Why should we 'eat the rainbow'?

We've all had 'eat your 5-a-day' drummed into us, but more recently, the idea of 'eating the rainbow' has established itself. Being brought up on home-grown veggies from my parents' garden, I'm used to a wide variety of colours on my plate - fresh beetroot, courgettes, sweetcorn, tomatoes, swiss chard, strawberries... the list goes on. For many though, it's easy to get stuck in a rut of having peas on the side of every meal and occasionally branching out to have an orange instead of an apple.

So if we're getting our 5-a-day (or 10 if you're really good), why does it matter what colour they are? Let's find out what makes each colour so important:

Red

Tomatoes, peppers, strawberries, cherries, red apples, etc. all contain a natural pigment called lycopene. Lycopene is one pigment in a family of pigments called carotenoids. Lycopene is known to be a 'hydrocarbon' carotenoid, meaning it is made up entirely from carbon and hydrogen. Some studies have found that the consumption of lycopene through tomatoes and tomato products has been associated with a reduced risk of some cancers, most notably, prostate, lung and stomach. Increased levels of lycopene have also been found to be associated with lower risk of cardiovascular disease, in some studies. Other studies have found positive relationships between consumption of lycopene and reduced instance of sunburn, osteoporosis, mental disorders and asthma! (1)

Orange

Orange foods contain another carotenoid pigment known as beta-carotene, which can be converted to vitamin A in the body. As we have all heard, orange foods are packed with vitamin C, which helps the body to form and maintain connective tissue, including bones, muscles and skin. Like other carotenoids, beta-carotene is an antioxidant, helping to protect the body from 'free radicals', which can damage cells through oxidation. Studies have found that there may be a link between consumption of beta-carotene and a slower cognitive decline, as well as better longevity of lung function. (2)

Yellow

Yellow foods are high in lutein, which has a wide range of health benefits, including anti-inflammatory, anticancer, antidiabetic, and can be used to reduce the effects of age-related eye problems including cataracts and macular degeneration. Citrus fruits also contain the phytochemical (chemicals produced by plants), hesperidin, which may reduce the risk of heart disease. (3)

Green

Foods that are green contain the natural pigment, chlorophyll, which gives them their colour. We've all had it drummed into us since birth to 'eat your greens', but they really are powerhouses in terms of nutrition! Lutein is again found in green vegetables, alongside zeaxanthin, which both play a protective role in our eye health. Some studies have also suggested that these antioxidants play a role in the prevention of certain types of cancer, heart attacks and strokes. (4)

Blue

Blue and purple foods contain pigments known as anthocyanins. Studies have found 'blue foods' to help reduce the risk of neuronal diseases, cardiovasclar illnesses, cancer, diabetes, inflammation and many other diseases (5). As you can see, blue foods have a huge range of benefits!

White

Although these foods aren't bursting with colour, they still play an important role in our diets. White foods contain flavanols, which are important phytochemicals (chemicals produced by plants). A notable flavanol in white foods is 'quercetin', which in some studies has shown to reduce risk of heart disease. Interestingly, other studies have found quercetin to block the release of histamine, which can aid those suffering from allergies and hayfever. Another great benefit of quercetin is its ability to reduce pain-causing inflammation by inhibiting enzymes (biological catalysts) that generate substances known as 'prostaglandins'. Better still, garlic has even been shown to act as a natural antibiotic and may help to reduce blood pressure. (6)

So, as you can see, every colour of food can benefit us in one way or another, and eating a combination of these foods on a daily basis can give us the best chance of a healthy life!

References

(1) Story, Erica N. et al. “An Update on the Health Effects of Tomato Lycopene.” Annual review of food science and technology 1 (2010): 10.1146/annurev.food.102308.124120. PMC. Web. 9 Feb. 2018.

(2) Kang, J. H., Cook, N., Manson, J., Buring, J. E., & Grodstein, F. (2006). A randomized trial of vitamin E supplementation and cognitive function in women. Archives of Internal Medicine, 166(22), 2462-2468. Retrieved from https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/769551

Touvier, M., Kesse, E., Clavel-Chapelon, F., & Boutron-Ruault, M. C. (2005). Dual association of β-carotene with risk of tobacco-related cancers in a cohort of French women. Journal of the National Cancer Institute, 97(18), 1338-1344. Retrieved from https://academic.oup.com/jnci/article/97/18/1338/2521382

(3) Kim, Jae Kwang, and Sang Un Park. “Current Results on the Potential Health Benefits of Lutein.” EXCLI Journal 15 (2016): 308–314. PMC. Web. 9 Feb. 2018.

(4) https://vegetarian-nutrition.info/green-leafy-vegetables/

(5) Yousuf, B., Gul, K., Abas Wani, A., Singh, P., (2015). Health Benefits of Anthocyanins and Their Encapsulation for Potential Use in Food Systems: A Review. Critical Reviews in Food Science and Nutrition. Volume 56, Issue 13.

(6) https://www.weightlossresources.co.uk/healthy_eating/eat-a-rainbow/quercetin-white-food.htm

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