Kale: Uses, Benefits, Side effects By Dr. Smita Barode

Introduction:

Kale, also called “the queen of vegetables”, has received celebrity status by appearing on the menus of Michelin-star restaurants. In addition, it has become the favourite ingredient of many millennial food bloggers. Brassica oleracea or kale is a cruciferous winter vegetable available in different varieties like curly kale, dinosaur kale (lacinato kale), and Russian kale, also called Siberian kale. Curly kale is the most common of all; the leaves of kale look like ruffles, are purple or deep red and have a pungent taste. Originating in the 16th century in North America and later spreading to Canada and the U.S. In India, the cultivation of kale is limited to Jammu and Kashmir, Himachal Pradesh and the Nilgiri hills. Kale is one of the healthiest foods, the perks of which have been mentioned in several books by Greek physicians and botanists. There are several reasons to add this vegetable to your diet. Let us find out more about the benefits of kale.¹ 

Nutritional Value of kale:

Kale is a nutritional powerhouse; it is packed with the goodness of fibres, minerals and antioxidants like zeaxanthin and lutein, folate, tocopherols and other phytoconstituents like nitrates, sulforaphane, insole-3-carbinol, etc. The nutritional components of kale are mentioned in the table below.  

• Carbohydrates: 4.4 g per 100 g
• Fibre: 4.1 g per 100 g
• Protein: 2.9 g per 100 g
• Iron: 1.6 mg per 100 g
• Total fat: 1.49 g per 100 g
• Calcium: 254 mg per 100 g
• Vitamin C: 93.4 mg per 100 g
• Folate: 241 micrograms per 100 g

Properties of Kale:

The consumption of kale shows numerous scientifically proven properties; some of these properties are mentioned below: 

• It may have antioxidant properties. 
• It may have neuroprotective properties. 
• It may have antiproliferative properties. 
• It may have anti-bacterial properties. 
• It may have anti-diabetic properties.² 

Potential Uses of Kale for Overall Health:

Some of the potential benefits of kale are described as follows: 

1. Potential uses of kale for cognitive function 

Literature suggests that consuming green leafy vegetables may have a protective effect towards cognitive decline. Morris et al. conducted a study in 2018 to assess the effect of the consumption of green leafy vegetables like kale on cognition. This study showed that kale consumption might help slow down age-related cognitive decline due to bioactive phytochemicals like lutein, folate, nitrate, tocopherols, etc. This indicates that the consumption of kale may have a positive impact on cognition. However, we need more studies to support these claims.³ 

2. Potential uses of kale on cancer  

Royston et al. conducted a literature review in 2015 to assess the impact of cruciferous vegetables on cancer prevention. The findings of this review conclude that cruciferous vegetables like kale contain chemical components like insole-3-carbinol (I3C), sulforaphane (SFN) which are regulators of microRNAs (miRNAs) and inhibitors of DNA methyltransferases (DNMTs) and histone deacetylases (HDACs) and may be helpful in chemoprevention. This indicates that the consumption of kale may positively impact chemoprevention. However, we need more studies to support these claims.⁴ 

3. Potential uses of kale for blood glucose 

Scientific studies have supported vegetarian diets, especially green leafy vegetables, for glycemic control. Sumio et al. conducted a study in 2016 to assess the effect of kale intake on plasma glucose. This study’s findings showed that kale intake might help suppress blood glucose levels. This indicates that kale consumption may help manage blood glucose levels. However, we need more studies to support these claims.⁵ 

4. Potential uses of kale for gut health 

Literature states that cruciferous vegetables like kale have a positive impact on the composition and health of gut microbiota (microorganisms in the gut). Shahinozzaman et al. conducted a study in 2021 to assess the impact of kale supplementation on gut health in mice. This study’s findings suggest that kale consumption may help improve gut microbial composition, bacterial microbial functions and, thus, gut health. This indicates that the consumption of kale may have a positive impact on gut health. However, there are no studies conducted on humans to support these claims.⁶ 

5. Potential uses of kale on hypercholesterolemia 

Hypercholesterolemia is defined as an increase in total cholesterol, an increase in LDL (low-density lipoprotein) and a reduction in HDL (high-density lipoprotein). Consumption of kale exerts a hypo-cholesterolaemic effect by HMG-CoA inhibition, the enzyme responsible for cholesterol synthesis. To evaluate the effect of kale supplementation in diet on lipid profile, Yeon et al. conducted a study in 2008 on hypercholesterolemia. The findings of this study showed that kale supplementation helped increase high-density lipoprotein or good cholesterol and decreased low-density lipoprotein or bad cholesterol. This indicates that the consumption of kale may have a favourable impact on lipid profile by inhibiting HMG-CoA. However, we need more studies to ascertain these claims.⁷ 

Other potential uses of kale:^8,9 

• Kale is low in carbohydrates and is also rich in fibres, both of which may promote weight loss. 
• It may promote bowel movements due to the presence of fibre. 
• Being a good source of calcium and Vitamin K, kale may help in boosting bone health. 
• Consumption of kale may help in detoxifying the body. 
• It may help in managing malnutrition problems. 
• Being a good source of iron and Vitamin C, it may help in boosting immunity. 
• Antioxidants like lutein present in kale may lead to healthier skin. 
• The presence of Vitamin K and iron may improve blood clotting. 
• Being a good source of omega-3 fatty acids and beta-carotene, it may improve hair growth. 
• Consumption of kale may help in managing macular degeneration because of the presence of lutein and zeaxanthin. 

Though there are studies that show the benefits of kale in various conditions, these are insufficient, and there is a need for further studies to establish the true extent of the benefits of kale on human health.  

I personally believe that kale is only nutritious but may also support your efforts to maintain a healthy weight. This leafy green vegetable is low in calories and high in fibre and protein. A mere two cups (500 mL) of raw kale have fewer than 50 calories and 4.5g of protein and fibre. This means you might enjoy a satisfying portion of kale without consuming excessive calories, making it a great choice for those looking to manage their weight while nourishing their bodies.

Dr. Siddharth Gupta, B.A.M.S, M.D (Ayu)

How to Use Kale?

• You can incorporate kale into your dietary routine as a raw ingredient in salads. 
• Kale can also be consumed boiled, sautéed and steamed.¹  

You must consult a qualified doctor before taking any herbal supplements. Do not discontinue or replace an ongoing treatment of modern medicine with an ayurvedic/herbal preparation without consulting a qualified doctor.   

In light of what I’ve observed, incorporating kale into your diet might be a tasty way to potentially safeguard against certain health issues. Kale might be effective in binding bile acids in the body. This unique property of kale may contribute to reducing the risk of premature degenerative diseases. By helping to bind bile acids, kale may have a positive impact on your health, potentially lowering the risk of certain conditions.

Dr. Rajeev Singh, BAMS

Side Effects of Kale:

A study conducted by Alfawaz et al. in 2021 emphasized the following facts:  

• Consumption of kale in excess can lead to constipation and stomach irritation. 
• Due to the presence of oxalates, kale can increase the risk of kidney stones. 
• Kale contains goitrogens, substances that inhibit the synthesis of thyroid hormone. So, its intake can increase the risk of iodine deficiency. 
• Being rich in iron, consumption of kale in excess can lead to iron toxicity. 
• Due to its potent antioxidant profile, it can trigger an allergic reaction in allergy-prone individuals. 

However, if you experience any adverse reactions to kale, it is advised to discontinue its intake and immediately contact a doctor or your Ayurvedic physician who has prescribed it. They will be able to guide you appropriately for your symptoms. 

Judging from what I’ve witnessed, kale is a surprising vegetable that is packed with vitamin C. In fact, it might have a higher concentration of vitamin C compared to other salad vegetables and even vegetables from the Brassicaceae family. It might be considered one of the best sources of vitamin C and may meet the recommended daily allowance (RDA) for both males and females.

Dr. Smita Barode, B.A.M.S, M.S.

Precautions to Take With Kale: 

Eating kale is okay if taken in moderate amounts. However, general precautions must be followed in the following conditions:⁸ 

• People with impaired kidney function should be cautious when consuming kale, as it can have a deteriorating effect on the kidneys. 
• Like all other vegetables, it is always advised to wash kale before consuming it. 

Interactions with Other Drugs:

There is no significant interaction of kale with other drugs. However, you must always seek the advice of your Ayurvedic physician about the possible interaction of kale with other drugs and follow the prescription thoroughly, as they will know your health condition and other medications you are taking. 

Frequently Asked Questions (FAQs)

References:

1. Ortega-Hernández, Erika et al. “Improving the Health-Benefits of Kales (Brassica oleracea L. var. acephala DC) through the Application of Controlled Abiotic Stresses: A Review.” Plants (Basel, Switzerland) vol. 10,12 2629. 29 Nov. 2021, doi:10.3390/plants10122629. Available at: https://pubmed.ncbi.nlm.nih.gov/34961097/ 

2. Morris, Martha Clare et al. “Nutrients and bioactives in green leafy vegetables and cognitive decline: Prospective study.” Neurology vol. 90,3 (2018): e214-e222. doi:10.1212/WNL.0000000000004815. Available at: https://pubmed.ncbi.nlm.nih.gov/29263222/ 

3. Royston, Kendra J, and Trygve O Tollefsbol. “The Epigenetic Impact of Cruciferous Vegetables on Cancer Prevention.” Current pharmacology reports vol. 1,1 (2015): 46-51. doi:10.1007/s40495-014-0003-9. Available at: https://pubmed.ncbi.nlm.nih.gov/25774338/ 

4. Kondo, Sumio et al. “Intake of kale suppresses postprandial increases in plasma glucose: A randomized, double-blind, placebo-controlled, crossover study.” Biomedical reports vol. 5,5 (2016): 553-558. doi:10.3892/br.2016.767. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5103670/pdf/br-05-05-0553.pdf 

5. Shahinozzaman, Md et al. “Kale Attenuates Inflammation and Modulates Gut Microbial Composition and Function in C57BL/6J Mice with Diet-Induced Obesity.” Microorganisms vol. 9,2 238. 24 Jan. 2021, doi:10.3390/microorganisms9020238. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7911404/ 

6. Soo Yeon KIM et al.Kale Juice Improves Coronary Artery Disease Risk Factors in Hypercholesterolemic Men1 1 This research was supported by the Brain Korea 21 Project from the Korea Research Foundation. Biomedical and Environmental Sciences, Volume 21, Issue 2,2008, Pages 91-97. Available at: https://www.sciencedirect.com/science/article/pii/S0895398808600124 

7. Alfawaz, Hanan A et al. “Awareness, Knowledge and Attitude towards ‘Superfood’ Kale and Its Health Benefits among Arab Adults.” Nutrients vol. 14,2 245. 7 Jan. 2022, doi:10.3390/nu14020245. Available at:  https://www.mdpi.com/2072-6643/14/2/245 

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