Wednesday, 24 October 2018
Food as Medicine: Chia (Salvia hispanica, Lamiaceae)
HerbalEGram: Volume 14, Issue 9, September 2017 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’s) Dietetic Internship Program, led by ABC Education Coordinator Jenny Perez. We would like to acknowledge Perez, ABC Special Projects Director Gayle Engels, and ABC Chief Science Officer Stefan Gafner, PhD, for their contributions to this project. By Hannah Baumana and Juliette Coronadob a HerbalGram Associate Editor b ABC Dietetics Intern (Texas State, 2016) Overview Chia (Salvia hispanica, Lamiaceae) is an annual herb native to Mexico and Guatemala that requires fertile, well-drained soil and subtropical climate conditions to set seed in the late summer months of July and August.1-4 Chia is the most common name for this plant, but it is also sometimes called Spanish sage, lime-leaf sage, Mexican chia, and black chia.2,4 The plant grows to three feet (0.9 meters) tall when mature, and has opposite, serrated leaves that are 1.5-3 inches (3.8-7.6 cm) long and 1-2 inches (2.5-5 cm) wide, and produces small white or purple flowers on the tips of its terminal stems.2,4,5 Chia’s leaves contain essential oil that acts as a defense mechanism to repel insects.2 The edible part of the chia plant is the seeds,5-7 which are small (2 mm in length), flat, and oval-shaped.2 Although dark chia seeds are predominantly gray with dark spots,7 they can also appear white, black, black spotted, or dark brown, and may differ slightly in size and weight.2,5 Phytochemicals and Constituents Chia seed has high levels of protein, omega-3 fatty acids, fiber, and specific vitamins and minerals.2,7 The seed also contains all essential amino acids and is high in antioxidants.8 A gram of chia seeds contains about 0.28 g fiber, 0.21 g protein, and 0.6 g/g of the omega-3 fatty acid alpha-linolenic acid (ALA), which is the highest proportion of ALA of any known plant source.9 Chia seed and its oil have an abundance of polyunsaturated fatty acids (PUFAs). ALA is the most predominant fatty acid found in chia, followed by the omega-6 fatty acids linoleic acid and oleic acid. Omega-6 fatty acids have pro-inflammatory, hypertensive, and prothrombotic properties.5 Omega-3 fatty acids, however, are associated with numerous health benefits and have anti-inflammatory, anti-diabetic, lipid-lowering, cardioprotective, and hepatoprotective properties. For maintenance of good health, omega-3 fatty acids should be incorporated in the diet at higher amounts than omega-6 fatty acids. The omega-3:omega-6 ratio found in chia seeds is about 3:1.6,7 The amount of oil within chia seed ranges from 25-40%.2,5 In comparable serving sizes, the protein content of chia seeds exceeds that of seeds such as amaranth (Amaranthus spp., Amaranthaceae) and quinoa (Chenopodium quinoa, Chenopodiaceae).2 The primary determinant of a high-quality protein is its digestibility, or the amount of protein absorbed by the body relative to the amount consumed. For chia seed flour, protein digestibility is nearly 80%, which is comparable to processed cereal grains such as wheat (Triticum aestivum, Poaceae) and oats (Avena sativa, Poaceae); however, chia contains a much higher percentage of protein per serving than these grains.10 Furthermore, chia seed contains high levels of the amino acids glutamic acid, arginine, and aspartic acid.2 In addition to an abundance of these non-essential amino acids, chia seed contains all nine essential amino acids that the body is unable to produce and is therefore considered a complete protein, unlike other plant protein sources such as chickpeas (Cicer arietinum, Fabaceae). Chia seed contains low concentrations of prolamins (< 15%), which suggests that it can be safely incorporated into the diet of patients with celiac disease.2,10 Approximately two tablespoons (one ounce or about 28 grams) of chia seed provides almost 40% of an average person’s daily fiber intake, as recommended by the US Food and Drug Administration (FDA). Total dietary fiber includes both soluble and insoluble forms that are important for reducing the risk of cardiovascular disease, diabetes, and certain types of cancer.2 Compared to other foods, chia seed contains more dietary fiber than an equivalent volume of flax (Linum usitatissimum, Linaceae) seed. High fiber intake also promotes gastrointestinal and digestive health. Chia seeds and oil are not only known for their macronutrient and micronutrient contents, but also for their antioxidant properties.7 Phenolic compounds present in chia have been found to protect against certain diseases, such as cardiovascular disease and diabetes.11 The most important polyphenols found in chia seeds and seed oil include chlorogenic and caffeic acids, which play a crucial role in the protection against free radicals and inhibit fat, protein, and DNA peroxidation.2,11,12 The flavonols myricetin, quercetin, and kaempferol are other active compounds present in chia seeds.7 Flavonols are known for their antioxidant, cytotoxic, anti-inflammatory, and anti-thrombotic effects.5,13 Researchers have found that these polyphenols and others found in chia seed and seed oil (e.g., rosmarinic, protocatechuic, and gallic acids) have a high antioxidant capacity.12,14 Historical and Commercial Uses Chia has been used by Mesoamerican cultures for more than 1,000 years for medicinal, culinary, artistic, and religious purposes.7,15 The Chumash and Cahuilla peoples in the coastal southern regions of California cultivated chia for its seeds, which were collected, hulled, and winnowed by hand.16 After the introduction of wheat, chia was still a preferred crop, and small amounts of chia flour were used to improve the flavor of wheat flour. The seed of the chia plant is the part most often used for medicinal purposes, but the root and aerial parts were also used occasionally.15 Prior to Spanish colonization in the 16th century, chia seed was used by native tribes to provide energy, treat respiratory infections, and for obstetrics treatment. Prized by Aztec warriors in central Mexico, chia seeds were eaten to promote endurance and consumed with bread prior to battle or with water before running long distances.8 The Diegueño people of Baja California took chia seeds on journeys, kept a few seeds in the mouth and periodically chewed them to maintain their strength.16 One tablespoon of chia seed was believed to be sufficient to feed a person for a day. After the 16th century, a mucilaginous paste made from chia seeds and water was used therapeutically to treat eye obstructions and infections.17 Medical uses of chia seed prior to Spanish colonization included soothing skin conditions, treating gastrointestinal conditions, lowering fevers, and as a poultice for open wounds.15,16 The chia seed has been used for culinary purposes in multiple forms: whole, ground (flour), mucilage, and oil.7,15 Seeds were ground into flour and used to make biscuits, cakes, and a porridge called pinole.16 Traditional foods, such as tortillas and tamales, were made from chianpinolli, or roasted and ground chia seed.15,17 Chia flour was used to make an array of beverages during the height of the Aztec Empire, but modern use of this tradition has declined.15 The most recognized use of chia seeds in the 18th and 19th centuries was infusing chia seeds in water, which was believed to make the alkaline desert water taste more palatable. “Chia fresca,” or “agua de Chia,” was also a popular, thirst-quenching beverage that combined chia seeds with fruit juices.15-17 Chia seed oil was also used for artistic purposes, primarily in paints and lacquers to create a glossy finish on clay or gourd vessels.15 The oil was also used as the basic ingredient for ceremonial face or body paint. Chia-infused beverages were historically consumed during ceremonies, festive occasions, and holy observances. Other religious uses included the use of chia flour to make dough that was formed into the shape of the goddess Chicomecoatl, the “maker and giver of things necessary to live,” as an offering. With the rediscovery of chia as an important food source, modern uses of chia seed and oil focus on its omega-3 fatty acid content for nutritional supplementation, and it is sold commercially as cold-pressed seed oil or whole seeds as ingredients for baked goods, snacks, bread, yogurt, and bars.2 In 1977, the Chia Pet, small hollow-bodied animal figurines made out of terra cotta, became a registered trademark of Joseph Enterprises, Inc.18 Moistened chia seeds are applied to the grooved ridges on the outside of the figurine, and water is added to the hole inside the figurine to help the seeds germinate. Within days, the figure grows a thick coat of chia sprouts. For more than 30 years, Chia Pets have offered customers amusement and an introductory lesson to the practice of cultivating plants. Modern Research Cardiovascular Disease Risk Factors The nutrient profile and bioactive compounds found in chia seed and oil have demonstrated cardioprotective effects by reducing disease risk factors in humans. Hypertension, a known risk factor for developing cardiovascular disease, is generally asymptomatic and can be difficult to control with drug therapies alone. Diet interventions can offer a complementary approach.19 Supplementation with ground chia seed for 12 weeks was shown to reduce blood pressure in individuals with treated and untreated hypertension. Participants in the study were randomly assigned to one of three groups: consumption of chia with previously used medications (CHIA-MD), chia without medications (CHIA-NM), or a placebo group with medications (PLA-MD). Subjects in the two treatment groups consumed 35 grams of chia flour per day. The PLA-MD group received 35 grams of roasted wheat bran as a placebo. Researchers found that the two chia groups had significantly reduced diastolic and systolic blood pressures from baseline. The CHIA-MD group also had significantly reduced total blood pressure from baseline. A 2015 systematic review investigated current literature on consumption of whole or ground chia seeds and its effect on preventing or managing risk factors associated with heart disease, such as hypertension, diabetes, dyslipidemia, and obesity.20 The review focused on seven clinical trials published between 2007 and 2013. The chia seed preparations used in the studies varied in quantity (4-50 grams per day) and type (e.g., whole or milled). There were also differences in sample size, methodology, and participant characteristics (e.g., diabetic, obese, hypertensive). Therefore, the authors state that the findings on chia consumption and the effects of reducing cardiovascular risk factors are inconclusive. They recommend additional randomized, double-blind, placebo-controlled clinical trials on the consumption of chia to obtain reliable results and to determine an appropriate dose for cardioprotective benefits. Obesity is a condition that has been associated with a state of chronic oxidative stress. Reactive oxygen species damage cell proteins, lipids, and DNA, and can result in impaired function and potentially cell death. Obesity also impedes the body’s enzymatic antioxidant system, reducing the activities of catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase.24 Additionally, obesity correlates with a reduction in levels of protective thiols, vitamins, minerals, and polyphenols. A study on chia seed’s efficacy for weight loss and decreasing disease risk factors in overweight adults found increases in plasma ALA levels. However, consumption of chia seed in high doses (50 grams per day) had no effect on weight loss or changes in disease risk factors related to cardiovascular disease (e.g., blood pressure, high-density and low-density lipoprotein, total cholesterol, or blood triglyceride levels).21 Another randomized, double-blind, placebo-controlled study assessed the effectiveness of chia seed (whole or ground) supplementation for changing disease risk factors for overweight women.22 For 10 weeks, participants consumed 25 grams per day of ground or whole chia seeds or a placebo. Multiple outcome measures were assessed, and researchers observed a 58% and 39% increase in plasma ALA and eicosapentaenoic acid (EPA) levels, respectively, in the ground chia treatment group. Glucose Levels The use of chia as a food ingredient holds promise in the area of so-called “functional foods.” A 2013 study observed the effects of bread supplemented with chia seed flour on post-prandial (after-meal) blood sugar levels in healthy adults. Thirteen healthy adults consumed nine test meals that included bread supplemented with different doses (seven, 15, and 24 grams) of whole or ground chia.23 Bread without chia was used as the control. Researchers concluded there was a significant dose-dependent effect on blood glucose levels for both whole and ground seeds compared to the control, but no differences were evident between the same doses of the whole and ground seed groups. This may indicate that the quantity of seeds given in the diet will demonstrate hypoglycemic properties and not the form in which chia is ingested. The seeds used in the study were a specific varietal bred from black chia and proved effective for reducing blood glucose levels, but future research is needed to further investigate the benefits of different chia strains. Antioxidant Properties Chia’s antioxidant potential was analyzed in a 2015 rat study.24 Results demonstrated that daily consumption of chia seed and chia seed oil enhanced plasma antioxidant levels through catalase, glutathione peroxidase and thiol level reduction. Chia seed and seed oil intake resulted in a significant reduction in plasma levels of 8-isoprostane, the most specific biological indicator for assessing oxidative stress in vivo. High levels of 8-isoprostane can occur with a diet high in fat and fructose and result in pro-oxidative effects. This may be the mechanism by which chia seed and seed oil produces a hypolipidemic effect. Lipid peroxidation in rat livers was not reversible; however, levels of glutathione reductase were increased as well as thiol levels, resulting in improved antioxidant status. Other Uses Carbohydrate-loading refers to the practice of increasing dietary intake of carbohydrates prior to athletic events that last more than 90 minutes. This intake results in greater capacity of muscle glycogen stores and aids in improved athletic performance.8 A 2011 study compared performance test results of six male marathon runners who were given two different carbohydrate-loading treatments: a commercial sports drink and the same commercial sports drink supplemented with chia. The runners participated in two trials in a crossover, counterbalanced, repeated-measure design with a two-week washout period between testing to allow participants to recover from the intense exercise and to avoid any carry-over effects from the treatments. While the researchers found no statistical difference between the control and the test groups in performance parameters, the athletes in the chia group significantly decreased their dietary intake of sugar while boosting intake of omega-3 fatty acids, which indicates that the chia drink may be a healthier option for athletes who choose to carbohydrate-load. Chia seed oil is also used topically. Approximately 30% of patients with diabetes or end-stage renal disease (ESRD) suffer from skin disorders including pruritus, which is characterized by itchy, dry skin and inflammatory lesions caused by scratching.13 This study followed five patients with these conditions (three with diabetes; two with ESRD) and five patients without these conditions who all exhibited xerotic pruritus (abnormally dry, itchy skin) for eight weeks. A topical oil and water emulsion containing 4% chia seed oil was applied to affected skin. Lotion without chia seed oil was used on participants as a placebo. After eight weeks of application, statistically significant improvements in skin hydration, chronic itching, and prurigo nodularis (hard, itchy lumps on the skin) were observed in the treatment group with diabetes and ESRD, while similar significant improvements in skin hydration and epidermal permeability were also observed in the group of patients without these conditions. Consumer Considerations Consumption of whole or ground chia seed has shown no evidence of toxicity or allergenic effects.2 However, the Dietary Guidelines for Americans, eighth edition, issued by the US Department of Health and Human Services and US Department of Agriculture listed a standard portion size of chia as one tablespoon (or roughly 50 grams) per day.25 This may be due to clinical studies that have not exceeded a dose of 50 grams per day, and thus the potential adverse effects have not been adequately studied above this amount. The PUFA content as well as the low concentration of tocopherol and phenolic compounds account for the low oxidative stability of chia oil. Within 300 days, a 30% drop in the tocopherol content of chia seed oil was observed.9 The antioxidant capacity of chia oil is relatively low due to the hydrophilic nature of the phenolic compounds within the chia seed. Despite chia seed’s rich omega-3 and omega-6 content, there is a technological disadvantage in the production of chia seed oil in regards to its stability and short shelf life, especially when exposed to light or oxygen. Chia seed oil is best kept in the refrigerator after opening and should be used quickly to gain its full range of nutrients. Nutrient Profile26 Macronutrient Profile: (Per 1 ounce seeds) 138 calories 4.7 g protein 11.9 g carbohydrate 8.7 g fat Secondary Metabolites: (Per 1 ounce seeds) Excellent source of: Manganese: 0.8 mg (40% DV) Dietary Fiber: 9.8 g (39.2% DV) Phosphorus: 244 mg (24.4% DV) Magnesium: 95 mg (23.8% DV) Very good source of: Calcium: 179 mg (17.9% DV) Thiamin: 0.2 mg (13.3% DV) Niacin: 2.5 mg (12.5% DV) Iron: 2.2 mg (12.2% DV) Also provides: Folate: 14 mcg (3.5% DV) Potassium: 115 mg (3.3% DV) Riboflavin: 0.05 mg (3% DV) Trace amounts of: Vitamin C: 0.5 mg (0.8% DV) Vitamin E: 0.14 mg (0.7% DV) Vitamin A: 15 IU (0.3% DV) DV = Daily Value as established by the US Food and Drug Administration, based on a 2,000-calorie diet. Recipe: Strawberries and Cream Chia Pudding Adapted from Emily Han27 Ingredients: 8 ounces fresh strawberries (Read more about the benefits of strawberries here.28) 3/4 cup coconut milk 2 tablespoons honey 1/2 teaspoon vanilla extract 1/2 teaspoon grated lime zest 1/4 cup chia seeds Directions: Combine the strawberries, coconut milk, honey, vanilla, and lime zest in a blender. Puree until smooth. Taste and add more honey, if desired. Place the chia seeds in a large bowl and add the strawberry mixture. Whisk thoroughly to combine. Let the mixture stand for 10 minutes, then whisk again. Cover and refrigerate for at least four hours and up to three days. Stir before serving. The pudding will set up thicker the longer it sits. Photo credits: Top: Salvia hispanica seeds. ©2017 Steven Foster. Middle: Image of Salvia hispanica from the 16th-century Florentine Codex by Fr. Bernardino de Sahagún. Bottom: Salvia hispanica seeds. ©2017 Steven Foster. References Salvia hispanica – L. Plants for a Future website. Available at: www.pfaf.org/user/Plant.aspx?LatinName=Salvia+hispanica. Accessed August 24, 2017. Muñoz LA, Cobos A, Diaz O, Aguilera JM. Chia seed (Salvia hispanica): An ancient grain and a new functional food. Food Reviews International. 2013;29:394-308. Taxon: Salvia hispanica L. US National Plant Germplasm System website. Available at: https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?32939. Accessed August 24, 2017. Kaiser C, Ernst M. Center for Crop Diversification Crop Profile: Chia. Lexington, KY: University of Kentucky College of Agriculture, Food and Environment. February 2016. Ali NM, Yeap SK, Ho WY, Beh BK, Tan SW, Tan SG. The promising future of chia, Salvia hispanica L. Journal of Biomedicine and Biotechnology. 2012;171956. Porras-Loaiza P, Jiménez-Munguía MT, Sosa-Morales ME, Palou E, López-Malo A. Physical properties, chemical characterization and fatty acid composition of Mexican chia (Salvia hispanica L.) seeds. International Journal of Food Science and Technology. 2014;49:571-577. Valdivia-López MA, Tecante A. Chia (Salvia hispanica): A review of native Mexican seed and its nutritional and functional properties. Advances in Food and Nutrition Research. 2015;75:54-71. Illian TG, Casey JC, Bishop PA. Omega 3 chia seed loading as a means of carbohydrate loading. Journal of Strength and Conditioning Research. 2011;25(1):61-65. Bodoira RM, Penci MC, Ribotta PD, Martínez ML. Chia (Salvia hispanica L.) oil stability: Study of the effect of natural antioxidants. LWT – Food Science and Technology. 2017;75:107-113. Kačmárová K, Lavová B, Socha P, Urminská D. Characterization of protein fractions and antioxidant activity of chia seeds (Salvia hispanica L.). Potravinarstvo. 2016;10(1):78-82. Pandey KB, Rizvi SI. Plant polyphenols as dietary antioxidants in human health and disease. Oxidative Medicine and Cellular Longevity. 2009;2(5):270-278. da Silva Marineli R, Moraes ÉA, Lenquiste SA, Godoy AT, Eberlin MN, Maróstica Jr MR. Chemical characterization and antioxidant potential of Chilean chia seeds and oil (Salvia hispanica L.). LWT – Food Science and Technology. 2014;59:1304-1310. Jeong SK, Park HJ, Park BD, Kim I. Effectiveness of topical chia seed oil on pruritus of end-stage renal disease (ESRD) patients and healthy volunteers. Ann Dermatol. 2010;22(2):143-148. Martínez-Cruz O, Paredes-López O. Phytochemical profile and nutraceutical potential of chia seeds(Salvia hispanica L.) by ultra high performance liquid chromatography. Journal of Chromatography A. 2014;1346:43-48. Cahill J. Ethnobotany of chia, Salvia hispanica L. (Lamiaceae). Economic Botany. 2003;57(4):604-618. Immel DL. Plant Guide: Chia. Washington DC: United States Department of Agriculture Natural Resources Conservation Service. 2003. Hershey DR. Don’t just pet your chia. Science Activities. 1995;32(2):8-12. Edwards O. Chia Pet. Smithsonian Magazine. December 2007. Available at: www.smithsonianmag.com/arts-culture/chia-pet-180308610/. Accessed August 24, 2017. Toscano LT, Oliveira da Silva CS, Toscano LT, Monteiro de Almeida AE, Santos AdC, Silva AS. Chia flour supplementation reduces blood pressure in hypertensive subjects. Plant Foods Hum Nutr. 2014;69:392-398. de Souza Ferreira C, de Sousa Fomes LdF, Santo da Silva GE, Rosa G. Effect of chia seed (Salvia hispanica L.) consumption on cardiovascular risk factors in humans: a systematic review. Nutrición Hospitalaria. 2015;32(5):1909-1918. Nieman DC, Cayea EJ, Austin MD, Henson DA, McAnulty SR, Jin F. Chia seed does not promote weight loss or alter disease risk factors in overweight adults. Nutrition Research. 2009;29:414-418. Nieman DC, Gillitt N, Jin F, et al. Chia seed supplementation and disease risk factors in overweight women: a metabolomics investigation. J Alt Complement Med. 2012;18(7):700-708. Ho H, Lee AS, Jovanonvski E, Jenkins AL, DeSouza R, Vuksan V. Effect of whole and ground Salba seeds (Salvia hispanica L.) on postprandial glycemia in healthy volunteers: A randomized controlled, dose-response trial. Eur J Clin Nutr. 2013;67:786-788. da Silva Marineli R, Lenquiste SA, Moraes ÉA, Maróstica Jr. MR. Antioxidant potential of dietary chia seed and oil (Salvia hispanica L.) in diet-induced obese rats. Food Research International. 2015;76:666-674. US Department of Health and Human Services and US Department of Agriculture. 2015-2020 Dietary Guidelines for Americans. 8th ed. December 2015. Available at: http://health.gov/dietaryguidelines/2015/guidelines. Accessed September 14, 2017. Basic Report: 12006, Seeds, chia seeds, dried. United States Department of Agriculture Agricultural Research Service website. Available at: https://ndb.nal.usda.gov/ndb/foods/show/3610. Accessed August 23, 2017. Han E. Dairy-Free Dessert Recipe: Strawberries & “Cream” Chia Pudding. The Kitchn website. May 8, 2013. Available at: www.thekitchn.com/recipe-strawberry-chia-pudding-recipes-from-the-kitchn-189016. Accessed August 23, 2017. Bauman H, Bates K. Food as Medicine: Strawberry (Fragaria x ananassa, Rosaceae). HerbalEGram. 2015;12(5). Available at: http://cms.herbalgram.org/heg/volume12/05May/FaM_Strawberry.html. Accessed September 11, 2017.