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Kale (Brassica oleracea), also sometimes referred to as borecole, is a relative of the more highly developed members of the same family like broccoli, cauliflower and Brussels sprouts. The vegetable has been so popular in Scotland that “come to kale” was an invitation to dinner. In addition to the typical green colour the vegetable is available in white, purple and pink too!

Kale is essentially a primitive cabbage that has held on to its characteristics since prehistoric times. The reason for kale’s perseverance is due to its virtues as a garden vegetable. Different varieties of kale are cultivated all around the world and while it grows well in various climates, it does particularly well in the cooler winter months. In fact some people claim their taste is sweeter when harvested after the first frost. While a member of the cabbage family, kale does not have a head, instead there are long fibrous stalks cascading outward from a centre bunch.

During World War II, kale was cultivated widely due to ease of growing and it supplemented the meagre war time rationing while supplying important nutrients. Once the war was finished, a lot of families moved away from kale, due to the association of its taste, and texture with wartime deprivations.

History of Kale

Kale is the descendent of the wild cabbage which has its origins in Asia Minor. Kale is a member of the Acephala cultivar, hence the full name Brassica oleracea acephala translates to “cabbage of the vegetable garden without a head”. The ruffled look of its leaves differentiate it from the more smooth leafed collard greens of the same family.

Kale was introduced to Europe by Celtic explorers around 600 B.C.E, and prevailed on the continent for over 2000 years.  It was among the most common green vegetable until the middle ages when cabbage started to gain acceptance. Kale played a vital role in early European food supplies and was a major crop in the ancient Roman era, known to Romans by the name of Sabelline Cabbage. Its high yield and ease of cultivation made it a popular vegetable among the peasants during the Middle Ages. Almost every Scottish household grew kale in their yards, known as “kaleyards”, due to its hardiness and they preserved it in barrels of salt. If a Scot was “off his kale”, it meant he was too ill to eat. Kale holds a vital position in cuisine of Scandinavia and Holland, and in Germany, “Kale King” is crowned during the annual kale festival. English settlers carried kale to the New World in the 17th century.

The Japanese bred the very first varieties of ornamental kale we see today. They first appeared in seed catalogs in the 1930s. The central leaves of ornamental varieties may be pink, rose, violet, yellow or white to creamy in colour, while the outer leaves are varying shades of green, blue or gray. The wrinkly edges give a ruffled ornate effect. The colour of the leaf becomes more intense after the first frost. While it is essentially a decorative plant, it can quiet easily be eaten also. The only difference between the decoration kale and the green kale is the pigmentation in leaves. The pigmentation has no affect on the taste of the leaf, but ornamental varieties are hardly ever sold for consumption mainly due to the high expense associated with them.

Health Benefits of Kale

Kale contains at least forty five flavonoids, and a wide array of vitamins and minerals. It offers benefits in three main areas: The high anti-inflammatory and antioxidant nutrients, the micronutrients a body requires in small quantities but can’t produce itself, and the cancer protecting glucosinolates (compounds housing sulphur and nitrogen that incite the body’s antioxidant system into action).

Kale is a low calorie food which is high in fibre content. This makes it the ideal food for individuals trying to lose weight, and the fibre helps in digestion and keeps movement of waste from the body steady. It provides more iron per calorie than beef and iron benefits the system by aiding in proper liver function, transportation of oxygen to all parts of the body and during formation of haemoglobin and enzymes. The high vitamin K content helps in keeping bones healthy, preventing blood clotting and elevated vitamin K levels also help people with Alzheimer’s disease. Antioxidants such as flavonoids and carotenoids offer protection against a number of cancers. The anti-inflammatory compound omega-3 fatty acids fight off arthritis, asthma and autoimmune ailments. Kale is also known to help stabilize cholesterol levels. The vitamin A in kale helps with vision, skin and lung cancer while vitamin C keeps metabolism in check and enhances the immune system. Kale has more calcium per calorie than milk, which prevents bone loss, osteoporosis and aids in maintaining healthy metabolism. The phytonutrients like quercetin prevent plaque formation, thus keeping the circulatory system healthy.

While kale is considered to be a very healthy food, excessive amounts can interfere with certain drugs like anticoagulants. It is associated with haemolytic anemia, where red blood cells breakdown to the point of threatening life.  It is also high in oxalates that can interfere with calcium absorption. This simply means you should not be drinking a litre of kale in smoothies every day.  You are now aware of the issues and should use it in moderation so you can benefit from its good points without being affected by its weak points.

Nutritional Value of Kale

In recent years kale has come to be known as one of the “superfoods”, and even cooked it delivers loads of vitamins and minerals. It is low in calories delivering only 28 in a 100 gram serving, and fat with only 0.4 grams. At the same time it provides 1.9 grams of protein and 2 grams of fibre. Out of the 100 gram serving 91.2 grams are water and 5.63 grams carbohydrates.

A one hundred gram serving of kale provides 778% of vitamin K, 85% of vitamin A, 49% vitamin C, 11% vitamin B6, 6% vitamin B2 and E, 5% vitamin B1, and 3% vitamin B3 and B9. Kale is rich in mineral content also, with a single one hundred gram serving delivering 20% manganese, 7% each of iron and calcium, 5% magnesium and potassium, 4% phosphorus, 3% zinc, and 2% zinc.

Uses of Kale

Kale is very fibrous so most people prefer to eat it cooked instead of consuming it raw. In either case, the woody stem needs to be removed before using kale. Kale can be steamed, boiled, sautéed, baked or stir fried. Kale makes a good addition to stews and soups as its hardy leaves hold up well even when boiled. Kale can be added to salads using an oil based dressing which helps in softening the stiff leaves. The slightly bitter taste of raw kale makes a nice contrast to things like honey and tahini.

In the U.S kale is typically used in combination with other greens like turnip leaves and collard. It is braised for hours with ham hock. It is also well accepted as a smoothie ingredient, due to its high nutritional value and fibre content. Baking it until turns it into a crunchy “chip” providing a healthy alternative to the potato chip.

Creamy Kale Smoothie

  • 1 cup frozen strawberries
  • 1 cup frozen cherries
  • ½ cup apple juice
  • 2 leaves of kale
  • ¼ tsp. cinnamon powder
  • 1 tbsp, yogurt

Instructions: Put everything into a blender and puree until smooth.

Clinical Trials

A fairly new study published in the Journal of Nutrition (2004) found that sulforaphane found in kale helps to halt proliferation of breast cancer cells. Sulforaphane forms when kale is cut up or chewed. This compound makes the liver produce natural enzymes that go on to detoxify cancer forming chemicals from our bodies.

In another study of lung cancer patients, it was found that elevated consumption of cruciferous vegetables like kale reduced lung cancer risk by 39%.

According to some studies, sulforaphane encourages a healthy immune system which in turn averts cancer. It increased the production of a number of chemicals that take part in the immune response.

Sulforaphane also has a direct effect on colon cancer. In one study, genetically bred animals that developed intestinal polyps, a precursor to tumour formation, were fed sulforaphane. The group of animals fed sulforaphane were found to have enhanced rates of cell suicide and smaller tumours developed more slowly as compared to animals that were not given sulforaphane.

Kale is rich in carotenoids, plant pigments known to absorb blue light. Two carotenoids kale is especially endowed with are lutein and zeaxanthin, and both of them behave like filters that avert eye damage from exposure to ultraviolet light. In a number of studies people who consume kale like lutein-rich foods had 22% reduced risk of cancer.

Lutein also aids in averting artherosclerosis. According to an 18 month long study at University of Southern California, people with minimum serum lutein concentration had five times higher carotid artery thickness, an indicator of heart disease risk, compared to people who had greatest serum lutein concentrations. Additionally it was found that cells pre-treated with lutein protected them against inflammation linked with LDL plaque development. This again proved that lutein offers protections against arterosclerosis.

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About Andy Williams

In a processed food culture, simply eating may not be enough. Dr. Andy Williams is a scientist with a strong interest in Juicing and how it can supply the body with the nutrients it needs to thrive in modern society. You can subscribe to his free daily paper called Juicing The Rainbow and follow him on Facebook orTwitter.

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