation above roughly 40mg per day tolerable upper intake can cause copper deficiency with long-term high-dose use.