It's been lauded for its part in treating depression, but a recent study found that a 1mg daily dose can triple your prostate-cancer risk.
This is an ingredient in red wine that increases the lifespan of lab mice, but human research shows it could cause kidney damage.
Once thought to protect against prostate cancer, selenium was recently linked to an increased risk for the disease.
Popular because of its supposed anti-stress properties, this root has been linked to severe liver toxicity.
This herb's brain- and memory-boosting claims have been shot down by science, and tests show it's often tainted with lead.