Here is a question, does the grapefruit take effect if taken at the same time as the Q10 or does it work for doses taken hours later after its absorbed into the body. If i understand correctly your taking the juice/Q10 several times a day so could it be that the juice affects the next Q10 instead of the concurrent one?
@Alvin2 I've wondered about that exact thing. The grapefruit juice will remain in the system for a while and I'm now taking it three times a day. In addition, different articles talk about the peak in the system being at different times. It's probably something that should be played with a little to find one's own best.
Here are some of the study summaries from my latest round of research.
Title: "The interaction effect of grapefruit juice is maximal after the first glass"
In this study, they used grapefruit juice and the medication felodipine ER tablets.
"Results: Similarly to previous single-dose studies, the treatment during the first day with grapefruit juice increased the AUC (+73%) and Cmax (+138%) of felodipine when compared with the control treatment. On day 14 a similar effect of grapefruit juice was observed, with an increased AUC24 (+57%) and Cmax (+114%) of felodipine compared with the control experiment. A significant accumulation of felodipine occurred during both the control (+37%) and grapefruit juice (+25%) period. The extent of accumulation was not significantly different in the two treatment periods."
https://link.springer.com/article/10.1007/s002280050424
Title: "Content of CYP3A4 inhibitors, naringin, naringenin and bergapten in grapefruit and grapefruit juice products"
In this study, they found that "The contents of these three grapefruit constituents in commercial juice and fresh grapefruit varied from brand to brand and also from lot to lot. ..... Differences in the concentrations of these three constituents, which have potential for drug interaction, may contribute to the variability in pharmacokinetics of CYP3A4 drugs and some contradictory results of drug interaction studies with grapefruit juice."
https://www.sciencedirect.com/science/article/pii/S003168659900062X
This is why there really should be a pharmaceutical version of this so that it's the same amount each time and doesn't differ.
Title: "Annual and seasonal changes in naringin concentration of ruby red grapefruit juice"
Findings "Naringen concentration of juice from the same grove and trees fluctuated during the season and varied considerably between crop years."
https://pubs.acs.org/doi/abs/10.1021/jf00106a031?journalCode=jafcau
Title: "Effect of Maturity, Processing, and Storage on the Furanocoumarin Composition of Grapefruit and Grapefruit Juice"
Findings: "This research provides information on how grapefruit drug interaction potential of grapefruit juice products are affected by processing and storage of juice products. Shelf stable products stored at room temperature in cans and glass containers will have lower levels of FCs (furanocoumarins) compared to fresh products made from the same juice. Those wishing to minimize drug interaction potential in grapefruit products may do so by heating to pasteurization temperatures for 30 to 60 min. However, this will only lower and not eliminate the drug interaction potential."
https://onlinelibrary.wiley.com/doi/full/10.1111/j.1750-3841.2011.02147.x
Does this mean that for those looking to increase absorption of CoQ10, that we should be looking for grapefruit juice that has not been pasteurized and has been refrigerated? Sounds like another study I'd like to seen done.
I've had the choice of buying bottled grapefruit juice room temperature off grocery shelves and red grapefruit juice from the refrigerator section of the grocery store. All three brands that I've bought were pasteurized. I'm not sure that I could find un-pasteurized even if I looked for it. I've been buying the refrigerated version because it cost the same. I'd like to see a study on the refrigerated version to see if it is higher in absorption. But then again, what I'd really like is an extended release pill with a true quantity.
Title: "The Use of Heat Treatment to Eliminate Drug Interactions Due to Grapefruit Juice"
"In the present study, it was found that the heat treatment of grapefruit juice decreases concentrations of BG and DHB as well as their interactions both in vitro and in vivo. We incubated GJ for 10, 20, 30, 40, 50, and 60 min at 37, 62, 72, and 95 °C; FCs in each sample were then measured, using high-performance liquid chromatography (HPLC). The concentrations of BG and DHB were decreased in a time- and temperature-dependent manner, by 82.5 and 97.9% respectively, after incubation for 1 h at 95 °C. In contrast, the concentration of bergaptrol (BT) increased in a time- and temperature-dependent manner (27.7% after 60 min at 95 °C). In addition, the effect of each GJ sample on testosterone 6β-oxidation in human liver microsomes was observed. The inhibitory effects of GJ heated to 95 °C were decreased in a time-dependent manner, as in the case of BG and DHB concentrations. Furthermore, 2 ml of GJ treated for 60 min at 95 °C was administered into the rat duodenum. After 30 min, nifedipine (NFP) was administered intraduodenally at a dose of 3 mg/kg body weight. The concentrations of NFP in the plasma samples were determined by HPLC. No significant increase in the AUC of NFP was observed in the rats given heat-treated GJ. These results suggest that the heat treatment of GJ reduces the concentrations of FCs, thus eliminating the potential for drug interactions."
https://www.jstage.jst.go.jp/article/bpb/29/11/29_11_2274/_article/-char/ja/
Title: "Variation in the content of bioactive flavonoids in different brands of orange and grapefruit juices"
https://www.sciencedirect.com/science/article/pii/S0889157505000803
Title: "Interaction of White and Pink Grapefruit Juice with Acetaminophen (Paracetamol) In Vivo in Mice"
"Abstract: Grapefruit juice increases bioavailability of a number of drugs because of inhibition of the P-glycoprotein pump and inhibition of intestinal cytochrome P450 3A4 enzyme. However, interaction between acetaminophen (also known as paracetamol in many parts of the world) and grapefruit juice has never been reported. The interaction of grapefruit juice with acetaminophen was examined in an in vivo mouse model. BALB/c mice were fed 200 μL of white grapefruit juice or pink grapefruit juice by oral gavage (three mice in each group) followed by oral delivery of 10, 50, or 100 mg/kg acetaminophen 1 hour later. Blood was withdrawn from the retro-orbital venous plexus at 1 hour and 2 hours after feeding with acetaminophen. The concentrations of acetaminophen in sera of mice were determined by fluorescence polarization immunoassay. White grapefruit juice increased concentrations of acetaminophen in mice both 1 hour and 2 hours after feeding compared to controls. In contrast, pink grapefruit juice increased acetaminophen concentrations 2 hours after feeding compared to controls. Because acetaminophen is almost completely absorbed these effects seems to be related to increased elimination half-life of acetaminophen because of interaction with grapefruit juice.
https://www.liebertpub.com/doi/abs/10.1089/jmf.2008.0059
