We all know it's important to eat our greens (and vegetables of any other colour) – but did you know some vegetables are more valuable than others in 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) plus 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 lightly to get maximum benefit. If you (or others in your household) aren't fans, try finely slicing the leaves to add to a stir-fry.

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 steamed, roasted or raw with a punchy dip.

Tiny yet potent, this bulb not only ramps up your food's flavour but 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. Then cook lightly or, better still, eat 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!

The vibrant, purplish hue of red cabbage is due to 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 a daily intake helps 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 veg 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 it 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 veg 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 classic.

Equally at home in slaws, salads, spiced halwa 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." But be sure to team your carrots with a healthy fat to help your body access that beta carotene.

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 and also, like broccoli, 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 veg. 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 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, 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 a pricey purchase, so either grow your own or go for a cheaper alternative. Its high fibre content can also cause stomach upset in some people.

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 vegetable has been used for centuries in folk medicine to ease coughs and colds, and modern studies have found onions 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 veg earns it 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." But remember basic, industrially grown mushrooms will have far less nutrients than wild or sunlight-enriched types.

Ever enjoyed a verdant green watercress soup or salad? Studies have shown this peppery leaf can have beneficial effects on the liver, helping reduce damage to this 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 the strong taste, which restricts portion size.

Consider this aniseedy veg a kind of 'celery-plus' from a nutritional perspective. It's just as crunchy in salads and as sweet when braised, but fennel is prized for its medicinal qualities, even if the 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, with one portion providing around a third of your day’s requirement, an essential nutrient not only to consume during pregnancy, but also for helping to prevent depression. They may also be well-tolerated by people with irritable bowel syndrome (IBS) because they are a low in FODMAPs – fermentable carbohydrates notorious for causing problems such as bloating and stomach discomfort in those sensitive to them.

These delicate, gourmet vegetables are known for their high antioxidant content. One of these is chlorogenic acid, which has been studied for its role in preventing cancer. They're also a great source of dietary fibre and help support liver health – ideal if you feel in need of a detox. The downside is the fiddly preparation 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 veg is so deeply versatile; fabulous roasted, seared, puréed and charred. The spongy texture means aubergine really soaks up punchy flavours, but remember it picks up all the 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. "The 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. 

A very low-calorie choice due to its high water content, this delicious squash stores most of its antioxidants in its skin. Courgettes also host 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. 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 chewy long fibres do help keep your digestion healthy. Celery also has small amounts of vitamins A and C, and 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 veg isn't a big hitter, nutritionally speaking. "Cucumber is refreshing and hydrating, but it doesn’t offer much beyond water," says GQ. "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 in brine to make a pickle with probiotic punch.

Bred in late 19th-century America, this pale and crispy salad brings fabulous texture, but 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 not a nutritional star." Upgrade to a darker romaine or cos to get a little more nutritional value.

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