NTK #2: How Rainbows Improve Your Health

NTK #2: How Rainbows Improve Your Health

Arrays of colors, such as rainbows, are often written off as childish or reserved for off the wall holiday parties. The good news is for all you colourful people that eating in rainbows, not actually eating rainbows mind you, has been shown to improve not only physical health but also mental health.


Proteins and carbs, normally portrayed in such boring colors as brown or white, need to be limited. Aiming for colorful foods to brighten up every meal allows for vegetables and fruits to be included more often and in higher quantities (btw that’s because veggies and fruits are colorful if you haven’t seen them before). According to Core Performance, planning a meal with three colors each night at dinner alone sums to over 500 servings of vegetables over a 6 month time period! One source even goes so far to mention that literature associates bland beige foods with food offered to suffering people.


Now for the scientific talk, colorful foods contain phytochemicals which are only produced naturally by plants. Often the color of these fruits is directly associated with the substances they contain such as vitamins, minerals, and fiber because of a direct synergistic relationship with phytochemicals but not always. Plants can be tricky little buggers. Phytochemicals act in a variety of different ways and research is still needed to iron out the nitpicky details, but it is thought one role is working as antioxidants, which protect the body from cancer causing substances and regulate/protect essential nutrients. Accord to Kathy Hoy, EdD, RD, a nutrition researcher manager, eating a variety of colorful foods is a pragmatic way to achieve optimal nutrition.


Now for the psychotherapy babble. In a randomised control study of 124 patients in the European Journal of Clinical Nutrition, less than three weeks proved that mood and cognition were linked to diet. Those patients in the study who received milk drink containing probiotics had improved mood and cognition compared to the group receiving the placebo. This effect has also been directly related to BMI on multiple occasions and think we are all smart enough to figure out the pathophysiology there. An article from health Harvard creates a very relevant analogy. Compare your body to a car, the motor being the brain, your stomach being the gaaaaas (or petrol) tank. Does a car work better on low-premium or the real premium? We all know which one is cheaper but if you use that one your car won’t last as long, will need more maintenance, and won’t travel as far. TL;DR: if you want to be a high-functioning person and want to live forever, then you shouldn’t take the cheap route.


A newly emerging field of nutritional psychiatry, has even more to say on this matter if the car analogy wasn’t doing it for you. That saying about the key to the heart of a man is through his stomach was apparently on to something. Serotonin is produced predominantly (95%) in the gastrointestinal tract. The neurons here are not surprisingly guided by the bacteria in your intestinal microbiome which is *dramatic pause* linked to what you put in your mouth. It seems more important now to protect your GI tract from inflammation and bad bugs doesn’t it? A study mentioned in an article by Harvard demonstrated that compared to the traditional diets of Mediterranean and Japanese diets, the Western diet has shown the risk of depression is 25-35% higher in a Western diet. Traditional diets tend to be higher in vegetables, fruits, unprocessed grains, fish, and seafood, which sounds pretty colorful if you ask me. Harvard recommends eating a clean diet for a couple weeks, see how you feel. If you don’t feel any noticeable differences, start eating some of your old diet and then see the results.


If you aren’t interested in this personally, too addicted to fast food, or think it’s too mainstream to eat healthy, that’s quite alright. But as doctors we owe it to our patient to give them the utmost care and best health opportunities. We received very little nutrition therapy as it has not often been deemed important to health, but the changing perspective has researchers stunned. So take a read, learn something, and maybe even impress your supervisors.


Crazy inspired? Here is your colour guide to your new diet, ahem I mean lifestyle.


Red Foods:

Red foods contain lycopene and anthocyanins and improve heart and circulatory health, improve memory, support urinary tract health, and decrease the risk of some cancers.

  • Cherries – Protect against HD, DM, and arthritis. Relieve pain from gout and arthritis!
  • Cranberries – Can help prevent bacteria from adhering to the urinary tract wall, and treats inflammation.
  • Red Capsicums – increased immunity, improved digestion, lower cholesterol, and decreased risk of CRC!
  • Tomatoes – Decrease risk of CVD, and DM.
  • Beets – Optimize digestive health, decrease inflammation, and fight HD.
  • Strawberries, Raspberries, Watermelon, Pink Grapefruit, Pomegranate, Red Kidney Beans, Red Apples, Red Grapes, Red Pears, Radishes, Radicchio, Red Onions, Red Potatoes, and Rhubarb.

Orange Foods:

High in antioxidants, specifically vitamin C, carotenoids, and bioflavonoids. Linked to better skin and eye health, increased immunity, decreased risk of cancer, and a healthier heart.

  • Carrots – Maintains integrity of skin and boost the immune system, helping to reduce risks of skin cancer (1 in 2 Australians people!)
  • Oranges – Increased immunity, CV health, and healthier skin. Also strengthen bones and improve digestion!
  • Sweet potatoes – Promote healthy skin, increased immunity, and decrease the risk of cancer.
  • Peaches – Prevent cellular damage, promote healthier digestion, reduce inflammation and help reduce cancer risk.

Others: Apricots, Cantaloupe, Cape Gooseberries, Golden Kiwifruit, Mangoes, Nectarines, Papayas, Persimmons, Tangerines, Butternut Squash, and Rutabagas.


Yellow Foods:

Promote good digestion and optimal brain function. Additionally, they increase immunity, decreased risk of certain cancers, and give healthier eyes and skin.

  • Pineapple – High in bromelain which helps regulate fluids and aids in digestion. Decreased HD, cancer, cataracts, and stroke.
  • Yellow Capsicums – Increased immunity, healthier skin, and decreased HD.
  • Star Fruit – Increased immunity, increased bone health, and helps muscles respond.

Others: Yellow Apples, Yellow Figs, Grapefruit, Golden Kiwifruit, Lemon, Yellow Pears, Yellow Watermelon, Yellow Beets, Yellow tomatoes, and Yellow Winter Squash.


Green Foods:

Contain lutein and indoles. Green food reduces the risk of certain cancers, improves eye health, rejuvenated musculature/bone, and stronger teeth.

  • Broccoli – Stronger teeth, bones, and muscles, with a reduced risk of cancer.
  • Spinach – Strengthen bones.
  • Kiwi – Decreased risk of HD and promotes overall constitutional health.
  • Kale

Others: Avocados, Green Apples, Green Grapes, Honeydew, Limes, Pears, Artichokes, Arugula, Asparagus, Broccoflower, Broccoli Rabe, Brussel Sprouts, Chinese Cabbage, Green Beans, Green Cabbage, Celery, Chayote Squash, Cucumbers, Endives, Leafy Greens, Leeks, Lettuce, Green Onions, Green Peppers, Peas, Snow Peas, Sugar Snap Peas, Watercress, and Zucchini.


Blue/Purple Foods:

Anthocyanins, aka antioxidants and anti-aging. They promote bone health and reduce the risk of cancer, improve memory, increase urinary tract health, and increase circulation and microcirculation.

  • Blueberries – Improved cholesterol, increased UT health, and boosts brain activity.
  • Blackberries – Promotes calcium absorption and bone health, increased immunity, improved CV health, lower cholesterol, and decreases cancer risk.
  • Plums – Help metabolise carbohydrates, proteins, and fat. Promote bone health.
  • Eggplant – Promote strong bones and teeth, high in fiber.

Others: Black Currants, Dried Plums, Elderberries, Purple Figs, Purple Grapes, Raisins, Purple Asparagus, Purple Cabbage, Purple Carrots, Black Salsify, Purple-fleshed Potatoes, and Purple Belgin Endive.


White Foods:

(Non-refined). Lower cholesterol, decrease blood pressure, increased immunity, reduced risk of heart disease. Specifically they enhance the immune system and help cells to recover.

  • Garlic – Increase heart health and decrease cancer risk. Anti-microbial. (oh and keeps the vampires away – direct link to improved health)
  • ONions – lower blood sugar, improve heart health by lowering blood pressure and cholesterol, and slows tumor growth while increasing cellular protection.
  • Cauliflower – Was trying to avoid the technical talk here, but cauliflower is just too dog gone good. It has 52 mg of vitamin C in one cup compared to a medium size orange that has 64 mg. Talk about the underdog!

Others: Ginger, Turnips, Jicama, White Corn, Shallots, White Potatoes, Parsnips, Mushrooms, Kohlrabi, Jerusalem Artichoke, White Peaches, and White Nectarines.


And just for those of you who are inspired, but not very creative, my wonderfully reputable source aka Buzzfeed provides direct links to 21 colourful and fascinating meals. I’ve tried 10 out of the 21 and haven’t looked back.



Disclaimer: Primum is not responsible for any healthier humans that are stressing the already overpopulated world.



Core Performance

Today’s Dietitian: The Magazine for Nutrition Professionals

Food Insight

The Food Network


Nutritional Psychiatry: Harvard

The National

Health Harvard

Nutritional medicine as mainstream in psychiatry, Sarris J, et al. Lancet Psychiatry. 2015


Would like to read some more? Here are some research articles:







And here are some systematic reviews, meta-analyses if you have less time: