A grapefruit a day is no substitute for blood pressure medicine

A Facebook post about alternative medicine falsely claims that eating a grapefruit a day will lower your blood pressure so effectively that you won’t need medication.

False information about health and medications can cause harm, especially if people use it to make decisions about their treatment. We have written many times regarding false claims about alternative treatments for disease and about conventional medications.

The post makes a large number of claims about different health conditions and treatments. We are only addressing the one quoted here, and have not assessed the others.

Grapefruit for blood pressure

The post says:

“Why aren’t you informed by your doctor that if you eat a grapefruit everyday, it will lower your blood pressure naturally and you don’t need 💊 ? (This is why a person can’t eat it while on blood pressure meds)”

A systematic review and meta analysis from 2015 did find that overweight and obese patients had some reduction in their systolic blood pressure from eating grapefruits, but noted serious limitations in the three studies included. In any case, the reduction in blood pressure found was small, at 2.43 mmHg (millimetres of mercury, the unit used to measure blood pressure).

For context, most prescribed blood pressure medications lower it by about 10 mmHg. NICE, the organisation that assesses medical evidence and provides guidance for doctors in the UK, recommends prescribing several different medications if needed. 

Lifestyle changes including diet modification are also advised for patients with high blood pressure, known medically as hypertension, but this involves eating a healthy diet in general, rather than grapefruit in particular.

Grapefruit and medications

Grapefruit can block the action of an enzyme that breaks down certain drugs, leading to the drug being active in the body for longer.

It can also interact with the absorption of other drugs, causing there to be too little in the body instead.

For these reasons, the NHS advises people on some medications, including some that treat high blood pressure, to avoid grapefruit and its juice.

The information included in this article contains the latest evidence and official guidance available at the time it was written. This is not a substitute for medical advice. If you require specific medical advice please consult your GP.

Featured image courtesy of א (Aleph)