Vegetable soup, that winter comfort food, might have some value in the prevention and treatment of colon, breast, lung and other cancers. Vegetables contain important antioxidants, minerals and other nutrients that show promise in protecting against cancer and in shrinking tumors. What's already certain is that vegetable soup is a healthy meal for anyone.

Cruciferous vegetables like broccoli, cabbage and cauliflower may protect normal cells from becoming cancerous. The Linus Pauling Institute says results of testing are mixed; consuming cruciferous vegetables appeared to lower the risk of lung, breast, colorectal or prostate cancer in some tests but not all. Research into the potential beneficial effects of cruciferous vegetables continues. Mushrooms, onions, garlic, potatoes, turnips and parsnips contain allicin, which possibly lowers the risk for stomach cancer, according to North Dakota State University Extension. Cooked tomatoes have large amounts of lycopene, used in treatments for prostate cancer.

Stanford Cancer Center offers a vegetable soup recipe for cancer patients that allows a choice of vegetables from a varied list. The soup has a chicken stock or beef broth base and may contain carrots, onions, potatoes, sweet potatoes, broccoli florets, zucchini, green peas or green beans. Serve the soup chunky style or blended. The veggies must be well-cooked. Don't add spices like pepper to the vegetables once the soup is finished cooking.

Selected Vegetable Soup and Sun’s Soup are variations of a vegetable soup being tested for anti-cancer properties. Some frozen and dried soup mixes can be purchased in the United States as dietary supplements. The American Cancer Society says the soup mix is safe to consume, but there is no verifiable evidence that it can help to treat cancer. The freeze-dried mix contains soybeans, shiitake mushrooms, mung beans, scallions, garlic, leeks, lentils, onion, ginseng, several medicinal roots, olives and parsley.

The Kushi Institute has long offered a macrobiotic diet as a cancer preventative. The institute recommends several versions of miso soup, made with the fermented soybean paste common to the Japanese diet. The institute points to Japanese government studies that linked a diet high in miso to lower instances of stomach and breast cancers. The Kushi Institute Basic Vegetable Miso Soup recipe includes dry wakame seaweed, sliced onions, spring water and miso. Recommended vegetables include squash, cabbage, carrots, daikon, daikon greens and dried nori.