December 2016 Issue
Ruby Red Produce
By Judith C. Thalheimer, RD, LDN
Vol. 18, No. 12, P. 22
Enjoy an in-depth look at some of the holiday's most healthful choices that can lower chronic disease risk.
Nutrient-dense and phytochemical-rich red winter fruits and vegetables are ideal for bringing nutrition and visual appeal to the holiday table and beyond.
In Chinese medicine, red foods are thought to nourish the heart.1 In Indian Ayurveda, they're believed to support healthy lymphatic flow in the fall and winter.2 Today, we understand that the red color in these foods comes from phytochemicals like flavonoids and carotenoids, known for their antioxidant powers and their role in reducing the risk of cardiovascular disease (CVD) and cancers.3,4
"Fruits and vegetables as a group have antioxidant activity and anti-inflammatory effects, and they also modulate production and uptake of cholesterol, regulate blood pressure, promote healthy endothelial function, reduce platelet aggregation, and more," says Elizabeth Pivonka, PhD, RD, president and CEO of the Produce for Better Health Foundation. "And red produce have all of these benefits." Each red fruit and vegetable has its own laundry list of health-promoting phytochemicals, along with a host of vitamins and minerals and plenty of fiber. In the dark days of winter, there's nothing like red to warm our hearts—and protect them, too. Here's an in-depth look at some of the season's reddest, healthiest choices.
The pomegranate is a traditional symbol of Christmas in Greece. In the winter months in the Mediterranean region, the round pink fruits hang like decorations on the green trees.5 Pomegranates are rich in the red-pigmented flavonoids called anthocyanins. These powerful antioxidants have been shown to lower cholesterol levels and reduce blood clotting,6 and high intake of anthocyanin-rich foods has been associated with lower concentrations of inflammatory chemicals and fewer markers of oxidative stress.3 They also have been linked to improved insulin sensitivity and lower blood pressure, and researchers have studied their role in controlling obesity, diabetes management, and improving visual and brain functions.7 "Intake of flavonoids like anthocyanins has been inversely associated with coronary heart disease," says Rachel K. Johnson, PhD, MPH, RD, FAHA, a professor of nutrition at the University of Vermont and a spokesperson for the American Heart Association. "A number of factors contribute to this link, including the potential for flavonoids to reduce atherosclerosis by inhibiting LDL oxidation, and their involvement in interfering with platelet aggregation and adhesion."
Pomegranates also are rich in another polyphenol: ellagic acid.8 Ellagic acid has been investigated for its ability to prevent or slow the spread of cancer cells, along with its anti-inflammatory effects and its potential to reduce obesity and related metabolic complications such as insulin resistance, type 2 diabetes, nonalcoholic fatty liver disease, and atherosclerosis.9
While it may seem remarkable that one food can have an impact on so many different conditions, pomegranates, while impressively rich in phytochemicals, aren't alone in having broad impact on chronic disease. "Many diseases have shared mechanisms," Pivonka says, "so the healthful effects of fruits and vegetables can impact a wide range of conditions." Pivonka cites a 2012 study by Boeing and colleagues that found convincing evidence that fruits and vegetables play a role in decreasing risk of high blood pressure, coronary heart disease, and stroke. "Evidence says it's probable that they reduce risk of cancer and diabetes, and it's possible that they play a role in asthma, body weight, cataracts and macular degeneration, COPD, dementia, osteoporosis, and rheumatoid arthritis," Pivonka says.
As with other fruits and vegetables, more than just phytochemicals contribute to the health effects of pomegranates. Just one-half cup of the ruby-colored seed sacs called arils provides 18% DV of blood-clotting vitamin K and 15% DV of tissue-repairing vitamin C.10 Vitamin C is a powerful antioxidant that supports a healthy immune system, helps with wound healing, and aids in the growth and repair of body tissues.11 Pomegranates also provide 14% DV of satiating dietary fiber.10 "We know that fiber from fruits helps lower blood cholesterol levels, which helps decrease risk of CVD," Johnson says. "The fiber in whole fruits like pomegranates also provides a feeling of fullness with fewer calories, helping to maintain a healthy weight, reducing the risk of heart disease."
Choose pomegranates that are plump, round, and heavy for their size. They will last for about one month in a cool, dry area, or up to two months in the refrigerator.12
Whether strung into garlands or gelled into "sauce," the cranberry is a mainstay of many holiday traditions. Native to North America, this hard red berry reportedly got its name from the pilgrims, who thought its flower resembled the head of a crane.13 While cranberries, like pomegranates, get their red color from the phytochemical anthocyanin, the most famous phytochemicals in cranberries may be the ones with antibacterial properties. Cranberries have been used for decades for prevention and treatment of urinary tract infections (UTIs), and also are recommended to fight tooth decay and stomach ulcers.13,14 The benzoic acid in cranberries is excreted in the urine as hippuric acid, which is known to inhibit bacterial growth. But it would take more than four liters of cranberry juice per day to achieve the levels of urine acidity necessary for this effect.15
Cranberry's ability to fight pathogens like E. coli is more likely due to another phytochemical, A-type proanthocyanidin, a colorless compound that prevents the adhesion of bacteria to cell membranes.16 While a 2008 Cochrane review concluded that cranberry juice may decrease the number of UTIs in women who are prone to them, an update of that review published in 2012 concluded that "cranberry juice cannot currently be recommended for the prevention of UTIs."14,17 But that doesn't mean there's no benefit to eating cranberries. Beyond their antibacterial attributes, proanthocyanidins also are known for their strong antioxidant properties and may reduce the risk of CVD and cancer.18
"Part of the reason fruits and vegetables are so beneficial is that they have a large impact at the cellular level," Pivonka says. "They contain vitamins and minerals that are very important for cellular function throughout the body." One cup of whole cranberries has 22% DV vitamin C, 18% DV manganese, and 6% DV vitamin K, all of which are known to support bone health, among other important cellular roles.19
When buying fresh cranberries, make sure you choose berries that are firm and not shriveled. Cranberries keep for up to two months in the refrigerator and can be frozen for future use.12 "I make my own cranberry sauce every year; it's very easy," says Nancy Farrell, MS, RD, a spokesperson for the Academy of Nutrition and Dietetics. "Dried cranberries are very versatile. They can be tossed in salads or oatmeal or baked into muffins and breads, and they're great in bread stuffing." Cranberries are so tart that they're not palatable without sweetener. Consumers watching their calorie or sugar intake should be aware that all dried cranberries are sweetened.
Perhaps the food with the richest ruby color is red beets. The deep red juice is used commercially as a food coloring and can be a natural dye for yarn, fabric, and even hair. The red color comes from betalains, the reddish pigments in foods not colored by anthocyanins. Betalains get their name from the Latin genus for beets, Beta. Potent antioxidants, betalains have been found to support cardiovascular health by interfering with the oxidation of LDL cholesterol in the formation of plaque.20
Beets are one of the top sources of a phytochemical compound with a name similar to betalain—betaine.21 There's evidence that betaine may protect internal organs, improve vascular risk factors, and enhance performance.22 Betaine protects cells, proteins, and enzymes from environmental stress and lowers homocysteine levels in the blood.21,22 It's also a methyl donor; inadequate dietary intake of methyl groups can lead to alteration in liver metabolism that may contribute to various illnesses, including cardiovascular and liver diseases.22
Besides an impressive complement of phytochemicals, one cup of these earthy roots also provides an excellent source of bone-building manganese (22% DV) and 37% DV folate. While most Americans get plenty of folate from enriched wheat flour, getting enough of this nutrient may be a concern for those on a gluten-free diet. Adequate intake of folate is necessary to prevent birth defects such as neural tube defects. Beets also are a very good source of healthful fiber (15% DV), antioxidant vitamin C, and potassium (13% DV). "We know that diets rich in potassium can help to maintain healthy blood pressure and can even have a blood pressure-lowering effect," Johnson says.
For those interested in trying whole beets, recommend they choose smaller beets with firm, smooth skins. If the leaves are attached, they shouldn't be wilted.12 To store, remove stems about an inch above the root and refrigerate in a perforated plastic bag for up to three weeks.12 The leaves can be eaten raw or cooked. "Beets can be an acquired taste," Farrell says, "but they are making headway in the marketplace. Beets are more common on restaurant menus, and you can even find beet chips in the snack aisle. They're great roasted, but they also can be baked, boiled, or sautéed." Beets are a festive addition to any holiday table. "For many people of Eastern European decent, beet soup called borscht is very traditional at holiday time," Farrell says. "It's simple to make and delicious served hot or cold with a dollop of sour cream on top." Individuals who want to increase their intake of beets or beet juice should be cautioned that betalain can cause urine and feces to turn red. This condition can be mistaken for rhabdomyolysis or colon damage, or could potentially mask conditions that cause blood in the urine.20
Red fruits and vegetables like the nutrition powerhouses described above are excellent additions to any diet, and their vibrancy and availability in the winter months make them ideal recommendations for clients looking to enjoy good eating and good health all year long. "Like the phytochemicals in all fruits and vegetables, those found in red produce may help reduce the risk of atherosclerosis, the buildup of fatty deposits in artery walls," Johnson says. "These compounds may be important in reducing the risk of many conditions, including cardiovascular disease. The American Heart Association recommends at least four to five servings per day of fruits and vegetables based on a 2,000-calorie diet as part of a healthful lifestyle that can lower your risk for cardiovascular disease." Red produce doesn't have a monopoly on healthful phytochemicals, nor is it the only source of healthful vitamins, minerals, and fiber, but encouraging clients to eat red can be helpful nonetheless. "While all fruits and vegetables have positive health effects, the benefit of talking about color is that it encourages people to eat a wide variety," Pivonka says.
For clients who like to deck the halls for the holiday season, there may be one caution to offer: "My understanding is that the color red in-and-of-itself creates an environment that makes us want to eat more," Farrell says. "When I'm talking to my patients about eating around the holiday season, I actually recommend they decorate in silver, gold, and green, and just use little sprinkles of red." Red holiday foods on the table may be just the thing.
— Judith C. Thalheimer, RD, LDN, is a freelance nutrition writer, a community educator, and the principal of JTRD Nutrition Education Services, LLC.
1. Sheppard D. The Tao of food: nutrition in Chinese medicine. Desert Health website. http://deserthealthnews.com/stories/the-tao-of-food-nutrition-in-chinese-medicine/
2. Douillard J. Eat red: lymph cleansing foods. John Douillard's LifeSpa website. http://lifespa.com/eat-red-lymph-cleansing-foods/. Published May 23, 2014.
3. Higdon J. Flavonoids. Linus Pauling Institute Micronutrient Information Center website. http://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/flavonoids. Updated February 2016. Accessed September 28, 2016.
4. Higdon J. Carotenoids. Linus Pauling Institute Micronutrient Information Center website. http://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/carotenoids. Updated August 2016. Accessed September 28, 2016.
5. Hall H. Pomegranates for Christmas. Peter Sommer Travels website. http://www.petersommer.com/blog/food/pomegranates-for-christmas/. Updated December 23, 2012.
6. Thompson K, Pederick W, Santhakumar AB. Anthocyanins in obesity-associated thrombogenesis: a review of the potential mechanism of action. Food Funct. 2016;7(5):2169-2178.
7. Tsuda T. Dietary anthocyanin-rich plants: biochemical basis and recent progress in health benefits studies. Mol Nutr Food Res. 2012;56(1):159-170.
8. Pomegranates & health. Pomegranate Council website. http://pomegranates.org/index.php?c=3. Published 2011. Accessed September 28, 2016.
9. Kang I, Buckner T, Shay NF, Gu L, Chung S. Improvements in metabolic health with consumption of ellagic acid and subsequent conversion into urolithins: evidence and mechanisms. Adv Nutr. 2016;7(5):961-972.
10. United States Department of Agriculture Agricultural Research Service. National Nutrient Database for Standard Reference Release 28. https://ndb.nal.usda.gov/ndb/search. Updated May 2016.
11. Moore M. How vitamin C supports a healthy immune system. Academy of Nutrition and Dietetics website. http://www.eatright.org/resource/food/vitamins-and-supplements/types-of-vitamins-and-nutrients/vitamin-c. Updated May 2016. Accessed October 2, 2016.
12. Fruit & vegetable nutrition database. Fruits & Veggies More Matters website. http://www.fruitsandveggiesmorematters.org/fruit-vegetable-nutrition-database
13. Cranberry. Phytochemicals website. http://www.phytochemicals.info/plants/cranberry.php
14. Jepson RG, Craig JC. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev. 2008;(1):CD001321.
15. Goldman RD. Cranberry juice for urinary tract infection in children. Can Fam Physician. 2012;58(4):398-401.
16. Camesano TA, Liu Y, Pinzon-Arango PA. Cranberry prevents the adhesion of bacteria: overview of relevant health benefits. Agro Food Ind Hi Tech. 2007;18(1):24-27.
17. Jepson RG, Williams G, Craig JC. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev. 2012;10:CD001321.
18. Proanthocyanidins. Produce for Better Health Foundation website. http://pbhfoundation.org/about/res/pic/phytolist/proanthocyanidins.php
19. Brown SE. 20 key nutrients for bone health — an overview. Better Bones website. http://www.betterbones.com/bonenutrition/20keybonenutrients.pdf
20. Betalains. Examine.com website. https://examine.com/supplements/betalains/
21. Beets nutrition facts. Nutrition and You website. www.nutrition-and-you.com/beets.html
22. Craig SA. Betaine in human nutrition. Am J Clin Nutr. 2004;80(3):539-549.