Why Is It So Important to Eat Our Greens?

Why Is It So Important to Eat Our Greens?

Whether it was Popeye eating his spinach or the green giant displaying his strength, we have all been encouraged from a young age to eat our greens because ‘they are good for us’. Despite being absolutely true, many of us don’t understand why green vegetables are some of the healthiest foods we could put on our plates and unfortunately a lot of people eat far too few. In this latest Healthylife article, we are going to explore what exactly makes green veg so nourishing so you can see why it’s a good idea to include more of them in your daily diet. 

Vitamins & Minerals

Green vegetables are commonly referred to as ‘nutrient dense’ due to their rich vitamin and mineral profile. Obviously the specific micronutrient content varies between different foods but on the whole greens are great sources of key nutrients such as:

Vitamin C – Peppers, broccoli, Brussels sprouts, kale, cabbage and bok choy all contain over 50% of our daily requirements per portion. Vitamin C is needed for a whole host of reasons including the immune system, metabolism, collagen formation, iron absorption and the reduction of tiredness and fatigue. As we cannot store vitamin C we need to ensure a daily intake for optimal health.

Folate – Also known as vitamin B9, folic acid is the one B vitamin that is found in higher concentrations in plant-based foods than animal-based ones. Specifically, green lentils, asparagus, broccoli, lettuce, bok choy, peas and Brussels sprouts are all high in folate, providing over 30% NRV per serving. We need folate for the immune system, blood formation, psychological function and to reduce tiredness. It is also critically important during pregnancy to reduce the risk of neural tube defects.  Lastly folate is needed for keeping homocysteine levels in check. High homocysteine has been linked to an increased risk of heart disease time and time again.

Iron – Leafy greens are some of the best sources of non-heme iron. Spinach, Swiss chard, collard greens, green lentils and asparagus are all rich in this essential trace mineral. Iron is needed for haemoglobin production, immune health, psychological function, metabolism and cell division. Non-heme isn’t as well absorbed as the iron from meat, but consuming it alongside a source of vitamin C can greatly increase the bioavailability. Moreover, heme iron has been linked to numerous health concerns such as an increased risk of cancer, heart disease and diabetes so people are being encouraged to get more of their iron from plants.

Vitamin K – Vitamin K, otherwise known as phylloquinone, is required for healthy blood clotting as well as maintaining strong bones. The vitamin K content of plants is directly related to the amount of chlorophyll they contain. As chlorophyll is the compound which gives plants their green colour, the deeper the colour, the higher the vitamin K content. So all greens are a good source of vitamin K, but kale, spinach and collard greens contain the highest amount and easily meet our daily requirements per serving.  

Calcium – When calcium is mentioned, most think of dairy products. Although dairy is generally higher in calcium than greens, the calcium found within greens is more bioavailable. You may be able to see a theme here, as spinach, kale, bok choy, collard and mustard greens are all a good source of this macromineral. As well as supporting bone strength and muscle function, calcium is also needed to produce the digestive enzymes that break down the food we eat.

Iodine – One of the reasons that sea vegetables such as kelp and wakame are so popular in South East Asia is because of their rich mineral content. One of these is iodine which we require for thyroid function, cognition, immunity and metabolism. Many of us in the UK don’t get enough iodine and this is one reason why we are encouraged to eat more foods from the sea.


Aside from vitamins and minerals, plants contain over 25,000 chemicals known collectively as phytotnutrients or polyphenols. These are often broken down into further categories such as carotenoids, anthocyanins, proanthocyanidins, flavanols and sterols. Although they are not deemed as essential to life like vitamins and minerals are, they do have a role in keeping us in optimal health. As there are so many different categories and individual compounds, not all of them have been researched. However some of the most prominent are:

Beta carotene – Beta carotene is a valuable nutrient which the body can use to produce vitamin A. Vitamin A is critically important for vision, skin health, the immune system and for its role as an antioxidant. Beta carotene is highest in orange foods such as carrots, sweet potato and butternut squash but it is also plentiful in greens like spinach and kale. Beta carotene is a fat-soluble nutrient so needs fat to be efficiently absorbed – a good excuse to put a knob of butter on your greens!

Lutein – Like beta carotene, lutein is also part of the carotenoid family. It is found in particularly high quantities in the eye where it works as a macular pigment, helping to filter out light to prevent damage from the sun. Lutein, which is also fat-soluble, has a well established role in eye health, helping to maintain healthy vision especially in older adults.  More recently, lutein intake has been positively associated with cognitive function – another good reason to include greens such as kale, spinach, broccoli, peas and lettuce in your meals.

Sulforaphane – Found in cruciferous vegetables such as broccoli, cabbage, kale and cauliflower, sulforaphane is known to have anti-cancerous properties. This has been confirmed in numerous test-tube studies, but has not yet been researched specifically in a human randomised control trial. That being said, scientists are confident it is beneficial, given that research has shown that those with a higher intake of sulforaphane have a lower risk of cancer.  Sulforaphane is sensitive to heat, so it’s recommended that you gently steam the vegetables instead of microwaving, boiling or frying to maximise their sulforaphane content.

Sterols – Certain plants also contain beneficial nutrients known as sterols or stanols. These compounds are a very similar shape and size to cholesterol and because of this they somewhat block the absorption of cholesterol into the blood stream. Broccoli, Brussels sprouts, spinach and apples are the best food sources of plant sterols, but it is widely accepted that extra sterols through a supplement or fortified foods are required to lead to a clinically significant reduction in blood cholesterol. Nevertheless, the aforementioned foods still contribute to our daily sterol intake and are certainly beneficial. 

EGCG – Found in particularly high amounts in green tea, EGCG is a catechin which has powerful antioxidant properties, helping to protect our cells from damaging free radicals.  It has also been shown to reduce inflammation, blood pressure, cholesterol and arterial plaque build-up which all support a healthier heart. Green tea is often touted for its fat-burning properties, given that is stimulates the body to metabolise fatty acids. However, results in weight-loss trials have been inconsistent as some people find a benefit whereas others do not.


Certain vegetables such as spinach, rocket, celery and beetroot are high in nitrates. In the body, nitrates can be converted to nitric oxide which helps to dilate the blood vessels, improving blood flow. Research studies have shown that dietary nitrates (mostly in the form of beetroot juice) can improve blood flow which improves exercise performance. They can also benefit heart health as they have demonstrated a significant reduction in blood pressure in a number of studies. Although the body produces nitric oxide from the amino acid L-arginine, a dietary intake from vegetables certainly helps to improve health.

Nitrates are a topic of controversy however. This is because they are used as preservatives in processed meats like sausages, ham and bacon which have been linked to cancer and other diseases. You may be wondering how they can be healthy when found in vegetables, but not when found in meat as after all, they are the same compounds. Well it seems that there are other components within meat that interact with the nitrates to form harmful compounds known as nitrosamines which are carcinogenic. Thankfully, 80% of the nitrates we get in our diet comes from plants and we should continue to prioritise these foods to maintain good health.


Latest government statistics have shown that, generally speaking, we get nowhere near the recommended 30g of fibre per day. On average, men consume 20g whereas women only get 17g which is barely half of the amount we should for best benefit. There are different types of fibre in food and these can be split into 3 categories: soluble, insoluble and resistant starch. A lot of foods contain a combination of different fibre types and they all have their nuances. Generally speaking though, they all help to support digestive health, healthy blood sugar, normal cholesterol levels, appetite responses and a healthy bodyweight. 

Fibre is only found in plant-based foods, so it’s no surprise that fruit, nuts, legumes and wholegrains can be great fibre sources. With regards to greens, peas, broccoli, sprouts, asparagus, spinach, kale and green beans are all high in fibre and adding portions of such foods in your daily diet will help you hit your 30g for the day.

Low Calorie

The amazing thing about greens are that they contain a wide array of vitamins and minerals, are packed with beneficial phytochemicals, nitrates and fibre while being very low in calories. Not long ago, the UK was given the title of the ‘fat man of Europe’ given that almost a third of adults were obese and many more were classed as overweight.

Obesity is a multi-faceted and complicated topic, but boils down to an imbalance between “energy in” and “energy out”. Looking at the “energy in” part of the equation, one of the reasons we as a nation are consuming too many calories is because we love foods that are very energy-dense, providing lots of calories but not much bulk to help us feel full. Another power of vegetables, and in particular green veg, is that their high water and fibre content provides bulk, helping us feel satiated after a meal.

Because there is more and more research emerging all the time indicating the benefits of a plant-heavy diet, Public Health England updated the Eatwell Guide in 2016 to reflect the latest evidence. There is now an even greater emphasis on fruit and vegetables as they now recommend that a third of our plates are full of nutrient-dense foods like the ones we have mentioned throughout this article.


Hopefully this whistle-stop tour of green vegetables has helped you learn why they are such an important component of our diets. In an attempt to get more of them in your daily meals, we would recommend trying different vegetables as I am sure there will be ones you haven’t tried before. You may be surprised and find a new favourite!

Another way is to try different cooking methods. Vegetables are versatile; they can be roasted, stir-fried, steamed, boiled and grilled as well as eaten raw, of course. We all know they can be bland at times, but trying different herbs, spices and other seasoning can easily overcome this and turn them into something rather tasty as well as nutritious.