Salvia hispanica

Salvia hispanica, commonly known as chia, is a species of flowering plant in the mint family, Lamiaceae, native to central and southern Mexico and Guatemala.^[2] The 16th-century Codex Mendoza provides evidence that it was cultivated by the Aztec in pre-Columbian times; economic historians have suggested it was as important as maize as a food crop.^[3] Ground or whole chia seeds are still used in Paraguay, Bolivia, Argentina, Mexico and Guatemala for nutritious drinks and as a food source.^[4][5]

Etymology

The word "chia" is derived from the Nahuatl word chian, meaning oily.^[1] The present Mexican state of Chiapas received its name from the Nahuatl "chia water" or "chia river".

It is one of two plants known as chia, the other being Salvia columbariae, commonly known as golden chia.

Description

Chia is an annual herb growing up to 1.75 metres (5.7 feet) tall, with opposite leaves that are 4–8 cm (1.6–3.1 in) long and 3–5 cm (1.2–2.0 in) wide. Its flowers are purple or white and are produced in numerous clusters in a spike at the end of each stem.^[6] Chia is hardy from USDA Zones 9–12. Many plants cultivated as S. hispanica are actually S. lavandulifolia.^[7]

Seeds

Chia is grown commercially for its seed, a food that is rich in omega-3 fatty acids, since the seeds yield 25–30% extractable oil, including α-linolenic acid (ALA). Of total fat, the composition of the oil can be 55% ω-3, 18% ω-6, 6% ω-9, and 10% saturated fat.^[8]

Chia seeds are typically small ovals with a diameter of about 1 mm (0.039 in). They are mottle-colored with brown, gray, black and white. The seeds are hydrophilic, absorbing up to 12 times their weight in liquid when soaked. While soaking, the seeds develop a mucilaginous gel-like coating that gives chia-based beverages a distinctive texture.

Chia seed is traditionally consumed in Mexico, and the southwestern United States, but is not widely known in Europe. Chia (or chian or chien) has mostly been identified as Salvia hispanica L. Today, chia is grown commercially in its native Mexico, and in Bolivia, Argentina, Ecuador, Nicaragua, Guatemala, and Australia. In 2008, Australia was the world's largest producer of chia.^[9] A similar species, Salvia columbariae or golden chia, is used in the same way but is not grown commercially for food. Salvia hispanica seed is marketed most often under its common name "chia", but also under several trademarks.

Nutrient content and food uses

Seeds, chia seeds, dried

Nutritional value per 100 g (3.5 oz)
Energy	2,034 kJ (486 kcal)
Carbohydrates	42.12 g
Dietary fiber	34.4 g
Fat	30.74 g
Saturated	3.330
Monounsaturated	2.309
Polyunsaturated	23.665
Protein	16.54 g
Vitamins
Vitamin A equiv.	(7%) 54 μg
Thiamine (B1)	(54%) 0.62 mg
Riboflavin (B2)	(14%) 0.17 mg
Niacin (B3)	(59%) 8.83 mg
Folate (B9)	(12%) 49 μg
Vitamin C	(2%) 1.6 mg
Vitamin E	(3%) 0.5 mg
Trace metals
Calcium	(63%) 631 mg
Iron	(59%) 7.72 mg
Magnesium	(94%) 335 mg
Manganese	(130%) 2.723 mg
Phosphorus	(123%) 860 mg
Potassium	(9%) 407 mg
Sodium	(1%) 16 mg
Zinc	(48%) 4.58 mg
Link to USDA Database entry
Units μg = micrograms • mg = milligrams IU = International units
Percentages are roughly approximated using US recommendations for adults. Source: USDA Nutrient Database

A 100 gram serving of chia seeds is a rich source (54% and 59%, respectively) of the Daily value, DV) of the B vitamins thiamine and niacin, and a good source (14 and 12%, respectively) of the B vitamins riboflavin and folate. The same amount of chia seeds is also a rich source (>20% DV) of the dietary minerals calcium, iron, magnesium, manganese, phosphorus, and zinc (see chart pictured right).

In 2009, the European Union approved chia seeds as a novel food, allowing up to 5% of a bread product's total matter.^[10]

Chia seeds may be added to other foods as a topping or put into smoothies, breakfast cereals, energy bars, granola bars, yogurt, tortillas, bread, made into a gelatin-like substance or consumed raw.^{[11][12][13][14]} The gel can be used to replace as much as 25% of egg content and oil in cakes while providing other nutrients.^[15]

Preliminary health research

Although preliminary research indicates potential for health benefits from consuming chia seeds, this work remains sparse and inconclusive.^[16]

Drug interactions

Case reports have shown that there is an increased bleeding risk in patients using an anticoagulant if also consuming chia seeds.^[17]

Cultivation

Climate and growing cycle length

The growing cycle length for chia varies over cultivation locations and is influenced by elevation.^[18] For production sites located in different ecosystems in Bolivia, Argentina and Ecuador, growing cycles are between 100–150 days in duration.^[19] Accordingly, commercial production fields are located in the range of 8–2200 meters altitude across a variety of ecosystems ranging from tropical coastal desert to tropical rain forest and inter-Andean dry valley.^[19] In north-western Argentina, a time span from planting to harvest of 120–180 days is reported for fields located at elevations of 900–1500 meters.^[20]

S. hispanica is a short-day flowering plant,^[21] indicating its photoperiodic sensitivity and lack of photoperiodic variability in traditional cultivars has limited commercial use of chia seeds to tropical and subtropical latitudes until 2012.^[22] Traditional domesticated lines of S. hispanica can now be grown in temperate zones at higher latitudes in the United States.^[21] In Arizona or Kentucky, seed maturation of traditional chia cultivars is stopped by frost before or after flower set, preventing seed harvesting.^[21] However, 2012 advances in plant breeding led to development of new early-flowering chia genotypes proving to have higher yields in Kentucky.^[22]

Seed yield and composition

Seed yield varies depending on cultivars, mode of cultivation and growing conditions by geographic region. For example, commercial fields in Argentina and Colombia vary in yield range from 450 to 1250 kg/ha.^[20][23] A small scale study with 3 cultivars grown in the Inter-Andean valleys of Ecuador produced yields up to 2300 kg/ha, indicating that favorable growing environment and cultivar interacted to produce such high yields.^[18] Genotype has a larger effect on yield than on protein content, oil content, fatty acid composition or phenolic compounds, whereas high temperature reduces oil content and degree of unsaturation and raises protein content.^[24]

Soil, seedbed requirements and sowing

The cultivation of S. hispanica requires light to medium clay or sandy soils.^[25] The plant prefers well-drained, moderately fertile soils, but can cope with acid soils and moderate drought.^[22][25] Sown chia seeds need moisture for seedling establishment, while the maturing chia plant does not tolerate wet soils during growth.^[22]

Traditional cultivation techniques of S. hispanica involve soil preparation by disruption and loosening followed by seed broadcasting.^[26] In modern commercial production, a typical seeding rate of 6 kg/ha and row spacing of 0.7–0.8 metres is usually applied.^[20]

Fertilization and irrigation

S. hispanica can be cultivated under low fertilizer input, using 100 kg nitrogen per hectare or in some cases, no fertilizer is used.^[21][23]

Irrigation frequency in chia production fields may vary from none to eight irrigations per growing season, depending on climatic conditions and rainfall.^[23]

Genetic diversity and breeding

There is a wide range of wild and cultivated varieties of S. hispanica based on seed size, shattering of seeds and seed color.^[27][28] Seed weight and color have high heritability, with a single recessive gene responsible for white color.^[28]

Diseases and crop management

Currently, there are no major pests or diseases affecting chia production.^[25] Essential oils in chia leaves have repellant properties against insects, making chia suitable for organic cultivation.^[22] However, virus infections possibly transmitted via white flies may occur.^[29] Weeds may present a problem in early development of the chia crop until its canopy closes, but because chia is sensitive to most commonly used herbicides, mechanical weed control is preferred.^[22]

Mesoamerican usage

S. hispanica is described and pictured in the Mendoza Codex and the Florentine Codex, sixteenth century Aztec codices created between 1540 and 1585. Both describe and picture Salvia hispanica and its usage by the Aztec. The Mendoza Codex indicates that the plant was widely cultivated and given as tribute in 21 of the 38 Aztec provincial states. Economic historians suggest that it was a staple food that was as widely used as maize.^[3]

Aztec tribute records from the Mendoza Codex, Matrícula de Tributos, and the Matricula de Huexotzinco (1560)—along with colonial cultivation reports and linguistic studies—give detail to the geographic location of the tributes, and provide some geographic specificity to the main S. hispanica growing regions. Most of the provinces grew the plant, except for areas of lowland coastal tropics and desert. The traditional area of cultivation was in a distinct area that covered parts of north-central Mexico south to Nicaragua. A second and separate area of cultivation, apparently pre-Columbian, was in southern Honduras and Nicaragua.^[30]

Decorative and novelty uses

In the United States, the first substantial wave of chia seed sales were tied to Chia Pets in the 1980s. These "pets" come in the form of clay figures that serve as a base for a sticky paste of chia seeds; the figures are then watered and the seeds sprout in a form suggesting the figure's fur. About 500,000 chia pets a year are sold in the US as novelties or house plants.^[31]

References

Wikimedia Commons has media related to Salvia hispanica.

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