TUESDAY, Oct. 21, 2014 (HealthDay News) — Despite potential health benefits, chia seeds may pose a risk if they are not consumed properly, according to new research.
The tiny, oval seeds — a rich source of fiber, protein and heart-healthy omega-3 fatty acids — should not be eaten in their dry, raw form, experts cautioned. This is particularly true for people with a history of swallowing problems or a constricted esophagus, the researchers said.
“Chia seeds have the ability to absorb up to 27 times their weight in water,” said study author Dr. Rebecca Rawl, from Carolinas Medical Center in Charlotte, N.C.
“For this reason, patients with a history of [swallowing problems] or known esophageal strictures should be cautioned that chia seeds should only be consumed when they have had the ability to fully expand in liquid prior to ingestion,” Rawl said.
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. 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. It is still used in Paraguay, Bolivia, Argentina, Mexico and Guatemala, sometimes with the seeds ground or with whole seeds used for nutritious drinks and as a food source.
It is one of two plants known as chia, the other being Salvia columbariae, which is more commonly known as the golden chia.
Chia is an annual herb growing up to 1.75 m (5.7 ft) 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. Chia is hardy from USDA Zones 9-12. Many plants cultivated as S. hispanica are actually S. lavandulifolia.
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.
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. 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.
According to the USDA, a one ounce (28 gram) serving of chia seeds contains 9 grams of fat, 5 milligrams of sodium, 11 grams of dietary fiber, 4 grams of protein, 18% of the recommended daily intake of calcium, 27% phosphorus and 30% manganese. These nutrient values are similar to other edible seeds, such as flax or sesame.
One pilot study found that 10 weeks ingestion of 25 grams per day of milled chia seeds, compared to intact seeds, produced higher blood levels of alpha-linolenic acid andeicosapentaenoic acid, an omega-3 long-chain fatty acid considered good for the heart, while having no effect on inflammation or disease risk factors.