Leafy greens are excellent sources of many vitamins and minerals, but researchers have found a new reason to eat these healthy vegetables every day. Certain cells within the digestive system which play a role in many health conditions can be controlled by these nutritious foods.
Researchers with the Walter and Eliza Hall Institute’s Molecular Immunology division have discovered that innate lymphoid cells (ILCs) found in the lining of the digestive system help protect the body from “bad” bacteria in the intestine. The gene T-bet is essential for producing these critical immune cells and this gene responds to signals in the food we eat.
Proteins found within green leafy vegetables are known to interact with a cell surface receptor that switches on T-bet which in turn affects the production of the ILCs. The cells are essential for helping to maintain a healthy environment within the intestine by promoting good bacteria and healing small wounds and abrasions that are common in the tissues of the gut. They may also have a role in resolving cancerous lesions, says Dr. Gabrielle Belz.
"The discovery of these immune cells has thrown open a completely new way of looking at gut biology," Dr Belz said. "We are just starting to understand how important these immune cells are in regulating allergy and inflammation, and the implications for bowel cancer and other gastrointestinal disorders such as Crohn's disease," she said.
In addition to promoting the production of healthy immune system cells, leafy green vegetables are rich in vitamins A and C which have been associated with the reduced risk of certain cancers. They are also excellent sources of calcium, iron, fiber and other nutrients while being low in calories and sodium, and free of fat and cholesterol.
Dark leafy greens include arugula, beet greens, Belgian endive, broccoli, bok choy, cabbage, collards, curly endive, dandelion greens, escarole, kale, lettuces, mustard greens, radiccho, rapini, spinach, swiss chard, turnip greens and watercress.
Here are some ideas from Whole Foods Market on how to incorporate leafy greens into your diet:
• Serve your favorite soup, beans or chili (canned is fine) over a bowl of raw tender greens such as spinach, watercress, Napa cabbage or arugula. The warmth of the soup will wilt the greens and make them more tender.
• Blend fresh or frozen greens like spinach or kale with your favorite fruit and almond milk, soy milk or yogurt for a smoothie.
• Add chopped greens like bok choy, chard, kale or cabbage to a stir-fry.
• Sauté onions and garlic in a bit of broth or olive oil, add kale, chard, broccoli rabe, mustard greens or collards and cook until tender.
• Add leafy greens to sandwiches — go for tender greens like watercress, baby spinach or arugula or simply wilt heartier greens first.
• Use large, flat-leaf greens like romaine lettuce or steamed collards as you would a tortilla to create healthier wraps.
• Add sautéed greens like chard and broccoli rabe to cooked whole-grain pasta dressed with a bit of extra-virgin olive oil and a light grating of Parmigiano Reggiano.
• Chop and stir greens like spinach, kale, collards and bok choy into soups, stews and pasta sauces, cooking until tender.
Lucille C Rankin, Joanna R Groom, Michaël Chopin, Marco J Herold, Jennifer A Walker, Lisa A Mielke, Andrew N J McKenzie, Sebastian Carotta, Stephen L Nutt, Gabrielle T Belz. The transcription factor T-bet is essential for the development of NKp46 innate lymphocytes via the Notch pathway. Nature Immunology, 2013; DOI:10.1038/ni.2545