By Milette Siler, registered dietitian
You might have heard the adage “5 a day” for fruit and vegetable servings as a goal for helping us feel our best and reduce our risk of developing chronic disease. Did you know that variety is just as important as quantity? There are categories of benefits from different substances called phytochemicals, which are naturally occurring, helpful compounds found only in plants. Each group of phytochemicals has different benefits for our health. Often, these substances are quite colorful, and we can identify the family of benefit by the color.
Blue and Purple
Blue and purple (and some deep red) plant foods owe their coloring to the presence of anthocyanin, a group of compounds from the flavonoid family most closely linked to heart health, especially for women. The Nurse’s Health Study followed 93,600 women over 18 years and found that those that ate at least three servings per week were 34% less likely to suffer from myocardial infarction1. Another area of benefit that has been well-studied is brain health. Anthocyanins are linked to improved memory and may even be able to reverse some aspects of age-related cognitive loss.
Blue/purple foods to try: Eggplant (with skin), purple carrots, red cabbage, black rice, cherries
Research shows the strongest links between reduction of cancer risk with consumption of green foods, primarily leafy greens and cruciferous vegetables (like broccoli and brussels sprouts). Green indicates powerful phytochemicals such as indoles and isothiocyanate, both powerful antioxidant supporters, with strong evidence supporting their ability to block tumor growth, repair damaged DNA, and decrease estrogen’s power to promote certain cancers. They are also rich in folic acid, vitamin K, and potassium, which helps keep our blood pressure naturally low. Unfortunately, Americans eat less of this color than any other, according to recent CDC reports2, but the good news is that there is a lot of room for improvement!
Green foods to try: bok choy, green cabbage, watercress, mustard greens, arugula
Foods in this category have one thing in common – the presence of lutein, which accounts for the rich color. Scientists are still learning about lutein’s many benefits, but evidence is very strong regarding its impact on eye and brain health, particularly with a preventive benefit against age-related macular degeneration3. These foods are also typically rich in vitamin C, which helps with collage repair and has antioxidant and immune benefits as well.
Yellow/green foods to try: kiwi (try a yellow variety!), pistachios, spinach, pumpkin
Lycopene, the predominant carotenoid that provides the beautiful red color, is one of the more well-studied phytochemicals. Lycopene is linked to a reduced risk of developing several cancers, with the strongest evidence showing benefit for lung and prostate cancer, and some evidence showing benefit for breast, cervical, and mouth cancers4. We know that foods containing lycopene are better absorbed into the body after being heated which is why cooked tomato sauce offers more antioxidant benefit than raw tomatoes.
Red foods to try: guava, watermelon, sun-dried tomatoes, apricot
These foods are rich in beta-carotene and other carotenoids, which our body needs to make vitamin A, a fat-soluble vitamin essential for strong immune function, skin, bone, and eye health. In addition, vitamin A may play a role in reducing our risk of stomach and lung cancer, although this link is not well established5.
Yellow/orange foods to try: butternut squash, mango, cantaloupe, turmeric
While not technically part of the rainbow, it is important to note that there are many foods where a bright pigment doesn’t tout the phytochemical benefit. Anthoxanthins, a family of flavonoid that ranges from colorless to white, are often found naturally alongside allium compounds. These powerful substances have known anti-inflammatory and anti-tumor benefits as well as benefits for arthritis and other inflammatory diseases, and stomach and colorectal cancers5.
White foods to try: cauliflower, chives, garlic, shallots, jicama, ginger, mushrooms
- Liobikas J, Skemiene K, Trumbeckaite S, Borutaite V. Anthocyanins in cardioprotection: a path through mitochondria [published online March 30, 2016]. Pharmocol Res. doi: 10.1016/j.phrs.2016
- Abdel-Aal el-SM, Akhtar H, Zaheer K, Ali R. Dietary sources of lutein and zeaxanthin carotenoids and their role in eye health. Nutrients. 2013;5(4):1169-1185. Published 2013 Apr 9. doi:10.3390/nu5041169