How Supplements Can Distort Your Blood Test Results

Some supplements do not just affect your health - they affect the measurement of it, producing results that are simply wrong.

The biotin problem

High-dose biotin, common in hair and nail products, interferes with immunoassays that use biotin-streptavidin binding chemistry. Depending on the assay design, this produces falsely high or falsely low results. Affected tests include thyroid function, troponin used to diagnose heart attack, and various hormone assays. Regulators have issued safety communications about this, and cases of clinical mismanagement including a reported death have been described.

Other interferences

High-dose vitamin C can interfere with some glucose meters and with faecal occult blood testing. Vitamin B12 supplementation renders B12 testing uninterpretable for assessing status. Iron supplements taken shortly before testing distort serum iron. Some botanicals affect liver enzyme readings. Creatine supplementation raises serum creatinine, which can look like impaired kidney function when it is not, and is a common source of unnecessary alarm.

What to tell your doctor

List everything you take before any blood test, and specifically mention biotin, B12, iron, vitamin C and creatine. Where relevant, the usual advice is to pause supplements for a period before testing, though the required interval varies by test and should come from the requesting clinician. If a result is unexpectedly abnormal and you take supplements, mention it before further investigation is arranged - it may be the explanation.

A note on Cognizil

We publish this blog on the Cognizil official website, so treat anything we say about our own product as coming from an interested party. What we can do is be specific: Cognizil is a liquid dropper supplement taken once daily, and it makes no claim to treat, cure or prevent any disease. It also contains St. John’s Wort, so if you take any prescription medicine, read our interaction guide before the sales page. If you want the drawbacks first, start with Cognizil reviews and complaints.