Tangeretin Interferes with Tamoxifen
 

Has any one read that Tangeretin interferes with Tamoxifen's ability to inhibit tumor growth? Tangeretin is found in the peel of citrus fruits. Does this problem also apply if you consume citrus juice such as lemon or lime juice? I always squeeze a lemon or lime in my water.

Re: Tangeretin Interferes with Tamoxifen
 

I too have read that Tangertin and Tangerines have a deleterious effect on Tamoxifen therapy---at least in certain lab experiments. see: http://jnci.oxfordjournals.org/cgi/c.../full/91/4/354 . But I don't know how much the suspect flavinoid involved with Tangerines is also found in other citrus fruits---perhaps not as much. And it may be that the real risk is linked more to the ingestion of peels and oils of tangerines and other citrus fruits, rather than the juice and pulp. I hope so since I eat a least one fresh orange a day. However, I do stay clear of tangerines just to be cautious.

bird

Re: Tangeretin Interferes with Tamoxifen
 

Tangeretin is found in the peels of citus fruits. It appears some small animal studies have found interaction between it and Tamoxifen. However, the dose was much higher than that found in the amount normally consumed in food daily. The studies caution against supplement forms (high doses) while on Tamoxifen. I don't know of any harm in consuming citrus, in fact there are many phytochemicals in citrus, like limonene, that have shown benefit in breast cancer.

Re: Tangeretin Interferes with Tamoxifen
 

Thanks, Tanya--I'll keep eating my oranges and look up limonene---bird.

Re: Tangeretin Interferes with Tamoxifen
 

Hmm. I thought Quercetin, found in peels, increased Tamoxifen absorption:

Int J Pharm. 2006 Apr 26;313(1-2):144-9. Epub 2006 Mar 3.
Enhanced bioavailability of tamoxifen after oral administration of tamoxifen with quercetin in rats.

Shin SC, Choi JS, Li X.
College of Pharmacy, Chonnam National University, Bukgu, Gwangju 500-757, Republic of Korea.
Abstract

Orally administered tamoxifen undergoes a first-pass metabolism and substrates for multidrug resistance (MDR) transporters efflux in the liver and intestines, which obstructs its systemic exposure. This study investigated the effect of quercetin, a dual inhibitor of CYP3A4 and P-gp, on the bioavailability and pharmacokinetics of tamoxifen and one of its metabolites, 4-hydroxytamoxifen, in rats. The pharmacokinetic parameters of tamoxifen and 4-hydroxytamoxifen in plasma were determined after orally administering tamoxifen (10 mg/kg) with or without quercetin (2.5, 7.5 and 15 mg/kg). The coadministration of quercetin (2.5 and 7.5 mg/kg) significantly (p < 0.05) increased the absorption rate constant (K(a)), peak concentration (C(max)) and the areas under the plasma concentration-time curve (AUC) of tamoxifen. The absolute bioavailability (AB%) of tamoxifen with 2.5 and 7.5 mg/kg quercetin ranged from 18.0% to 24.1%, which was significantly higher than the control group, 15.0% (p < 0.05). The relative bioavailability (RB%) of tamoxifen coadministered with quercetin was 1.20-1.61 times higher than the control group. The coadministration of quercetin caused no significant changes in the terminal half-life (t(1/2)) and the time to reach the peak concentration (T(max)) of tamoxifen. Compared with the control group, the coadministration of 7.5 mg/kg quercetin significantly (p < 0.05) increased the AUC of 4-hydroxytamoxifen. However, the metabolite ratios (MR; AUC of 4-hydroxytamoxifen to tamoxifen) were significantly lower (p < 0.05). This suggests that quercetin inhibits the both MDR transporters efflux and first-pass metabolism of tamoxifen. The enhanced bioavailability of tamoxifen as a result of its coadministration with quercetin might be due to the effect of quercetin promoting the intestinal absorption and reducing the first-pass metabolism of tamoxifen. If the results are further confirmed in the clinical trials, the tamoxifen dosage should be adjusted when tamoxifen is administered with quercetin or quercetin-containing dietary supplements in order to avoid potential drug interactions.

PMID: 16516418 [PubMed - indexed for MEDLINE]

Re: Tangeretin Interferes with Tamoxifen
 

Which of the two contians less of Tmageretine?
Sweet Lime
Orange

Re: Tangeretin Interferes with Tamoxifen
 

I have been adding a slice of lemon to my green tea because I read it aides the body in absorbing more of the antioxidants. I take Tamoxifen, so should I stop putting the slice of lemon in my green tea?

Amelia

Re: Tangeretin Interferes with Tamoxifen
 

I suspect it's only an issue if you consume the peel or a bioflavenoid supplement that contains peel. Some Vitamin C supplements contain added bioflavenoids which may have peel. Quercetin is found in the peel of apples and appears to help Tamoxifen and has anticancer properties on its own. I don't know if apple peel has tangeretin..but there are Quercetin only supplements.
I suppose you could avoid the issue in your tea by squeezing the lemon juice into the tea.
If you really want benefits from green tea, you might benefit more from a supplement. There is a combo called Capsibiol T that combines decaf green tea with Capsaicin for synergy.

Re: Tangeretin Interferes with Tamoxifen
 

I heard about this and asked my doctor about it. He assured me that I would be fine since I am not actually consuming the peel, and if I were they levels would not be significant enough to make an impact. With this being said, I have continued to enjoy me tea with lemon, thankfully. I am wondering if anyone has ever been to Dr. Robert Goulet? Is he a good doctor? Thank you.

Re: Tangeretin Interferes with Tamoxifen
 

I didn't know, nor did my Dr say, anything about Quercetin. I have taken it even before being Dx and she knows about it. Should I mention this as it states the dosage of Tamoxifen may need to be adjusted? I'm guessing either I'm not taking as much or she doesn't know of this study.

Re: Tangeretin Interferes with Tamoxifen
 

Thank you for posting this as I had never heard of it before. I posted a link to something interesting I found below. It appears, according to this website, that tangeretin is found mostly in the peels and tissues of various oranges and tangarines. Only very trace amounts are found in lemons and grapefruit. I eat the juice and pulp of two lemons diluted in hot water every day to detoxify my liver (breast cancer mets to liver) so when I saw this I was concerned, as I'm on tamoxifen as well. Thanks so much for posting this - very interesting!

Re: Tangeretin Interferes with Tamoxifen
 

Sorry, I guess I didn't post the link! Here it is!
http://www.purematters.com/herbs-sup...s/t/tangeretin