Broccoli is one of those super foods that we all need to eat more often. Broccoli is high in nutrients and fiber, and is a particularly good source of glucoraphanin—a compound that is converted into sulforaphane, which has been found to improve phase II liver detoxification, and to have potent anti-cancer activity. If broccoli is not a regular part of your diet, it should be. But a recent study published in the Journal of Functional Foods found that not all forms of broccoli are equal.

Scientists found that frozen broccoli does not produce sulforaphane, likely due to the inactivation of the enzyme myrisonase, which is needed to convert glucoraphanin into sulforaphane. “Coupled with the cooking procedures that frozen broccoli undergoes, this process far exceeds the reported temperature stability of the broccoli enzyme myrisonase,” stated Elizabeth Jeffrey, PhD, lead researcher. Frozen broccoli is blanched before freezing, which introduces high temperatures that deactivate this crucial enzyme.

They also tested the ability of freeze-dried broccoli to produce sulforaphane. Although freeze-dried broccoli did show increased ability to convert to sulforaphane, after being heated in a microwave it didn’t perform any better than the frozen broccoli. “The results show that in these products, there was very little potential to form sulforaphane prior to cooking and essentially none after the recommended cooking method was performed,” they stated.

The bottom line? Raw broccoli may be the best way to obtain the beneficial sulforaphane compound. Juicing is a great way to obtain nutrients from broccoli. I certainly wouldn’t stop eating cooked broccoli, because sulforaphane is not the only nutrient in broccoli, but be sure to also add some raw broccoli to get the full spectrum of nutrients available.