Food as Medicine: Arugula (Eruca sativa, Brassicaceae)

HerbalEGram: Volume 13, Issue 4, April 2016

Editor’s Note: Each month, HerbalEGram highlights a conventional food and briefly explores its history, traditional uses, nutritional profile, and modern medicinal research. We also feature a nutritious recipe for an easy-to-prepare dish with each article to encourage readers to experience the extensive benefits of these whole foods. With this series, we hope our readers will gain a new appreciation for the foods they see at the supermarket and frequently include in their diets. The basic materials for this series were compiled by dietetic interns from Texas State University in San Marcos and the University of Texas at Austin through the American Botanical Council’s (ABC) Dietetic Internship Program, led by ABC Education Coordinator Jenny Perez. We thank Min Kwon (TSU, 2014) for her research and work on arugula. History and Traditional Use Range and Habitat Arugula (Eruca sativa, Brassicaceae), also known as rucola and rocket, is a weedy annual that is drought-tolerant and prefers a hot, dry climate.1,2 The name “arugula” is a modern American designation and likely derives from the Italian term “rucola.”3 The name “rocket” is more common in British English, as isroquette in France. Both rucola and roquette are diminutives of the Latin eruca, which means “caterpillar” and may refer to the fuzzy appearance of the young stems. The different names for arugula demonstrate the wide area where it grows, in a swath of the northern Mediterranean and the near east that stretches from Portugal to Afghanistan.1 It has been naturalized in northern Europe and North America.4 Arugula is distinguished by its upright stem, which can have four-petaled white, yellow, or purple flowers, as well as its green, aromatic, serrated leaves.5 Its thin, narrow fruit is a pod filled with small, oil-rich seeds.1 Although it is commonly thought of as a relative of spinach or lettuce, it is actually a cruciferous vegetable of the family Brassicaceae, which includes broccoli, brussel sprouts, kale, and cabbage. The leaves and seeds of arugula are both edible. The leaves boast an aromatic, peppery, and slightly mustard-like flavor and are mainly consumed raw in salads. Young leaves are tenderer and have a milder flavor, while mature leaves are larger, woodier, and more bitter.4 The seeds can be pressed for oil.1 Phytochemicals and Constituents As a leafy green vegetable and a member of the family Brassicaceae, arugula is an extremely nutrient-dense food. It is low in calories and rich in vitamins A, C and K, folate, magnesium, and calcium.3 Calcium, magnesium, and potassium help control blood pressure and maintain bone health. It also provides riboflavin, potassium, copper, iron, and zinc. Arugula’s health benefits are a potent combination of cruciferous vegetable and leafy green, as it contains compounds found in both: glucosinolates, a group of compounds which exert powerful anticancer and detoxifying mechanisms, and antioxidant phytochemicals such as carotenes and chlorophyll. Compared to other brassica plants, arugula has one of the highest beta-carotene, kaempferol, and quercetin contents.6 Arugula seed oil, commonly called taramira or jamba oil, is likewise rich in glucosinolates.2 It also contains high amounts of erucic and gadoleic acids, which have more commercial than health benefits, as detailed in the following section. Historical and Commercial Uses Ancient and modern practitioners interpret arugula’s peppery taste as a fiery, “lively” quality, which lends itself to a variety of different uses. In the ancient world, the Romans and the Egyptians considered arugula to be a potent aphrodisiac which was used to “restore vigor to the genitalia,” and planted it at the base of statues of the god Priapus7, who was considered the god of fertility, livestock, and gardens. Its reputation as an aphrodisiac was widespread and persistent, and some monasteries banned its cultivation on their grounds, citing its “hotness and lechery.” Arugula had widespread use in Greco-Arab and Islamic medicine practices, primarily for its antimicrobial and anti-inflammatory properties.8 It was taken orally as a general tonic for wellness and as an aid to digestion and kidney function. Additionally, records exist of a physician’s prescribing a topical treatment of ground seeds mixed with cream for acne. Evidence of arugula use and cultivation dates back to the Hellenistic Period in Greece (323 BCE – 31 BCE). Due to its high vitamin A and C content, arugula has been used as a therapeutic food for eye infections and nightblindness, and its sharpness and astringency reveals its stimulant, diuretic, and antiscorbutic (effective against scurvy) properties.2 Many of its modern and traditional uses overlap with dandelion greens, to which it is very similar in taste and nutritional profile. The leaves have also been used topically as a rubefacient (drawing blood to the surface of the skin) to improve circulation. The fresh leaves of arugula has been consumed and favored as a salad green in Mediterranean countries for centuries. With the growing popularity of the Mediterranean cuisine, its consumption continues to grow in the United States as well as the rest of the world. Arugula is best consumed raw or very lightly cooked, as many of its beneficial compounds (chlorophyll, glucosinolates, and isothiocyanates) degrade quickly when heated. In India, Pakistan, and Iran, arugula is grown as a commercial oilseed crop. Due to its high erucic acid content, taramira oil and similar oils are used as commercial lubricants and as massage oils.2 The seed matter left behind after oil processing is used as livestock fodder. Where it is popular, including India, taramira oil also has widespread culinary use, though it must age for six months after processing to mellow its initial overwhelming acrid taste. Once aged, the oil can be used in salads and for cooking purposes, and is a traditional ingredient in pickles and mustard. Modern Research As a member of the Brassicaceae family, arugula shares the extensively-studied effects of its relatives, such as broccoli and kale. Cruciferous vegetables are excellent sources of antioxidants and are highly regarded for their anti-inflammatory, antimicrobial, chemo-preventive, and cardio-protective effects.9-13 They have high levels of sulfur-containing compounds called glucosinolates which, when crushed or chewed, turn into indoles and isothiocynates. These two bioactive constituents have been shown to be potent cancer-fighters, protecting against many forms of cancers, including breast,14 prostate,15 and colorectal cancer.16 Arugula can be a valuable addition to the diet of people with Crohn’s disease and other gastrointestinal conditions, providing valuable vitamins, minerals, and insoluble fiber.6 Those who suffer from Crohn’s disease are at higher risk for vitamin deficiencies and malnutrition as a result of a limited diet; however, in a 2012 clinical study, almost 80% of subjects reported no change to their symptoms after consuming steady amounts of arugula. Though cruciferous vegetables are considered off-limits to people following a low-FODMAP diet (which seeks to eliminate fermentable oglio-, di-, and mono-saccharides and polyols due to a bacterial imbalance in the gut), arugula was well tolerated and also should be considered as a nutrient-dense addition for people with these sensitivities. Nutrient Profile17 Macronutrient Profile: (Per 1 cup arugula leaves) 5 calories 0.52 g protein 0.73 g carbohydrate 0.13 g fat Secondary Metabolites: (Per 1 cup arugula leaves) Excellent source of: Vitamin K: 21.7 mcg (27.13% DV) Good source of: Vitamin A: 475 IU (9.5% DV) Vitamin C: 3 mg (5% DV) Folate: 19 mcg (4.75% DV) Vitamin E: 0.09 mg (4.48% DV) Calcium: 32 mg (3.2% DV) Also provides: Magnesium: 9 mg (2.25% DV) Potassium: 74 mg (2.11% DV) Iron: 0.29 mg (1.61% DV) Dietary Fiber: 0.3 g (1.2% DV) Riboflavin: 0.02 mg (1.18% DV) Vitamin B6: 0.02 mg (1% DV) Phosphorus: 10 mg (1% DV) DV = Daily Value as established by the US Food and Drug Administration, based on a 2,000 calorie diet. Recipe: Arugula and Walnut Pesto Ingredients: 1/2 cup raw, unsalted walnuts halves 2 cups fresh arugula leaves 1-2 garlic cloves, peeled and roughly chopped 1/2 cup grated Parmesan cheese 1/2 cup extra virgin olive oil Salt to taste Directions: In a dry, nonstick skillet over medium heat, toast walnuts until lightly browned and fragrant. Be careful not to burn. Remove from the heat. In a food processor, combine arugula, walnuts, and garlic and pulse until roughly chopped. Continue pulsing, drizzling in olive oil in a steady stream until combined. Stir in Parmesan cheese and add salt to taste. Alternatively, this recipe can be made with a mortar and pestle. Roughly chop the arugula leaves and toast walnuts as described, then combine nuts, salt, and garlic in mortar and grind until smooth. Then add the cheese, olive oil, and arugula, and continue grinding until smooth. —Hannah Bauman References Van Wyk B. Food Plants of the World: An Illustrated Guide. 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Sulforaphane induces cell type-specific apoptosis in human breast cancer cell lines. Molecular Cancer Therapeutics. 2007;6:1013–1021. Herman-Antosiewicz A, Johnson DE, Singh SV. Sulforaphane causes autophagy to inhibit release of cytochrome c and apoptosis in human prostate cancer cells. Cancer Research. 2006; 66: 5828–5835. Seow A, Yuan JM, Sun CL, Van Den Berg D, Lee HP, Yu MC. Dietary isothiocyanates, glutathione S- transferase polymorphisms and colorectal cancer risk in the Singapore Chinese Health Study.Carcinogenesis. 2002;23:2055–2061. Basic Report: 11959 Arugula, raw. Agricultural Research Service, United States Department of Agriculture website. Available here. Accessed March 29, 2016.