Turnip greens

• Due to their rich carotenoid content, turnip greens rank as our 8th best source of vitamin A at WHFoods. This "Top 10" status for turnip greens has been confirmed in a recent study on the beta-carotene and lutein content in the leaves of this cruciferous vegetable. Two varieties of turnips (and turnip greens)—Topper and Alamo—were analyzed in the study. Not only were both varieties found to be rich in beta-carotene and lutein (two well-studied and health-supportive carotenoids), but both varieties were also found to have significant concentrations of these carotenoids in both their upper and lower leaves. This finding is good news for anyone who enjoys turnip greens in their meal plan because all of the leaves of the plant— provided that they are unblemished and richly green in color—can serve as excellent sources of carotenoids, including beta-carotene, which is the easiest carotenoid for our body to convert into the retinol form of vitamin A. (Our Vitamin A nutrient profile will provide you with more detailed information and carotenoids and vitamin A.)
• Glucosinolates are unique sulfur-containing nutrients that are well known for their link to cancer prevention as well as their ability to support detox processes within our cells. While turnip greens, like most cruciferous vegetables, are rich in glucosinolates, recent studies on turnip greens suggest that they may be unique among their fellow cruciferous vegetables in terms of their specific glucosinolate composition. These studies show that the most plentiful glucosinolate in turnip greens is gluconapin, followed by a second glucosinolate called glucobrassicanapin. These particular glucosinolates give scientists reasons to think about turnip greens (and turnips) as being more closely linked to Brassica family plants like rapeseed (which is the source of canola oil) than to broccoli or other members of this vegetable group. Although more research is needed to flesh out the health significance of the unique glucosinolate mixture in turnip greens, this new information is one more reason to consider adding turnip greens to your meal plan as a unique food in its potential for nutrient support.
• All nine of our WHFoods cruciferous vegetables can make outstanding nutrient additions to your meal plan. That being said, only one member of this cruciferous vegetable group achieves 10 separate ratings of "excellent" in our nutritional rating system—and that group member is turnip greens! Our two next closest cruciferous vegetables in terms of having "excellent" nutrient scores are bok choy and mustard greens (each achieving eight ratings of "excellent"). Collard greens show up next on the list, with six ratings of "excellent." Exactly which 10 nutrients get provided in an "excellent" amount by turnip greens? They are vitamin K, vitamin A (in the form of carotenoids), vitamin C, folate, copper, manganese, fiber, calcium, vitamin E, and vitamin B6.
• It's important to not overcook your turnip greens. A recent research study has shown that a difference of even 1 or 2 minutes in cooking time can decrease the total chlorophyll content, total phenol content, and overall antioxidant capacity of the turnip greens. In this study, the turnip greens were blanched by placing them directly in water that was previously heated to 194°F (90°C). At WHFoods, we go one step further, avoiding direct contact with water altogether: our Quick Steaming method for turnip greens is described in detail in our Tips for Preparing Turnip Greens section in this profile.

WHFoods Recommendations

You'll want to include turnip greens as one of the cruciferous vegetables you eat on a regular basis if you want to receive the fantastic health benefits provided by the cruciferous vegetable family. At a minimum, we recommend 3/4 cup of cruciferous vegetables on a daily basis. This amount is equivalent to approximately 5 cups per week. A more optimal intake amount would be 1-1/2 cups per day, or about 10 cups per week. You can use our Veggie Advisor for help in figuring out your best cruciferous vegetable options.

We recommend Quick Steaming turnip greens for maximum nutrition and flavor. Cut greens into 1/2-inch slices and let sit for at least 5 minutes to enhance it health-promoting benefits and steam for 5 minutes. Toss with our Mediterranean Dressing (see the Nutrient-Rich Way to Cook Turnip Greens in the How to Enjoy section below).

Health Benefits

Unlike some of their fellow cruciferous vegetables, turnip greens have not been the direct focus of most health-oriented research studies. However, turnip greens have sometimes been included in a longer list of cruciferous vegetables that have been lumped together and studied to determine potential types of health benefits.

Broad-Based Nutritional Support of Turnip Greens

As mentioned earlier in this profile, turnip greens achieve more ratings of "excellent" in our food rating system than any of their fellow cruciferous vegetables. Included in their 10 "excellent" ratings are fat-soluble vitamins, water-soluble vitamins, minerals, and antioxidants; turnip greens also contain a wide variety of phytonutrients including carotenoids, flavonoids, and glucosinolates. If you combine the "excellent" nutritional ratings achieved by turnip greens with their "very good" and "good" ratings, you end up with 20 total ratings, including high scores for fiber, protein, and omega-3 fats. In short, turnip greens will provide you with measurable nutrient benefits in every major category of nutritional science.

Glucosinolate Benefits of Turnip Greens

Like all of its fellow cruciferous vegetables studied thus far, turnips (including both their leaves and their roots) are sources of unique sulfur-containing compounds called glucosinolates. In our article Feeling Great with Cruciferous Vegetables you can get fuller details about glucosinolates and their link not only to cancer prevention but also to support of detoxification processes in our cells. Recent studies on turnip greens, however, suggest that this particular cruciferous vegetable may have a somewhat unusual glucosinolate profile in comparison with other "crucifers" like broccoli or cauliflower or collard greens. According to these recent studies, the most plentiful glucosinolate in turnip greens turns out to be gluconapin, followed by a second glucosinolate called glucobrassicanapin. These particular glucosinolates give scientists reasons to think about turnip greens (and turnips) as being more closely linked to Brassica family plants like rapeseed (which is the source of canola oil) than to broccoli and other members of this vegetable group. It's not yet clear how this unique glucosinolate profile in turnip greens (and turnip roots) translates into specific health benefits, but we suspect that turnip greens will eventually be shown to provide unique health support owing to this factor, giving us yet another reason to include this specific cruciferous vegetable in our meal plan.

Antioxidant Benefits of Turnip Greens

Since turnip greens rank in our Top 5 Foods for vitamin E, our Top 10 Foods for beta-carotene, our Top 15 Foods for manganese, and our Top 20 Foods for vitamin C, we end up with a pretty impressive contribution of antioxidant nutrients from this vegetable since each nutrient above has been extensively studied and is known to be critical for helping us lower our risk of unwanted oxidative stress and the chronic diseases (for example, atherosclerosis and rheumatoid arthritis) that have been linked to excessive oxidative stress.

In the case of vitamin E and turnip greens, it is interesting to note that beta-tocopherol and beta-tocotrienol appear to be the major forms of vitamin E in the leaves of this cruciferous vegetable. While all forms of vitamin E found in food provide us with nutritional support, it is generally helpful for us to consume foods that provide us with vitamin E in a variety of different forms, including both tocopherols and tocotrienols. Turnip greens clearly rise to the occasion in this regard!

Research on carotenoid antioxidants in turnips greens is especially strong. Beta-carotene and lutein are two carotenoids that have been carefully studied in the leaves of this plant, and we know that they are present in plentiful amounts in both upper and lower leaves. (In some plants, due to the angle of sunlight and the positioning of the leaves, the lower leaves end up with substantially lower concentrations of some carotenoids, including lutein and beta-carotene. But this situation does not appear to be the case with the turnip plant and its greens.) The antioxidant flavonoids quercetin and kaempferol have also been identified in fresh turnip greens.

Description

All cruciferous vegetables provide integrated nourishment across a wide variety of nutritional categories and provide broad support across a wide variety of body systems as well. For more on cruciferous vegetables see:

• Eating Healthy with Cruciferous Vegetables
• Feeling Great with Cruciferous Vegetables

Turnip greens are, of course, the leaves of the turnip plant. You will also sometimes hear these greens being referred as turnip "tops." The vast majority of turnip plants that are grown commercially are grown primarily for their roots rather than their leaves, but you can enjoy the leaves of any turnip plant alongside of their better-known roots.

Turnips belong to the scientific genus/species of plant officially named Brassica rapa. Within this group are many turnip varieties, which are often classified according to the color of their root. White root turnips include varieties like Snowball, Egg White, and Tokyo Cross. Yellow/orange root turnips include Golden Globe, Orange Jelly, and Petrowski. Red root turnips include Red Round, Scarlet Queen, and Red Root. For the most part, popular purple root varieties of turnips—including Purple Top White Globe, Royal Crown, and Milan— feature a root that has a purple top half and a lower white half.

Turnips have an especially interesting relationship to rutabagas. Somewhere along the evolutionary process, turnips (Brassica rapa) crossed with their fellow cruciferous vegetable cabbage (Brassica oleracea) and the result was rutabagas. You may find several different scientific terms being used to refer to rutabagas, including Brassica napobrassica, Brassica napus var. napobrassica, and Brassica napus subsp. rapifera).

Turnips may also have a special relationship with their fellow cruciferous vegetable rapeseed (Brassica napus subsp. oleifera), perhaps best known as the source of the widely enjoyed cooking oil, canola oil. Several recent studies on the glucosinolate content of turnip roots/greens and rapeseed have found some special similarities between these two plants in terms of their glucosinolates.

History

Like most of its fellow cruciferous vegetables, turnips and turnip greens have a long and geographically diverse history. For the most part, turnips are regarded as being native to several areas including the Middle East, parts of the Mediterranean, Western Asia, and Eastern Asia. The history of turnip cultivation in Europe apparently came much later, and it may be this part of the turnip's history where it received the name "turnip." This name is likely related to the Latin word napus and also to the Old English word turnepe—in which you can see the word "turn." This word history makes sense to some researchers because of the many varieties of turnip with roots that are both round and slightly elongated, almost as if those roots had been turned and rounded on a lathe.

Turnips grown worldwide and in the U.S. are primarily cultivated for their roots rather than their leaves. States like California that grow a fairly large volume of cruciferous vegetables do not tend to grown large numbers of turnips, and the total acreage of turnip crops in California is typically less than 500. Most of the turnips consumed in the United States are imported from Canada and Mexico. Turnips have a long history of cultivation in Scandinavia, the United Kingdom, and parts of Asia, including Japan and China.

How to Select and Store

Turnip greens are usually available with their roots attached. Look for greens that are unblemished, crisp, and deep green in color.

At WHFoods, we encourage the purchase of certified organically grown foods, and turnip greens are no exception. Repeated research studies on organic foods as a group show that your likelihood of exposure to contaminants such as pesticides and heavy metals can be greatly reduced through the purchased of certified organic foods, including turnip greens. In many cases, you may be able to find a local organic grower who sells turnip greens but has not applied for formal organic certification either through the U.S. Department of Agriculture (USDA) or through a state agency. (Examples of states offering state-certified organic foods include California, New York, Oregon, Vermont, and Washington.) However, if you are shopping in a large supermarket, your most reliable source of organically grown turnip greens is very likely to be turnip greens that display the USDA organic logo.

If you have purchased turnip greens with roots attached, remove them from the root. Store root and greens in separate plastic bags, removing as much of the air from the bags as possible. Place in refrigerator where the greens should keep fresh for about 4 days.

Here is some background on why we recommend refrigerating turnip greens. Whenever food is stored, four basic factors affect its nutrient composition: exposure to air, exposure to light, exposure to heat, and length of time in storage. Vitamin C, vitamin B6, and carotenoids are good examples of nutrients highly susceptible to heat, and for this reason, their loss from food is very likely to be slowed down through refrigeration.

How to Enjoy

A Few Quick Serving Ideas

• Serve healthy sautéed turnip greens seasoned with some soy sauce, lemon juice and cayenne pepper.
• Make a simple meal with a little Southern inspiration. Serve cooked turnip greens with beans and rice.
• Healthy sauté turnip greens, sweet potatoes and tofu, and serve alongside your favorite grain.
• Use turnip greens in addition to spinach when making vegetarian lasagna.

If you'd like even more recipes and ways to prepare turnip greens the Nutrient-Rich Way, you may want to explore The World's Healthiest Foods book.

Safety

Turnip Greens and Goitrogens

Nutritional Profile

Introduction to Food Rating System Chart

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