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Dark leafy greens are supposedly the most nutritionally dense vegetables. They come with many health benefits, and kale is no exception. What is kale, and what gives it the top position in so many salad and green juice recipes nowadays? Join us to explore.
Kale stems from the plant brassica oleracea, which is also called “mustard plant”, and is of the same family as other vegetables such as broccoli, brussels sprouts and cabbage. This vegetable is distinguished by its broad, curly leaves, and although it is more commonly seen in its dark green version, it also comes in deep purple, blue-green or red-purple. Another vegetable of the same family, “gai-lan” (also called “Chinese kale” or “Chinese broccoli”), may be more familiar to people in Hong Kong, with different growing conditions and nutritional makeup.
Here are some of the health benefits of kale:
Kale naturally has good quantities of nutrients such as vitamin A from beta-carotene (an antioxidant that can turn into vitamin A), C, and K, as well as a wide range of key minerals such as calcium, magnesium and potassium, plus other antioxidants. Consuming 1 cup of kale brings you over 100% of the recommended dietary allowance (RDA) of vitamin C, which we need for a good immune system and synthesis of collagen. Likewise, for vitamin A, which helps with cell metabolism and supports brain health, 1 cup of kale can provide over 200% of our RDA!
Kale is a great source of fiber — each cup of kale contains 2.5g of fiber, which is more than 3 times that of spinach. Fiber in kale adds bulk to the stool and aids bowel movement to allow smooth passage of wastes through the digestive tract, decreasing the chance of constipation.
On the other hand, according to the Journal of Agricultural and Food Chemistry, kale also contains antioxidants such as kaempferol and quercetin, which help to minimize inflammation due to oxidative stress (accumulation of free radicals generated from within the body or from external sources, e.g. processed foods), while their alkaline qualities also help to cleanse the blood from excessive intake of animal protein. Together with other antioxidants in kale, including beta-carotene and vitamins and various flavonoids and polyphenols, they can reduce the risk of cancer or aging caused by oxidative stress.
For good vision and healthy eyes, it is important that we have a sufficient intake of beta-carotene and vitamin A. Other than these nutrients, kale also contains abundant lutein and zeaxanthin, which are crucial nutrients responsible for shielding eye tissues from UV damage, as well as preventing the risks of developing cataracts and macular degeneration, according to research studies.
Vitamin K is an important nutrient for blood clotting because it activates responsible proteins to bind with calcium to form blood clots. Kale has a rich source of vitamin K, almost 7 times that of the recommended daily allowance. Inefficient blood clotting may give rise to a higher chance of uncontrolled bleeding upon injuries. Having an inefficient clotting mechanism also implies thinner blood and a higher likelihood of low blood pressure, making the body more prone to dizziness or even fainting.
Eating kale is able to bring about a decrease in low-density lipoprotein (LDL) cholesterol (the “bad” cholesterol) that can build up as plaque on the inner wall of blood vessels, resulting in higher risks of heart attack and stroke. As a research article on Food Chemistry suggests, the rationale is that cholesterol is used to make bile salts in the liver, the emulsifying agent of fats (the breakdown of ingested fats into small lipid droplets physically). Supposedly, bile salts can be efficiently recycled as they are reabsorbed into the bloodstream after serving their part in digestion. Nonetheless, kale contains bile salt sequestrants that hinder the reabsorption of bile salts, thus lowering cholesterol levels by hindering the absorption of fats. A 12-week study found that a continuous daily intake of kale juice can significantly lower the “bad” cholesterol levels and thus reduce the risk of coronary artery disease.
Kale also helps to increase high-density lipoprotein (HDL) cholesterol, which is responsible for removing “bad” cholesterol in the bloodstream.
Kale has been found to contain cancer-fighting compounds such as sulforaphane and indole-3-carbinol that disrupt the growth of cancer cells. When cancer cells grow, they release compounds that inhibit the normal growth of healthy cells. The cancer-fighting compounds in kale may be able to counteract and cancel this inhibitive effect and normalize healthy cell metabolism. As more healthy cells are produced, the body gains strength to fight the cancerous cells.
Kale works great in salads or green juices; you can buy it at supermarkets or through local growers which you can find online.
Kale can bring you multiple health benefits: supply micronutrients, detoxify your body, improve your eye health, heart health and lower the risk of cancer.
Kale can be eaten raw or cooked. It is commonly served raw in salad, smoothies, and cooked in soup, pasta or boiled vegetables. However, you may want to limit your cooking time as prolonged cooking may affect kale’s nutritional value.
Raw kale contains a high content of goitrins, a type of goitrogen which can affect thyroid function when consumed excessively (more than 1 kg of kale per day).
Eating too much kale may harm your thyroid function as it can inhibit the uptake of iodine, which is essential in the production of thyroid hormones.
This article was independently written by Healthy Matters. It is informative only and not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be relied upon for specific medical advice.
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