Tell Your Doctor if You Eat Grapefruit

Tell Your Doctor if You Eat Grapefruit
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The role white and pink (red) grapefruit may play in weight loss and cholesterol control, as well as the suppression of drug-clearance enzymes within the body.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

If you have people eat half a grapefruit three times a day before each meal for a couple months, they may lose about two pounds. But, that’s no more than if they ate three 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, you repeat the experiment, and instead ask people to drink a half-cup of water before each meal, you get the same result. So, this belief that grapefruit has some special fat-burning quality appears to be just a “long-held myth.”

Here’s the latest, showing grapefruit consumers had a drop in weight, significant drop in cholesterol, significant drop in blood pressure. “Conclusion: This study suggests that consumption of grapefruit daily for 6 weeks does not significantly decrease body weight, cholesterol, or blood pressure.” What?! That made me do a little double take. But again, it’s because the grapefruit just didn’t do any better than placebo.

Other studies have found a legitimate cholesterol-lowering benefit—especially eating red, as opposed to white, grapefruits—and, even a little dip in triglycerides. This was one grapefruit a day for 30 days. But, as you can see, though, they went from one life-threatening cholesterol level to another life-threatening cholesterol level. To prevent heart disease, you really have to get down to a total cholesterol of around 150—the average cholesterol of those eating diets composed exclusively of plant foods, not just grapefruits.

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, whereas grapefruit alone don’t have any side effects. But, ironically, combine grapefruits and drugs together, and you can make drug side effects even worse.

Now, hopefully, if you eat lots of fruits and veggies, you won’t need a lot of drugs. But, certain phytochemicals in plants can affect the metabolism of drugs in the body, and 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 so, less drug clearance means higher drug levels in the body. Now, this may be good, if you want a better caffeine buzz from your morning coffee, or your doctor wants to help you save thousands of dollars boosting the effects of expensive drugs, instead of just peeing them down the toilet.

But, higher drug levels may mean higher risk of side effects. Women taking the pill are at a higher risk of blood clots, particularly, perhaps, if they have been consuming grapefruit. Taking the pill with grapefruit may increase blood concentrations by 137%.

If suppressing our drug-clearance enzymes with grapefruit juice elevates levels of ingested estrogen, what might it be doing to our own estrogen levels? This 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. In fact, if anything, the Harvard Nurses’ Study found a decreased risk of the scariest breast cancer type.

So, it doesn’t look like one has to worry about grapefruit affecting our natural chemistry. But, 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 one of the grapefruit-affected drugs, like Lipitor, to one of the citrus-proof alternatives.

Please consider volunteering to help out on the site.

Images thanks to Dan Zen, Mtsofan, gálibo and sewm via flickr and Lokal_Profil via Wikimedia

 

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

If you have people eat half a grapefruit three times a day before each meal for a couple months, they may lose about two pounds. But, that’s no more than if they ate three 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, you repeat the experiment, and instead ask people to drink a half-cup of water before each meal, you get the same result. So, this belief that grapefruit has some special fat-burning quality appears to be just a “long-held myth.”

Here’s the latest, showing grapefruit consumers had a drop in weight, significant drop in cholesterol, significant drop in blood pressure. “Conclusion: This study suggests that consumption of grapefruit daily for 6 weeks does not significantly decrease body weight, cholesterol, or blood pressure.” What?! That made me do a little double take. But again, it’s because the grapefruit just didn’t do any better than placebo.

Other studies have found a legitimate cholesterol-lowering benefit—especially eating red, as opposed to white, grapefruits—and, even a little dip in triglycerides. This was one grapefruit a day for 30 days. But, as you can see, though, they went from one life-threatening cholesterol level to another life-threatening cholesterol level. To prevent heart disease, you really have to get down to a total cholesterol of around 150—the average cholesterol of those eating diets composed exclusively of plant foods, not just grapefruits.

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, whereas grapefruit alone don’t have any side effects. But, ironically, combine grapefruits and drugs together, and you can make drug side effects even worse.

Now, hopefully, if you eat lots of fruits and veggies, you won’t need a lot of drugs. But, certain phytochemicals in plants can affect the metabolism of drugs in the body, and 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 so, less drug clearance means higher drug levels in the body. Now, this may be good, if you want a better caffeine buzz from your morning coffee, or your doctor wants to help you save thousands of dollars boosting the effects of expensive drugs, instead of just peeing them down the toilet.

But, higher drug levels may mean higher risk of side effects. Women taking the pill are at a higher risk of blood clots, particularly, perhaps, if they have been consuming grapefruit. Taking the pill with grapefruit may increase blood concentrations by 137%.

If suppressing our drug-clearance enzymes with grapefruit juice elevates levels of ingested estrogen, what might it be doing to our own estrogen levels? This 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. In fact, if anything, the Harvard Nurses’ Study found a decreased risk of the scariest breast cancer type.

So, it doesn’t look like one has to worry about grapefruit affecting our natural chemistry. But, 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 one of the grapefruit-affected drugs, like Lipitor, to one of the citrus-proof alternatives.

Please consider volunteering to help out on the site.

Images thanks to Dan Zen, Mtsofan, gálibo and sewm via flickr and Lokal_Profil via Wikimedia

 

Doctor's Note

Another benefit of not taking drugs? You don’t have to worry about grapefruit consumption! See Say No to Drugs by Saying Yes to More Plants.

We don’t want to take cholesterol-lowering drugs unless we need to. See Statin Muscle Toxicity. To get cholesterol down naturally, see:

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

Other videos on citrus include:

Can’t eat grapefruit without sprinkling sugar on top? Try erythritol instead, just to avoid the empty calories: Erythritol May Be a Sweet Antioxidant.

For more context, check out my associated blog post: How Grapefruit Affects Prescription Drugs.

If you haven’t yet, you can subscribe to my videos for free by clicking here.

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34 responses to “Tell Your Doctor if You Eat Grapefruit”

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  1. Please check out the petition below (link included) petitioning Whole Foods

    Market to provide to the consumer a different line of dairy products.

    While the likelihood of Whole Foods doing this is slim, the awareness it will raise will possibly create a lot of people getting off dairy. The average consumer has absolutely no idea that 99 percent of US dairy comes from mother cows separated from their calves, denied what they gave birth to. Please let me know what you think of the petition, and please pass it on if this resonates with you.

    https://www.change.org/petitions/whole-foods-market-sell-a-line-of-dairy-products-sourced-from-milk-of-cows-who-are-not-separated-from-their-calves-all-allowed-to-live-their-lives-as-a-family-no-forced-pregnancies-no-veal-beef-futures-for-calves




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  3. Interesting, I suppose we could use grapefruit to have a better buzz from tea instead of coffee. Correct me if I’m wrong, but it seems that is the opposite effect of broccoli ! Is that overall great ? Could it decrease the benefice of broccoli ?




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    1. Bergamottin from grapefruit juice is one of many direct inhibitors of the CYP3A4 enzyme. Sulforaphane is not metabolized by CYP3A4, so there doesn’t appear to be any inhibition in that direction. In vitro, extraordinarily high sulforaphane levels can reduce transcription of the CYP3A4 gene. The tested 10μM concentration is much higher than that seen from broccoli ingestion (< 0.1 μM peaks from 200g broccoli is typical), and even that just resulted in 30% reduction of CYP3A4 transcripts. Very high doses of broccoli sprouts might have a minor and additive effect upstream of grapefruit on CYP3A4 drug metabolism.




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  5. The dear doctor has it mostly just backwards. Grapefruit will enhance the adsorption of many foods. For example, if you need to eat a cup of broccoli you can get about the same effect by eating 1/2 cup along with grapefruit. Also, most oral medicines can be significantly reduced (25-75%) by taking some grapefruit with them. Saves money and you a quicker effect from the consumption.




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    2. Pres: I thought Dr. Greger did an excellent job of explaining *how* grapefruit can be of both benefit and of harm (ex: when combined with certain drugs). And he has the studies to back up his statements. Just what is it that you think Dr. Greger got wrong?




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  6. I guess the point is to eat grapefruit, other fruit, vegetables, beans and grains (98% of the time) in the first place, in an attempt to avoid prescription drugs.




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  7. Lately the videos are coming through but not the voice part. I get other videos so I am not sure it is me. Has anyone complained about that. thanks.




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    2. Ra: I am having the same problem. The solution is to click the Volume symbol that is right next to the play symbol.

      For some reason, YouTube is setting the volume to “mute” by default for several of us. I have no idea why. I first noticed this problem for myself yesterday and it persists through today. At least there is an easy work around.

      Hope that helps.




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  11. Not trying to be a stickler about it, but at 3:09 in the video it should be “blood concentrations *to* 137%”, not *by* 137%. I was listening to the audio and this had me do a double take.




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  12. I’m a student NP, I would like to keep the last chart entitled ‘Grapefruit-Drug interactions and alternative therapies’ handy, but I cannot see the reference, could you please direct me to the origination of this chart?




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  13. So . . . does grapefruit consumption enhance the bioavailability or blood levels of natural nutrients such as alma, broccoli sprouts, etc.?




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    1. I was only on beta blockers, but now I’m on a plant based diet and have normal blood pressure without the beta blockers.
      I take no drugs prescription or otherwise and feel great.




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  16. I have been able to find studies of Chloroform extract of Papaya Seed being used as a MALE CONTRACEPTIVE conducted on animals but was intrigued to know if there were any further studies that have been conducted on actual humans. A male contraceptive with no adverse side effects derived from a Whole food, what a concept!!




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  17. Suggested related topic for a future video: Tell Your Doctor if You take St. John’s Wort

    The active compound in the herb St. John’s Wort, hyperforin, is a potent inducer of the pregnane X receptor and subsequent cytochrome and drug transporter expression, and hence dramatically speeds metabolism and reduces tissue levels of many drugs. Undisclosed St. John’s Wort self-medication has resulted in transplant rejection and unwanted pregnancy with oral contraceptives, and is common enough that a video covering the topic would be a public health service.




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  18. I would appreciate your comments (or maybe a new video…) on this chapter, Dr. Greger: Fruit/Vegetable-Drug Interactions: Effects on Drug Metabolizing Enzymes and Drug Transporters [http://www.intechopen.com/books/drug-discovery/fruit-vegetable-drug-interactions-effects-on-drug-metabolizing-enzymes-and-drug-transporters]




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      1. Hi, thanks for the reply!
        Well, I found it very confusing… it seems anything we eat has a potential bad effect, particularly if a person is taking any drugs. I have particular interest in how to make the enzyme Cyp3a4 work in our benefit (through diet), helping in estrogen detox. It seems that eating grapefruit, grapes and even leafy vegetables, for example, deplete the enzyme, increasing circulating estrogen!? Cranberry juice seems to have the opposite effect, though. Could you clarify this, please. I believe this is very important for people with estrogen dominance, and estrogen induced cancers. I wonder how these would also relate to young females taking contraceptives.




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        1. Plant’s do not contain estrogen. Only in isolated and concentrated forms could be they be problematic. Doctor’s are pretty good about discussing potential drug-nutrient interactions. Grapefruit is perhaps the most common. Also, too much vitamin K from dark leafy greens can effect warfarin, but to my knowledge doses can be adjusted so folks can still eat greens. Other Doctor’s may be able to help me answer this question in more depth. I really like your link, thanks for sharing! Especially table 1 describing traditional uses for plants. I think you’re onto something, as “food is medicine” and it will have thousands of biochemical reactions in the body. Still, plant-based diets seem to offer the best protection for health and wellness.




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          1. Thanks! I am onto plant based diets! :) Now, my question would be which foods, besides cranberry juice (which has too much sugar…), would help enhance Cyp3a4 enzyme and estrogen detox?




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  19. Does grapefruit affect the absorption or effectiveness of any supplements? Specifically the two that many Vegans take: B12 and D3?

    Also, how about testosterone or levothyroxine (synthroid)?




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