The U.S. Food and Drug Administration is warning that consuming high levels of a B-vitamin commonly found in over-the-counter supplements can interfere with the results of certain lab tests.

The FDA recently issued a safety alert warning that high levels of biotin, also called vitamin B7, can interfere with test results for a variety of conditions.

Biotin occurs naturally in foods, including eggs, spinach and almonds. It’s also commonly found in multi-vitamins, prenatal vitamins and supplements marketed to promote healthy hair, skin and nails.

The interference with lab tests can occur when people consume higher than the daily recommended allowance, according to the FDA.

The National Institutes of Health recommends people consume 5-35 micrograms of biotin, depending on age and whether the individuals is pregnant or lactating. Many multi-vitamins provide about 30 micrograms of the vitamin, but some supplements, especially those marketed to promote healthy hair, skin, and nails, can contain as much as 650 times the daily recommended intake of the vitamin.

Depending on the lab test being performed, high levels of biotin in blood and other samples can cause falsely high or falsely low  results, and could lead to misdiagnosis or inappropriate treatment, according to the FDA.

The safety alert was issued after a reported increase in the number of “adverse events” related to biotin interference with lab results, according to the FDA. Cases included the death of a patient who was taking high levels of biotin and had a falsely low test result for troponin, a biomarker used to help diagnose a heart attack.

Patients who are taking a supplement containing biotin, are considering doing so, should speak to a physician, according to the FDA. The same recommendation holds true for patients who are concerned biotin may have interfered with previous lab testing.