Among them are glucosinolates, which can be broken down into other compounds when the vegetable is cut, chewed, or otherwise processed.
One of the compounds generated through this process is sulforaphane.
Researchers have investigated sulforaphane because laboratory and observational research has suggested that it may influence several biological pathways, including pathways involved in oxidative stress and cellular defense.
However, it is important not to overstate these findings.
Research involving isolated compounds, cells, animals, or observational populations does not automatically prove that eating a particular amount of broccoli will prevent a specific disease in humans.
What can reasonably be said is that broccoli contributes useful nutrients and plant compounds to the diet, making it a valuable component of an overall healthy eating pattern.
The cooking method, however, can affect those compounds.
And this is where the story becomes particularly interesting.
Why Cooking Can Change Broccoli's Nutritional Value
Heat changes food.
Sometimes those changes are beneficial. Sometimes they reduce certain nutrients. In other situations, the effect depends on the compound being studied.
Water also matters.
When vegetables are boiled, some water-soluble nutrients can move out of the vegetable and into the cooking water. If that water is then discarded, some of those nutrients are discarded with it.
Vitamin C is one example of a nutrient that can be affected by heat and water exposure.
This does not mean that boiled broccoli suddenly becomes unhealthy. It simply means that prolonged cooking in large quantities of water can reduce the amount of certain heat-sensitive or water-soluble compounds remaining in the vegetable.
The length of cooking matters as well.