Frozen assets

While we’re on the subject of cancer prevention, here’s a good way not to get results: eating frozen broccoli.

As you might remember, broccoli is the granddaddy of all disease-fighting foods. That’s because it’s rich in a compound called sulforaphane, which also happens to be a powerful anti-cancer agent.

There’s a catch, though. This benefit is entirely dependent upon the presence of an enzyme called myrosinase, which is responsible for converting sulforaphane from another compound called glucoraphanin.

Needless to say, that little detail makes all the difference.

A team of researchers recently sampled three different commercial frozen broccoli products. Two of them showed no measurable myrosinase activity whatsoever. And no sulforaphane was formed in any of the products after a trip through the microwave.

I can’t say this is surprising. A lot of frozen vegetables are blanched before freezing in order to extend their shelf life by halting enzymes that contribute to spoiling. But unfortunately, it’s a pretty indiscriminate process.

That’s a problem. Because the live enzymes in produce–and in cruciferous vegetables in particular–play a vital role in their disease-fighting benefits.

On the bright side, these researchers found fresh-picked, flash-frozen vegetables generated significantly more sulforaphane than their commercial counterparts. Although given their point of reference, well… that’s not necessarily saying much.

Obviously, the best way to get the most nutritional benefits from any kind of produce is to buy (and eat) it fresh–and preferably organic.

One more tip when it comes to broccoli: let it sit for about five minutes after you chop it up, and before you eat or cook it. This activates myrosinase, which guarantees you’ll get a maximum serving of sulforaphane in every bite.

But please…keep it out of the microwave. It’s far too easy to nuke the nutrients right out of your food when you cook it this way. Instead, steam it on the stove.

Just put a little bit of water (an inch or two) into the bottom of a pot and bring it to a boil. Throw the broccoli into a steamer basket, add it to the pot, cover, and let it steam for about five minutes. Just long enough to make it slightly tender–and to keep as many of broccoli’s beneficial nutrients as possible.

Commercially produced frozen broccoli lacks the ability to form sulforaphane. Journal of Functional Foods 5.2 (2013): 987-990.