About GrapeFruit

Hey Peps!

Was wondering … when I peal my GF, Im left with 300g of fruit.

Did any1 tried to juice it … how much it is in juice? I guess its a around half!?

300g of fruit = 150ml of juice give or take!?

Also, I was wondering, if I take two GF in total 600g of fruit, give me more Rapamune absorption and blood concentration then one fruit?

Im taking it before dinner ( 1 hour before )with 2mg of Rapamune taken after dinner.

Any thoughts?

Good questions - I’ve never juiced but some people here have.


I’m not sure if anyone here has done any blood testing after dosing and different grapefruit “dosings” to find out.

This study seems to suggest that more dosings of GFJ doesn’t increase things further… see this graph:

From the second study in this post: Improve Bioavailability of Rapamycin (2) - #47 by RapAdmin

We’ve had many discussions on GFJ and bioavailability in the past - I recommend you review those too and perhaps some information in them is helpful:

Here: Not all grapefruit juice is the same for the purpose of Sirolimus enchancment

Here: Grapefruit interaction with longevity meds?

Here: Rapamycin and Grapefruit Juice


Thanks for Data Rapa

Question that I have is if I take double dose of GF 1 hour before Rapa, will it increase the blood concentration more then “standard” ( for me ) one GF!?

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I haven’t seen any data or any studies on the dose/response relationship for GFJ on sirolimus levels. Its a good question - I just don’t know the answer. The best way to find out is do the test yourself with blood tests afterwards each time.

The other much less accurate approach is by “feel” or side effects. Perhaps @Agetron or @DeStrider have some thoughts or experiences with this approach, or even some opinions based on their blood test results?


In the original study that got everyone interested in this GFJ approach they did mention this:

Although the magnitude of the interaction is highly variable, it is reproducible within individuals and seems to be dependent on small bowel CYP3A4 content, i.e. persons with the highest intestinal CYP3A4 content have the largest reduction in enzyme levels and subsequently the greatest effect on drug metabolism

This suggests to me that there likely is a positive dose response relationship, but it will likely vary by person. So - I would guess that more grapefruit (or juice) up to some point may increase the AUC for the rapamycin.

Lots of discussion on this issue in the original bioavailability thread here: Improve Bioavailability of Rapamycin (2)

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My perspective is that taking multiple grapefruits whole as juice or otherwise… day before, hours before and with dose … has no difference for me.

I fresh squeeze 1 red grapefruit from Walmart… makes about 5 fl. ounces… I down the GF juice and rapamycin simultaneously.

Get a 3x ’ s or more increase…up to 6x’s . I am seeing if rapamune pill gives only 3xs and sirolimus gives 6x’s. Will do a new Labcorp test in 2 weeks.

Just discovered this possibility on my last test.


Yes, I haven’t really noticed a difference between 1 or 2 grapefruits. Now if I take Metformin at the same time as the GFJ, I do feel an increase in Rapamycin absorption.