You'll want to include collard 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.
It is very important not to overcook collard greens. Like other cruciferous vegetables overcooked collard greens will begin to emit the unpleasant sulfur smell associated with overcooking. To help collard greens to cook more quickly, evenly slice the leaves into 1/2-inch slices and the stems into 1/4-inch pieces. Let them sit for at least 5 minutes and then steam for 5 minutes Serve with our Mediterranean Dressing. See 5-Minute Collard Greens.
Unlike broccoli and kale and cabbage, you won't find many research studies devoted to the specific health benefits of collard greens. However, collard greens are sometimes included in a longer list of cruciferous vegetables that are lumped together and examined for the health benefits they provide. Based on a very small number of studies looking specifically at collard greens, and a larger number of studies looking at cruciferous vegetables as a group (and including collard greens on the list of vegetables studied), cancer prevention appears to be a standout area for collard greens with respect to their health benefits.
This connection between collard greens and cancer prevention should not be surprising since collard greens provide special nutrient support for three body systems that are closely connected with cancer development as well as cancer prevention. These three systems are (1) the body's detox system, (2) its antioxidant system, and (3) its inflammatory/anti-inflammatory system. Chronic imbalances in any of these three systems can increase our risk of cancer, and when imbalances in all three systems occur simultaneously, our risk of cancer can increase significantly. Among all types of cancer, prevention of the following cancer types is most closely associated with intake of collard greens: bladder cancer, breast cancer, colon cancer, lung cancer, prostate cancer, and ovarian cancer.
Our body's detox process involves two distinct steps—called Phase 1 and Phase 2—and collard greens provide nutrients that support both of these steps. In Phase 1 of detox, potentially toxic compounds are activated to make them more reactive. Phase 1 of detox requires strong antioxidant support, and collards are antioxidant-rich greens that contain phenols, polyphenols, and conventional antioxidant nutrients like vitamins C and E. In Phase 2 of detox, activated compounds get hooked together with specific nutrients to make them water-soluble and allow for excretion from the body. Here is where the detox support provided by collards is perhaps most unique. Collard greens provide us with unique sulfur-containing compounds called glucosinolates. These glucosinolates can be converted into related compounds called isothiocyanates, or ITCs. The ITCs made from glucosinolates in collard greens (and other cruciferous vegetables) have been shown to modify enzyme activity in Phase 2 of detox and increase the likelihood of detox success. The chart below shows some of the best-studied glucosinolates in collard greens and ITCs that can be made from each of them.
|Glucosinolate||Derived Isothiocyanate||Isothiocyanate Abbreviation|
* Indole-3-carbinol (I3C) is not an isothiocyanate. It's a benzopyrrole, and it is only formed when isothiocyanates made from glucobrassicin are further broken down into non-sulfur containing compounds.
As an excellent source of vitamin C, vitamin A (in the form of carotenoids), and manganese, and a good source of vitamin E, collard greens provide us with four core conventional antioxidants. But the antioxidant support provided by collard greens extends far beyond the conventional nutrients into the realm of phytonutrients. Caffeic acid, ferulic acid, quercetin, and kaempferol are among the key antioxidant phytonutrients provided by collard greens. This broad spectrum antioxidant support helps lower the risk of oxidative stress in our cells. Chronic oxidative stress—meaning chronic presence over overly reactive oxygen-containing molecules and cumulative damage to our cells by these molecules—is a risk factor for development of most cancer types. By providing us with such a great array of antioxidant nutrients, collard greens help lower our cancer risk by helping us avoid chronic and unwanted oxidative stress.
As an excellent source of vitamin K and a good source of omega-3 fatty acids (in the form of alpha-linolenic acid, or ALA), collard greens provide us with two hallmark anti-inflammatory nutrients. Vitamin K acts as a direct regulator of our inflammatory response, and ALA is the building block for several of the body's most widely-used families of anti-inflammatory messaging molecules. In addition to these two anti-inflammatory components, one of the glucosinolates found in collard greens—glucobrassicin—can be readily converted into an isothiocyanate molecule called I3C, or indole-3-carbinol (I3C). I3C is an anti-inflammatory compound that can actually operate at the genetic level, and by doing so, prevent the initiation of inflammatory responses at a very early stage.
Like chronic oxidative stress and chronic weakened detox ability, chronic unwanted inflammation can significantly increase our risk of cancers and other chronic diseases (especially cardiovascular diseases).
Given the extensive list of antioxidant and anti-inflammatory nutrients provided by collard greens, it is not surprising that these greens provide us with cardiovascular support. In particular, many chronic blood vessel problems begin with excessive oxygen-related damage to blood vessel walls and blood constituents, as well as chronic inflammation.
Of particular interest with respect to collard greens has been the isothiocyanate (ITC) sulforaphane, which is made from glucoraphanin, one of the glucosinolates provided by collard greens. Not only does this ITC trigger anti-inflammatory activity in our cardiovascular system, it may also be able to help prevent and even possibly help reverse blood vessel damage.
A second area you can count on collard greens for cardiovascular support involves their cholesterol-lowering ability. As mentioned earlier in this profile, when we eat collard greens, fiber-related nutrients in this cruciferous vegetable bind together with some of the bile acids in the intestine in such a way that they simply stay inside the intestine and pass out of our body in a bowel movement, rather than getting absorbed along with the fat they have emulsified. When this happens, our liver needs to replace the lost bile acids by drawing upon our existing supply of cholesterol, and as a result, our cholesterol level drops down. Collard greens, in both raw and cooked form, have been shown to provide this cholesterol-lowering benefit. However, a recent study has shown that the cholesterol-lowering ability of raw collard greens improves when they are steamed. In addition to the support factors described above, it would be wrong to talk about the cardiovascular benefits of collard greens without mentioning their diverse array of B vitamins. Collard greens are a very good source of vitamins B2, B6, and choline, and a good source of vitamins B1, B3, folate, and pantothenic acid. A well-balanced intake of B vitamins - especially vitamins B6, B12, folate, and choline - can be important in controlling cardiovascular disease risk. Since excessive or deficient intake of these B vitamins can have an unwanted impact on your disease risk, it is great to have a food like collard greens that provide a helpful amount of so many B vitamins.
The fiber content of collard greens—over 7 grams in every cup—makes this cruciferous vegetable a natural choice for digestive system support. Yet the fiber content of collard greens is only one of their digestive support mechanisms. Researchers have determined that the sulforaphane made from a glucosinolate in collard greens (glucoraphanin) helps protect the health of our stomach lining by preventing bacterial overgrowth of Helicobacter pylori in our stomach or too much clinging by this bacterium to our stomach wall.
The anti-inflammatory nature of glucosinolates/isothiocyanates and other nutrients found in collard greens has been the basis for new research on inflammation-related health problems and the potential role of collard greens in their prevention. Current and potentially promising research is underway to examine the benefits of collard greens in relationship to our risk of the following inflammation-related conditions: Crohn's disease, inflammatory bowel disease, insulin resistance, irritable bowel syndrome, metabolic syndrome, obesity, rheumatoid arthritis, type 2 diabetes, and ulcerative colitis.
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:
The Brassicaceae family of plants—more frequently referred to in previous years as the Cruciferae family includes a large number of edible plants. Many commonly enjoyed foods in this plant family come from a single genus/species of plant called Brassica oleracea. These foods include broccoli, Brussels sprouts, cabbage, cauliflower, kale, and kohlrabi. Collards come from this same genus/species as well, but also from a particular subspecies called Brassica oleracea subspecies viridis. Within this genus/species of plant, kale and collards are closely related since both belong to what is called the Acephala group. However, unlike kale, collards are relatively smooth in texture and relatively broad leafed, whereas kale can be more narrow and either curly or ruffled in texture. Depending on the specific variety of collard, this cruciferous vegetable can be mild-to-slightly strong in flavor. Some food writers have also referred to collards as slightly "smoky" in flavor. Raw collards can also sometimes be tougher in texture than their fellow leafy greens. It is also worth noting that unlike most varieties of cabbage, cauliflower, and broccoli, collard plants are loose-leafed and non-head-forming. Common varieties of collards enjoyed in the U.S. include Champion, Georgia Southern, Morris Heading, Vates, and Ole Timey Blue. Like most of their fellow greens, collards are considered cool season crops and do especially well in temperatures between 50-65°F (10-18°C).
Like kale, cauliflower, modern cabbage, Brussels sprouts, kohlrabi, and broccoli, collards are considered by many plant historians to be descendents of wild cabbage that was found in many parts of Europe over 2,000 years ago. This line of descent may be especially accurate for collards, since the ancestral wild cabbages in Europe were loose leafed and didn't form a head, much like present-day collards and kale.
Collards are currently enjoyed worldwide as a staple part of different cuisines. Collards are staple vegetables in diets in some parts of East Africa (for example, in areas of Tanzania and Kenya); in some parts of South America (for example, in areas of Brazil); in southern Europe (especially Portugal); in south Asia (especially in the Kashmir Valley region); and also in the southeastern United States. As mentioned earlier in this profile, older adults in the southeastern United States still rank collard greens as their second most favorite food (after chicken), and collard greens still provide an unusual amount of the diet's total antioxidant capacity for some individuals in this region of the U.S. We have not seen reliable data, however, for total collard green production or consumption in the U.S. or worldwide.
Look for collard greens that have firm, unwilted leaves that are vividly deep green in color with no signs of yellowing or browning. Leaves that are smaller in size will be more tender and have a milder flavor. They should be displayed in a chilled section in the refrigerator case to prevent them from wilting and becoming bitter.
At WHFoods, we encourage the purchase of certified organically grown foods, and collard 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 collard greens. In many cases, you may be able to find a local organic grower who sells collard 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 collard greens is very likely to be collard greens that display the USDA organic logo.
Place collard greens in a plastic bag, removing as much of the air from the bag as possible. Store in the refrigerator where they should keep fresh for about three to five days.
Here is some background on why we recommend refrigerating collard 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.
If you'd like even more recipes and ways to prepare collard greens the Nutrient-Rich Way, you may want to explore The World's Healthiest Foods book.
You may sometimes hear collard greens being described as a food that contains "goitrogens," or as a food that is "goitrogenic." For helpful information in this area—including our WHFoods Recommendations—please see our article What is meant by the term "goitrogen" and what is the connection between goitrogens, food, and health?.
Collard Greens, chopped, cooked
GI: very low
|vitamin K||772.54 mcg||858||246.4||excellent|
|vitamin A||722.00 mcg RAE||80||23.0||excellent|
|vitamin C||34.58 mg||46||13.2||excellent|
|choline||72.96 mg||17||4.9||very good|
|vitamin B2||0.20 mg||15||4.4||very good|
|vitamin B6||0.24 mg||14||4.1||very good|
|iron||2.15 mg||12||3.4||very good|
|vitamin E||1.67 mg (ATE)||11||3.2||good|
|pantothenic acid||0.41 mg||8||2.4||good|
|omega-3 fats||0.18 g||8||2.2||good|
|vitamin B3||1.09 mg||7||2.0||good|
|vitamin B1||0.08 mg||7||1.9||good|
Density>=7.6 AND DRI/DV>=10%
Density>=3.4 AND DRI/DV>=5%
Density>=1.5 AND DRI/DV>=2.5%