Fruits and vegetables come in a rainbow of colors, from vibrant shades of yellow, orange, red, green, to hues of blue and purple. Are you getting enough in your diet? If you aren’t adding purple vegetables to your plate, you’re missing out on some potentially powerful health benefits.
When you browse the produce aisle this year, you’ll likely see more purple vegetables and fruit than ever and some might be a bit unexpected. You might not be accustomed to seeing purple asparagus or purple sweet potatoes but these foods join a growing list of fruits and vegetables dressed in shades of wine and violet. In fact, Whole Foods Market listed purple produce as one of the top dietary trends for 2017.
What’s So Special about Purple Vegetables and Fruits?
Plant-based foods get their colors from pigments that protect against insects and other predators. Although these pigments effectively deter birds and bugs, they actually have health benefits for humans. The plant pigment you’re likely most familiar with is chlorophyll, the coloring that makes green, leafy vegetables and certain crucifers, like broccoli, green. Yet, plants contain hundreds of other pigments and non-pigments, collectively known as phytochemicals, that have antioxidant activity.
As you know, one of the ways cell membranes and the DNA blueprint inside becomes damaged is by exposure to oxygen. In the presence of oxygen, free radicals may form that cause cellular mayhem. Antioxidants help prevent the formation of free radicals and, in turn, protect cells against damage. Other ways chemicals in plants benefit health is by subduing inflammation, optimizing immune health, and by activating enzymes that aid in detoxification.
The pigments that gives purple vegetables and fruits their brilliant hue are called anthocyanins. They are members of a class of phytochemicals called flavonoids. Anthocyanins often look purple but may also come in various shades of dark red or blue, depending upon the pH. Anthocyanins have antioxidant activity in plants, so it’s not surprising that they fight free radicals in humans too. In plants, the antioxidant activity of anthocyanins protects plants against cellular stress like temperature extremes and exposure to ultraviolet light.
Naturally, we’re more concerned about what benefits these pigments have in humans. Anthocyanins are regarded for their anti-inflammatory activity but they also support immune health. One way your immune system protects you against viruses is by producing cells that destroy these unwanted pathogens. One such cell is called a natural killer cell. These cells not only eradicate viruses they also destroy cancer cells.
In one study, researchers gave runners, 250 grams of blueberries daily for 6 weeks. They also ate 375 grams of blueberries before each run. When the researchers measured their blood and urine an hour after exercise, the group that consumed blueberries had higher levels of natural killer cells. Why is this beneficial? Natural kill cells help fight off viruses and lower markers of inflammation and oxidative stress. Researchers believe the anthocyanins in blueberries are likely responsible for these benefits, although it’s hard to separate the impact of anthocyanins from the effect of other phytochemicals in blueberries. However, in a laboratory setting, anthocyanins have strong antioxidant activity.
Heart-Healthy Too?
Another area where purple vegetables and fruit shines is for heart disease prevention. Not only are these foods rich in heart-healthy fiber, anthocyanins and other flavonoids could lower your risk for heart disease. In a study published in the journal Circulation, researchers found that young and middle-aged women, who consumed lots of anthocyanin-rich foods enjoyed a 32% reduction in heart attack risk. This was true even when researchers controlled for other factors that influence heart attack risk. Some of the ways by which anthocyanins may lower the risk of cardiovascular disease are by lowering cholesterol, by reducing oxidation of cholesterol, and by improving endothelial function so that blood vessels are more flexible.
Beyond Blueberries
While blueberries with their intense purple/blue coloration are a prime example of a food rich in anthocyanins, the list of other foods that contain this pigment is extensive. In the fruit department, blackberries, black raspberries, blueberries, cherries, black currants, cranberries, and purple grapes make the grade. In the veggie arena, look for red cabbage, purple carrots, purple sweet potatoes, purple asparagus, eggplant, and purple cauliflower. Darkly pigmented beans and black rice are other lesser known source of anthocyanins.
Are all purple fruits and vegetables rich in anthocyanins? As a general rule, but there are exceptions, purple beets are not a substantial source of anthocyanins. Beets appear purple because they contain betalain pigments that are also antioxidants but are not anthocyanins. That doesn’t mean beets aren’t good for you. In fact, research shows that beetroot juice helps to lower blood pressure, although it’s a bit high in natural sugar.
The Bottom Line
As you can see there’s power in purple, as long as you’re not eating purple gummy bears! With purple vegetables and fruit being trendy right now, you should see more of it when you’re grocery shopping. Keep in mind that purple fruits and vegetables are only one of the plant pigments that offer health benefits. When you “eat the rainbow,” you get the benefits of all the healthful phytochemicals in plants.
A number of studies link plant-based foods with a lower risk of chronic health problems, including cardiovascular disease, type 2 diabetes, obesity, and some forms of cancer. You don’t have to adopt a vegetarian diet to get the benefits of purple vegetables or plant-based foods in general. Focus on adding plant-based foods to every meal and eat a diversity of fruits and vegetables – but don’t forget to add some purple to your plate.
References:
United States Department of Agriculture. “Plant Pigments Paint a Rainbow of Antioxidants”
Biotechnol J. 2006 Apr;1(4):388-97.
J Agric Food Chem. 2014 May 7;62(18):3886-903. doi: 10.1021/jf4044056. Epub 2014 Mar 17.
Appl Physiol Nutr Metab. 2011 Dec;36(6):976-84. doi: 10.1139/h11-120. Epub 2011 Nov 23.
Circulation. “High Anthocyanin Intake Is Associated With a Reduced Risk of Myocardial Infarction in Young and Middle-Aged Women”
Nutrients 2016, 8(1), 32; doi:10.3390/nu8010032.
WebMD. “Beetroot Juice Lowers Blood Pressure”
Am J Clin Nutr September 2003. vol. 78 no. 3 544S-551S.
Harvard T.H. Chan School of Public Health. “Healthy plant-based diet linked with substantially lower type 2 diabetes risk”
Perm J. 2013 Spring; 17(2): 61–66. doi: 10.7812/TPP/12-085.
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