Get your daily dose of colour
Updated: Jan 9, 2019
Fruits and vegetables get their colour from natural compounds which signify their health-promoting properties. Read on for the science behind the rainbow of colours.
Doctors, nutritionists, and researchers agree: eating a wide range of colourful foods (from plants!) is good for your health. This post explores the science behind the colours, and how they work to help keep you healthy.
The quick & dirty
Fruits and vegetables get their eye-catching colours from phytochemicals, natural bioactive compounds present in plants that promote good health. Originally, plants developed their bright hues to attract animals like birds and insects for pollination and seed dispersal. For humans, colour serves as a good indicator of the health properties of the plant.
The most vibrantly coloured fruits and vegetables are often the richest in vitamins, minerals, fibre and antioxidants. However, nutrients in our food work synergistically, and no one food contains the range of vitamins and minerals our bodies need.
Eating a colourful, varied diet full of plant foods ensures you can access a wide range of nutrients your body needs for good health.
The science behind the colour: Red fruits and vegetables get their colour from a host of molecules: carotenoids, anthocyanins and betalains. Lycopene, a carotenoid, is the predominant pigment in red fruits and vegetables and a powerful antioxidant that has been associated with a reduced risk of some cancers (especially prostate cancer!) and heart attacks.
Red fruits and vegetables are packed with antioxidants, vitamin C, vitamin A (beta carotene), potassium, manganese, and fibre, making them great for your heart and overall health. They are a great sources of flavonoids - compounds that reduce inflammation and have antioxidant properties.
Tomato-based products are one of the most concentrated source of the phytochemical lycopene. The nutrient they contain support healthy prostate and breast tissue. Although some nutrients (like vitamin C) are diminished or eliminated with heat, some others are activated by cooking. Lycopene is one such nutrient which benefits from cooking, making cooked tomatoes more healthful than uncooked ones.
Cranberries (whose colour comes from anthocyanins, not lycopene), are famously good for urinary tract health. They are a good source of tannins, which prevent bacteria from attaching to cells.
Examples: Tomatoes, raspberries, watermelon, pink grapefruit, guava, cranberries, red beans
The science behind the colour: Orange fruits and vegetables predominantly get their colour from carotenoids (from the Latin carota, or carrot), a class of phytonutrients found in the cells of a wide variety of plants. Carotenoids help plants absorb light energy for use in photosynthesis. Lucky for us, they also have an important antioxidant function of deactivating free radicals — single oxygen atoms that can be harmful to our cells.
Orange fruits and vegetables often contain beta-cryptoxanthanin, beta-carotene, and alpha-carotene, carotenoids which can be converted to vitamin A in our body. Vitamin A is a vital nutrient for vision and immune function. It also benefits skin and bone health, reproduction, and growth.
Orange fruits and vegetables are loaded with the antioxidant vitamin C (citrus fruits are particularly packed), which support a healthy immune system. They also contain potassium, fibre, and vitamin B6 which promote good general health.
It is possible, though, to have too much of a good thing. If consumed in large quantities, beta carotene can turn the skin temporarily orange. On a more serious note, toxicity can develop from elevated levels of vitamin A. Those who regularly take vitamin A supplements of 25,000 IU a day are at risk for developing hypervitaminosis A.
Examples: butternut squash, carrots, sweet potatoes, peaches, oranges
The science behind the colour: Similar to orange foods, the backbone of most yellow fruits and vegetables are carotenoids. They are also loaded with antioxidants and minerals. They contain manganese for bone health, potassium for preventing cramps, vitamin A (beta carotene) for healthy skin, fibre for food digestion, and vitamin B6 for a variety of healthy benefits.
You've likely never heard of manganese, but is nevertheless essential - especially for bone growth and structure. It is especially useful for women who have gone through menopause as they frequently suffer from manganese deficiency. Pineapple is a great source of manganese (as well as bromelain, a digestive enzyme which breaks down proteins).
Many of the most popular yellow foods, like lemons, bananas, and sweet corn, are chock full of nutrients. Lemons are high in vitamin C and citric acid, and can be useful as a natural detoxifier. Bananas are an excellent source of potassium, an essential micronutrient that regulates fluid balance and controls the electrical activity of our heart and other muscles. Sweet corn contains good amounts of fibre (which aids digestion), as well as vitamins B1, B5, C, and manganese.
Examples: lemons, bananas, summer squash, pineapple, sweet corn
Tan and white
The science behind the colour: No colour? No problem. The largest class of phytochemicals, known as flavanoids, are mostly colourless. Flavanoids, a massive group of 5,000+ polyphenolic compounds, are powerful antioxidants which help combat damaging free radicals. Tan and white fruits and vegetables such as mushrooms, onions and potatoes, are good for the heart and help to control blood pressure and cholesterol levels.
Alliums are a class of vegetables including onions and garlic amongst others that are seen to help protect against cardiovascular disease and some cancers. They are rich sources of allicin, which is the cause of their pungent aroma as well as the likely cause of their heart health benefits.
The mineral selenium, found in high quantities in Brazil nuts and edible mushrooms, is needed for proper functioning of the thyroid gland and may help protect against free radical damage and cancer. Not enough selenium can result in muscle and joint pain and unhealthy hair. Too much can result in bad breath, diarrhoea, and even hair loss.
Cauliflower, like other cruciferous vegetables, contains indoles and isothiocyanates, compounds that may protect against certain cancers. Even the humble potato can do wonders for your heart health thanks to antioxidant anthocyanins. They also contain fibre (especially the skins), potassium, and vitamins C and B6.
Examples: mushrooms, onions, garlic, potatoes, coconuts
The science behind the colour: Green foods get their colour from natural plant pigment chlorophyll, which is used along with sunlight to deliver nutrients to plants. Practically synonymous with healthy, green foods and vegetables contain heaps of healthful nutrients and minerals that support various bodily functions.
Green often means lots of heart-protective potassium and vitamin K, which aids the blood clotting process. Green fruits and veggies also help to maintain vision health and strong bones and teeth. Dark green, leafy vegetables have the highest concentration of antioxidants and fibre. They also contain folic acid, which protects against neural tube defects during pregnancy.
Cruciferous vegetables, like broccoli, Brussel sprouts and cabbage, may have detoxifying, anticancer properties due to the presence of a sulphurous compound called sulfurophane. A cup of cooked broccoli offers as much vitamin C as an orange, and is a good source of beta-carotene, vitamins B1, B2, B3, B6, iron, magnesium, potassium, and zinc.
Lighter green fruits and vegetables are often rich in lutein, which is particularly beneficial for eye health. Lutein helps protect against age-related macular degeneration. It can be found in spinach and other leafy greens, as well as on the skin of pistachios,
Examples: Avocado, broccoli, cabbage, kiwi, spinach, pistachios
Blue / purple
The science behind the colour: Blue / purple fruits and vegetables get their colour primarily from the phytochemical anthocyanin they contain. Generally, the darker the blue hue, the higher the concentration of the phytochemical. Anthocyanins are antioxidants that benefit the heart and blood pressure. They help prevent clot formation and may also lower the risk of some cancers.
Purple foods fight cancer, ulcers, and urinary tract infections (UTIs). Resveratrol, an antioxidant found in grape skins, blueberries, and famously, red wine, is thought to prevent heart disease, cancer, and even ageing. Anthocyanins present in blackberries, purple cabbage, and purple carrots, have been shown to decrease ulcer formation and to fight the bacteria that promote UTIs.
Blue / purple superfoods include blueberries and açai. Blueberries are considered to have some of the the highest antioxidant activity of all foods. They can lower your risk of cancer and heart disease, and are also anti-inflammatory. Açai berries, with a unique profile for a fruit of high fat and low sugar, are also loaded with antioxidants, and may even boost brain function.
Examples: Aubergine / eggplant (especially the skin), blueberries, blackberries, prunes, plums