A balikbayan patient asked me recently about the anticancer effects of custard apple or sour sop. I was embarrassed to admit I didn’t quite know what the fruit was, but promised her I would request my research staff to search the scientific literatures about it.
I gave the assignment to my senior researcher and editor Gigi de Leon, and she came back to me a few hours later educating me on what the custard apple or sour sop is. It is our good old guyabano, which I fondly remember I loved eating when I was a child. During summer when we vacationed in our hometown, we would climb our neighbor’s wooden fence and help ourselves to the several guyabano trees they have in their backyard. I can still taste the luscious, sweet pulp of our neighbor’s guyabano.
Many years later when that neighbor came to see me in the clinic, I would joke that I can’t charge him for professional fees because I have to pay back for all the guyabano fruits my friends and I have stolen from their backyard when we were children.
Marketed as a cure-all
It came as a pleasant surprise to hear that the fruit has some anticancer potential. But that’s how it stands for now. There is some suggestion that it might have the property to inhibit the growth of some cancer cells, but this has only been shown in the laboratory—or at most, in experimental animals—but never in humans. It’s a long way from being declared an anticancer fruit with truly clinically meaningful effects.
I hear that it’s now being unscrupulously marketed by several networking companies as a cure-all. The fruit, together with its leaves, stem, roots, seeds and bark, is concocted into expensive juices and capsules, and is marketed to cure asthma, arthritis, heart and liver diseases. It also reportedly lowers blood pressure, strengthens the immune system, improves energy levels, heals wounds, eliminates worms, relieves diarrhea and fever, treats gonorrhea and herpes. But its biggest draw is...