We're Told to 'Eat a Rainbow.' Here's What Each Color Does in Our Body.

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We're Told to 'Eat a Rainbow.' Here's What Each Color Does in Our Body.

Most of us know we should eat different colored fruits and vegetables, but do you know why?




By Evangeline Mantzioris


Hands holding a basket of vegetables


Nutritionists recommend eating a rainbow of fruits and vegetables. This isn't just because they look nice on the plate. Each color signifies different nutrients our bodies need

Phytonutrients are nutrients found in plant foods. At least 5,000 phytonutrients are known, and there are probably many more.

So, what does each color do for our body and overall health?

Red

Red fruit and veg contain antioxidants. Forgotten what they do? Me too. 

Red fruits and vegetables are colored by a type of phytonutrient called "carotenoids" (including ones named lycopene, flavones, and quercetin – but the names aren't as important as what they do). These carotenoids are found in tomatoes, apples, cherries, watermelon, red grapes, strawberries, and capsicum.

These carotenoids are known as antioxidants. You will have heard this name before, but you might not remember what it means. It has something to do with "free radicals," which you've also probably heard of before.

Free radicals are formed naturally in the body as a byproduct of all our usual bodily processes, such as breathing and moving. However, they can also be produced by UVV light exposure, smoking, air pollutants, and industrial chemicals.

Free radicals are unstable molecules that can damage our body's proteins, cell membranes, and DNA. This natural but damaging process is known as oxidation or oxidative stress. It contributes to aging, inflammation, and diseases, including cancer and heart disease.

Importantly, antioxidants "mop up" the free radicals that form in our body. They stabilize the free radicals so they no longer cause damage.

Increasing antioxidants in your diet lowers oxidative stress and reduces the risk of many diseases, including arthritis, type 2 diabetes, heart disease, stroke, and cancer.

Orange

Your parents didn't lie about carrots: orange fruits and veggies are good for our eyes and sight. 

Orange fruits and vegetables also contain carotenoids but differ slightly from red veggies (including alpha- and beta-carotene, curcuminoids, and others). Carrots, pumpkins, apricots, mandarins, oranges, and turmeric are found in these.

Alpha and beta-carotene are converted to vitamin A in our bodies, which is essential for healthy eyes and good eyesight. Vitamin A is also an antioxidant that can target the parts of your body made of lipids (or fats), such as cell membranes.

Vitamin A targets the free radicals building up around our cell membranes and other areas made of lipids, reducing the risk of cancers and heart disease.

Yellow

Yellow fruits and veggies protect your eyes from sun damage (but you should probably still wear sunnies) 

Yellow fruits and vegetables also contain carotenoids and other phytonutrients, including lutein, zeaxanthin, meso-zeaxanthin, and violaxanthin. These are in apples, pears, bananas, lemons, and pineapple.

Lutein, meso-zeaxanthin, and zeaxanthin are particularly important for eye health. They can reduce the risk of age-related macular degeneration, which causes blurring of central vision.

These phytonutrients can also absorb UV light in your eyes, acting like sunscreen for the eyes and protecting them from sun damage.

Green

Your parents were right again. Greens are suitable for, well, lots. Read on. 

Green fruits and vegetables contain many phytonutrients,  including chlorophyll (which you probably remember from high school biology), catechins, epigallocatechin gallate, phytosterols, nitrates,  and also an essential nutrient known as folate (or vitamin B9). These are found in avocados, Brussels sprouts, apples, pears, green tea, and leafy vegetables.

These also act as antioxidants and,, therefore,, have the benefitsdescribed above for red veggies. However, this group also promotes vasodilation, which is essential in keeping blood vessels healthy,

These phytonutrients help make our blood vessels more elastic and flexible, allowing them to widen or dilate. This improves blood circulation and blood pressure, reducing our heart and other vessel complications and disease risk.

Folate is recommended before pregnancy because it helps reduce the risk of neural tube defects (such as spina bifida) in babies. During the first few weeks of pregnancy, it also helps develop the fetal nervous system, as it has been shown to promote healthy cell division and DNA synthesis.

Blue and purple

Forgotten where you put your keys? You haven't been eating your blueberries. 

Blue and purple produce contain other phytonutrients,  including anthocyanins, resveratrol, and tannins. They are found in blackberries, blueberries, figs, prunes, and purple grapes. As explained under red fruit and vegetables, anthocyanins also have antioxidant properties, which can reduce the risk of cancer, heart disease, and stroke.

Evidence has indicated that they may also improve memory. This is thought to occur by improving signaling between brain cells and making it easier for the brain to change and adapt to new information (brain plasticity).

Brown and white

Garlic: may ward off bacteria as well as vampires. 

Flavones, phytonutrients found in foods such as garlic, potatoes, and bananas, color brown and white fruits and vegetables.

Another phytonutrient found in this color of vegetables, particularly garlic, is allicin. Allicin has been shown to have antibacterial and antiviral properties.

Most of this research is still at the lab bench, and few clinical trials have been conducted in humans. Still, lab-based studies have found that it reduces microorganisms when grown under laboratory conditions. In systematic reviews, 

Allicin has also been found to normalize high blood pressure by promoting blood vessel dilation.

How can I get more veggies in my diet?

Colored fruits, vegetables, herbs, spices, legumes, and nuts provide many phytonutrients. Promoting rainbow fruits and vegetables is a simple strategy for maximizing health benefits across all age groups.

However, most don't get the recommended fruit and vegetables daily. Here are some tips to improve your intake:

1. when doing your fruit and vegetable shopping, include a rainbow of colors in your shopping basket (frozen varieties are wonderful

2. try some new fruits and vegetables you haven't had before. The internet has tips on many different ways to cook veggies

3. buy different colors of the fruit and vegetables you usually, like apples, grapes, onions, and lettlettuceeat the skin, as the phytonutrients may be present in the skin in higher amounts

5. Don't forget herbs and spices also contain phytonutrients, so add them to your cooking (they also make vegetables more appealing!)

Evangeline Mantzioris is Program Director of Nutrition and Food Sciences, Accredited Practising Dietitian, University of South Australia.

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