Broccoli is one of the most nutrient-dense vegetables that dogs can eat. In addition to vitamins A, C, D and beta carotene, broccoli contains folic acid, fiber, chromium and calcium.
When you cook broccoli, indole, a cancer-fighting enzyme, is released. In fact, more than 33 cancer-preventing compounds are found in broccoli [source: The BARF Diet]. Broccoli also contains several phytochemicals that stop carcinogens from forming and prevents them from attacking cells. They also build enzymes to breakdown carcinogens.
Broccoli is an excellent food for dogs because it is a low glycemic vegetable, meaning that it does not raise blood glucose levels. Broccoli converts to glucose very slowly, preventing the release of insulin that can lead to weight gain. Aside from broccoli's nutrient-rich and cancer-fighting properties, it also features sulforphane, a compound that helps boost the immune system.
Although broccoli can be fed to a dog safely, give this vegetable to him in moderation, as it can reduce thyroid function when given in large quantities.