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How Grapefruit Affects Prescription Drugs

Does grapefruit particularly help people lose weight?

If someone eats half of a grapefruit three times a day before each meal for a couple months, they may lose about two pounds ó but that’s no more than if they ate 3 apples or pears a day. In this study, the grapefruit eaters not only saw their weight go down, but their waist got slimmer, and their body fat melted away. If, however, we repeat the experiment and instead ask people to drink a half cup of water before each meal, we get the same result. So this belief that grapefruit has some special fat-burning quality appears to be just a long-held myth.

The researchers reported that grapefruit consumers had a drop in weight, a significant drop in cholesterol, and a significant drop in blood pressure. They concluded that consumption of grapefruit daily for 6 weeks does not significantly decrease body weight, cholesterol, or blood pressure, though. That made me do a little double take, but again, it’s because the grapefruit didn’t do any better than placebo.

Other studies have found a legitimate cholesterol-lowering benefit of grapefruit, and even a little dip in triglycerides, especially eating red as opposed to white . For example, one study showed a decrease in cholesterol, but only from one life-threatening cholesterol level to another life-threatening cholesterol level. To prevent heart disease, we really have to get down to a total cholesterol of around 150, which is the average cholesterol of those eating diets composed exclusively of plant foods, not just grapefruits (See, for example, One in a Thousand: Ending the Heart Disease Epidemic).

Even though grapefruits alone don’t do much, the researchers suggest that people might be more likely to stick with them than cholesterol lowering drugs, noting that most people with heart disease stop taking their statin drugs within a couple years because of the adverse side effects (see Statin Muscle Toxicity). While grapefruits alone don’t have any side effects, ironically, combining grapefruits and drugs can make drug side effects even worse.

If we eat lots of fruits and vegetables, we hopefully won’t need a lot of drugs (Say No to Drugs by Saying Yes to More Plants), but certain phytochemicals in plants can affect the metabolism of drugs in the body. Grapefruit is the poster child, described as a “pharmacologist’s nightmare.” Natural phytochemicals in grapefruit suppress the enzymes that help clear more than half of commonly prescribed drugs, and less drug clearance means higher drug levels in the body. This may actually be good if we want a better caffeine buzz from our morning coffee, or our doctors want to help us save thousands of dollars by boosting the effects of expensive drugs instead of just peeing them away.

But higher drug levels may mean higher risk of side effects. Women taking the Pill are normally at a higher risk of blood clots, but even more so, perhaps, if they have been consuming grapefruit. Taking the Pill with grapefruit juice may increase blood drug concentrations by 137 percent.

If suppressing our drug clearance enzymes with grapefruit juice elevates levels of ingested estrogen, what might it be doing to our own estrogen levels? A study associating grapefruit consumption with breast cancer freaked out the medical community, but subsequent studies on even larger groups of women found no evidence of a link. The Harvard Nursesí Study even found a decreased risk of the scariest breast cancer type, so it doesn’t look like we have to worry about grapefruit affecting our natural chemistry. For those prescribed unnatural chemistries, it may be a good idea to discontinue grapefruit consumption for 72 hours before use of a drug that may interact with it. If you don’t want to give up your grapefruit, you can ask your doctor about switching from a grapefruit-affected drug like Lipitor to one of the citrus-proof alternatives (the replacement drug chart is in the above video).

Other videos on citrus include:

And another video on the risks associated with taking estrogens: Plant-Based Bioidentical Hormones.

Canít eat grapefruit without sprinkling sugar on top? Try erythritol instead to avoid so many empty calories: Erythritol May Be a Sweet Antioxidant.

In health,
Michael Greger, M.D.

PS: If you havenít yet, you can subscribe to my free videos here and watch my live year-in-review presentations†Uprooting the Leading Causes of Death and More Than an Apple a Day.

Related:
Which Common Fruit Fights Cancer Better?
Keeping Your Hands Warm With Citrus
Reducing Muscle Fatigue with Citrus

Read more: Health, Cancer, Cholesterol, Diet & Nutrition, Drugs, Eating for Health, General Health, Heart & Vascular Disease, High Blood Pressure, Natural Remedies, Obesity, Videos, , , , ,

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Dr. Michael Greger

A founding member of the American College of Lifestyle Medicine, Michael Greger, M.D., is a physician, author, and internationally recognized speaker on nutrition, food safety, and public health issues. Currently Dr. Greger serves as the Director of Public Health and Animal Agriculture at The Humane Society of the United States. Hundreds of his nutrition videos are freely available at NutritionFacts.org.

85 comments

+ add your own
6:19PM PDT on Apr 5, 2014

Grapefruit is one of my very favorites.

Both whole, & as juice.

2:53AM PST on Mar 2, 2014

Don't actually like grapefruits. thanks.

1:08AM PST on Mar 1, 2014

Thank you :)

11:41PM PST on Feb 28, 2014

Thanks.

1:39PM PST on Feb 27, 2014

Thanks for the info.

9:39PM PST on Feb 26, 2014

One medication I take has a warning not to eat grapefruit while taking the medication. Now I know why. Grapefruit is my least favourite fruit anyway, so it is no problem.

1:38AM PST on Feb 25, 2014

Thanks for sharing

9:50PM PST on Feb 24, 2014

Years ago, I read that eating grapefruit with eggs, especially hard-boiled, is a good method for losing weight.
Of course, how many eggs can you eat?

7:16PM PST on Feb 24, 2014

Years ago I went on a low-carb diet and ate a half grapefruit everyday for one year.
I lost 40 lbs!
However, about nine months in to eating the grapefruit, my body got very acidic and
had to stop the grapefruit.
I think everything is about moderation. Do not know about eating grapefruit and taking
medication, but it would be wise to ask the doc.

1:34PM PST on Feb 23, 2014

important consideration. Some drugs are also affected by calcium consumption according to their labels

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Disclaimer: The views expressed above are solely those of the author and may not reflect those of
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people are talking

All sound delicious :-)

I agree with Carol P--- I too am on the 'less-expensive side' of the these tips and still my grocery…

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