Good intentions, perilous results

Some supplements can interfere with lab tests to diagnose or monitor health conditions, which can lead to life-threatening misdiagnoses or unnecessary additional testing. Biotin (vitamin B₇) can skew results from a blood test to diagnose heart attack. Other problematic supplements include vitamin C, which can interfere with blood sugar readings and stool tests; calcium, which can make bones appear denser than they are on bone density scans; and creatine, which can lead to falsely high readings of creatinine, a marker for kidney disease.