Phytonutrients: Why You Should Eat a Rainbow

by Brian Cormack Carr on April 12, 2015 · 4 comments

in Real Food, Real Food Revival Plan, WELLNESS

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You’ve almost certainly heard that it’s a good idea to “eat your greens” and we’re increasingly being made aware that eating other colours of fresh plant foods is a good idea too – “eat a rainbow” is today’s advice for those wanting as much benefit as possible from their daily fare.

But do you know why it’s a good idea to “eat a rainbow”?

An obvious initial reason is that to do so almost certainly means eating a wide variety of fruit and vegetables which are filling and low in calories and fat, making them a good choice for those trying to manage their weight.

However, this isn’t the whole story. Fruit and vegetables also contain an array of naturally occuring plant-based substances – phytonutrients – which have been found to protect humans from a whole range of health issues including heart disease, cancer, eye defects, urinary tract infections, degenerative disorders, and musculoskeletal problems.

There are hundreds of plant chemicals – including many not yet widely studied by science – and while many contribute nutrition to our diet,  others act as antioxidants which neutralize free radicals, the potentially harmful molecules which can trigger disease and accelerate the aging process.

Yes, it’s important to “eat your greens” – but it’s also important to eat your reds, oranges, yellows, greens, blues, indigos, violets, whites and browns too!

Eat a rainbow, and enjoy the following foods and benefits:

Red Foods

To enjoy red foods in your diet, include tomatoes, red onions, radishes, red peppers, raspberries, cranberries, strawberries, cherries, red grapes, pomegranates, red plums, rhubarb, pink grapefruit, watermelon and many more.

Red foods can help build a healthy heart, lower the risk of several cancers and protect the skin from the sun’s ultra-violet radiation.

Tomatoes – as well as watermelon and pink grapefruit – contain a carotenoid called lycopene, which gives them their reddish colour. This powerful antioxidant has been shown to protect against cancers of the lung, colon, breast, skin, oesophagus and – in particular – the prostate.

Our bodies are better able to absorb lycopene from foods that have been cooked – so don’t neglect to enjoy that tomato sauce, or to throw some red onions into your casserole!

Other red food ideas:

  • Berry smoothies including raspberries and strawberries
  • Cranberry juice with breakfast
  • Red peppers and radishes in salads
  • A tablespoon or two of tomato puree to thicken soups and stews
  • Snack on frozen cherries while watching a favourite movie
  • Start your meal with half a pink grapefruit

Orange and Yellow Foods

To enjoy orange and yellow foods in your diet, include apricots, oranges, butternut squash, pineapples, orange and yellow peppers, sweetcorn, papayas, gala melons, sweet potatoes, yams, carrots and many more.

Orange and yellow foods are good for ensuring a healthy immune system, healthy skin, protecting against several cancers, and protecting the heart.

Yellow and orange foods tend to be full of carotenoids, the most common of which – alpha-carotene and beta-carotene – can be converted into vitamin A in the body. This vitamin helps ensure good vision in dim light, normal cell growth, and has strong antioxidant properties which protect against heart disease and certain cancers, including lung cancer. Be aware, however, that extracted supplements of beta-carotene do not demonstrate the same protective effect, and some studies indicate that they may even increase the risk of lung cancer among smokers. Get your nutrients from whole foods!

Other fantastic phytochemicals in yellow and orange foods include: beta-cryptoxanthin (found in papaya, mangoes, pumpkin and sweetcorn) which helps keep the respiratory tract healthy; hesperidin (found in citrus fruits) which may protect against heart disease; and tangeritin and limonene (also in citrus) which may prevent cancers of the head and neck.

Other red and yellow food ideas:

  • Mix cooked carrots and butternut squash into your potatoes before you mash them
  • Enjoy a baked sweet potato with your salad
  • Mix chopped apricots into your morning porridge
  • Add grated carrots and sliced yellow and orange peppers to sandwiches
  • Include gala melon, pineapple, mango and tangerine segments in your fruit salad
  • Make a soup out of all yellow and orange ingredients: carrots, sweet potatoes, butternut squash, yellow peppers and a squeeze of lemon juice!

Rainbow Produce

Green Foods

These are the ones we know are good for us – we’ve been hearing it for years! They include avocado, asparagus, rocket leaves, kale, spinach, cabbage, brussels sprouts, green beans, peas, green peppers, spring onions, leeks, green grapes, green apples, kiwi fruit, courgettes, pak choi, cucumbers and many herbs including parsley, basil, coriander, dill, rosemary and mint.

Green  foods are mineral rich and heart-protective, and help defend us against several cancers and the risk of macular degeneration.

Greens  include more carotenoids – including lutein and zeaxanthin, which can slow down or prevent the progression of cataracts in the eye. Cruciferous greens such as broccoli, kale, and watercress include indoles which are believed to protect against breast cancer. Research has also shown that a powerful phytochemical in greens called sulphorophane can protect against colon cancer.

So, your mother was right: eat your greens!

Other green food ideas:

  • Salads, salads and more salads!
  • Include mild-tasting greens like kale, pak choi, or spinach in your smoothies
  • Dip sugar-snap peas in your hummus
  • Enjoy a warming bowl of green split pea soup
  • Add leeks and broccoli florets to your stir fries
  • Include spring onion and courgettes in your casseroles

Blue and Purple Foods

We forget how many of these actually exist! They include blueberries, blackberries, beetroot, figs, prunes, raisins, red cabbage, aubergine, blackcurrants and black grapes.

Blue and purple foods are cancer-protective, help lower blood pressure, and may prevent age-related memory loss.

The National Health and Nutrition Examination Survey reports that those who eat blue and purple food on a regular basis have a reduced risk of heart disease and diabetes and they also have smaller waists and lower blood pressure. True blue!

The star phytochemicals in these foods seem to be anthocyanins. These are linked to improved memory in old age, as well as a reduced risk of stomach ulcers and colon cancer. Many blue, purple (and red) foods contain ellagic acid, a cancer-fighting, cholesterol-lowering phytochemical.

Other blue and purple food ideas:

  • Top your yoghurt with stewed plums
  • Include blackberries in your morning smoothie
  • Stir blueberries or raisins into your morning cereal
  • Chose frozen black grapes as a great finger food
  • Include aubergine and beetroot in a ratatouille-style veggie stew
  • Eat beetroot raw in salads, or cooked in soups.

White and Brown Foods

I know, I know – these colours don’t feature in the rainbow – but it’s worth including them here, because plant foods in these categories bring with them many benefits.

White foods include onions, garlic, turnips, parsnips and bananas. These foods are rich in flavonoids including quercetin (found in abundance in shallots and onions) which is a powerful anti-inflammatory compound. Garlic features allicin, an antioxidant believed to help reduce blood pressure. Sulphur-containing vegetables like garlic and onions are also thought to be cancer-protective.

Eat more white foods by:

  • Including garlic and shallots in your savoury dishes
  • Slicing onions into your salad
  • Ensuring you include parsnips and turnips in delicious autumnal stews

Brown foods include wholegrains and legumes which are rich in fibre as well as a range of useful compounds which may reduce the risk of coronary heart disease. These foods also make a useful contribution in terms of protein and complex carbohydrates which provide sustained energy.

Include more brown foods in your diet by:

  • Exploring different wholegrain options: rice, amaranth, quinoa, barley, polenta, kamut, wheatberries, teff, spelt…
  • Exploring different legume options: black-eyed peas, chickpeas, borlotti beans, red kidney beans, red or green or puy lentils, butter beans…
  • Using wholegrain flours in baking
  • Swapping to wholegrain breads and crackers

The Rainbow of Phytonutrients

There’s a highly informative and very comprehensive review of the richest sources of polyphenol antioxidants over here, at the excellent Nutrition Advance site. Well worth checking out!

Finally, here’s a useful guide from the Physicians Committee for Responsible Medicine to keep you briefed on the reasons to eat a rainbow. Click the image, and you can download a handy printable PDF copy!

Image credit: Physicians Committee for Responsible Medicine (click the image to download the high resolution PDF)

Image credit: Physicians Committee for Responsible Medicine (click the image to download the high resolution PDF)


Want to bring more REAL FOODS into your life and onto your plate?
Download my FREE guide ‘Real Food Reset’ for top tips on adopting a real food lifestyle. Includes
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Thanks for visiting! You can find more of my writing in my Amazon bestselling self-help guides How To Find Your Vital Vocation and Real Food Revival Plan both of which are available worldwide in e-book and paperback formats. Find out more here.

{ 4 comments… read them below or add one }

judee@ Gluten Free A-Z Blog July 1, 2015 at 12:40 pm

This is a very informative, well researched, and helpful post. Great reminder about the importance fruits and vegetables in our diet for our health!


Brian Cormack Carr March 11, 2016 at 9:33 pm

Thanks Judee, glad you liked it!


Cynthia April 27, 2016 at 11:36 pm

Great information on how & why to eat the rainbow! Thanks for this great article Brian 🙂


Brian Cormack Carr May 2, 2016 at 11:17 am

Thanks Cynthia, glad you liked it!


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