Chia seeds
Salvia hispanica (Chia) are seeds commonly used to supplement dietary fiber and are claimed to have other health promoting properties. Its mechanical properties may provide use during baking and the fiber content good for bowel health with health promoting effects not yet demonstrated.
Last Updated:September 28, 2022
1.
Sources and Summary
Chia seed (Salvia hispanica L of the family Lamiaceae) is an oilseed native to southern Mexico and northern Guatemala,[1] and a dietary supplement that is used for its dietary fiber component, and has traditional usage as a food product (roasted seeds being referred to as chiapinolli in Columbia[2] where it was consumed for energy[3][4]). Chia appears to be classified as a grain product,[5] and due to its physical properties it is sometimes used as an egg/oil substitute in bakery products.[6]
1.1
Composition
Chia seeds contain:
- Dietary protein at 19-23% of seed weight[5] (other sources giving a more variable range of 15-25%[3])
- Non-fibrous carbohydrates, consisting of 26-41% of the seed by dry weight[3]
- Fatty acids, between 30-33% of total seed weight[3]
- Fiber, which is highly insoluble (about 5-fold more insoluble than soluble[2]) and has a high water holding capacity[7] and is at 9.4g of fiber per 25g serving (37.6%),[2] although usually it is estimated to be around 30% dry weight[8]
- Kaempferol (1.1mM/kg)[9]
- Quercetin (0.2mM/kg)[9]
- Myricetin (3.1mM/kg)[9]
- Cinnamic acid[9]
- Caffeic acid (6.6mM/kg, which increases to 13.5mM/kg when hydrolyzed) and Chlorogenic acid (7.1mM/kg)[9]
In general, the seeds of chia (which can be ground into a powder) have a respectable protein content of around 20% and a high fiber content of around 30%, which appears to have high water resorbing properties. The remaining 50% of the seed is split between fatty acids, carbohydrates, and some polyphenolics. No polyphenolics identified to date are unique to chia seeds
Whereas the fatty acid component (25-35% of the seed by dry weight[2]) in particular contains:
- Alpha-linoleic acid (ALA, an omega-3 fatty acids with the designation of 18:2) at 4.4g per 25g (17.6%) dry weight[2] but elsewhere has been noted to be 6.3% of total fatty acids[9] which can be increased to 69% upon hydrolyzation.[9] Usually chia is claimed to have a high ALA content in the range of 60% total fatty acids[3][10]
- Linoleic acid (18:2) at 46.3% total fatty acids (declines to 15.3% after hydrolyzation)[9] but commonly said to be approximately 20% of total fatty acids[3]
- Oleic acid (18:1) at 21.3% total fatty acids[9]
- Stearic acid (18:0) at 16.2% total fatty acids[9]
- Palmitic acid (16:0) at 9.9% total fatty acids[9]
Appears to be a very high level of polyunsaturated fatty acids (PUFAs) and is generally thought to contain more omega-3 fatty acids (as ALA) relative to omega-6 fatty acids (as LA)
Total phenolics have been quantified at 47mM per 1,000g chia seeds (caffeic acid equivalents)[9] and otherwise stated to be 0.8800-0.9211mg/g gallic acid equivalents of mostly flavonols.[2] At least ex vivo, these phenolics appear to reduce lipid peroxidation and oxidation.[2] The antioxidant capacity appears to be greater than other herbs in the salvia genera (including Clary Sage[11]) and at 0.5mL showed comparable efficacy to Trolox (concentration not stated).[2]
Appears to have a surprisingly respectable antioxidative potential when tested ex vivo
2.
Neurology
2.1
Appetite
Adding chia to a carbohydrate containing meal (50g carbohydrates, 7-24g chia) appears to result in less subjetive appetite ratings (41-68%) relative to chia-free control bread when measured up to 180 minutes after; overall food intake for the day not reported, and this decrease in appetite was correlated with blood sugar (the spike of which was attenuated following ingestion of chia).[12]
3.
Cardiovascular Health
3.1
Blood Pressure
Chia has been found to reduce blood pressure (by 6.3+/-4.2mmHg to the level of 123+/-16mmHg systolic) with no significant influence on diastolic in type II diabetics given 15g chia per 1000kcal dietary intake (placebo of wheat bran)[13] but failed to reduce blood pressure in otherwise healthy overweight adults given 50g chia (18.8g fiber) daily for 12 weeks.[1]
4.
Interactions with Glucose Metabolism
4.1
Absorption
Chia, when added to a meal standardized to 50g carbohydrate (7-24g chia seeds), appears to reduce postprandial glucose spikes in a dose-dependent manner by 21-48% (AUC values) when measured 60 minutes after ingestion.[12]
4.2
Interventions
Chia seeds, at 15g per 1000kcal dietary intake and compared to wheat bran as control, failed to significantly influence HbA1c or either glucose or insulin in type II diabetics.[13]
5.
Fat Mass and Obesity
5.1
Interventions
In rats fed chia to account for dietary carbohydrates (2.6%), fatty acids (22.8%), and protein (7.75%) over three months seemed to confer an anti-obese effect by attenuating the rate of weight gain relative to control groups (Maize oil at 23% of the diet; 50% linoleic acid by weight and no omega-3 content).[14] Along this reduction in fat mass came reduction in triglycerides, NEFA, and insulin resistance.[14]
In overweight adults given chia seeds (9.4g dietary fiber and 130kcal twice a day, placebo given similar caloric intake from various food products) for 12 weeks failed to reduce weight to a larger degree than the placebo product (mostly consisting of tapioca and carrot fiber).[1]
6.
Inflammation and Immunology
6.1
Interventions
Supplementation of 25g chia twice daily (18.8g fiber and 260kcal total) for 12 weeks in overweight persons has failed to influence inflammatory biomarkers of MCP, TNF-α, C-reactive protein (CRP), and IL-6 (control was a mixed food product to match macronutrients)[1] although elsewhere a reduction of CRP has been noted in diabetics given chia seeds (15g per 1000kcal dietary intake) over wheat bran.[13]
7.
Interactions with Aesthetics
7.1
Skin
In a small (n=5) sample of healthy persons with xerotic pruritus and persons with end stage renal disease (where xerotic pruritus increases in frequency[15]), topical application of the oil of chia seeds (4% of solution) was applied for 8 weeks appeared to improve symptoms of pruritus (lichen simplex chronicus and prurigo nodularis significantly reduced, pruritus and abrasion nonsignificantly) and increase skin hydration.[16] Benefits appeared to occur at 2 weeks and reach maximal effects at 4 weeks.
8.
Interactions with Organ Systems
8.1
Intestines
The fiber from chia tends to have a very high water holding capacity (and relatively low oil holding capacity) at up to 2.5-fold more than wheat bran, which contributes to water resorbing properties.[7]
9.
Interactions with Cancer Metabolism
9.1
Mechanisms
Chia (n-hexane extract) has been noted to have poor antiproliferative effects in vitro on cancer cells from breast (MCF7), cervix (HeLa), and skin carcinoma (A431)[17] while the oil has shown a beneficial modulation in eicosanoid production (less 12-HETE and arachidonic acid) in breast cancer cells (due to the alpha-linoleic acid content)[18] and 6% of mouse feed prior to a mammary tumor inoculation was able to reduce tumor weight (relative to control) and reduce metastasis (relative to both control and safflower oil).[18]
Weak antiproliferative effects in vitro and some potential anti-cancer effects on tumor proliferation that seem to simply be due to the omega-3 content of chia seeds (and thus not unique to chia containing products)