Eat the rainbow!


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The expression “eat the rainbow” has been a popular healthy eating tip for kids and adults regarding the importance of a diet rich in fruits and veggies. What’s exciting is that the science is now catching up and starting to reveal that there is a lot more substance to this phrase than we may have initially thought.

Apart from being an abundant source of vitamins and minerals, fruit and vegetables (as well as legumes, grains, and even spices) contain bioactive compounds known as phytonutrients (also referred to as phytochemicals)1. Phytonutrients are chemical compounds produced by plants to help them resist microbes (such as bacteria and fungi), prevent them from being eaten by insects and other animals, and to help them against the natural elements. Exactly these innate plant defence mechanisms are thought to confer benefits for human health, and they are what give plants their vibrant colours and distinctive tastes and smells.

A recent umbrella review (in other words, a mega review of existing reviews) found that over 40% of the investigated health outcomes were improved by the intake of phytonutrients, ranging from body weight, lipid profile, inflammation - and even cancer.2. This study also highlights the importance of eating a variety of plant foods so that you can maximise the intake of a range of beneficial phytonutrients. For instance, the phytonutrient lycopene is commonly found in fruit and vegetables with bright reds, purples, and blues (think grapes, tomatoes, and purple cabbage) and has been linked with improved risk for all-cause mortality, stroke, and inflammatory markers. On the other hand, beta-carotene (found in yellow and orange plants such as carrots, sweet potatoes, cantaloupe) is not only known to be good for vision and eye health but is also associated with lower risk for breast and gastric cancers.2. While all of the known links have so far only been investigated in relation to physical health, it will be important to understand how phytonutrients may be related to brain and mental health - an important area for future study.

In a future post, we’ll delve more into the details around the well-studied phytonutrients and their specific health properties, as well as practical tips on how to diversify the colours on your plate. In the meantime, I recommend checking out this handy guide on the ins and outs of phytonutrients provided by the Institute for Functional Medicine.

Blumfield M, Mayr H, Vlieger ND, Abbott K, Starck C, Fayet-Moore F, et al. Should We ‘Eat a Rainbow’? An Umbrella Review of the Health Effects of Colorful Bioactive Pigments in Fruits and Vegetables. Molecules. 2022;27(13):1–26.