Surprising Side Effects of Eating Grapefruit, According to Dietitians — Eat This Not That

The grapefruit is a sweet and sour fruit that is a cross between an orange and pomelo. This fruit had its 15-minute of fame when the Grapefruit Diet claimed that this superfood burned fat more quickly than other foods. However, with few studies to back this up, the end result was people just eating lots of grapefruit and figuring out ways to incorporate it into their diets. We asked registered dietitians and other experts about the benefits, drawbacks, and side effects of including grapefruit in a healthy diet, Keep reading to find out some great things about this superfood and a couple of reasons to think twice about picking it up next time you hit up the grocery store.

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Gabriela Barreto, RD, registered dietitian at Kencko, points to research that indicates how consuming grapefruit might help with insulin resistance. A study published in the Journal of Medicinal Food had shown that when participants consumed a grapefruit prior to a meal, compared to grapefruit juice and a placebo, they saw a reduction of 2-hour postprandial (post-meal) glucose levels and well as an overall reduction in insulin resistance.

hold slice of grapefruit

A standard cup of grapefruit has roughly 300 milligrams of potassium per serving compared to a banana which has around 400 milligrams. “Potassium’s role in the body includes serving as a major electrolyte to help maintain fluid balance and hydration, maintaining heartbeat, muscle contraction, and nerve function, and moving fluids in and out of cells such as waste products,” says Barreto.

Additionally, potassium can help to reduce blood pressure in those with hypertension making it an even better choice.


If you take prescribed medication for other health conditions, you may want to steer clear of grapefruit. “Grapefruit interacts with many drugs, which can cause too much or too little of the drug in our body,” says Nicole Lindel, RD, registered dietitian and Everlywell advisor. “For example, grapefruit can block the action of enzymes needed to break down certain cholesterol-lowering medications such as Lipitor.”

Other medications that might interact with grapefruits include statins (medications to lower cholesterol), anti-anxiety drugs, corticosteroids, and antihistamines

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eating grapefruit

Grapefruit has a large amount of vitamin C per serving and as a result, can help increase collagen production. As you age, collagen production tends to decrease so adding grapefruit to your diet may be able to help your body generate more.

“Collagen makes up about 30% of bone structure, a large amount of tendon and ligament tissue, and is important for skin and blood vessel structure,” says Barreto.

heart health

If there’s one more thing you can add to your diet to keep your heart healthy, you may want to consider grapefruit. “Grapefruit supports heart health thanks to its high fiber, potassium, and antioxidant content,” says Breanna Woods, MS RD, registered dietitian for Blogilates.

Barreto adds that studies like this one from the National Library of Medicine have found an association between grapefruit intake and decreased risk of coronary heart disease, acute coronary events, and ischemic stroke.

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grapefruit w meal

Now, there’s nothing inherent in grapefruit that causes weight loss aside from the fact that it’s a low-calorie food that might help create a caloric deficit. Woods notes that it’s high in fiber which can help keep you feeling satisfied for longer which may be good for weight loss.

eating grapefruit

A single grapefruit has nearly 64% of the daily recommended value of vitamin C for adults according to Barreto. With that said, Vitamin C can help with iron absorption due to its high Vitamin C concentration.

“Iron is important for moving oxygen through the bloodstream via red blood cells to bring oxygen to cells,” says Barreto.

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Casey Clark

Casey Clark is a current journalism student at Hofstra University with a passion for food, beauty, and entertainment. Read more

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