I have heard about the rainbow diet from a long time ago, may be like 1999. I tried to find the best website that could explain its main principles and this is what came up:
The Rainbow Diet
The phytochemicals in red foods are carotenoids and anthocyanins. One of the most abundant carotenoid is lycopene. Lycopene helps reduce damage from free radicals in your body and it also prevents heart disease, cancer, prostrate problems, and reduces the skin damage from the sun. These red foods help memory function, urinary tract health, and makes your heart healthy.
Blue/Indigo/Violet Foods: The blue, indigo, and violet foods are great for their anti-aging properties. These foods have tons of antioxidants, which are called anthocyanins and phenolics. They help improve circulation and prevent blood clots, so they are great for the heart and can help prevent heart disease. They are also known to help memory function and urinary tract health and to reduce free radical damage.
Carotenoids are the powerful phytochemical in orange foods, and they are what give the foods their color. Carotenoids repair DNA and help prevent cancer and heart disease, as well as strengthening our vision.These orange foods also give us the right amount of potassium and vitamin A, which keeps our eyes and skin healthy, and protects against infections. They are also known to boost the immune system because of the vitamin C content in many of them.
Yellow Fruits/Veggies Yellow foods are high in antioxidants like vitamin C. Vitamin C keeps our teeth and gums healthy, helps to heal cuts, improves the mucus membranes (like when we have colds), helps to absorb iron, prevents inflammation, improves circulation, and therefore prevents heart disease. Some of the darker ones also cross over with the health benefits of orange foods
Greenish White Fruits/Veggies The strong phytochemical in these whitish/greenish vegetables is called allicin and allium, which create an anti-bacterial, anti-fungal, and anti-viral chemical environment in your body.
Green Fruits and Vegetables: These foods have the phytochemicals sulforaphane and indoles, which both prevent cancer. They are also good for the circulatory system and have good vitamin B and minerals. Green vegetables also help with vision, and with maintaining strong bones and teeth. Some of the yellower green vegetables have carotenoids lutein and zeaxanthin that help to prevent cataracts and eye disease, as well as osteoporosis.
There is a juicing diet that Don Tolman offers in his lectures for the people with terminal deceases. He recommends one day of red, the next day on orange, then yellow etc - all rainbow colors juices: 5-6 or 7 days a week. Each day is a different color juice. It can be cleansing or you should stay on this diet till your total recovery. The results are outstanding but the diet is hard to folow and needs your full dedication and deep belief.