We have all been told by our mothers, doctors, teachers, and other sages of healthy living to remember to eat our vegetables, particularly those that are green and leafy. Evidence is overwhelming that these delicious and beneficial greens contribute to a well-balanced and nutritious diet, especially those belonging to the cruciferous or cabbage family of vegetables. These are the vegetables, also called brassica vegetables, whose four-petal flowers form the shape of a cross – cruciferous means "cross-bearing."

Cruciferous vegetables include Swiss chard, broccoli, cabbage, Brussels sprouts, cauliflower, watercress, radish, rapini, arugula, spinach, turnip, kale, and bok choy. Packed with vitamins and minerals (some crucifers have more than others), these vegetables boast impressive nutritional qualities and potent anticancer properties.

Nutrition experts often refer to brassica vegetables as "functional foods." Functional foods are foods with benefits beyond basic nutrition, including disease prevention. Cruciferous vegetables have high levels of vitamin C, vitamin E, and vitamin K; carotenoids such as beta-carotene and lutein; folate, minerals and fibre. These compounds may help reduce the risk of cardiovascular disease by lowering blood pressure, homocysteine level, oxidative stress, and inflammation in the blood vessels. Additionally, because of the high amount of calcium found in crucifers (especially kale, Chinese cabbage, and broccoli), they protect bone density and may help prevent the onset of osteoporosis, particularly in women.

Most findings on crucifers support their cancer-fighting abilities. Researchers have isolated sulfur-containing phytochemicals called glucosinolates abundant in cruciferous vegetables with the potential to inhibit cancer. When chopped, chewed, and digested, glucosinolates are converted into compounds (indoles and isothiocyanates) that act to prevent normal cells from becoming cancerous cells by stimulating the body to clear potential cancer-causing agents (carcinogens). They also inhibit tumour blood vessel formation and tumour cell migration. In rats and mice, indoles and isothiocyanates have been found to prevent cancer development in bladder, breast, colon, liver, lung and stomach. However, studies in humans have shown varying results.

Before gorging on crucifers, heed a few cautions. While they are loaded with beneficial nutrients, cruciferous vegetables also contain goitrogens and nitriles, which early studies have shown to be linked to thyroid cancer. One way to lower the levels of goitrogens and nitriles in cruciferous vegetables is to cook them before consuming.

In any case, the many benefits of crucifers far outweigh the small negatives. Not only are they cancer fighters, they also help control the appetite due to their high soluble fibre content, and they are thought to decrease the absorption of fats from other foods eaten during the same meal.

The next time you're planning a meal, reach for cruciferous vegetables, whether they be tried-and-true favourites or new and exciting options. Your body will thank you! And when choosing them, keep these things in mind:

  • Canada’s Food Guide recommends 7 to 8 servings of vegetables and fruits for adult females and 8 to 10 servings of vegetables and fruits for adult males.An example of one food serving is ½ cup of cooked leafy vegetables or 1 cup of raw leafy vegetables.
  • Have at least one serving of dark green vegetable each day.
  • Look for firm, dark green leaves or heads; avoid leaves or heads that are yellow.
  • Keep fresh cruciferous vegetables in the refrigerator in large, airy plastic bags.

Brennan Robertson, Hon. B.Sc. (Nutrition)