July 24, 2017

The Colour of Food: Any Nutritional Significance?


A rainbow of colour

“Eat a rainbow of colours,” is often a recommendation made by nutrition experts. But what does food colour have to do with nutrition you may ask?


It’s fairly well established that we eat with our eyes. Colour attracts our intention and it may actually stimulate the appetite. In fact, it is often said that our brains must process the colour of food before we even attempt to taste it—as if the food needed to pass a visual test. As omnivorous beings, we are attracted to a wide variety of colours.  And what we regard as acceptable for one food—fruit for example, may not be acceptable for another such as meat and fish.

In fruit for example, it is believed that bright colour attracts birds and other animals which are responsible for spreading seeds around the countryside. And for many red fruits, the pigments are only skin deep as can be seen in red grapes,  The colour of our chosen fruits and their juices is determined by a group of compounds probably best described as ‘short chain polyphenols” or anthocyanins.

Once peeled, fruit often unveil a succulent flesh crammed with flavonoids. or flavourful pigments.


The red/blue/purple pigments found in some foods are known as anthocyanins. They are a direct product of photosynthesis, the process used by plants to harness energy from sunlight. In fact, these red pigments are produced from flavonoids. So flavonoids are in reality precursors of anthocyanins—but unlike anthocyanins, flavonoids have a distinctive flavour. The molecules responsible for the flavour and the colour of fruit are often found alongside each other in the fruit.

Although beets and eggplants have always been dressed in purple, today one can find purple cabbage, purple potatoes and purple carrots in the marketplace. So what’s the deal you may ask? Plants produce a variety of pigments specific to their needs and genetic composition. The pigments were believed to protect the food from harmful ultraviolet rays. When we eat them, these same substances go to work for us in a variety of capacities. Each color produces different benefits, such as helping stave off certain cancers, boost memory or provide anti-aging effects.


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Behind the color: The blue/purple hues in foods are due primarily to their anthocyanin content. The darker the blue hue, the higher the phytochemical concentration. We call these foods red/purple because many of the foods that are rich in anthocyanins also have a red or pink hue. Anthocyanins are antioxidants that seem particularly heart healthy and may help support healthy blood pressure.

Cranberries, another red fruit [whose color is due to anthocyanins, not lycopene], are also a good source of tannins, which prevent bacteria from attaching to body cells,” The anthocyanins that give these fruits their distinctive colors may help ward off heart disease by preventing clot formation. They may also help lower risk of cancer.Blueberries are considered to have the highest antioxidant activity of all foods.

And the color’s richness is actually one sign that the food is ripe and ready to eat. adding that

Examples: Eggplant (especially the skin), blueberries, blackberries, prunes, plums, pomegranates

The natural plant pigment chlorophyll colors green fruits and vegetables. These foods are typically rich in isothiocyanates, which induce enzymes in the liver that may assist the body in removing potentially harmful compounds. Cruciferous vegetables such as broccoli and cabbage contain the phytochemicals “indoles and isothiocyanates”, which may have anticancer properties. Sulforaphane, a phytochemical present in cruciferous vegetables, was shown to disarm cancer-causing chemicals before they cause damage to the body.IMG_1054

In addition to the benefits associated with colour pigments,  green vegetables are excellent sources of vitamin K, folic acid, potassium, as well as carotenoids. Folic acid is needed to prevent neural tube defects during pregnancy, and vitamin K is essential in blood clot formation.

Diets high in potassium are associated with lowering blood pressure, and there is an inverse relationship between cruciferous vegetables and cancer, especially colon and bladder cancers.

Leafy greens, avocado, kiwi, pistachios offer a variation of the green colour which is synonymous to richness in lutein. Lutein is particularly beneficial for eye health and helps protect against macular degeneration.



Lycopene, a member of the carotenoid family, is the predominant pigment in reddish fruits and veggies.  These are known to be poweful antioxiants that have been associated with a reduced risk of some cancers, especially prostate cancer. They may protect against heart attacks. Tomato-based products are the most concentrated sources of this phytochemical.

And although some nutrients, such as vitamin C, are diminished with the introduction of heat, the benefits of eating red produce are not dependent on eating the food raw. In fact, cooking seems to enhance the activity of some phytochemicals, such as lycopene. Interestingly cooking tomatoes makes lycopene more easily absorbed. Obtaining optimal benefit from the nutrients in food, especially produce, also depends on proper selection, storage, and cooking of the produce. In addition to vitamin C and folate, red fruits and vegetables are also sources of flavonoids, known for their antioxidant properties. they have been known to reduce inflammation.

Other examples of red produce include watermelon, pink grapefruit, guava, cranberries

Beta-cryptoxanthin, beta-carotene, and vitamin C are typically found in the orange/yellow colour group of produce. The orange group of foods  are also rich in  which are particularly good antioxidants.”

Beta-cryptoxanthin, beta-carotene, and alpha-carotene are all orange-friendly carotenoids found in yellow/orange produce such as carrots, mangos, cantaloupe, apricots, winter squash, pumpkin, sweet potatoes. They can be converted to vitamin A in the body, a nutrient integral for vision and immune function, as well as skin and bone health.

Beta-carotenes in some orange fruits and vegetables may also play a part in preventing some cancers such as lung, esophagus and stomach. They may reduce the risk of heart disease and improve immune function.

Other examples of yellow/orange produce include: carrots, mangos, cantaloupe, winter squash, sweet potatoes, pumpkins, apricots


While colour can give clients a general idea about what lies beneath a food’s exterior, hue does not tell all. And it is certainly not an exclusive indicator of phytochemical content. While some phytochemicals are pigments that give colour, others are colorless. The largest class of phytochemicals are the flavonoids, which for the most part are colorless. Flavonoids are powerful antioxidants. They help the body to counteract free-radical formation. When free-radical damage goes unchecked, it can cause significant damage to body cells and tissues.

There are more than 4,000 different flavonoids, and according to information from the PRODUCE FOR BETTER HEALTH FOUNDATION (PBH). They are classified into the following categories:


myricetin –in berries, grapes, parsley, and spinach
quercetin–in onions, apples, broccoli, cranberries, and grapes


apigenin–in celery, lettuce, and parsley
luteolin–in beets, bell peppers, and Brussels sprouts


hesperetin and naringenin–both in citrus fruits and juices


catechin –in tea, red wine, and dark chocolate
epicatechin, gallate, epigallocatechin, and epigallocatechin gallate–in teas, fruits, and legumes

anthocyanidins–in blue/purple and red fruits and vegetables

Although not enough research has been conducted to definitively match specific phytochemicals with particular benefits, researchers are currently investigating the effect of flavonoids on lowering the risk of cardiovascular disease and several types of cancer. Their role in promoting lung health and protecting against asthma is also being studied.

The concept that we eat a certain colour ratio of foods may be premature, but from new research one might want to include a variety of colours in the diet for better overall health, especially in relation to produce. Epidemiological research suggests that food patterns that include fruits and vegetables are associated with lower risk for some diseases. And a recent article suggested that more variety in fruit and vegetable intake was associated with a lower risk for pharyngeal and laryngeal cancer. Since different foods can offer different nutrients, regardless of colour, it is impossible to recommend the consumption of specific amounts of coloured foods.

But considering that the majority of individuals are currently not meeting recommendations for fruit and vegetable intake, encouraging them to use colour as a guide for increasing produce consumption may be a good strategy.

However we believe  it may be best to simply recommend a variety of different fruits and vegetables of varying colours instead of dwelling on complex and complicated conversations about phytochemicals. Keep it short and sweet!