Q: Are there any negative effects associated with chia seeds which would make them inappropriate in The Paleo Diet?Thank you.A: Good question. I would imagine that many of our readers have never even heard of chia seeds much less eaten them. Chia seeds (Salvia hispanica L.) are a member of the Labiatae plant family and are native to southern Mexico and northern Guatemala. The seeds are small, oval shaped; either black or white colored and resemble sesame seeds1. These seeds were cultivated as a food crop for thousands of years in this region by the Aztecs and other native cultures. Chia seeds can be consumed in a variety of ways including roasting and grinding the seeds into a flour known as Chianpinolli which can then become incorporated into tortillas, tamales, and various beverages2. The roasted ground seeds were traditionally consumed as a semi-fluid mucilaginous gruel (Pinole) when water is added to the flour. In post-Columbian times the most popular use of chia flour was to make a refreshing beverage in which the ratio of seeds to water is decreased, thereby resulting in a less gelatinous consistency to which lemon, sugar or fruit juice are added2. The sticky consistency of chia seed Pinole or chia beverages comes from a clear mucilaginous, polysaccharide gel that remains tightly bound to the seeds3. This sticky gel forms a physical barrier which may impair digestion and absorption of fat from the seed4 while also causing a low protein digestibility5.In the past 20 years a revival of interest in chia seeds has occurred primarily because of their high fat content of about 25-39% by weight, of which 50-57 % is the therapeutic omega 3 fatty acid and alpha linolenic acid (ALA)6, 7. In the past 10 years chia seeds have been used as a foodstuff for animals to enrich their eggs and meat with omega 3 fatty acids8-11. So I wholeheartedly approve of feeding chia seeds to animals and then eating the omega 3 fatty acid enriched meat or eggs of these animals.How about feeding chia seeds to humans – should we consume chia seeds because of their high omega 3 fatty acid (ALA) content? The Table below shows the entire nutrient profile of chia seeds. At least on paper, it would appear that chia seeds are a nutritious food that is not only high in ALA, but also is a good source of protein, fiber, certain B vitamins, calcium, iron and manganese.
Table 1. Nutrient profile for chia seeds (Salvia hispanica L.), 100 gram portion.NutrientAmount% DRIKilocalories49025Protein15.6 g31Carbohydrate43.9 g15Fat30.8 g47Saturated Fat3.2 g6Monounsaturated Fat2.9 gnaPolyunsaturated Fat23.3 gna18:1 oleic acid2.0 gna18:2n6 linoleic acid5.8 gna18:3n3 alpha linolenic acid17.6 gnaFiber37.7 g151Vitamin A36 IU1Vitamin DnaVitamin EnaVitamin KnaVitamin B10.87 mg58Vitamin B20.17 mg10Vitamin B35.82 mg29Vitamin B60.69 mg35Vitamin B1200Folate114 mcg29Pantothenic acid0.94 mg9Biotinna0Vitamin C15.7 mg26Sodium19 mg1Potassium100 mg5Phosphorus94895Calcium631 mg26Copper0.19 mg9Iron10.056Magnesium770 mg19Manganese2.17 mg108Zinc3.5 mg23
Unfortunately, the devil is always in the details, and as is the case with many other plant seeds (e.g. cereal grains, legumes) a frequent evolutionary strategy to prevent predation by animals and microorganisms is the natural selection by the plant for toxic compounds known as antinutrients. As I previously mentioned, the thick mucilaginous gel which is tightly bound to chia seeds may impair fat absorption in animals4 which, along with their high fiber content, causes the available protein to be poorly absorbed5. Another antinutrient found in chia seeds (~2,000 mg/100 g) is phytate or phytic acid, which impairs absorption of all divalent ions (calcium, iron, zinc, magnesium, manganese, etc) in a dose-dependent manner12, 13. Meaning that once in your body (in vivo), the available calcium, iron, zinc, magnesium and manganese from chia seeds are poorly absorbed, hence making chia seeds a poor dietary source for these minerals. Although Table 1 suggests that chia seeds may be good sources of vitamin B6, the bioavailability of B6 from plant foods tends to be low, whereas bioavailability of B6 from animal products is generally quite - high approaching 100%14.A number of chia seed supplementation studies in rats and experimental animals have demonstrated certain favorable health effects including improvements in blood lipids, and insulin metabolism9, 15, 16. However, these effects could not be replicated in a recent, well controlled study in humans, who consumed 50 grams of chia seeds per day for 12 weeks19. In fact, despite an increase in blood ALA concentrations, overweight men and women experienced no changes in body weight, blood pressure, blood lipids or inflammatory blood markers17. A recent review of all human chia supplementation studies concluded: "There is limited evidence supporting the efficacy of Salvia hispanica for any indication; thus far, only two clinical studies have examined the effects of Salvia hispanica on cardiovascular disease (CVD) risk factors (including body weight). One study showed some effects on some CVD risk factors, while the other did not. Neither study showed any effects of Salvia hispanica on weight loss."One of the outcomes of the Nieman et al. study17 that will require further scrutiny suggests that chia seed consumption may contain one or more antinutrients which may promote chronic low level inflammation – not a good thing. If you look at the data carefully, both men and women experienced increases in a blood inflammatory marker called interleukin 6 (IL-6). After 12 weeks of eating chia seeds the men’s blood levels of IL-6 increased 10.2% and the women’s increased 10.1%. Additionally another inflammatory marker called monocyte chemotactic protein (MCP) increased 6.9% in men, and 6.1% in women. Although the authors deemed these increases to be statistically insignificant, the large standard deviations for the measurements suggest that confounding extraneous factors may have influenced the results. In support of the notion that chia seed consumption may adversely affect the immune system and promote inflammation is a rat study showing that a one-month high-chia seed diet increased blood levels of IgE by 112.8%18. IgE is an immunoglobulin that is a marker for allergenic food proteins that are processed through the gut19.Just how chia seed consumption may promote chronic low-level systemic inflammation via their presence in the gastrointestinal tract is unclear. Although many species of Salvia have a high lectin content20, which may adversely affect the gut by increasing intestinal permeability21, Salvia hispanica or chia seeds do not contain any known lectins22. Consequently, it is possible that other antinutrients found in chia seeds may adversely affect gut tissue, including saponins, which are frequently found in Salvia species23, and which cause a "leaky gut"24-27. To date, the saponin content of chia has not been measured. The thick mucilaginous gel which is tightly bound to chia seeds is a complex polysaccharide, and these types of polysaccharide gums are known to adversely alter small intestinal cell function - including increased mucosal cell production28, which could increase intestinal permeability.When the gut becomes "leaky" it is not a good thing, as the gut contents may then have access to the immune system, which in turn becomes activated, and thereby causes chronic low-level systemic inflammation. In particular, a component of the cell walls of gut gram negative bacteria called lipopolysaccharide (LPS) is highly inflammatory. Any LPS which gets past the gut barrier is immediately engulfed by two types of immune system cells (macrophages and dendritic cells). Once engulfed by these cells, LPS binds to Toll Like Receptor 4, which in turn causes an immediate immune system response including increases in blood levels of IL-6 as shown in the Nieman et al study17. Until further human studies are conducted, I would be cautious in recommending chia seeds for human consumption, particularly in people with food allergies or known autoimmune diseases.References:
-08.svg)