If you’re looking for ways to fend off colds and flu this winter, consider stocking your vegetable crisper with broccoli, cauliflower and cabbage.
According to new research findings published this month in the journal Cell, these healthy vegetables – known as cruciferous vegetables – can bolster the immune system.
The immune system is made up of a network of cells, tissues and organs and defends the body every day from bacteria, viruses and other invaders. Special immune cells in the skin and gut – intraepithelial lymphocytes (IELs) – serve as the body’s first line of defence, producing substances harmful to microbes.
It turns out that phytochemicals in broccoli and other cruciferous vegetables such as bok choy, cauliflower, cabbage, Brussels sprouts, rapini, turnip and rutabaga, are needed to ensure that IELs work properly.
In the study, researchers fed mice a diet lacking vegetables for two to three weeks and observed a 70- to 80-per-cent decline in these protective immune cells. They found that the number of IELs depend on levels of a specific cell protein that can be regulated by phytochemicals found mainly in cruciferous vegetables.
Mice fed the vegetable-poor diet lacked this protein, had lower levels of IELs and lost control over the number and composition of microbes living on the lining of the intestinal tract.
With reduced numbers of these key immune cells, the animals showed lower levels of germ-fighting proteins, greater susceptibility to injury and slower time to recover.
These new findings add to growing evidence that cruciferous vegetables protect immune health.
While it’s too soon to say whether these findings also apply to people, there are plenty of other reasons to add cruciferous vegetables to your diet.
Eating cruciferous vegetables on a regular basis has been associated with a lower risk of heart attack, stroke and cancers of the breast, lung, colon, prostate and pancreas.
The health benefits of these vegetables are largely attributed to phytochemicals called glucosinolates. Once consumed, glucosinolates are converted to active compounds called isothiocyanates and indoles, which have anti-cancer, antioxidant and anti-inflammatory effects.
One of the best known isothiocyanates is sulforaphane, a phytochemical that’s plentiful in broccoli and broccoli sprouts.
An enzyme in cruciferous vegetables, called myrosinase, converts glucosinolates to isothiocyanates when they’re chopped or chewed.
But this enzyme is destroyed by heat, so overcooking your broccoli will reduce its disease-fighting potential.
A study published last month by researchers from Oregon State University revealed that myrosinase is also missing from most supplements of cruciferous vegetable blends. Without this enzyme, the study revealed that the body absorbs substantially less isothiocyanates and indoles.
In other words, to reap the health benefits of cruciferous vegetables, you need to eat the real thing raw, lightly cooked or steamed until still crunchy.
Use the following tips to include three to five servings of cruciferous vegetables in your diet each week. (One serving is equivalent to one-half cup.) Even kids will like some of these suggestions.
•Sprinkle fresh lemon juice and sesame seeds over lightly steamed broccoli.
•Top a pizza, homemade or frozen, with steamed broccoli florets.
•Add chopped broccoli florets to omelettes and frittatas.
•Snack on raw broccoli florets with hummus dip.
•Add Brussels sprouts, halved lengthwise, to a stir-fry.
•Try roasted Brussels sprouts, a hit even with people who typically dislike this vegetable. Place sprouts, halved lengthwise, face up in a shallow baking dish. Drizzle with olive oil, season with pepper. Bake at 400 F for 20 to 25 minutes.
•Combine halved cooked Brussels sprouts with toasted walnuts and goat cheese for a delicious side dish.
•Shred Brussels sprouts and add to soups and stews.
•Braise red cabbage with chopped apple and red wine. (The alcohol evaporates during cooking.)
•Use cabbage leaves to wrap your next taco or burrito.
•Add shredded cabbage to sandwiches as a change from lettuce.
•Mix shredded red cabbage into a green salad for added colour.
•Serve steamed cauliflower dusted with grated Parmesan cheese.
•Add cauliflower florets to curry recipes, pasta sauces and soups near the end of cooking.
•Lightly sauté cauliflower florets with garlic and minced fresh ginger. Or sauté it with a pinch of turmeric or saffron.
•Add raw cauliflower florets to a vegetables platter and serve with a healthy dip.
Turnip and rutabaga
•Stir fry julienne-cut rutabagas and turnips with fresh ginger, garlic and snap peas.
•Peel and wash raw turnip, slice into coins and enjoy as a snack with your favourite low-fat dip.
•Combine diced turnips and rutabagas with other favourite root vegetables in a roasting pan. Drizzle with olive oil, dried rosemary and thyme, and bake until tender but slightly crispy.
•Add small cubes of turnip or rutabaga to homemade soup; simmer until slightly crispy.
Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV’s Canada AM every Wednesday. Her website is lesliebeck.com .