The health benefits of kale

Learn about the nutritional profile of this leafy green vegetable, how much counts as one of your 5-a-day, and the healthiest ways to cook it.

Kale leaves in a wicker basket

What is kale?

Kale is a cruciferous vegetable, like cabbage, broccoli and cauliflower, and has large, edible leaves which have a slightly tougher stem running through the middle. The leaves are usually a dark green, although you can find purple varieties as well. The edges of the leaves are either flat or curly. When you buy kale, you'll normally find it sold whole or pre-chopped, and it can be eaten raw or cooked.

Nutritional profile

Kale has around 33 calories per 100g. It's largely water (about 88%), but also contains 3.4g protein, 1.4g carbohydrate (of which 1.3g is sugars), 1.6g fat and about 2g fibre per 100g raw kale. There are about 43mg sodium in kale (per 100g) which is a fraction of the 2.4g that is recommended as the maximum by the NHS for adults a day.

Kale has been touted by the media as a superfood because it is nutrient-dense. It contains B vitamins such as folate, which we need for energy, to form healthy blood cells and to reduce the risk of central neural tube defects in pregnancy. Kale also contains vitamin C and vitamin E which are important antioxidants needed to help support the immune system, but it’s probably most well-known as being a very good source of vitamin K, which we need to help wounds heal properly.

As for minerals, kale contains most of the everyday minerals we need, including potassium, which supports effective heart function; calcium, for strong bones and teeth; magnesium, for good hormone health, and selenium, which supports the immune system.

Sweet potatoes topped with kale and feta

How much kale counts as one of your 5-a-day?

An 80g serving of kale counts as one of your 5-a-day, which is about one double handful of raw kale.

What’s the best way to cook kale?

Some nutrients are reduced when cooking kale, such as vitamin C and the B vitamins, as they are water-soluble. So, steaming is a more stable way to cook this leafy green veg as it limits its contact with water. Stir-frying and roasting are also effective methods for cooking kale so that you retain as much of its goodness as possible.

Should anyone be cautious when eating kale?

As kale is high in vitamin K, those on anti-coagulants (or blood thinners) do need to be cautious when choosing to eat kale and other green leafy vegetables, as it may interact with the medication. It shouldn't mean that you have to avoid kale altogether, but it's best to check with your GP as they may recommend limiting your intake.

Some people with thyroid issues or those on thyroid medication should also be concerned about consuming cruciferous vegetables like kale because of the potential effect they may have on the thyroid’s ability to absorb iodine, which is vital for making certain thyroid hormones. However, a 2002 study found that cruciferous vegetables were not associated with increased thyroid cancer risk, and a 2018 study found that certain brassica vegetables (such as kale) demonstrated no negative effect on the thyroid function in humans. As always though, speak to your GP if you are concerned.

Healthy kale recipes

Kale pesto
Feta & kale loaded sweet potato
Broccoli & kale green soup
Prosciutto, kale & butter bean stew
Chargrilled chicken & kale Caesar salad
Cherry tomato, kale, ricotta & pesto pasta
Roasted new potato, kale & feta salad with avocado
Mushroom brunch

This article was published on 4 June 2019.

Nicola Shubrook is a nutritional therapist and works with both private clients and the corporate sector. She is an accredited member of the British Association for Nutrition and Lifestyle Medicine (BANT) and the Complementary & Natural Healthcare Council (CNHC). Find out more at

All health content on is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other healthcare professional. If you have any concerns about your general health, you should contact your local healthcare provider. See our website terms and conditions for more information.

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