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What’s New and Beneficial About Kale

• Among all 100 of our WHFoods, kale tops the list in terms of lutein content. Kale is not only our most lutein-rich food at WHFoods, it is also the top lutein-containing food in the USDA’s National Nutrient Database that analyzes 5,350 foods that contain this carotenoid nutrient. Among the carotenoids, lutein is perhaps best known for its supportive role in eye health, and in particular, for its ability to protect different parts of the eye from potential damage by light or oxygen. A recent study on African-American women has shown decreased likelihood of glaucoma (an eye problem usually caused by increased pressure within the eye) when dietary intake of kale reaches higher intake levels. In this case, “higher intake levels” were defined as any levels exceeding at least one half-cup serving per week. Since our WHFoods serving size for kale is one cup, you will be getting more than this amount from one serving based on our standard. Among all of the vegetables examined in this particular study, kale and collards came out at the top of the vegetable list in this study for decreasing the likelihood of glaucoma!
• A recent study has analyzed the combination of kale with lentils and found this food combination to be especially complementary in providing us with nutrient-richness. Interestingly, this study focused on two areas of nutrition: mineral nourishment and “prebiotic nutrients.” Prebiotic nutrients are nutrients that support the growth of desirable bacteria within our digestive tract. These nutrients often involve short chains of simple sugars called “oligosaccharides.” (Glucooligosaccharides, fructooligosaccharides, and xylooligosaccharides are well-studied examples of oligosaccharides.) In this study, researchers determined that the combination of prebiotic nutrients in kale-plus-lentils and the combination of mineral nutrients in kale-plus-lentils were especially were especially complementary as each food provided the nutrients that the other one lacked. In each nutrient category, kale and lentils were able to “bring something special to the table” that the other could not, resulting in outstanding combined nutrient richness. Why not take advantage of this unique food combination by starting with our Curried Lentils? Each serving of this vegetarian entreé will provide you with 1/2 cup of kale and 1/2 cup of lentils.
• The research track record for kale in providing overall cardiovascular support is fairly strong, and not limited to improvement in blood cholesterol levels. However, research on kale and cholesterol levels is especially interesting. Recent studies show that kale can provide you with some special cholesterol-lowering benefits if you cook it by steaming. The fiber-related components in kale do a better job of binding together with bile acids in your digestive tract when they’ve been steamed. When this binding process takes place, it’s easier for bile acids to be excreted, and the result is a lowering of your cholesterol levels. Raw kale still has cholesterol-lowering ability—just not as much. Along these same lines, a recent study has examined the impact of 5 ounces of kale juice per day for 12 weeks in men with high blood cholesterol levels (above 200 mg/dL). Consumption of kale juice was determined to raise the HDL levels in these study participants, lower their LDL levels, and also improve their atherogenic profiles (which measured their likelihood of developing coronary artery disease). At WHFoods, we always encourage consumption of whole foods in their minimally processed forms. However, we also believe that this study on kale juice underscores the remarkable health benefits that can be derived from this cruciferous vegetable.
• Recent genetic studies on kale have shown it to have remarkable diversity, not only in terms of its physical varieties but also in terms of its nutrient content. For example, over 45 different flavonoids are known to be present in significantly differing amounts across the many different varieties of kale that can be found within the very broad kale family. One recent study has compared an Italian Lacinato-type variety of kale (also sometimes called Tuscan Black or Dinosaur kale) to a North American broad-leafed kale (often called a Napus or Siberian type kale) as well as to a German curly-leaf variety of kale (belonging to the Scotch/Scotch-Curled type of this cruciferous vegetable). As you can see, the very description of these kale types requires us to think about two continents and even more countries in which the kale was being grown. This particular study focused on sulfur-containing compounds in kale—including its glucosinolates. The researchers determined that glucosinolate content in kale can vary by as much as 10-fold depending on the specific variety in question and the conditions of cultivation and harvest. In general, this study showed that curly-leafed kale varieties and darker Lacinato varieties of kale contained higher levels of glucosinolates (and especially one particular glucosinlate called glucoraphanin) than the broad-leafed, Napus/Siberian types of kale. For glucosinolate-related health benefits from kale, you might want to focus on these varieties. In our Description section, you can find more details about each of these kale varieties.
• Kale is now recognized as providing comprehensive support for the body’s detoxification system. New research has shown that the ITCs made from kale’s glucosinolates can help regulate detox at a genetic level.

WHFoods Recommendations

You’ll want to include kale 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.

Kale is one of the healthiest vegetables around and one way to be sure to enjoy outstanding nutrition and flavor from kale is to cook it properly. We recommend Healthy Steaming kale for 5 minutes. To ensure quick and even cooking cut the leaves into 1/2″ slices and the stems into 1/4″ lengths. While there might be potential health benefits from letting the stems and slices sit for about 5 minutes prior to cooking, the scientific research in this area is definitely mixed. You can find many key details in our article, Can Preparation Methods Impact the Benefits of Cruciferous Vegetables?.

Cruciferous Vegetable Benefits

All cruciferous vegetables—including kale—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

Health Benefits

Kale provides numerous health benefits including:

• Antioxidant properties
• Anti-inflammatory benefits
• Cancer prevention
• Cardiovascular support
• Detoxification benefits

For more details on kale’s health benefits, see this section of our kale write-up.

Nutrient Profile

Our rating system shows kale to be an excellent source of vitamin K, vitamin C, vitamin A, manganese, and copper; a very good source of vitamin B6, fiber, calcium, potassium, vitamin E, and vitamin B2; and a good source of iron, magnesium vitamin B1, omega-3 fats, phosphorus, protein, folate, and vitamin B3. Over 45 different flavonoids have been identified in kale, and especially kaempferol, quercetin, and isorhamnetin. Its glucosonolates include glucobrassicin, glucoraphanin, gluconasturtiian, glucopaeolin, sinigrin, glucobrassicanapin, glucoiberin, and gluconapin. Kale also provides the lignans lariciresinol and pinoresinol.

Kale and Goitrogens

You may sometimes hear kale 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?.

For more on this nutrient-rich vegetable, including references related to this Latest News, see our write-up on kale.