Eat the Rainbow!

Published by Nick Williams on

Work with a nutritional therapist and you’ll know how passionate they are about fruit and vegetables. And rightly so! According to Luo et al. (2015) eating red / purple, yellow / orange as well as white fruit and vegetables is associated with lower risk of colorectal cancer (1). Eat the rainbow! Enough said?!

Eat the rainbow, take the challenge!!

Nature provides us with an abundance of wonderful fruit and vegetables. In all colours, shapes and sizes. Why? For us to enjoy and to improve our health!

Plants are living things (doh!), needing nutrients and chemicals to help them grow and for protection. These compounds are known as phytonutrients or phytochemicals. By eating plants, we can use these compounds for our benefit too, with a caveat, some are also bad for our health!

This article looks at the benefits we derive from eating fruit and vegetables. I check out the amazing properties we gain when eating a healthy selection of the good stuff.

Eat the rainbow!
Recommended – Eat a rainbow of different coloured fruits and vegetables

Phenols and Polyphenols (Phenolic Compounds) are the largest family of phytonutrients. They include Flavonoids, Lignans, Phenolic acids and Tyrosol esters. We then have Terpenes (including Carotenes), Lipids and Sulphur Compounds. I will sample the different categories so you get a good flavour! (sorry, couldn’t help myself!). Eat the rainbow!


No article on healthy eating would be complete without mentioning Quercetin. This amazing compound is the most abundant flavonoid. We find it in apples, green tea, red onions, bilberry, cranberry, capers, brassica vegetables and tomatoes. It is best absorbed with fats. Therefore, if you are having an apple, chop it up and eat it with a tablespoon of nut butter for example.

There are 57 studies that I have found on Quercetin between 2016 and 2018. It is massively researched. A summary of the benefits (9):

  • Has protective effects on the gut lining
  • Involved with positive cell signalling of apoptosis (cell death) and cell cycle
  • Protects against gout
  • Helps the liver as it has antioxidant properties


In our Red, Blue and Purple coloured fruit and vegetables we find Anthocyanins (Flavonoid category). This compound helps protect the plant against UV radiation. Very high levels are found in Acai, Blackcurrant, Bilberry, Cherry. Benefits include:

  • Cherries have been found to reduce diastolic blood pressure (4)
  • A diet high in Anthocyanins has been proven to be beneficial for the heart (5)
  • Cherry Juice has been shown to have positive effects for those with mild to moderate dementia (6)


Proanthocyanidins can be found in red grapes, almonds, peanuts and apples to name a few. This compound has been found to be beneficial (7) because it displays:

  • Antioxidant capabilities
  • Evidence of anti-cancer properties (7)
  • Anti Allergy properties


We find a compound called Indole-3-Carbinol within cruciferous vegetables such as cauliflower, broccoli and cabbage. An 18 year study in Europe found an inverse relationship between weekly cruciferous vegetable intake and some cancers such as colorectal, breast and kidney (8).

Eat the rainbow!
ehsan hasani at Pexels


Isoflavonoids are found in soybean products, chickpeas, legumes, alfalfa sprouts, brussel sprouts etc. This compound is considered to be chemoprotective (10). It is also beneficial for cardiovascular health, osteoporosis and menopausal symptoms. But beware, because of the oestrogenic effects this maybe cause hormonal disruption if not metabolised efficiently (10). It is recommended to source non Genetically Modified (GM) Soy to help avoid complications.

Lignans include flaxseeds (one of my favourites!) as well as sesame seeds, kale and broccoli. It is a great source of dietary fibre and has similar effects to the Isoflavonoids.

Red Wine Resveratrol

Now, you will probably have heard that Red wine is good for you?! Maybe an occasional small glass is. After that, the negative effects on the liver outweigh the benefits of resveratrol. Benefits of resveratrol (11) (which is also found in peanuts, red grapes, eucalyptus, blueberries etc):

  • Antioxidant – keeping cells healthy from oxidative damage
  • Anti-tumor activity
  • Improves skin health
  • Heart health
  • Beneficial for diabetes


Next up are the carotenoids. The brightly coloured, red, orange, yellow colours of many plants. Carrots, sweet potato, pumpkins etc. Evidence has been found that this category can benefit (12):

  • Eye Health
  • Cognitive Function
  • Cardiovascular health
  • Cancer protection

Finally its lycopene – a saturated carotenoid. This is most famously found in red tomatoes but can be found in water melon, papaya, red grapefruits etc (13). It is beneficial (13) for:

  • Heart Health
  • Anti Oxidant
  • Anti inflammatory
  • Lowering blood pressure

In Summary. Take the challenge!

It is easy to find plenty of research on the benefits of fruits and vegetables. They add plenty of fibre to our diet and help us with our gut movements. We should be keeping things moving along nicely (if you know what I mean!) to remove unwanted toxins.

Fancy a little bit on the side? No, that’s not enough! Make sure you fill half your plate with brightly coloured vegetables (2). Go on, treat yourself! 😊

Will you take on my challenge? It’s a 7 day challenge to eat as many different coloured fruits and vegetables as possible! Eat a minimum of 20 different types of fruit and vegetables. As part of the challenge you have to eat all the colours of the rainbow too.

Download your rainbow challenge sheet here! The kids will love the challenge. Promise! 😂🌈 Make sure you tag me into Instagram @acenutrition_ with your challenge photos!

My kids tried to think of all the fruits and veg that they could. Their list below should get you off to a good start – have fun! Eat the rainbow!


Tomatoes, Strawberries, Raspberries, Red Apples, Pomegranates, Cranberries, Radish, Peppers, Rhubarb, Watermelon etc etc…


Aubergines, Red Onions, Beetroot, Purple Cabbage, Purple Potatoes, Plums, Grapes, Figs etc etc…


Blueberries, Blue Carrots, Concord Grapes, Blackberries etc etc…


Oranges, Peppers, Butternut Squash, Apricot, Carrots, Peach, Papaya, Pumpkin etc etc…


Banana, Sweetcorn, Lemon, Pineapple, Mango, Melon, Tomatoes, Peppers, Yellow Kiwi etc etc…


Avocado, Rocket, Kiwi, Pepper, Broccoli, Cucumber, Spinach, Lettuce, Kale, Pears, Apples etc etc…

Success! You're on the list.


  1. Luo, W.-P., Fang, Y.-J., Lu, M.-S., Zhong, X., Chen, Y.-M., & Zhang, C.-X. (2015). High consumption of vegetable and fruit colour groups is inversely associated with the risk of colorectal cancer: a case–control study. British Journal of Nutrition, 113(07), 1129–1138
  2. Slavin, J. L., & Lloyd, B. (2012). Health Benefits of Fruits and Vegetables. Advances in Nutrition, 3(4), 506–516.
  3. Khoo, H. E., Azlan, A., Tang, S. T., & Lim, S. M. (2017). Anthocyanidins and anthocyanins: colored pigments as food, pharmaceutical ingredients, and the potential health benefits. Food & Nutrition Research, 61(1), 1361779
  4. B. Han, A. Srikanth Bhagavathula, M. Rashid, M. Chhabra, C. Clark, H.M. Abdulazeem, M. Abd-ElGawad, H. Kord Varkaneh, J. Rahmani, Y. Zhang, The effect of sour cherry consumption on blood pressure, IL-6, CRP, and TNF-α levels: a systematic review and meta-analysis of randomized controlled trials sour cherry consumption and blood pressure, Journal of King Saud University – Science (2020)
  5. Li, D., Wang, P., Luo, Y., Zhao, M., & Chen, F. (2015). Health benefits of anthocyanins and molecular mechanisms: Update from recent decade. Critical Reviews in Food Science and Nutrition, 57(8), 1729–1741
  6. Kent, K., Charlton, K. E., Netzel, M., & Fanning, K. (2016). Food-based anthocyanin intake and cognitive outcomes in human intervention trials: a systematic review. Journal of Human Nutrition and Dietetics, 30(3), 260–274.
  7. De la Iglesia, R., Milagro, F. I., Campión, J., Boqué, N., & Martínez, J. A. (2010). Healthy properties of proanthocyanidins. BioFactors, 36(3), 159–168
  8. Katz, E., Nisani, S., & Chamovitz, D. A. (2018). Indole-3-carbinol: a plant hormone combatting cancer. F1000Research, 7, 689
  9. Kim & Park (2018). Quercetin and its role in biological functions: an updated review. EXCLI Journal. 17. pp. 856-863.
  10. Křížová, L., Dadáková, K., Kašparovská, J., & Kašparovský, T. (2019). Isoflavones. Molecules, 24(6), 1076.
  11. Salehi, B., Mishra, A., Nigam, M., Sener, B., Kilic, M., Sharifi-Rad, M., … Sharifi-Rad, J. (2018). Resveratrol: A Double-Edged Sword in Health Benefits. Biomedicines, 6(3), 91
  12. Eggersdorfer, M., & Wyss, A. (2018). Carotenoids in human nutrition and health. Archives of Biochemistry and Biophysics, 652, 18–26
  13. Mozos, I., Stoian, D., Caraba, A., Malainer, C., Horbańczuk, J. O., & Atanasov, A. G. (2018). Lycopene and Vascular Health. Frontiers in Pharmacology, 9


None of the information written in this article should be considered as medical advice. It is your responsibility to consult your doctor before considering any form of nutritional approach.

Nick Williams

Nick Williams is a qualified and insured Nutritional Therapist. He is a member of BANT and registered with CNHC. He supports individuals and groups improve their health through the use of nutrition and lifestyle. He is a qualified mentor with the European Mentoring and Coaching Council. He is also a tennis coach and content developer for the UK's Tennis Coaching qualifications.