Why you should eat the rainbow: Phytochemicals!

Introducing phytochemicals

Diversity is essential to a healthy diet. Every food contains different nutrients, and no one food supplies all that we need. Therefore, to meet the body’s requirements we must eat a balanced, diverse diet.

But when it comes to plants, the principle of diversity extends beyond their nutritive value. Because, in addition to macronutrients (carbohydrate, protein, fat) and micronutrients (vitamins and minerals), plants contain non-nutrient substances that are associated with reduced risk from many chronic diseases.

Phytochemicals!

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What are phytochemicals

Phytochemicals are defined as bioactive (i.e. biologically active) non-nutrient chemical compounds present in plant-based foods and beverages that have been linked to reduced risk of major chronic diseases.[1] The root of the word, ‘phyto’, comes from the Greek word for plant (phytón). Thus, phytochemicals are literally plant chemicals. ‘Phytonutrients’ is simply another term for phytochemicals – you’ll find both in the scientific literature and health materials.

Phytochemicals act as pigments, giving plant-based foods and beverages (fruits, vegetables, whole grains, nuts, seeds, legumes, tea, coffee, red wine) their vibrant or deep, dark and intense colours. They also contribute to their taste and smell. Phytochemicals are found in all edible parts of a plant, but they’re especially concentrated in the skin or peel.

The more colour, the higher a food's phytochemical content.

Classification of phytochemicals

To date, about 10,000 phytochemicals have been identified, and many still remain unknown.[2] Classification systems abound, separating phytochemicals into groups according to their chemical structure and characteristics. Most identify five or six major categories, of which polyphenols are the largest and most diverse. Notably, polyphenols constitute the main source of antioxidants in the human diet.

The health benefits of phytochemicals

Phytochemicals protect us from pretty much every chronic disease on the planet.[1] Interestingly, it’s now thought they’re what makes the Mediterranean diet so healthy.

Epidemiological research shows that diets high in plant foods (fruits, vegetables, whole grains, nuts, seeds, legumes, tea, coffee, red wine) are inversely associated with the risk of many major chronic diseases, including:

• Cardiovascular disease

• Diabetes

• Obesity

• Cancers

• Osteoporosis

• Neuro-degenerative conditions

• And inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohn’s disease.[2]

The relationship is dose-response – the more plant foods consumed, the lower the risk of disease.

How phytochemicals protect our health

Phytochemicals protect our health via a range of biological mechanisms. They’re:

1. Antioxidant – phytochemicals are potent antioxidants, molecules that limit the oxidative damage to cells associated with ageing and degenerative disease (caused by free radicals scavenging electrons)

2. Anti-inflammatory – they are also powerfully anti-inflammatory

3. Anti-proliferative – they inhibit cell proliferation and induce apoptosis (programmed cell death), conferring cancer protection

4. Pro- and anti-angiogenic – they control the growth of new blood vessels, important in wound-healing (pro-angiogenic) and cancer (anti-angiogenic)

5. Metabolism-regulating – phytochemicals lower blood pressure, blood lipids, blood sugar and improve insulin sensitivity.[2,3]

Colour-coded bioactive superpowers

With so many phytochemicals, it would be overwhelming to select specific ones to protect your health. Conveniently, nature has provided an inbuilt colour-coded system to help you scoop up as many as possible. Because they act as pigments, each different food colour signifies different phytochemicals, each with its own health benefits. Here are some examples.

Should you take a phytochemical supplement?

No. When phytochemicals have been isolated from food source and taken alone as a supplement, clinical trials have failed to consistently replicate their beneficial health effects. The benefits are observed in populations that eat a whole foods diet, rich in fruit and veg and other plant foods, leading to the hypothesis that the effects of phytochemicals are ‘additive and synergistic’.[8,1] Meaning, the benefits are attributed to the combined effects of the complex mixture of phytochemicals and other nutrients found in whole foods. 

Eat the rainbow

To reap the benefits of phytochemicals, simply eat the rainbow and nature will cleverly take care of the rest! Eat a varied, whole foods diet, with plant-based foods and beverages of every colour. For maximum benefit, also eat broadly within each colour – for example, don’t always eat the same red food, or the same blue/purple/black food. Mix it up and do diversity both across the rainbow and within each colour.

Sonnda’s top 10 tips to eat the rainbow

Check out Sonnda’s Top 10 Tips to Eat the Rainbow to make eating the rainbow a total cinch.

References

1. Liu RH. Potential synergy of phytochemicals in cancer prevention: Mechanism of action. The Journal of Nutrition. 2004;134(12):3479S–3485S. Available from: https://doi.org/10.1093/jn/134.12.3479S.

2. Zhang YJ, Gan RY, Li S, et al. Antioxidant phytochemicals for the prevention and treatment of chronic diseases. Molecules. 2015;20(12):21138-21156. Available from: doi:10.3390/molecules201219753.

3. Upadhyay S, Dixit M. Role of polyphenols and other phytochemicals on molecular signalling. Oxidative Medicine and Cellular Longevity. 2015;2015:504253. Available from: https://doi.org/10.1155/2015/504253.

4. McManus, KD. Harvard Health. Phytonutrients: Paint your plate with the colors of the rainbow. Harvard Health Publishing, Harvard Medical School: 2019. Available from: https://www.health.harvard.edu/blog/phytonutrients-paint-your-plate-with-the-colors-of-the-rainbow-2019042516501 [Accessed 15th September 2020].

5. Burri BJ, La Frano MR, Zhu C. Absorption, metabolism, and functions of β-cryptoxanthin. Nutr Rev. 2016;74(2):69-82. Available from: doi:10.1093/nutrit/nuv064.

6. Kim JK, Park SU. Current potential health benefits of sulforaphane. EXCLI Journal. 2016;15:571-577. Available from: doi:10.17179/excli2016-485.

7. Buscemi S, Corleo D, Di Pace F. The effect of lutein on eye and extra-eye health. Nutrients. 2018;10(9):1321. Available from: doi:10.3390/nu10091321.

8. Liu RH. Health benefits of fruit and vegetables are from additive and synergistic combinations of phytochemicals. The American Journal of Clinical Nutrition. 2003;78(3):517S–520S. Available from: https://doi.org/10.1093/ajcn/78.3.517S.

9. McDonald D, Hyde E, Debelius JW, et al 2018. American Gut: An Open Platform for Citizen Science Microbiome Research. American Society for Microbiology: mSystems. 2018;3(3):e00031-18. Available from: DOI: 10.1128/mSystems.00031-18.

10. Aune D, Giovannucci E, Boffetta P, et al. 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. International Journal of Epidemiology. 2017;46(3):1029-1056. Available from: https://doi.org/10.1093/ije/dyw319.

11. Franco R, Oñatibia-Astibia A, Martínez-Pinilla E. Health benefits of methylxanthines in cacao and chocolate. Nutrients. 2013;5(10):4159-4173. Available from: doi:10.3390/nu5104159.

12. Department of Health & Social Care. UK Chief Medical Officers’ Low Risk Drinking Guidelines 2016. London: Williams Lea; 2016. Available from: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/545937/UK_CMOs__report.pdf.

13. Wood AM, Kaptoge S, Butterworth AS, et al. Risk thresholds for alcohol consumption: combined analysis of individual-participant data for 599,912 current drinkers in 83 prospective studies. The Lancet. 2018;391(10129):1513–1523. Available from: https://doi.org/10.1016/S0140-6736(18)30134-X.