by Travis DeGraff
Grapefruit Juice vs. Grapefruit Juice Supplements
Recently researchers at the University of North Carolina set out to put some supplements to the test [Ref]. Specifically they wanted to see if supplements that advertise the components of grapefruit juice known as bergamottin, and 6,7-dihydroxybergamottin (or DHB). These components of grapefruit juice are known to be potent cytochrome P450 3A (CYP3A) inhibitors. What this does for supplements is a bit controversial, but it is believed to improve the overall pharmocokinetics and potentially increase the half life, and bioavailability.
The researchers at UNC were more concerned about people using these supplements in conjunction with drugs that react poorly with CYP3A inhibitors (the “grapefruit juice effect”). For this reason they tested six different supplements for their bergamottin and DHB content, and they also tested each supplements ability to inhibit CYP3A in vitro. Finally they compared their CYP3A inhibition to known CYP3A drugs, and actual grapefruit juice that they literally purchased at a local store. The six supplements they tested were as follows:
- SciFit DHB 300
- Anabolic Xtreme Trisorbagen
- VitaSport Xceler8 DHB
- Hi-Tech Pharmaceuticals AttentionLink
- Redefine Nutrition FinaFlex 1-Alpha (this also contains the prohormone 1-Andro with the enanthate ester attached)
- Redefine Nutrition FinaFlex 1-Andro (this also contains the prohormone 1-Andro without a fatty ester)
FinaFlex 1-Andro and 1-Alpha Fail
The FinaFlex 1-Alpha and 1-Andro do not list specific quantities of bergamotin, and DHB. But ScitFit does list their product as having 300 mg’s of DHB. After analyzing each product they found pretty pathetic results for these supplements makers. ONLY 2 of the 6 had detectable amounts of bergamottin and DHB.
The product with the most of either bergamottin or DHB was SciFit DHB and it only contained 12.13 micrograms of bergamottin, and 65.51 micrograms of DHB. MICROGRAMS! Not milligrams! The bottle advertises SciFit DHB to contain 300 milligrams of DHB. So clearly it was far from accurate.
Meanwhile a 240 mL cup of Simply Grapefruit Juice contained .449 and 0.743 mg’s of bergamottin and DHB. In other words a simple serving of Grapefruit Juice had more than all these supplements advertised. But what happens when they put them to the test? If they still inhibit CYP3A then do we really care? Well this is where it gets a bit more interesting. The CYP3A inhibition activity can be summed up in this graphic. The smaller the height of the bars the more it inhibited CYP3A. Each supplement, drug, and grapefruit juice was tested at two different levels (open bar is the lower level).
As you can see, even though SciFit DHB, Trisorbagen, and AttentionLink didn’t seem to contain much of any bergamottin and DHB they still significantly inhibited CYP3A activity. The Redefine FinaFlex 1-Alpha and 1-Andro however did not. In fact the authors make this mention about the Fina Flex products:
“Finaﬂex 1-Alpha appeared to stimulate CYP3A activity at the lower concentration, which has been observed with low concentrations of bergamottin (<2.5 M) in incubations with HIM and midazolam .”
Which is exactly the opposite of what you might think you are getting from the product. To explain how the other supplements were able to inhibit CYP3A, the authors suggest the following:
“This additional inhibitory activity may have been due to other furanocoumarins, including multimers, and/or other classes of CYP3A inhibitors.”
Needless to say this new research does not bode well for the quality and reputation of these companies.