Grapefruit interaction with longevity meds?

We just exchanged a brief text. He mentioned that it’s unclear whether a 2 week regime is better than 1 week. I was leaning toward a 2 week schedule but, based on this, decided to go back to weekly. Although, for now, just 6 mg. When I visited his office in October, he was doing 2 week.

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i read someone in the Age Reversal Forum said so.

This article is about how grapefruit juice works and the various medications it interacts with:

Drug Interactions with Grapefruit Juice | British Journal of Medical Practitioners.


from Dr. Mark Thimineur on age reversal forum:

Mark is a practicing physician and uses Rapa in many of his patients. In order to control cost of Rapa he has a grapefruit juice protocol. The best 2 ways to save money on Rapa is to use grapefruit juice or buy powder like I do. Hope this helps you or anyone else taking Rapa.

Karl For myself and anyone who is “self pay” the source is Biocon “Sirolimus” through online Canadian Pharmacy. Price $349 per 100 1mg tabs. For patients who go through insurance it is Pfizer Rapamune. It seems some of the Medicare D plans cover it, at least for now. Once I started the higher cycling regimen, I started using grapefruit juice to impair intestinal P450 and spike absorption 3 fold (half life is unnaffected). It becomes to expensive for many people otherwise and I always do myself what I tell my patients to do. I have to accept that there is a known variability of grapefruit juice effect on sirolimus absorption of 250%-350% so the actual dose may be a little lower or higher and I accept this small risk (again, well studied insider info). Grapefruit juice protocol is one fresh squeezed large fruit about 8 hours prior to dose (night before) and one large fresh squeezed grapefruit morning of with rapamycin taken 30 minutes later. Assume an average 300% increased absorption to determine the proper dose (1/3 of the mg/kg/wk without juice). So far so good.
The grapefruit juice option should be considered if a person is not concurrently taking drugs metabolized by intestinal P450 enzyme complex. The example of statins for cholesterol lowering is the most well known. Barring that, tactical use of grapefruit juice can overcome the poor bioavailability of oral rapamycin.

After an oral dose 86% of rapamycin is chewed up by the intestinal P450 enzyme and is excreted in feces. Inhibition of this enzyme complex with either ketoconazole or grapefruit juice has been pretty well studied in the oncology literature. In one such study the target dose of rapamycin was 90mg in a once weekly dose which provided the target AUC for the solid tumor being studied. Patients could not tolerate that dose due to GI side effects. It was shown that Ketoconazole administration reduced the required amount of rapamycin to 16mg and administration of grapefruit juice reduced the required amount to 25-35mg rapamycin to reach the same AUC. In other words the intestinal absorption of rapamycin was increased about 300% with grapefruit juice and 500% with ketoconazole. Cohen EE. Clin Cancer Res. 2012;doi:10.1158/1078-0432.CCR-12-0110.

The details about grapefruit juice: fresh squeezed is necessary as bottled or canned do not show the same amount of P450 inhibition. Approximately 8 ounces of juice pretty strongly inhibiit the enzyme in about 4 hours and lasts about 24 hours. One large grapefruit provides about 8oz juice.

Personally, and in select patients, I utilize this P450 inhibition to predictably maximize absorbtion and minimize cost. Consider that 2mg now becomes, in effect, 6mg and the cost savings are large. This is especially true for larger persons. My protocol is to take 8oz freshly squeezed the night before and also the morning of the rapamycin dose. Before deciding about this it would be best to check if any pharmaceuticals a person is taking would be effected by P450 inhibition (only in intestine) or check with your physician.


Ask your pharmacist.

Also, the sugar in the GF juice may cause GI issues if you take Acarbose that day.

Acarbose only blocks starch. So I don’t see how this could be the case. I wish it blocked fructose.

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Is it ok to eat the grapefruit rather than squeezing it?

Absolutely - that is fine. I’m sure either way is good.

So eat a whole grapefruit both night before and following morning.

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That seems reasonable. There unfortunately have been no studies on this, so we’re making our best guess here.

A major problem with grapefruit, though, is that it’s associated with a significantly increased risk of melanoma.

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But with the grapefruit protocol, you’d only be eating grapefruit once a week or every two weeks. And, of course, association is not necessarily causation… and I wonder about the amount of data supporting this type of association.

Have not seen an info on the effects of all the pulp that is associated with squeezing grapefruits or eating it whole. There has to be some of P450 in there. Some may be drinking pulp with juice.


According to the literature, Crestor is one of the statins NOT affected by grapefruit juice.


Is there any conclusive evidence that pink is just as good as white grapefruit? Having a hard time finding white here! Is store squeezed juice OK? Trying to get ready for my first batch of Rapa next week!

White and colored grapefruit juice produce similar pharmacokinetic interactions

Thus, colored grapefruit juice may produce drug interactions at the same rate as white grapefruit juice.


Thanks, MAC! :slightly_smiling_face: That was just the information I was looking and hoping for!!!

I am now just buying an average size pink grapefruitl and hand squeezing with a strainer to catch seeds and pulp.Iget about 1 cup.

Take 6 mg rapamycin with the fresh grapefruitl juice simultaneously. Last Labcorp test 3 hours after my rapa ddose was 56 nl mg, so for me it didn’t take much GFJ for a huge effect.


Beware of incomplete information.

For example, GFJ inhibits other things besides CYP3A4 not listed in common apps or information sources.