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Eat a rainbow!
Colors of vegetables

Vegetables are colorful. Have you ever wondered what gives fruits and vegetables their eye popping hues? Why carrots are orange, why broccoli and spinach are green? In fact, their colors make them appealing to the eyes. Have you ever wondered how they got their colors? Well, the answer is here – phytochemicals! These are the naturally occurring plant chemicals and provide plants with color, odor and flavor.  Once we eat them, however, research shows they can influence the chemical processes inside our bodies in helpful ways. Healthy eating quotes often guide people to "eat the rainbow". It's a simple way of reminding you that a variety of fruits and vegetables in our diet will provide vitamins and minerals that we need. It also calls out the fact that we can learn a lot about our food just by looking at it.

Different colors are caused by varying plant pigments that add nutritive value; each color family has specific health benefits. The deeper the coloring, the more effective will be the nutrient! However, the amount of vegetables we eat isn't the only thing we need to take into consideration. We also need to attempt to consume fruits and vegetables in a variety of different colors. This is because the different colors of fruits and vegetables indicate the different nutrients they contain. Consuming a rainbow of them help insure we get enough of the different nutrients we need for good health. Here's what it means, and how it works.

Phytochemicals – The hidden ingredient in food that repairs everything!
Phytochemicals usually have antioxidant properties — that is, they help prevent and fight cell damage 
What are phytochemicals?

Plant-based foods, such as whole grains, fruits and vegetables contain significant amounts of bioactive phytochemicals, may provide desirable health benefits beyond basic nutrition to reduce the risk of chronic diseases. Plants use phytochemicals as a defense against potential threats which may include bacteria, viruses, and fungi. When we consume these plants as fruits and vegetables, these defenses are passed along to us in order to fight off threats to our health. Brightly colored fruits and vegetables contain the highest concentrations of phytochemicals, and may help us fight off diseases such as cancer and heart disease.
Yet every fruit and vegetable has a unique complement of vitamins, minerals, fiber, and phytonutrients (specifically refers to compounds that have a positive effect. In other words, all phytonutrients are phytochemicals, but not all phytochemicals are phytonutrients.) that provide benefits. So it's important to sample from the complete color spectrum as well as to eat a variety within each color group.  Phytochemicals contain lot of antioxidants as well in them. Antioxidants are substances that protect cells in our body from free radical damage that can occur from exposure to certain chemicals, smoking, pollution, radiation, and as a byproduct of normal metabolism. Most experts believe that getting antioxidants from food is the most healthful way to obtain them but they may also be taken as supplements.

Findings from laboratory studies have shown that phytochemicals have the potential to stimulate the immune system, prevent the DNA damage and help with DNA repair, block substances we eat, drink and breathe from becoming carcinogens, reduce the kind of oxidative damage to cells that can spark cancer, slow the growth rate of cancer cells and help to regulate hormones for healthy living. Thus, phytochemicals play an incredible role for being healthy. Now, let’s see the different types of phytochemicals. So what do the different colors mean?

Red, blue and purple veggies are rich in lycopene and anthocyanins
Red, Blue and Purple

Red, blue and purple vegetables usually contain anthocyanins, and red vegetables often contain lycopene. Red vegetables are colored by a natural plant pigment called lycopene. Lycopene is a powerful antioxidant that can help reduce the risk of cancer and keep our heart healthy. Anthocyanins have antioxidant properties that help limit damage caused to our cells by free radicals and may also lower the risk for heart disease, stroke, cancer, macular degeneration and memory problems. These brightly colored vegetables often also contain essential vitamins and minerals such as potassium, vitamin A, vitamin C and folate. Compounds in these vegetables also help keep our vision and immune system healthy and limit our risk for urinary tract infections.

 Research findings and experiments on cell culture, animal models, and human clinical trials, show that anthocyanins possess antioxidative and antimicrobial activities, improve visual and neurological health, and protect against various non-communicable diseases. These studies confer the health effects of anthocyanins, which are due to their potent antioxidant properties. Different mechanisms and pathways are involved in the protective effects, including free-radical scavenging and inflammatory cytokines signaling (preventing from inflammations in the body). Therefore, this review focuses on the role of anthocyanins as natural food colorants and their nutraceutical properties for health.

Some white foods, like garlic, contain allicin, which may help lower your risk for high blood pressure, high cholesterol, cancer and heart disease
Orange and Yellow

The compounds that give orange and yellow vegetables their color are called carotenoids. Carotenoids may help improve the immune function and lower the risk for heart disease, vision problems and cancer. The carotenoids that have been most studied in this regard are beta-carotene, lycopene, lutein, and zeaxanthin. A well-known carotenoid called Beta carotene is found in sweet potatoes, pumpkins and carrots. It is converted to vitamin A, which helps maintain healthy mucous membranes and healthy eyes. Furthermore, lutein and zeaxanthin may be protective in eye disease because they absorb damaging blue light that enters the eye.  Folate, potassium, bromium and vitamin C are also often found in orange and yellow fruits and vegetables.

White vegetables

White vegetables get their color from polyphenol compounds with antioxidant properties called anthoxanthins (Anthoxanthins are water-soluble pigments which range in color from white or colorless to a creamy to yellow, often on petals of flowers), which may help lower your risk for heart disease and cancer. Some white foods, like garlic, contain allicin, which may help lower your risk for high blood pressure, high cholesterol, cancer and heart disease. These foods may also be good sources of potassium, vitamin C, folate, niacin and riboflavin. A study published in the April 2017 issue of "World Journal of Gastroenterology" found that consuming more white fruits and vegetables may help protect against colorectal cancer. [Source:healthyeating]

When we think of health, we think green!
Green vegetables

Chlorophyll gives green vegetables their color. Some of these vegetables also contain indoles, which may lower the risk for cancer, and lutein, which helps prevent problems with the vision. They are useful in reducing the risk of cancer and heart disease since they are low in fat, high in dietary fiber, and rich in folic acid, vitamin C, potassium and magnesium, as well as containing a host of phytochemicals, such as lutein, beta-cryptoxanthin, zeaxanthin, and beta-carotene. Lutein and zeaxanthin, carotenoids found in dark-green leafy vegetables, are concentrated in the eye lens and macular region of the retina, and play a protective role in the eye. They protect against both cataract and age-related macular degeneration, the major cause of blindness in the elderly. Because of their high magnesium content and low glycemic index, green leafy vegetables are also valuable for persons with type 2 diabetes. The high level of vitamin K in greens makes them important for the production of osteocalcin, a protein essential for bone health. Foods high in boron (broccoli, avocados etc..) work to promote bone density by supporting calcium, magnesium and other trace minerals.

Thus, diets high in vegetables are extensively recommended for one's health-promoting properties. Vegetables have historically held a place in dietary guidance because of their concentrations of vitamins, specially vitamins C and A; minerals, especially phytochemicals and antioxidants.

Phytochemicals reference table

Food Phytochemicals Benefits
Apples Flavonoids Protect against cancer, lower cholesterol
Beans Flavonoids (saponins) Protect against cancer, lower cholesterol
Broccoli Indoles, isothiocyanates Protect against cancer, heart disease and stroke
Carrots Beta-carotene Antioxidant
Flaxseed Isoflavones Protect against cancer, lower cholesterol
Garlic Allium (allyl sulfides) Protect against certain cancers and heart disease, boost the immune system
Grains Isoflavones Protect against cancer, lower cholesterol
Onions Allium (allyl sulfides) Protect against certain cancers and heart disease, boost the immune system
Sweet potatoes Beta-carotene Antioxidant
Soy (soybeans) Isoflavones Protect against cancer and heart disease, strengthen bones
Tomatoes Flavonoids Protect against cancer, fight infection

References

  • https://lifehacker.com/what-it-means-to-eat-the-rainbow-1594799068
  • http://www.aicr.org/reduce-your-cancer-risk/diet/elements_phytochemicals.html
  • https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5613902/
  • https://science.howstuffworks.com/innovation/edible-innovations/phytochemical3.htm
  • https://vegetarian-nutrition.info/green-leafy-vegetables/