We all know it's important to eat our greens (and vegetables of any other colour), but did you know that some vegetables are more valuable than others when it comes to protecting our health and powering our bodies? With the help of an expert nutritionist, we've unpacked the contribution each vegetable makes to a healthy balanced diet and unearthed the factors that restrict their impact. Read on to discover which are most dense with essential nutrients – and which are pretty pointless.

Click or scroll through our gallery to discover the best and worst vegetables according to experts – counting down to the one with the least nutritional value.

We've based our ranking on the health-boosting credentials of each vegetable, with input from a registered nutritionist.

For sheer versatility, ease and availability, this leafy green is hard to beat. "Kale is a favourite for good reason," says registered nutritionist GQ Jordan. "It’s packed with vitamins A, C and K, and is a great source of antioxidants like quercetin – ideal for supporting your immune system and overall health." Keep a bag of the chopped leaves in your fridge to drop into anything from soups and stews to curries and noodle bowls.

Next time you see these humble cruciferous greens, pile your plate high. Sprouts pack in vitamin K (essential for blood clotting and bone health) and vitamin C, which promotes iron absorption and immune function. They also boast numerous anti-cancer properties, and their fibre content is huge – almost twice that of carrots. Steam them lightly to maximise their benefits. If you (or others in your household) don't like them, try slicing the leaves finely to add to a stir-fry.

Bok choy (also called pak choi) and other types of Chinese cabbage, such as napa cabbage and tatsoi, would make excellent additions to a balanced diet. Bok choy is high in calcium, iron and vitamins A, C and K, and it couldn’t be easier to cook with. Throw it into a stir-fry with your favourite sauce or seasonings and you'll reap the benefits from these vitamins and minerals, which support immune health, red blood cell production, blood clotting and strong bones. If you can find it, try baby bok choy, which offers a higher concentration of nutrients thanks to its smaller, darker leaves.

Broccoli is charged with vitamins C and K, but the goodness doesn't stop there. "Broccoli is fantastic for supporting detoxification, thanks to anti-inflammatory sulforaphane," says Jordan. "It’s also high in fibre, helping with digestion and gut health." If the florets we all know (and some moan about) don't float your boat, opt for a long-stemmed variety and enjoy it steamed, roasted or raw with a punchy dip.

Tiny yet potent, this bulb not only ramps up your food's flavour, but it also boosts the nutritional benefits of any meal. Most of its health benefits come from the sulphur compounds that form when you cut or chew a clove. To enhance its effects (which include easing inflammation, helping prevent bacterial infections and supporting heart health), let prepared garlic stand for 10-15 minutes before cooking. After that, cook it lightly – or better still, eat it raw.

Fighting off a virus? "Red peppers are an excellent source of vitamin C, even more than oranges," says Jordan. "They support the immune system and are packed with carotenoids, which are great for skin and eye health." In fact, a portion of red pepper can pack three times more vitamin C than an orange, though this nutrient is easily damaged through heating or exposure to air – so enjoy yours raw and freshly chopped to get the full benefits.

Delicious baked, mashed or cut into wedges, sweet potatoes are an excellent source of beta carotene, the plant form of vitamin A that's important for eye health, our immune system, reproduction, and growth and development. But be sure to incorporate the skins into your dish, as this is where the majority of the vitamin C and potassium sit – not to mention the fibre. Getting enough fibre lowers your risk of heart disease, stroke, type 2 diabetes and bowel cancer, so no throwing that peel in the bin!

If it’s leafy and dark green, you can almost guarantee it deserves a spot on your plate. Swiss chard is especially high in vitamin K – and it has vitamin A, vitamin C and magnesium in significant amounts, too. As if that weren't enough, it also contains manganese, copper, iron, vitamin D and potassium, and it’s loaded with fibre. All these nutrients mean it can help support the health of your bones, heart and digestive system. It’s versatile too, going well in soups, stews and salads. Alternatively, sauté or steam it to create an easy side dish.

The vibrant purplish hue of red cabbage comes courtesy of its anthocyanins, a family of colourful nutrients that offer protective antioxidant effects for the body. They help to neutralise the damage done to cells as we age, and studies have found that a daily intake helps to protect the brain and the heart against degenerative diseases. It's delicious braised, but to protect those precious nutrients, eat yours raw in a salad – or, even better, lightly fermented in a zingy slaw.

Here comes another colourful hero vegetable boasting beta carotene, which your body converts into vitamin A. This (and an impressive vitamin C content) supports immunity, boosting white blood cell production – and therefore making pumpkin a great vegetable to cook to ward off winter bugs. If you’re carving up a whole fresh one, be sure to save the seeds to roast and eat. Packed with healthy fats and antioxidants, they help to support heart health.

The world has fallen head over heels for the healthy fats in avocado – the monounsaturated oils have been found to protect against heart disease and lower blood pressure. They’re packed with vitamin E, too, which studies have shown is effective at reducing the risk of cancer, arthritis and cataracts. Their sustainability for people in non-growing regions is questionable, though; two small imported avocados have almost twice the carbon footprint of a kilo of bananas.

'Eat the rainbow' remains a strong call from dietitians, and this high-pigment root vegetable is a great way to get your reds. "Beetroot is rich in betalains, which have anti-inflammatory benefits, and nitrates that help improve circulation and lower blood pressure – making it a great choice for your heart," says Jordan. Its sweet and earthy flavour can put people off, so team beets with tangy tastes that cut through the earthiness; salty and sour feta is a classic pairing.

Before you throw away the greens from your beetroot, keep in mind that the whole plant is edible – and deliciously nutritious. The leaves are high in vitamin A, an important nutrient for eye health, and vitamin C, which helps to support the immune system. Like the root of the vegetable, the greens are also packed with nitrates, which can help to lower blood pressure and keep your heart healthy. You can make use of the greens from other vegetables too, from cauliflower leaves to carrot tops.

Equally at home in slaws, salads and sushi rolls, or as a side with roasted meats, this versatile vegetable is a no-brainer when it comes to planning your meals. "Carrots are known for their beta carotene content, which our bodies convert into vitamin A – important for eye health and immunity," says Jordan. "They’re also a good source of fibre for blood sugar balance." However, be sure to team your carrots with a healthy fat to help your body access that beta carotene.

Heart friendly and a good source of antioxidants, piquant radishes may also support liver function and digestion. The antioxidant properties of radishes help to prevent damage caused by oxidative stress, a process linked to heart disease. Radishes are high in vitamin C, too – perfect for healthy blood vessels, as well as healthy skin and bones. The vitamin C they contain may also help with bile flow, promoting digestive function and a healthy liver. Get the full benefits of eating radishes by slicing them thinly; they'd add a deliciously crunchy, peppery bite to a salad or slaw.

It's easily overcooked, and its pale florets can look rather lacklustre, but taking time to roast, steam or purée your cauliflower is well worth doing. "Cauliflower might be underrated, but it’s high in fibre and vitamin C. Also, like broccoli, it contains anti-inflammatory sulforaphane," explains Jordan. "It’s incredibly versatile and often used as a low-carb substitute." Blitzing the florets to make 'rice' gives a lower-energy, less filling side dish that delivers on vitamins.

You may not think you get your dietary education from cartoons, but Popeye left most of us believing spinach is a wonder vegetable. In fact, our body can only absorb a small fraction of the iron in its leaves. That doesn't mean you should write it off, however. "Spinach may not get as much attention as kale, but it’s a solid all-rounder," says Jordan. "It’s a source of iron for energy and vitamin K for strong bones, and it also provides folate and magnesium."

You may think of them as a luxury, but these green spears pull their weight when it comes to nutrients. "Asparagus is an excellent source of folate, which is especially important for women of childbearing age," says Jordan. "It’s high in fibre and antioxidants and acts as a natural diuretic, supporting digestion." The main problem is that asparagus is generally an expensive purchase, so either grow your own or go for a cheaper alternative. Its high fibre content can also cause stomach upset in some people.

Looking for plant-based protein? Whether you’re cutting down on meat or cutting it out altogether, peas are a good option to make sure you don’t miss out on one of the most essential nutrients for healing, healthy muscles, digestive health and more. Green peas are high in fibre and contain the starch amylose, which slows digestion and might help with managing blood sugar levels. However, peas contain plant compounds that could slow the absorption of some nutrients, such as iron and calcium. Despite this, they're still nutritious, and it’s always convenient to have a bag of frozen peas on hand; they’re quick to cook, and freezing them locks in their nutrients.

Onions are one of the richest sources of inflammation-lowering compounds called flavonoids, which may help prevent chronic conditions such as cancer and diabetes when eaten regularly. The versatile vegetables have been used for centuries in folk medicine to ease coughs and colds, and modern studies have found that they really do pack a mean antibacterial punch. Their star flavonoid is quercetin, a nutrient that becomes more potent in older, stored onions. Red onions are the ones to go for, though, as they contain twice as much quercetin as their white counterparts.

Sometimes a vegetable earns its stripes by bringing a single precious nutrient to the table, and that's the case with mushrooms, an important plant source of a vitamin otherwise found in animal products. "Mushrooms are a unique source of vitamin D if they’ve been exposed to sunlight," says Jordan. "They’re also full of antioxidants and support immune health, making them a great addition to your diet." However, it's worth remembering that basic, industrially grown mushrooms will have far fewer nutrients than wild or sunlight-enriched types.

Ever enjoyed a verdant watercress soup or salad? Studies have shown that this peppery leaf can have beneficial effects on the liver, helping reduce damage to the hard-working organ. It’s a good source of vitamin A, is high in vitamin E and, gram for gram, contains more calcium than milk. The downsides are its high cost – the aquatic plant is expensive to grow and fades very fast once picked – and its strong taste, which restricts portion size.

Consider this aniseedy vegetable a kind of 'celery-plus' from a nutritional perspective. It's crunchy in salads and sweet when braised – and fennel is also prized for its medicinal qualities, even if its high water content limits its nutritional value somewhat. Fennel has been found to help decrease inflammation in the bowels and reduce the bacteria that cause gas and bloating. If the distinctive taste isn't to your liking, consider teaming it with a strong citrussy flavour, like lemon, for balance.

They might not be the most nutrient-packed choice, but green beans are still a great source of folate; one portion provides around a third of your day’s requirement. Folate is not only an essential nutrient to consume during pregnancy, but it also helps to prevent depression. Green beans may also be well tolerated by people with irritable bowel syndrome (IBS) because they're low in FODMAPs – fermentable carbohydrates notorious for causing problems such as bloating and stomach discomfort in those sensitive to them.

Swede is great for soups and stews, and it can be mashed to make a delicious side dish – plus, it offers some essential nutrients too. Vitamin B6 helps to support the function of both the immune system and the nervous system, and it also works together with folate (vitamin B9) to combat tiredness and fatigue. Versatile swede can be boiled, steamed or roasted; just be careful not to overcook it, or it'll turn into flavourless mush.

These delicate gourmet vegetables are known for their high antioxidant content. One of these antioxidants is chlorogenic acid, which has been studied for its role in preventing cancer. Globe artichokes are also a great source of dietary fibre, and they help support liver health – which is good news if you feel in need of a detox. The downside is that they're fiddly to prepare, which makes the edible hearts an expensive option to buy. They're also generally stored and served in oil or a buttery dressing; delicious, but not helpful if you're trying to lower your fat intake.

This Mediterranean vegetable is incredibly versatile; it's equally tasty roasted, seared, puréed or charred. Aubergine's spongy texture means it really soaks up punchy flavours, but it's worth remembering that it picks up fat and sodium, too. It does bring some benefits to your body, though. "Aubergine’s deep purple skin is full of anthocyanins, powerful antioxidants that protect cells," says nutritionist Jordan. "Its flesh is low in nutrients, but its fibre content is great for digestion." What it doesn't have is protein – so if you're making it the focus of plant-based meals, be sure to add nuts, pulses or peas. 

Is it a fruit or is it a vegetable? There may be some debate as to which category tomatoes fall into, but what’s more important is the nutrition they provide. Tomatoes are around 95% water, which limits their nutritional value somewhat, but makes them more hydrating than watermelon, for example. What’s left is mostly fibre and carbohydrates, which contribute to healthy digestion and provide energy. On top of delivering vitamin C, folate, potassium and vitamin K, tomatoes are an especially good source of the antioxidant lycopene, which could help to prevent heart disease.

A very low-calorie choice due to their high water content, these delicious squashes store most of their antioxidants in their skin. Courgettes also contain a nutrient called lutein, part of a family of compounds that boost your skin and heart health, and may help protect against some forms of cancer, including prostate cancer. Courgettes are easy to grow and cheap to buy in the summer months, making them a great addition to your diet, even if they aren't a heavy hitter in the nutrition stakes.

They might be an essential element of a Waldorf salad, but these chunky stems wouldn't earn their keep in a survival situation. Each celery stalk is 95% water, though those long, chewy fibres do help to keep your digestion healthy. Celery also has small amounts of vitamins A and C, and it contains plant nutrients that provide anti-inflammatory and antioxidant benefits to the body. Just don't make it the hero on an unhealthy plateful; all the sticks in the world won't offset a bad diet.

It gives life to your tzatziki and is amazing smashed with soy and rice vinegar, but this salad vegetable isn't a big hitter, nutritionally speaking. "Cucumber is refreshing and hydrating, but it doesn’t offer much beyond water," says Jordan. "It’s a low-calorie option, but not a standout in terms of nutrients." To make the most of its potential, always eat your cucumbers with the green skin attached – and consider fermenting it in brine to make a pickle with probiotic punch.

Bred in late 19th-century America, this pale and crispy salad vegetable brings fabulous texture to dishes, but it lacks the essential nutrients packed into greener leaves. "Iceberg lettuce provides a nice crunch but is low in nutrients, mostly consisting of water with a bit of fibre," says Jordan. "It's good for adding texture to salads, but it's not a nutritional star." Upgrade to a darker romaine or cos lettuce to get a little more nutritional value.

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Last updated by Laura Ellis.