HerbalEGram:Volume 12, Issue 6, June 2015

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.

History and Traditional Use

Range and Habitat

Coriandrum sativum, known by the common names coriander and cilantro, is a bright green herbaceous member of the Apiaceae (or carrot) family. Often grown as an annual, it has thin, hollow stems that can reach several feet in height. The stems bear glossy, aromatic, dissected leaves, and pale pink or white flowers forming an umbel inflorescence.^1,2,3 Coriander originated in the eastern Mediterranean region and western Asia, and is commonly cultivated in all parts of the world for its aromatic leaves and seeds. The leaves of the plant historically have been used in Asian, Indian, Mexican, Spanish-American, and Middle Eastern cuisine.² Coriander seeds are globular and aromatic with a slightly bittersweet taste, and have a long history of use as an important culinary spice. Internationally, India is the largest producer, consumer, and exporter of coriander seed. Only 10-15% of total production is exported; the rest is consumed domestically.⁴

Phytochemicals and Constituents

The seeds of the coriander plant contain different types of volatile oils with proven health benefits. Coriander seeds have 25% fatty oil content and are made up of a high amount of petroselenic acid, followed by lesser amounts of linoleic acid, an omega-6 essential fatty acid.⁵ Coriander seed oil contains 60–70% linalool, a terpenoid that is a powerful cellular antioxidant as well as the source of coriander’s pleasant smell. Spices and seeds represent an important source of fatty acids in the human diet, and insufficient intake can result in inflammation and symptoms of dermatitis.⁶ In addition to the essential oil, the seeds contain sugars, alkaloids, flavones, resins, tannins, anthraquinones, sterols, and fixed oils.^7,8

An alcohol extract of coriander produced antioxidant action comparable to other commercial antioxidants. The leaves appear to have more antioxidant activity than the seeds, likely due to their phenolic content.⁸ Coriander leaves contain beneficial flavonoids, polyphenols, and phenolic acids. The polyphenols present include kampferol and quercetin, which have also been shown to have an antioxidant and anti-inflammatory effect. Phenolic acids include caffeic acid, protocathenic acid, glycitin, and vanillic acid.⁵ These secondary plant metabolites have attracted interest and study for their potential protective role against oxidative damage and its associated diseases, including coronary heart disease, stroke, and cancers.⁹ The leaves of the plant are high in vitamins A, K, and C, as well as calcium.²

Historical and Commercial Uses

The coriander plant has a long history of use dating back to the Neolithic Age, around 7000 BCE.⁷ Mentions of coriander have been documented in ancient Indian Sanskrit texts, the Old Testament, and Egyptian papyrus scrolls.³ Coriandrum sativum has been cultivated in Greece since the second millennium BCE, its fragrant seeds used in perfumes and both the seeds and leaves used in cooking.⁸

In both traditional Chinese medicine and Ayurvedic medicine, the seeds are used as a digestive, carminative, or a stomachic.⁸ In Ayurvedic medicine, the seeds are combined with caraway (Carum carvi) and cardamom (Elettaria cardamomum) seeds or with caraway, fennel (Foeniculum vulgare), and anise (Pimpinella anisum) seeds in European medicine to treat digestive complaints.^5,10

The leaves of C. sativum have been traditionally used for common digestive issues including gastrointestinal spasms, dyspepsia, and as an appetite stimulant.⁵ Coriander has been reported to act as a stomachic, carminative, and spasmolytic due to its high essential oil content.¹⁰ Leaf preparations were also ingested and applied externally to the chest to treat coughs and chest pains.

The seeds of C. sativum have been used to treat gastrointestinal upset such as indigestion, vomiting, diarrhea, and dysentery; as an antispasmodic and expectorant for coughs and bronchitis; and topically as an anti-inflammatory ointment for arthritis and rheumatism and skincare and cosmetic products.⁵ In Iranian traditional medicine, coriander seed was primarily used to treat anxiety and insomnia. The traditional dose of seed powder is from 1 g to 5 g, three times per day. This translates to a 14-71 mg/kg dose, three times per day, for a 150-pound individual.⁸

Currently, coriander seed is used in medicinal teas in Germany and can be found in various laxative and carminative remedies. Coriander’s carminative and stimulant effects are noted in the British Herbal Pharmocopoeia and The German Commission E Monographs; Wichtl’s Herbal Drugs and Phytopharmaceuticals confirms coriander’s use as a stomachic, spasmolytic, and carminative agent, and also notes its hypolipidemic effects and insulin-like activity.¹¹ The seeds are a common component of curry powder and many other spice mixtures. They also are used to flavor gin and other liquors, such as Chartreuse and Benedictine.²

Modern Research

The seeds of the coriander plant have been shown to in many studies to decrease blood sugar and reduce insulin resistance.^12-14 This effect likely is due to the flavonoids and polyphenols present in the seed. Studies also have shown that the seeds can lower cholesterol levels, making it beneficial for heart health. In several animal studies, coriander seed extract decreased LDL cholesterol, triglycerides, and total cholesterol in rats.¹² The extract also increased HDL cholesterol (the “good” cholesterol).¹⁵

Constituents and phytochemicals present in coriander seeds make them a popular component of aromatherapy treatments. Linalool, the most abundant terpenoid in coriander seed oil, repressed stress-induced effects on rats when inhaled.¹⁶ Coriander seed extract also has been shown to have a mild sedative effect, and is being studied for its suitability to treat mild anxiety and insomnia. The extract increased sleep time in mice,¹⁷ and another study found that the seed extract acted to decrease anxiety and relax muscles when mice were exposed to a stressful environment, which researchers linked to the polyphenols quercetin and isoquercetin present in the extract.¹⁸ While results from animal studies are promising, the anxiolytic and calming properties of coriander seed and its potential to promote sleep in those with insomnia do not appear to have been clinically tested in humans.

The leaves of the coriander plant have been shown to decrease symptoms in people with arthritis. Researchers link this antioxidant effect to the presence of vitamins A and C, phenolic acids, and polyphenols in the leaves.¹⁹ The leaves’ phenolic content, specifically ethanolic extract, has been shown to protect against liver damage in rats.²⁰

The topical use of diluted essential oils obtained from coriander seeds appears to be well-tolerated and effective in treating superficial skin infections and oozing dermatitis associated with Streptococcus pyogenes. Using the standard agar dilution method, coriander seed oil also has been shown to inhibit Staphylococcus aureus, S. haemolyticus, Pseudomonas aeruginosa, Escherichia coli, and Listeria monocytogenes.⁸ Coriander leaf oil contains aldehydes effective against Candida spp., S. aureus, Salmonella typhi, Salmonella choleraesuis, and other bacteria.

The use of cilantro or coriander leaf has been falsely promoted as an herb that can remove accumulated heavy metals, specifically mercury, from the body, a process known as “chelation.” However, no scientific or clinical evidence supports these claims.⁸ Some pre-clinical evidence does suggest that concomitant use of coriander leaf while consuming foods considered high in heavy metals can reduce the absorption of toxins and potential toxic effects, but does not support the theory that coriander can remove heavy metals already present in the body. Consuming coriander leaf-based pesto, salsa, or chutney at the same time as foods often laden with mercury, like seafood, could potentially decrease the absorption of heavy metals in the body. More research is needed to validate these findings and determine proper dosing.⁸

Nutrient Profile²¹

Macronutrient Profile: (Per 20 g [approx. nine sprigs] coriander)

5 calories

0.43 g protein

0.73 g carbohydrate

0.1 g fat

Secondary Metabolites: (Per 20 g [approx. nine sprigs] coriander)

Excellent source of:

Vitamin K: 62 mcg (77.5% DV)

Vitamin A: 1350 IU (27% DV)

Good source of:

Vitamin C: 5.4 mg (9% DV)

Also provides:

Potassium: 104 mg (3% DV)

Folate: 12 mcg (3% DV)

Dietary Fiber: 0.6 g (2.4% DV)

Iron: 0.35 mg (1.94% DV)

Vitamin E: 0.5 mg (1.67% DV)

Vitamin B6: 0.03 mg (1.5%DV)

Calcium: 13 mg (1.3% DV)

Magnesium: 5 mg (1.25% DV)

Niacin: 0.22 mg (1.1% 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: Cilantro-Mint Chutney

This condiment does more than add a new dimension to a dish — it helps aid the digestion as well. Cilantro leaves, mint, ginger, and cumin all have traditional uses as carminative agents that soothe upset stomachs.²²

Ingredients:

• 1 cup fresh mint leaves, chopped
• 1 cup fresh cilantro leaves, chopped
• 1 small green chili, such as serrano, stem and seeds removed (optional)
• ½-inch piece of fresh ginger, peeled and roughly chopped
• 1 teaspoon ground cumin
• 1-2 tablespoon fresh lemon juice, to taste
• 1-2 tablespoons of water, as needed
• Kosher or black salt, to taste

Directions:

1.    In a food processor, combine all ingredients except for salt and blend until the mixture forms a smooth paste. Add water to create a thinner consistency, if necessary.

2.    Mix salt into chutney. Serve chutney on sandwiches, or with rice, lentils, potatoes, samosas, or potato chips.

References

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4. Burark, SS. Coriander prices to remain stable during harvest. Maharana Pratap University of Agriculture and Technology – Udaipur website. Available here. Accessed May 21, 2015.
   
   
5. Sahib NG, Anwar F, Gilani A, Hamid AA, Saari N, Alkharfy KM. Coriander (Coriandrum sativum L.): A potential source of high-value components for functional foods and nutraceuticals – a review. Phytotherapy Research. 2013(10):1439.
   
   
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14. Srinivasan K. Plant foods in the management of diabetes mellitus: spices as beneficial antidiabetic food adjuncts. Int J Food Sci Nutr. 2005;56(6):399-414.
    
    
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