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How many colours do you eat every week? And why does it matter? Discover why food diversity is crucial for both our physical and mental health and how you can bring more awareness to the variety and colour on your plate by taking the “50 Food Challenge.”
I’ve just received my weekly box of organic fruit and vegetables full of the most vibrant Summer produce – bright red tomatoes and capsicums, deep purple plums and eggplant, orange nectarines and carrots, green salad leaves and broccoli – a rainbow of colours.
When I feast my eyes on the rich colours of my fruit and vegetable box I can’t help wonder if our human ability to see colour is because biologically we are so dependent on fruits and vegetables for our survival. Did you know that humans are in fact one of few species that have evolved to be trichromatic which means being able to discriminate between greens, blues and reds? And indeed, one of the theories put forward that led us to develop this advantage was that it helped our ancestors locate and eat fruit more quickly than those who didn’t – and those ancestors lived longer, healthier lives which could be why you and I are around today.¹
We all know we need to eat our fruit and vegetables – and yet we’re just not eating nearly as much as is necessary to enjoy good health and long lives. Here are a few facts and figures that I found startling. The 2017 Global Burden of Disease Study evaluated the consumption of major foods across 195 countries and looked at the impact of a less than optimal diet on death and disability from chronic diseases.² They found that diets high in sodium, low in whole grains, low in fruit, low in nuts and seeds, low in vegetables, and low in omega-3 fatty acids were the leading dietary risk factors for death. A suboptimal diet is responsible for more deaths than any other risk factor, including smoking!
In Australia, dietary guidelines recommend 2 daily servings of fruit and 5-6 daily servings of vegetables but here is another alarming fact – only 22% of Australian adults achieve the recommendations for fruit, just 1.5% the recommendations for vegetables, and only 0.7% achieve recommendations for both combined.³ Similar results are found in other countries.
Fruits and vegetables contain critical nutrients: fibre (See article on fibre), and vitamins A, C, E, folate and minerals such as magnesium, iron, calcium and potassium. They also contain phytochemicals (responsible for the colourful pigments) – over 25 000 are known! These have numerous functions in our bodies and act synergistically too – we cannot begin to think we could ever replicate this complexity in supplement form. The higher the phytochemical content of a food the lower the risk of chronic health conditions. These phytochemicals, for example carotenoids (found in capsicums, carrots, oranges), glucosinolates (found in cruciferous vegetables) and flavonoids (found in apples, grapes, cocoa, nuts, berries) have been shown to reduce cholesterol levels, blood pressure, inflammation, oxidation and platelet aggregation, improve vascular and immune function and subsequently reduce the risk of many chronic diseases ⁴⁵⁶, such as:
• coronary heart disease and stroke
• cognitive decline and dementia
It used to be thought that it was the antioxidant effects of phytochemicals that were responsible for their health benefits – but it is now understood that they also feed our gut microbiome – in other words they act like prebiotics, just like fibre. The wider the diversity in fruits and vegetables consumed, the wider the microbial diversity. Healthier gut flora are often involved in producing enzymes that convert certain phytochemicals in plants into the active forms our bodies can use – a win-win situation for both humans and bacteria!⁷
It’s not only chronic diseases that we will be protected against. It has been hypothesised that dietary habits may play a role in COVID-19 infection – the severity of symptoms and duration of illness – and this was indeed found to be the case in a recent study in front-line healthcare workers from six countries where those who followed plant-based diets higher in vegetables, legumes and nuts and lower in poultry, red and processed meat, had 73% lower odds of moderate-to-severe COVID-19.⁸
You can also improve your psychological well-being by eating more fruits and vegetables. In an Australian study of more than 12 000 adults who were followed over 2 years, those who ate up to 8 servings a day reported being happier and more satisfied with life.⁹ It is remarkable how quickly these positive effects can be experienced. A study of young adults in New Zealand found that those who ate more fruit and vegetables over just 13 consecutive days reported greater flourishing in daily life. They experienced higher levels of well-being and intense feelings of curiosity and creativity compared to young adults who ate less. These positive emotions correlated with fruit and vegetable intake on a daily basis!¹⁰
Phytochemicals directly influence the expression of our genes through epigenetic changes. Epigenetic sequences are non-DNA components of our genes that act like gene-switches, switching genes on and off, modifying and controlling their expression. These sequences or “gene switches” are inherited and may predispose us to certain conditions like diabetes, obesity or heart disease – that is until they get switched off by certain phytochemicals in food.
A good example of a phytochemical that has a direct effect on the expression of our genes is one called sulforaphane derived from broccoli and other cruciferous vegetables. Sulforaphane has been shown to be a potent inducer of our liver’s detoxification enzymes, which are continuously working to deactivate and excrete many carcinogens from the body.⁴
This is why healthy eating guidelines will emphasise the importance of eating a wide variety of fruits, vegetables, herbs and spices and why you have probably come across the phrase ‘eat the rainbow’. Although, compared to our ancestor’s diet, when over 3000 plant species may have been available, today we only utilise just more than 100 plant species for food and even that sounds like a lot to me.⁶ It got me thinking – how many varieties of plant foods do I eat on a weekly basis?
Remembering to get in those daily servings of fruits and vegetables is not easy. So why not focus on variety of colour instead. It’s much more fun and it’s an activity that anyone at any age can participate in. The younger we start the better. Eating a rainbow every day ensures you are sampling from thousands of phytochemicals that can help prevent chronic diseases later on in life. Miguel Toribio-Mateas in his excellent article recommends a “50 Food Challenge” chart to log all the fresh fruits, vegetables, herbs and spices you can eat over a week.⁷
Print The Fifty Food Challenge Chart here and use it to track just how much variety and colour you and your family are eating. Get the kids involved and see if you can improve your score over a few weeks. I managed 43 this past week – can you beat that?
- www.science.org. (n.d.). You can thank your fruit-hunting ancestors for your color vision. [online] Available at: https://www.science.org/news/2017/02/you-can-thank-your-fruit-hunting-ancestors-your-color-vision [Accessed 24 October 2021].
- GBD 2017 Diet Collaborators. Health effects of dietary risks in 195 countries, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet. 2019 May 11;393(10184):1958-1972. doi: 10.1016/S0140-6736(19)30041-8. Epub 2019 Apr 4. Erratum in: Lancet. 2021 Jun 26;397(10293):2466. PMID: 30954305; PMCID: PMC6899507.
- Australian Institute of Health and Welfare (2019). Poor diet, Poor diet in adults – Australian Institute of Health and Welfare. [online] Australian Institute of Health and Welfare. Available at: https://www.aihw.gov.au/reports/food-nutrition/poor-diet/contents/poor-diet-in-adults.
- Aune D, Giovannucci E, Boffetta P, Fadnes LT, Keum N, Norat T, Greenwood DC, Riboli E, Vatten LJ, Tonstad S. Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality-a systematic review and dose-response meta-analysis of prospective studies. Int J Epidemiol. 2017 Jun 1;46(3):1029-1056. doi: 10.1093/ije/dyw319. PMID: 28338764; PMCID: PMC5837313.
- Hever J, Cronise RJ. Plant-based nutrition for healthcare professionals: implementing diet as a primary modality in the prevention and treatment of chronic disease. J Geriatr Cardiio. 2017 May; 14(5): 355-368 DOI: 10.11909/j.issn.1671-5411.2017.05.012
- Minich DM. A Review of the Science of Colorful, Plant-Based Food and Practical Strategies for “Eating the Rainbow”. J Nutr Metab. 2019 Jun 2;2019:2125070. doi: 10.1155/2019/2125070. Erratum in: J Nutr Metab. 2020 Nov 28;2020:5631762. PMID: 33414957; PMCID: PMC7770496.
- Toribio-Mateas M. Harnessing the Power of Microbiome Assessment Tools as Part of Neuroprotective Nutrition and Lifestyle Medicine Interventions. Microorganisms. 2018 Apr 25;6(2):35. doi: 10.3390/microorganisms6020035. PMID: 29693607; PMCID: PMC6027349.
- Kim H, Rebholz CM, Hegde S, LaFiura C, Raghavan M, Lloyd JF, Cheng S, Seidelmann SB. Plant-based diets, pescatarian diets and COVID-19 severity: a population-based case-control study in six countries. BMJ Nutr Prev Health. 2021 Jun 7;4(1):257-266. doi: 10.1136/bmjnph-2021-000272. PMID: 34308134; PMCID: PMC8219480.
- Mujcic R., Oswald A. J. Evolution of well-being and happiness after increases in consumption of fruit and vegetables. American Journal of Public Health. 2016;106(8):1504–1510. doi: 10.2105/AJPH.2016.303260.
- Conner T. S., Brookie K. L., Richardson A. C., Polak M. A. On carrots and curiosity: eating fruit and vegetables is associated with greater flourishing in daily life. British Journal of Health Psychology. 2015;20(2):413–427. doi: 10.1111/bjhp.12113.