A few days ago, I decided to eat a grapefruit. We had gone to a Korean market earlier that day, and the citrus fruits beckoned to me with an enticing fragrance. I couldn’t resist.
So as I was finishing up one of the most delicious grapefruits that I’d had in a long time, I started thinking. Back when I was taking tamoxifen, I’d come across an admonishment not to eat grapefruit because it could interfere with absorption of the medication. But I wasn’t taking tamoxifen anymore, I was taking letrozole. Could the same be true?
I started googling, first on my phone. And as the search results came in, I had to switch to my computer because things were looking confusing. Many sites said “NO” in no uncertain terms. Grapefruit can prevent the letrozole from breaking down in the body completely, leading to higher levels remaining than could be safe.
It wasn’t that the grapefruit was hindering the efficacy of the letrozole, it was that grapefruit could set up a dangerous situation of “overdose”.
Of course, googling often results in messages that are big on warnings and short on details. So I dug further and happened upon forum posts where other women were asking the same questions.
I read the following exchange: one woman said she’d spoken to two different hospital pharmacists, both of whom had given her the okay to eat grapefruit. A number of other women (like, everyone else) chimed in on how they had unequivocably been warned to stay away from grapefruit (for the above mentioned reasons). The first woman reiterated that she had been told by HOSPITAL PHARMACISTS that she could each grapefruit with impunity…and so it went.
What really bothers me about this is that so many websites suggest that, it really it best to avoid grapefruit due to possible interactions with letrozole. But I slogged through the entire bloody informational insert from the manufacturer of my drug and NOWHERE did it mention that I shouldn’t eat grapefruit. There was also nothing on the bottle itself, nor did my oncologist say anything about that.
However, WebMD’s grapefruit interactions webpage, while not mentioning letrozole by name, did suggest issues with estrogen and also Cytochrome P450 substrates (of which letrozole is one, but I just happen to know that; others wouldn’t necessarily). WebMD’s letrozole info pages made no mention an issue with grapefruit. I mention WebMD mainly because many people consider it a reputable site and may go there for information.
If it truly is that dangerous to eat grapefruit while taking letrozole, why is that not explicitly stated on the container? Why would any woman think to google a random fruit or vegetable, like, “I think I’ll eat an artichoke and shiitake mushrooms today, but first I’ll do an internet search to make sure they don’t affect my medication.” Who plans their meals like that?
The bottom line is, the effect the grapefruit has depends on a variety of factors. It depends on when you’re eating and how much you’re eating, and how many days in a row. But all of that is so unsatisfying to me, who wants a concrete answer. Cancer is not about answers, however, it’s about getting comfortable with living with the unknown.
So, back to the grapefruit. Spooked, I skipped the medication that evening, although I’m sure I could have taken it and still lived through the night. I’ll ask my oncologist about it during my next visit, but I expect that his answer will be, “just don’t overdo it.”
And there’s another fragrant grapefruit sitting on the counter, which I will eat at sometime in the future, maybe half at a time. Here’s to living with uncertainty!