Leafy green vegetables and turnips are low-calorie, low-fat sources of many vitamins and minerals, including vitamins A and C and minerals calcium and iron. Greens and turnips also both provide a variety of antioxidants and other phytochemicals that might help protect the body from certain chronic diseases such as cardiovascular coronary disease and cancer. Additionally, both greens and turnips are low in sodium and free of cholesterol.
About Greens
The classification "greens" most typically runs the gamut of leafy green vegetables, from basic iceberg and romaine lettuce to spinach and kale. By the USDA standards, even vegetables such as bok choy, broccoli, cabbage, endives, escarole and watercress qualify as leafy greens.
Greens: Nutrition
While some variation in nutrient content exists among different greens, their general nutritional profiles are similar. For example, most leafy greens are potent sources of vitamin A as beta-carotene; vitamin C; the B vitamins folate or folic acid, niacin and riboflavin; and the minerals iron, calcium, magnesium and potassium. Dark leafy greens tend to have a higher concentration and potentially broader variety of nutrients than lighter-colored leafy greens. For example, NDSU's Garden-Robinson reports that iceberg lettuce is lower in vitamins A, C, K, folate and iron than red leaf lettuce.
Greens: Considerations
According to the USDA, not only do the processes of canning or cooking greens not diminish their vitamin A content, but in certain greens such as collards, spinach and turnip greens, they might even enhance vitamin A content, i.e. make more of it available for human absorption. Fresh greens should be tender, crisp and bright green in color. When greens start to spoil, they turn yellow in color and either dried out or slimy in texture. The University of California Cooperative Extension advises that spinach contains a substance called oxalic acid that reduces the body's ability to absorb iron, but by eating foods high in vitamin C with spinach, that effect can be countered or minimized.
About Turnips
As members of the mustard family, turnips are relatives of cauliflower and cabbage. Turnips are considered a root vegetable, although technically, the edible part of a turnip is not a root at all, but a swollen subterranean portion of the stem. Turnips are generally round in shape and typically have white flesh, although they might be yellow or purple as well. Their leaves, or turnip greens, are thin, rough and covered in prickly hairs. Fresh turnips should be firm and free of blemishes. To retain freshness, store in the refrigerator, ideally in a plastic bag in the crisper drawer.
Turnips: Nutrition
Turnips are high in dietary fiber, vitamin C, potassium and calcium, while their greens are high in vitamins A, C, K, calcium, folate and the antioxidants lutein and zeaxanthin. The antioxidants lutein and zeaxanthin can help promote the health of the eyes, and in a 2004 "Journal of Nutrition" study, they were found to help prevent cataracts and were almost 10 times better than vitamin E at protecting the cells of the eyes from damage caused by ultraviolet radiation from sunlight and tanning booths.
References
- "NDSU Agriculture Communication"; "Prairie Fair: Leafy Garden Greens and Nutrition to Your Menu"; Julie Garden-Robinson
- USDA National Nutrient Database for Standard Reference: Release 23
- University of California Cooperative Extension: "Fresh from the Garden: Leafy Greens"
- "Journal of Nutrition"; "Xanthophylls and alpha-Tocopherol Decrease UVB-Induced Lipid Peroxidation and Stress Signaling in Human Lens Epithelial Cells"; Chureeporn Chitchumroonchokchai et al.; December 2004
- "Agricultural Outlook"; "Leafy Greens: Foundation of the Vegetable Industry"; Gary Lucier; February 1998
- "Courier Mail"; "Turnip Patch"; Gillian Hirst; August 2006
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