Why you SHOULD ‘eat a rainbow’ of fruit and vegetables each day

You’d be forgiven for assuming the old saying ‘eat the rainbow’ was just another baseless piece of advice to encourage people to consume more fruit in veg.

But colors are extremely important when it comes to our health, and whether it’s a bright red apple or a earthy green pear, the color of natural foods is a sign of the nutrients they contain.

Red apples, peppers and tomatoes are high in lycopene which gives them their radiant red color and helps protect against cancers and arthritis.

Blueberries, blackberries and eggplants are stuffed with purple-colored anthocyanins, tannins and other compounds that previous research has suggested improve memory.

While yellow-colored lutein behind the colors in pineapples, lemons and squashes can help protect your eyesight.

Dr Evangeline Mantzioris, a nutritionists at the University of South Australia, says there are at least 5,000 nutrients in different fruits and vegetables.

She recommends ensuring a multi-colored diet to ‘maximize health benefits’.

This graphic shows fruits and vegetables divided by their colors, which indicate which antioxidants they contain. All antioxidants work by hoovering up ‘free radicals’ in cells, made by natural processes but which cause damage to cell membrances and DNA if they are not removed. Evidence shows orange-colored fruit and veg can boost fertility and lower blood pressure, while red ones can protect against some cancers and blue ones can boost memory

Guidelines say everyone should get at least five portions of fruits and vegetables a day, of varying colors to ensure the best nutrition benefits.

The Centers for Disease Control and Prevention (CDC) says 87 per cent of Americans are not getting enough fruit and vegetables every day in their diet.

RED: Protects against cancer and arthritis

Red apples, strawberries, cherries and tomatoes can reduce your risk of suffering cancer and arthritis, major studies suggest.

They are top sources of carotenoids including astaxanthin and lycopene, which gives the foods their famous red color.

These reduce the numbers of dangerous ‘free radicals’ in the body, which are made naturally via breathing and movement, and can also appear due to too much sunlight, smoking, air pollution and industrial chemicals.

Free radicals cause damage to the lining of cells, proteins and DNA raising the risk of a whole host of diseases including cancer and arthritis.

But anti-oxidants in red fruits — such as lycopene — work by hoovering up these molecules shortly after they are made, reducing the risk of damage to cells.

A systematic review from 2020, found that the substance reduced the risk of prostate cancer by suppressing these mutations. Another review — also from 2020 — also found lycopene could protect against other cancers including those of the breasts, lung and stomach.

Red-colored foods also contain vitamin C, which can cut inflammation levels helping to alleviate arthritis symptoms.

Many small-scale studies have already linked eating strawberries with improved control of arthritis.

They include a 2017 paper which found that eating 50 grams of strawberries a day for 12 weeks reduced inflammation and symptoms of osteoarthritis in participants.

The Arthritis Foundation — America’s leading organization on the condition — says strawberries, raspberries and red cherries can all help with arthritis because of the antioxidants they contain. 

‘Some researchers compare the anti-inflammatory properties of cherries to non-steroidal anti-inflammatory drugs (NSAIDs),’ they wrote.

ORANGE: Reduces blood pressure and boosts fertility

Oranges, peaches, carrots and satsuma owe their warming color to antioxidants known as carotenoids.

But these compounds also have specific benefits for someone’s health by helping lower blood pressure.

Known specifically as beta-carotene and beta-cryptoxanthin, they also work by hoovering up free radicals that can damage cells and lead to a rise in blood pressure.

Orange fruits and vegetables also contain vitamins C, which multiple studies show can lower blood pressure.

The vitamin can act as a diuretic, prompting kidneys to remove more salt and water from the body helping to relax blood vessel walls and lower blood pressure.

There is also evidence that antioxidants from these fruits may help to boost fertility.

A 2018 major study involving 70,000 women found those who ate more citrus fruit had a 22 per cent lower risk of endometriosis. This is a condition where growths form around the uterus, harming chances of conceiving.

A 2020 meta-analysis on 440,000 women also suggested a fertility benefit, concluding those who ate more orange fruits and vegetables were significantly less likely to get ovarian cancer than their counterparts.

There is also some evidence that the antioxidants can help with sperm production.

Carotenoids can be converted into vitamin A by the body, which is known to promote eye health.

BLUE AND PURPLE: Protects memory

Blueberries, blackberries and egg plants could help protect the brain, a growing list of studies suggest.

Their deep hue is from anthocyanins, tannins and other antioxidants.

Two meta-analyses in 2019 and 2022 which reviewed about 12 papers each pointed to a benefit to memory.

While many smaller studies have also suggested the link, including a 2012 landmark Harvard University study suggesting blueberry consumption delayed brain aging by two-and-a-half years.

Scientists say eating blue and purple fruits and vegetables boosts blood flow to key areas of the brain, ensuring a good supply of nutrients and oxygen for cells.

Anthocyanins, tannins and other antioxidants in the plants have also been linked to reducing the number of ‘free radicals’ in the body — helping to reduce  inflammation.

YELLOW: Protect eyesight

Pineapples, corn, lemons and even bananas can all help protect eyes from sun damage and vision loss.

They are excellent sources of lutein, zeaxanthin and other antioxidants which give these their color.

When we are exposed to too much sunlight free radicals build up in the eye — which can damage cells and DNA.

But lutein and other compounds hoover these up, staving off the worst effects.

There is also evidence that these yellow-color giving compounds protect the eye from macular degeneration.

This affects about one in 10 US adults, and tends to strike later in life with sufferers gradually losing the central area of their vision.  

Meta-analyses from 2012 show how eating more yellow-colored fruits and vegetables significantly reduced the risk of developing this condition in participants.

Another major review of more than 20 studies from 2018 concluded that ‘many studies support lutein’s favorable effects on the eye’.

GREEN: Lowered risk of heart disease

Avocadoes, broccoli, brussel sprouts, kale and other leafy greens can reduce the risk of heart disease, studies suggest — and cut the risk of spina bifida in developing infants.

They are a top source of nitrates, which are broken down when consumed to trigger the dilation of vessels — and a subsequent drop in blood pressure.

This cuts strain on the heart and reduces the risk of damage to blood vessels, in turn lowering the risk of heart disease.

A meta-analysis from 2016 found there was a 15.8 per cent lower risk of cardiovascular disease among those who ate leafy greens regularly.

Nitrates are a key ingredient in chlorophyll, which give leaves their green color.

Green fruit and vegetables are also a top source of vitamin K, which helps to stop calcification of major blood vessels — which raises blood pressure and leads to heart disease.

They are also sources of folate — the natural form of vitamin B9 — which is recommended for all pregnant women.

Numerous studies have shown that this lowers the risk of spina bifida in children, or when an infant is born with the spinal cord sticking out of their back — rather than enclosed by the spine.

BROWN AND WHITE: Anti-viral and anti-bacterial properties

Brown and white fruits and vegetables get their color from ‘flavones’ such as apigenin, luteolin, isoetin and others found in garlic, potatoes and cauliflower.

But they are also major sources of allicin, which studies suggest has anti-bacterial and anti-viral properties.

Very few clinical trials have been carried out to date in humans, but those in the lab showed it could kill off viruses and bacteria — which even led to suggestions last year it could be used against Covid.

At this point, however, it is still unclear whether the compounds have the same effect in humans.

There is also evidence that allicin helps to lower blood pressure by triggering a dilation in blood vessels, similar to as in other vegetables.