Kale

Question 1

What is kale a cultivar of?

Answer 1

Cabbage

Question 2

Why is kale grown?

Answer 2

For their edible leaves

Question 3

How can kale be differentiated?

Answer 3

According to low, intermediate or high length of the stem and the leaf type which can range from light to dark green to green/purple

Question 4

What four types of kale are there?

Answer 4

o Curly leaf
o Bumpy leaf
o Plain leaf
o Leaf and spear

Question 5

How well can kale survive in the cold?

Answer 5

Some kale varieties can survive the cold and be grown in winter in temperatures as low as -15 degrees Celsius (between September to March/April)

Question 6

When does kale use date back to?

Answer 6

2000 BC originally from the mediterranean

Question 7

Where did kale move in the 9th century?

Answer 7

To Russia, with lots of different varieties e.g. Siberian and red Russian first observed due to ability to withstand cold climate

Question 8

What happened in the 14th century?

Answer 8

First records of kale in the UK which included the curly kale variety

Question 9

Why was kale popular in WW2?

Answer 9

It was part of the “Dig for Victory” campaign as easy to grow, high in nutrients and can grow in the colder months

Question 10

What has the most detrimental effect on water soluble vitamin and glucosinolate loss?

Answer 10

Boiling by leaching

Question 11

What vitamins withstand boiling?

Answer 11

Vitamin A, C, K and manganese

Question 12

What happens when kale is boiled?

Answer 12

It only retained 27% of the total glucosinolates (steaming, stir frying and blanching had much higher retention)

Question 13

What did Murador et al (2016) find?

Answer 13

Steamed kale had the highest phenolic content (more so than raw, boiled and stir fried)

Question 14

What happens with antioxidant effects with different processing?

Answer 14

Increased in steamed kale but decreased in boiled kale compared to raw

Question 15

What are the positive effects of heating?

Answer 15

Open food structure to make compounds more bioavailable, sensory qualities

Question 16

What are the negative effects of heating?

Answer 16

Heat can degrade compounds and leaching of any water soluble compound

Question 17

What are some popular ways of eating kale?

Answer 17

Smoothies, soups, sauces, stir fry

Question 18

What are secondary plant metabolites in kale?

Answer 18

Flavonoids (quercetin and kaempferol)

Question 19

Describe the flavonoids?

Answer 19

They are considerably bioavailable. The phenol rings plus hydroxyl groups make it readily available to donate electrons and they exist as glucosides (sugar attached)

Question 20

When is sulforaphane made?

Answer 20

Sulforaphane is made when myrosinase in the plant or gut bacteria convert glucosinolates

Question 21

How nutrient dense is kale?

Answer 21

It is one of the most nutrient dense foods

Question 22

What are the six nutrients of interest in kale?

Answer 22

Antioxidants, vitamin C, bile sequestrants, vitamin K, anti-cancer compounds, carotenoid antioxidants

Question 23

What antioxidants is kale high in?

Answer 23

Beta-carotene, vitamin C, polyphenols and flavonoids: quercetin and kaempferol

Question 24

What do the free radicals in antioxidants do?

Answer 24

Counteract oxidative damage which is believed to be a leading driver of aging and many diseases including cancer

Question 25

What effect does quercetin and kaempferol have?

Answer 25

Heart protective, blood pressure lowering, anti-inflammatory, anti-viral, antidepressant and anti-cancer effects (but in test tube and animal studies)

Question 26

Describe beta-carotene in kale?

Answer 26

Kale is high in beta-carotene, which is a precursor of vitamin A. It is converted to vitamin A in the liver. Two molecules of vitamin A are formed from one molecule of beta carotene.

Question 27

Describe vitamin C in kale?

Answer 27

• Vitamin C is an important water soluble antioxidant that serves many vital functions in the body’s cells, e.g. its necessary for the synthesis of collagen.
• Kale is much higher in vitamin C than most other vegetables, 4.5 times much as spinach and more than an orange.

Question 28

What do bile sequestrants do?

Answer 28

They can lower cholesterol levels which might reduce risk of heart disease

Question 29

What are bile sequestrants?

Answer 29

They are polymeric compounds which bind bile acids through ion exchange. The liver produces more bile acid to replace those lost, using up cholesterol and reducing LDL.

Question 30

What did Soo Yeon (2008) find?

Answer 30

Drinking kale juice every day for 12 weeks increased HDL (good) cholesterol by 27% and lowered LDL (bad) cholesterol by 10%, while also improving antioxidant status

Question 31

What did Kahlon et al (2008) find?

Answer 31

Steamed kale is 43% as potent as cholestyramine, a cholesterol-lowering drug that functions in a similar way

Question 32

What is vitamin K critical for?

Answer 32

Blood clotting by activating proteins and enabling them to bind calcium, Warfarin works by blocking the function of this vitamin.

Question 33

How much vitamin K does kale have?

Answer 33

Single raw cup contains almost 7 times the recommended daily amount

Question 34

What form is vitamin K in in kale?

Answer 34

The form of the vitamin in kale is K1, different to K2 which is found in fermented soy foods and certain animal products

Question 35

What is kale a top food source of?

Answer 35

At least four glucosinaolates which are converted into cancer preventive compounds in the body, for example sulforaphane, which helps prevent formation of cancer at a molecular level.

Question 36

What else does kale contain? Of anti-cancer compounds

Answer 36

It contains indole-3-carbinol, which is a benzopyrrole and is only formed when isothiocyanates made from glucobrassicin are further broken down into non-sulfur containing compounds and is another substance that is believed to help prevent cancer.

Question 37

What did a study into sulforaphane find?

Answer 37

• Sulforaphane is capable of switching genes on and off for the purpose of stopping tumour cells from replicating and spreading. Sulforaphane may also cause cancer cells to self-destruct (apoptosis).
• Research has shown that sulforaphane blocks DNA methylation and controls certain processes in cell cycle progression that would otherwise contribute to the development of cancer.
• Evidence in humans in mixed.

Question 38

What carotenoid antioxidants are in kale?

Answer 38

Lutein and zeaxanthin

Question 39

What have studies regarding lutein and zeaxanthin find?

Answer 39

That people who eat sufficient levels of these nutrients have a much lower risk of macular degeneration and cataracts

Question 40

What are lutein and zeaxanthin?

Answer 40

Antioxidants that accumulate in the lens and retina of the human eye and protect ocular tissues against singlet oxygen and lipid peroxide damage.

Question 41

What happens to the eye with age?

Answer 41

Antioxidant protection is depleted and this leads to the formation of age related cataracts and macular degeneration.

Question 42

What are the two major mechanisms of protection offered for lutein and zeaxanthin against age related blue light damage?

Answer 42

The quenching of singlet oxygen and other reactive oxygen species and the adsorption of blue

Question 43

How much fibre is in cooked kale?

Answer 43

One cup of cooked kale contains 10% of daily fibre needs which has been found to reduce blood glucose levels during the standard fasting blood glucose test so may be helpful for those managing diabetes.

Question 44

What is the rules for superfood in the UK?

Answer 44

Department of Health has allowed for the use of the claim ‘superfood’ as a general health claim (under section 5 of the Nutrition and Health claims regulation). It is considered a general health claim as the DH knows consumers will expect some general benefit from use of the term ‘superfood’.

Question 45

What article does DH refer to?

Answer 45

Article 10(3) of the EU Regulation 1924/2006 and find superfood is more of a general reference to health as opposed to a specific health claim. - They thus state that it would have to be accompanied by a specific health claim from an authorised list, explaining to consumers why the product is beneficial to health and what makes it a super food, e.g. as below.

Question 46

What claim is there for zeaxanthin?

Answer 46

There is a non-authorised claim for zeaxanthin for maintenance of normal vision.

Question 47

What is the rules in the UK?

Answer 47

Similar in USA with FDA and the term ‘healthy’ needing low quantities of nutrients to limit e.g. total fat as well as certain levels (10% of RDA) of nutrients to encourage e.g. vitamin C

Question 48

What is the kale craze?

Answer 48

The ‘kale craze’ started in the US. Oberon Sinclair, who works at Young Aunties PR begun publicising kale under the pretence of having been hired by the American Kale Association. Due to connections to celebrities and PR expertise, she managed to make kale more popular.

Question 49

How did kale become bigger?

Answer 49

• Bon Appetit named 2012 as the Year of the Kale
• From around 2007 onwards, Kale slowly increased in popularity. Beyonce wore a sweater inscribed with KALE in her 2014 ‘7/11’ music video it grew dramatically.

Question 50

What is the potential as a future functional food?

Answer 50

• More in human studies is needed as mainly been test tube and animal or at a molecular level
• Plenty of evidence that the nutrients in kale are effective and functional but need to know more about the interaction of the food matrix and processing and how is eaten.