chia-seeds

What are Chia seeds

Chia plant (Salvia hispanica L.) is a biannually cultivated plant, categorized under the mint family (Labiatae), superdivision of Spermatophyta, and kingdom of Plantae 1). Prominently grown for its seeds, Salvia hispanica also produces white or purple flowers. The chia seed (Figure 1) is gluten free 2) and contains from 25% to 40% oil with 60% of it comprising (omega) ω-3 alpha-linolenic acid (Omega-3 ALA) and 20% of (omega) ω-6 linoleic acid (Omega-6 LA). Both essential fatty acids are required by the human body for good health, and they cannot be artificially synthesized. Chia plant can grow up to 1 m tall and has opposite arranged leaves. The chia seed color varies from black, grey, and black spotted to white, and the shape is oval with size ranging from 1 to 2 mm 3), 4). Wild and domesticated chia differs little. Currently, only Salvia hispanica but not other species of the genus Salvia can be grown domestically. To prevent the misidentification of Salvia hispanica and other species of Salvia, clear understanding of the morphological and genotypical differences among them had been proposed as solutions 5). Known for its medicinal uses, Salvia hispanica L. acquired the common name chia from the indigenous South American people of the pre-Columbian and Aztec eras 6). Owing to the fact that it can grow in arid environments, it has been highly recommended as an alternative crop for the field crop industry 7).

Figure 1. Chia Seeds

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[Source 8)]

Summary Chia Seeds Healthy Facts:

  • Chia seeds have an unusually high content (18%) of omega-3 fatty acids – essential fats that are important for heart health and brain function. Of the 30% total fat found in chia seeds, more than half is alpha linolenic acid (ALA), which is the plant form of omega-3. The oil in chia seeds contains higher amounts of essential fatty acids compared to other oils, even flax seed (linseed) oil.
  • In Chia seed oil, the ratio between Omega-6 fatty acids and Omega-3 fatty acids is 0.32-0.35 9), 10). The high content of Omega-3 fatty acids in chia seed oil enables reduction of the share of Omega-6 fatty acids in daily
    food rations. Apart from that, an adequate supply of unsaturated fatty acids reduces the risk of ischaemic heart disease and increases immunity in humans 11).
  • Chia seeds have outstanding fiber content. Chia’s 34% fiber is higher than that of flaxseeds (linseed) or sesame seeds, and works out to be about 10g in two tablespoons (which would make a significant contribution to the 25–30g it’s recommended we consume daily).
  • Chia seeds are a good source of insoluble fiber. The seeds expand quite a bit and form a gel when they come into contact with water. This gel adds bulk to your stool, which keeps bowel movements regular and helps prevent constipation. The added bulk also may help you feel fuller and so you eat less. Just 1 tablespoon (15 milliliters, mL) of chia seeds will give you 19% of your recommended daily fiber 12).
  • Chia seeds are also an excellent source of protein and extremely high in calcium – at 631 mg per 100g, this is five times the level in milk (although it may not be so readily absorbed). Just 1 little tablespoon (15 mL) will give you at 7% to 9% of your recommended daily amount of calcium and magnesium minerals.
  • Chia seed is also a source of other important minerals including iron, magnesium and zinc. And it’s gluten free, too 13).

Chia seeds calories and nutrition facts

Chia seed is composed of protein (15–25%), fats (30–33%), carbohydrates (26–41%), high dietary fiber (18–30%), ash (4-5%), minerals, vitamins, and dry matter (90–93%). However, chia seed is mainly valued for its oil. Thus, many oil extraction methods had been utilized. Differences in the extraction methods caused variations in the oil yield, quality of fatty acids, fatty acid contents, total dietary fibers, and also antioxidant content. Table 1 summarises the current methods used in the extraction of chia seed oil.

There are many factors that may cause variations in the concentrations of the active compounds in chia seed. One of them is the cultivation area of the plant itself. Differences in the environment, climate changes, availabilities of nutrient, year of cultivation, or soil conditions play crucial roles to the variations 14), 15). For example, the protein content tends to decrease as the temperature increased 16). Furthermore, an inverse relationship between altitude and the content of saturated fatty acids had been observed whereby, at low elevation, an increase in fatty acid saturation was noted in areas where the temperature was high 17). In Argentina, Ayerza 18) demonstrated that temperature largely contributed to the type of fatty acid found in the oil. They found that, during seed development from April to May, an increase in the temperature of the environment brought about a decrease in the polyunsaturated fatty acid (PUFA) content.

Another factor that may contribute to differences in the chemical compositions of chia seed is the developmental stage of the plant. It was shown that the (α-linolenic acid) ALA content decreased by 23% from the early stage to the matured stage of the seed. This concurrently resulted in the increase of linolenic acid (LA) and lignin content 19).

Table 1. Extraction of oil from chia seed

Methods of extractionDetails
Seed compression(i) Cold pressing technique and storage at low temperature (4°C) in dark 20).
(ii) Komet screw press at 25–30°C using electrical resistance heating.
(1) Pro: better preservation of antioxidant contents (quercetin and myricetin) than solvent extraction 21).
(2) Con: only partial recovery of oil yield 22).

Solvent(i) Soxhlet method using n-Hexane (less preferable than other methods).
(1) Pro: it favors the functional characteristics of the oil such as water holding and absorption capacity, organic molecule absorption, and emulsifying stability.
(2) Con: it causes slight loss of antioxidant content 23) and health and environment safety issues of using hexane 24).

Supercritical fluids(i) Use of carbon dioxide at optimum pressure P = 408 and 80°C (more preferable method).
(1) Pros: better purity and higher ALA/LA content of the final products 25), 26). The oil yield can be increased with pressure enhancement, but high temperature will slightly affect it 27).
[Source 28)]

Chia Seeds Oil

Chia seeds contain 25 – 40% of fat, most of which is in the form of polyunsaturated fatty acids, such as Omaga-3 alpha-linolenic acid (ALA) and Omega-6 linoleic acid (LA) 29). As a result of the processes of desaturation and elongation these acids are converted into long-chain polyenoic acids, such as Omega-3 eicosapentaenoic acid (EPA) and Omega-3 docosahexaenoic acid (DHA) 30). In comparison with other vegetable oils, chia seed oil is characterised by high content of polyunsaturated fatty acids (PUFAs). The therapeutic quality of a diet is affected not only by the amount of omega-3 PUFAs consumed but also by their proportion to omega-6 acids. The adequate ratio between the supply of Omega-6 fatty acids (Linoleic acid (LA)) and Omega-3 fatty acids (Alpha-linolenic acid (ALA)) is 4-5:1 31). This proportion is far from the ratio of Omega-6 and Omega-3 (15-20:1) in the diet of an average Europeans due to excessive consumption of Omega-6 fatty acids and saturated fatty acids. In chia seed oil the ratio between Omega-6 and Omega-3 fatty acids is 0.32-0.35 32), 33). The high content of Omaga-3 fatty acid, Alpha-linolenic acid (ALA), in chia seed oil enables reduction of the share of Omega-6 fatty acid (Linoleic acid (LA)) in daily food rations. Apart from that, an adequate supply of unsaturated fatty acids reduces the risk of ischaemic heart disease and increases immunity of the organism 34).

chia-seeds-oil-fatty-acids-composition
[Source 35)]

Chia Seeds Protein

The content of proteins in chia seeds is 16-26%, most of them being prolamins (538 g/kg of crude protein), followed by glutelins (230 g/kg of crude protein), globulins (70 g/kg of crude protein) and albumins (39 g/kg of crude protein) 36), 37), 38). Patients suffering from coeliac disease can consume chia seeds because they do not contain gluten proteins 39). Chia seeds contain more proteins than rice, maize, barley or oats seeds 40). According to the data of the United States Department of Agriculture 41), chia seeds contain 18 amino acids, including 7 exogenous amino acids, which are considered to be indispensable. The study by Olivos-Lugo et al. 42) revealed that glutamic acid, which is responsible for proper functioning of the brain, is the predominant amino acid in chia seeds.

Table 2. Chia Seeds Amino Acids content

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[Source 43)]

Chia Seeds Dietary Fiber

Dietary fiber is an important component of everyday diet. Optimal consumption of dietary fiber, i.e. 25-35 g/day has positive influence on health. The American Dietetic Association established the preferable ratio between insoluble and soluble dietary fibre fractions at 3:1 44). The content of fiber in chia seeds is 23-41%, where the insoluble fraction makes about 85% and the soluble fraction makes about 15% 45), 46). The content of fiber in chia seeds depends on the region of cultivation and climate. Chia seeds contain about twice as much fibre as bran, 4-5 times more than almonds, soy, quinoa or amaranth 47). They may play an important role in preventing and treating diseases of the digestive and circulatory systems, diabetes, colorectal cancer, kidney stones, haemorrhoids and metabolic disorders 48).

Chia Seeds Vitamins and minerals

Vitamins and minerals are necessary for normal function of the organism. An adequate supply of these elements enables optimal control of the amount of hormones, growth regulators and differentiation of cells and tissues. It also protects the organism from oxidative stress. Chia seeds are a source of B vitamins:
thiamine (0.62 mg/100 g), riboflavin (0.17 mg/100 g), niacin (883 mg/100 g) and folic acid (49 mg/100 g) 49). In comparison with rice and maize seeds chia seeds contain more niacin and comparable amounts of thiamine and riboflavin 50).

Apart from that, chia seeds are a source of minerals. They contain 6 times more calcium, 11 times more phosphorus and 4 times more potassium than cow’s milk 51).

Chia Seeds Antioxidants

Oxidation is an important biological process, which is indispensable for the production of energy in the human organism. During metabolism molecular oxygen is reduced to water. When electrons are being transferred, free reactive forms of oxygen are being generated, such as hydrogen peroxide, hydroxyl and peroxide radicals. Free radicals are considered to be the cause of neurological diseases, inflammations, immunodeficiency, ageing, ischaemic heart disease, strokes, Alzheimer’s and Parkinson’s diseases and cancers 52), 53).

Chia seeds also contain a high amount of antioxidants 54). The following substances have been detected in chia seeds: tocopherols, sterols (approx. 50% β-sitosterol), and polyphenolic compounds, such as protocatechuic acid, gallic and p-coumaric acids, caffeic acid, chlorogenic acid as well as epicatechin, quercetin, kaempferol, rutin and apigenin 55), 56), 57). The total content of vitamin E in chia seeds is 238-427 mg/kg and it is comparable to peanut oil (398.6 mg/kg), but it is lower than in linseeds (588.5 mg/kg), sunflower (634.4 mg/kg) or soybean (1,797.6 mg/kg). Reyes-Caudillo et al. 58) observed that the content of antioxidants was different, depending on the method of their extraction.

Heavy metal analysis showed that chia seed contains them at safe levels, not exceeding the maximum metal levels for food safety, and the seed is also free from mycotoxins 59). Recent studies on chia seeds have focused on phytochemicals and their extractions from the seed. Only very little studies have focused on in vivo or clinical bioactivities and the safety aspects of chia seed.

Table 3. Chia seeds calories and nutrition facts

[Source 60)]

Health benefits of chia seeds

Seed from Salvia hispanica L. or more commonly known as chia seed is a traditional food in central and southern America. Currently, it is widely consumed for various health benefits especially in maintaining healthy serum lipid level. This effect is contributed by the presence of phenolic acid and omega-3 and omega-6 PUFA oils in the chia seed. Besides, the additive effect of ALA (α-linolenic acid) an Omega-3 long chain PUFA was observed to exhibit cardioprotective effects in women 61), which led to consequent human clinical studies of chia on disease risk factors. To date, four clinical trials have been carried out, and the details are summarised in Table 3. Among these trials, only that of Nieman et al. 62) showed no health benefits from chia seed. This difference could be due to the treatment durations employed and also the actual biochemical components of the dietary chia seed used in the various studies. Nevertheless, later studies 63), 64), 65) demonstrated well the benefits of chia on human health. However, studies of chia’s intake in human diet which take into consideration factors such as lifestyle and genetic variations are still limited. Hence, studies which target these factors should be done in the future.

Various active ingredients including essential fatty acids and phenolic compounds have been identified in chia seed. These active compounds which contribute to the health benefits of chia seeds are summarised in Table 4.

Table 4. Active compounds identified in Chia seeds and their chemical structure.

health benefits of chia seeds
chia seeds health benefits
[Source 66)]

Therapeutic and Dietetic Properties of Chia Seeds

The nutritional properties of chia seeds, such as: high content of polyunsaturated fatty acids, vegetable protein, dietary fibre, vitamins, minerals and bioactive
substances result in numerous studies on these seeds in order to prove their therapeutic properties. Hypotensive 67), antineoplastic, laxative and analgesic properties are attributed to chia seeds. They are said to protect the cardiovascular system, exhibit anti-inflammatory
properties, control lipid metabolism, have anti-oxidative properties and increase the performance of athletes 68). A randomized, single blind trial on 20 adults with type 2 diabetes found significant reduction in systolic blood pressure and C-reactive protein concentration in blood plasma even after ingesting 37g chia seeds added to bread per day for 12 weeks, a double  increase of α-linolenic acid (ALA) and eicosapentaenoic acid (EPA) in plasma was noted as compared to the control group. Anticoagulant and anti-inflammatory effect of chia seeds may help in preventing strokes and heart attacks in type-II diabetic patients 69). Increase of unsaturated fatty acids in plasma blood was observed also in the study of postmenopausal healthy women supplemented with 25 g milled chia seeds per day for 7 weeks 70). Effect of ingesting 50 g chia seeds for 12 weeks was examined on 76 adults. This study found no significant reduction in inflammatory  markers, body weight, blood pressure, lipid profile and blood sugar levels 71). Similar results were obtained in the study
conducted with 62 obese women supplemented with 25g whole or 25g milled chia seeds 72). However, reduction in postprandial glycaemia in healthy subjects was showed in another studies 73), 74), 75). Effect of dietary intervention in checking metabolic syndromes was evaluated through randomized double blind trial. This trial conducted on 67 adults found significant reduction of triacylglycerols, C-reactive protein concentrations and insulin resistance in group with chia-based diet 76). It was observed that ingesting 35 g chia flour for 12 weeks decreased total cholesterol level and increased LDL cholesterol 77). Although the presence of active ingredients in chia seeds contributes to health benefits, safety and efficiency of this medicinal food or natural product, they need to be validated by scientific protocols, since clinical studies on the safety and efficiency of chia seeds are still limited and those reported have not shown conclusive results 78).

Table 5. Human clinical trials of chia seeds

DurationMode of trialFormulationResultsReference
7 weeks10 postmenopausal women25 g chia seed/dayPolyunsaturated fatty acid content particularly ALA, and eicosapentaenoic acid (EPA) was elevated after supplementation with milled chia. The result was in agreement with previous studies conducted in hens, rats, and rabbits.79)

5-6 weeksHypercholesterolaemic rabbits10 g chia oil/kg diet or 10 g chia oil + 1g cholesterol/kg dietReduced concentration of triacylglycerols and increased content of α-linolenic acid in the serum in 10 g chia oil + 1g cholesterol/kg diet group. Chia seed oil may have protective effect on blood vessels.80)

6-12 weeks36 young obese rats133 g chia seeds/kg diet or 40 g chia oil/kg dietChia seeds and oil reduced oxidative stress in vivo by improving the antioxidant status and reducing lipid peroxidation in diet-induced obese rats.81)

10 weeksRandomized double-blind trial, 62 overweight women aged 49-75 years25 g whole chia seeds /day or 25 g ground chia seeds/dayNo influence of [whole/ground] seeds on inflammatory markers, blood pressure, body composition. Increased concentration of α-linolenic and eicosapentaenoic acids in the blood serum of obese women consuming ground seeds vs the control group and the group consuming whole chia seeds.82)

12 weeks26 men and women aged 45-55 years (placebo 7; chia flour 19)35 g chia flour/dayDecreased body weight in the group consuming chia flour, a greater decrease in obese people, no difference from the placebo group. Reduced total cholesterol and increased LDL cholesterol in the supplemented group.83)

12 weeksSingle blinded with 76 subjects (placebo 37; chia seed 39)25 g chia seed in 250 mL water twice/dayAlthough Nieman et al. have hypothesized that the high dietary fiber and ALA content in chia can promote human weight loss and reduce disease risk factors related to heart disease and obesity, no significant results on weight loss and disease risk factors even though the plasma level of ALA increased.84)

2 monthsRandomized trial, with control diet (500 kcal for 2 weeks), 67 metabolic syndrome subjects (placebo 35; beverage 32)Beverage of 235 kcal that contains soy protein, nopal, chia seed, and oatBody weight loss and reduction of triglyceride and blood glucose levels.85)

120 minutesRandomized, double-blind trial on 11 healthy subjects50 g white bread containing either 0, 7, 15, or 24 g of chia seedReduced postprandial glycemia.86)
[Source 87)]

The studies investigating the effect the consumption of chia seed has on cardiovascular risk present inconclusive results 88). Researchers are continuing to look at whether consuming more of the fatty acids found in chia seeds can improve blood pressure, heart health, blood sugar, or provide other benefits.

  • If you plan to consume chia seeds or chia seed oil on a regular basis, talk with your doctor. Chia seeds can thin your blood and may affect how medicines such as warfarin (Coumadin) and aspirin work. You may need to avoid chia seeds before surgery.

How to Eat Chia Seeds

Chia seeds can be eaten raw or prepared in a number of dishes. Sprinkle ground or whole chia seeds on cereal, rice, yogurt or vegetables. In Mexico, a dish called chia fresco is made by soaking chia seeds in fruit juice or water. Chia seeds are very absorbent and develop a gelatinous texture when soaked in water making it easy to mix them into cooked cereal or other dishes.

Chia seeds can be added or sprinkled on almost anything. There is no preparation needed.

To add chia seeds to your diet:

  • Add them to your bread crumbs.
  • Sprinkle them on salads.
  • Add them to your drinks, smoothies, yogurt, or oatmeal.
  • Add them to soups, salads, or pasta dishes.
  • Add them to your pancakes, French toast, or baked goods mix.

You can also grind chia seeds into a paste and add the paste to your dough or other mixes before cooking or baking.

Chia seeds and weight loss

A small double-blind, randomized, controlled trial with two parallel groups involving 77 overweight or obese patients with type 2 diabetes (HbA1c: 6.5-8.0%; BMI: 25-40 kg/m2) were used to study the health benefits of chia seeds in the treatment of overweight and obese patients with type 2 diabetes 89). Both groups followed a 6-month calorie-restricted diet; one group received 30 g/1000 kcal/day of chia seeds, the other 36 g/1000 kcal/day of an oat bran-based control. Primary endpoint was change in body weight over 6-months. Secondary endpoints included changes in waist circumference, body composition, glycemic control, C-reactive protein, and obesity-related satiety hormones.

At 6-months, participants on chia seeds group had lost more weight than those on control (1.9 ± 0.5 kg and 0.3 ± 0.4 kg, respectively), accompanied by a greater reduction in waist circumference (3.5 ± 0.7 cm and 1.1 ± 0.7 cm). C-reactive protein was reduced by 1.1 ± 0.5 mg/L (39 ± 17%) on chia seeds, compared to 0.2 ± 0.4 mg/L (7 ± 20%) on control (oat bran group). Plasma adiponectin on the chia seeds intervention increased by 6.5 ± 0.7%, with no change observed on control (oat bran group) 90).

The results of this study 91), support the beneficial role of chia seeds in promoting weight loss and improvements of obesity related risk factors, while maintaining good glycemic control. Supplementation of Salba-chia may be a useful dietary addition to conventional therapy in the management of obesity in diabetes 92).

However in another earlier study involving chia seeds and weight loss on 90 overweight adults (men & women, age 20-70 years) showed consumption of 50 g/day chia seeds vs placebo for 12 weeks by overweight/obese men and women had no influence on body mass or composition, or various disease risk factor measures 93). In that study, participants were randomized to chia seed and placebo groups, and under single-blinded procedures, ingested 25 g chia seeds or placebo supplements mixed in 0.25 L water twice daily before the first and last meal for 12 weeks. Pre- and poststudy measures included body mass and composition (dual energy x-ray absorptiometry), inflammation markers from fasting blood samples (C-reactive protein, interleukin 6, monocyte chemoattractant protein 1, and tumor necrosis factor alpha), oxidative stress markers (trolox equivalent antioxidant capacity and plasma nitrite), blood pressure, and a serum lipid profile. Plasma ALA increased 24.4% compared to a 2.8% decrease in chia seeds and placebo, respectively. No group differences were measured for changes in plasma eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Pre-to-post measures of body composition, inflammation, oxidative stress, blood pressure, and lipoproteins did not differ between chia seeds and placebo for both sexes. In conclusion, ingestion of 50 g/day chia seeds vs placebo for 12 weeks by overweight/obese men and women had no influence on body mass or composition, or various disease risk factor measures 94).

Commercial uses of chia seeds

At present, chia seed is used as a healthy oil supplement for humans and animals. Table 6 presented a summary of the current commercial usages of chia seeds. Human consumption of chia in diet is mainly from the extracted oil through its incorporation into cooking oil, confections, or supplements. In 2000, the US Dietary Guidelines recommend that chia seed can be used as a primary food not exceeding 48 g/day. Chia is commonly consumed as salad from chia sprout, in beverages, cereals, and salad dressing from the seed, or it is eaten raw 95), 96). The European Commission approved the use of chia seed in bread products with a limit of not more than 5%. Other than bread, the food industry of various countries around the world including US, Canada, Chile, Australia, New Zealand, and Mexico has widely used chia seeds or its oil for different applications such as breakfast cereals, bars, cookie snacks, fruit juices, cake, and yoghurt 97), 98).

Table 6. Commercial usage of chia seeds

Chia seed usageProductsRemarks
Animal feedChicken(1) Increased Omega-3 alpha-linoleic acid and Omage-6 linoleic acid of egg and yolk 99).
(2) Increased Omage-3 alpha-linoleic acid and decreased palmitic fatty acid of meat.
(3) Taste, sensory evaluation, and production of eggs and broilers were not affected 100), 101), 102).
Pigs and rabbitsIncrease of PUFA in meat fats as well as improved aroma, flavor, and digestibility of meat 103), 104), 105), 106).

Food formulationComposite flour (15–20% of chia with corn flour)Increased total dietary fiber and a decrease in Glycemic Index 107).
Ingredient for cookies, cereal bars, chips, desserts, breads, jellies, and emulsionsImproved water holding, absorption capacity, and emulsifying stability 108), 109), 110).

Health supplementChia seed oilTopical application for skin diseases such as pruritus and xerotic especially in diabetic and renal dysfunction patients 111).
Carbohydrate-loading drinksEnhanced athletes’ sports endurance by more than 90 minutes but not athletes’ performance 112).
Supplement for postmenopausal womenEnhanced the levels of ALA and eicosapentaenoic acid (EPA) 113).
[Source 114)]

Summary

The studies investigating the effect the consumption of chia seed has on cardiovascular risk present inconclusive results 115). Based on the current research findings, chia seed is a good choice of healthy oil to maintain a balanced serum lipid profile. However, unlike vitamin E and coenzyme Q10, in vivo clinical bioactivity and safety evaluation of chia seeds are still limited and contradictions still exist in this area and the need for continued research in this direction and considerations on the role of chia seed as a functional food. Furthermore, details on the mechanisms of chia seed’s hypolipidemic effects need to be studied and compared with those of the isolated omega 3 and omega 6 fatty acids.

References   [ + ]

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