The Fatty Acid Composition of Seeds

In my book, The Paleo Answer, I discuss a food-gathering strategy referred to by anthropologists as the optimal foraging theory. It refers to historically studied foragers, hunting, gathering, and fishing for foods in a manner that maximized their caloric intake versus the energy they expended to obtain these foods. Based on this strategy, hunter-gatherers typically maintained the following order of food preferences:

1. Large animals
2. Medium-size animals
3. Small animals, birds, and fish
4. Roots and tubers
5. Fruit
6. Honey
7. Nuts and seeds
8. Grass seeds (cereals)

As we can see, seeds are toward the bottom of the list, above only cereals, which certainly should be avoided on The Paleo Diet®. [1] That being said, there are numerous nutrients in seeds that do offer health benefits, [2-4] but, as with all plant foods, seeds can contain anti-nutrients that might be problematic for certain individuals. [5,6] Interestingly, if the antinutrients in the seeds are problematic, it has been shown that roasting seeds can not only decrease the anti-nutrient content, but also improve the antioxidant activity and phenolic content. [5-7]

Important to consider with respect to your health, is the omega-6/omega-3 fatty acid ratio which we have addressed in detail. So, when consuming—particularly in large quantities—it is worth noting the fatty acid composition of seeds.

Seeds vs. Pseudo-Grains

But what about starchy seeds that are frequently used by celiac patients and others to replace gluten-containing grains? Technically, these seeds are not true grasses (cereals) because they are not members of the Poaceae family and are actually pseudo-grains. They include chia seeds, buckwheat, quinoa, and amaranth.

As I addressed in The Paleo Answer, these pseudo-grains are loaded with a variety of moderately toxic antinutrients that probably have minimal adverse health effects if we eat them occasionally, in limited quantities, or for only short periods. However, their regular consumption should be avoided.

RELATED: Are Whole Grains Healthy?

The Fatty Acid Composition of Seeds

The following table lists the fatty acid content of several commercially available seeds. As you can see, both flaxseed and chia seeds are an excellent source of the omega-3 fatty acid alpha-linolenic acid (ALA).

When I wrote the first edition of The Paleo Diet back in 2002, chia seeds were not on my radar, and I imagine that many of you would have never even heard of chia seeds, much less eaten them. However, chia seeds have since become an extremely popular item in co-ops and health food stores.

Chia seeds are small, oval shaped; either black or white in color, and resemble sesame seeds. They are native to southern Mexico and northern Guatemala and 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 be made into tortillas, tamales, and beverages. The roasted ground seeds are traditionally consumed as gruel called pinole.

In the past 20 years, chia seeds have become an increasingly popular food source, primarily because of their high content of the omega-3 fatty acid, alpha-linolenic acid (ALA). Chia seeds have also been fed to domestic livestock and chickens to enrich their meat and eggs with omega-3 fats.

Chia Seed Nutrient Profile

I can endorse feeding chia seeds to animals, but I have serious reservations when it comes to humans eating these seeds as staple foods. The table below shows the nutrient profile for a 100-gram serving 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, manganese and zinc.

Unfortunately, in the game of human nutrition, the devil is almost always in the details. As is the case with many other plant seeds (e.g., cereal grains, legumes) chia seeds contain numerous antinutrients which reduce their nutritional value.

If you look at the table above, notice the high phosphorous concentrations found in chia seeds. This revealing marker tells us that chia seeds are concentrated sources of phytate, an antinutrient that binds many minerals (calcium, iron, zinc, magnesium and copper) thereby making them unavailable for absorption. So, in our bodies, chia seeds actually become inferior sources of all these minerals.

Similarly, the table suggests that chia seeds are a good source of vitamin B₆. Unfortunately, in our bodies the utilization this vitamin from plant foods such as chia seeds is quite low, whereas bioavailability of B₆ from animal products is quite high, approaching 100%.

Further Research Supporting Why The Paleo Diet Does Not Recommend Chia Seeds

One of the unusual characteristics of chia seed food products comes from a clear mucilaginous gel that surrounds the seeds. This sticky gel forms a barrier which impairs digestion, fat absorption, and causes low protein digestibility. Based upon animal and human studies, it is likely that other antinutrients together with this gel may promote a leaky gut, chronic systemic inflammation, and food allergies.

Dr. Nieman et al. completed a study in humans who consumed 50 grams of chia seeds per day for 12 weeks. [8] At the experiment’s end, different plasma cytokines were measured as indicators of inflammation. While the increases (Men: 10.2%; women: 10.1%) in interleukin 6 did not reach statistical significance, a second inflammatory marker, monocyte chemotactic protein 1 showed a significant increase in both men (6.9%) and women (6.1%).

In support of the notion that chia seed consumption may adversely affect the immune system and promote inflammation is a rat study showing that after only one month, high chia seed diets increased blood levels of immunoglobulin E (IgE) by 112.8 % (p=0.06). [9] Because IgE is a marker for allergenic food proteins that are processed through the gut, chia seeds likely cause a leaky gut and food allergies.

As you can see, the nutritional problems with chia seeds involve similar issues as with cereals grains—they simply are second-rate foods compared to meats, fish, fresh fruits and vegetables, and some nuts and true seeds.

References

1. Cordain L. Cereal grains: humanity’s double-edged sword. World Rev Nutr Diet. 1999;84:19-73. doi: 10.1159/000059677. PMID: 10489816.
2. Alasalvar C, Chang SK, Bolling B, Oh WY, Shahidi F. Specialty seeds: Nutrients, bioactives, bioavailability, and health benefits: A comprehensive review. Compr Rev Food Sci Food Saf. 2021 May;20(3):2382-2427. doi: 10.1111/1541-4337.12730. Epub 2021 Mar 14. PMID: 33719194.
3. Zaini NS, Karim R, Abdull Razis AF, Zawawi N. Utilizing Nutritional and Polyphenolic Compounds in Underutilized Plant Seeds for Health Application. Molecules. 2022 Oct 12;27(20):6813. doi: 10.3390/molecules27206813. PMID: 36296406; PMCID: PMC9612334.
4. Samtiya M, Acharya S, Pandey KK, Aluko RE, Udenigwe CC, Dhewa T. Production, Purification, and Potential Health Applications of Edible Seeds’ Bioactive Peptides: A Concise Review. Foods. 2021 Nov 4;10(11):2696. doi: 10.3390/foods10112696. PMID: 34828976; PMCID: PMC8621896.
5. Bueno-Borges LB, Sartim MA, Gil CC, Sampaio SV, Rodrigues PHV, Regitano-d’Arce MAB. Sacha inchi seeds from sub-tropical cultivation: effects of roasting on antinutrients, antioxidant capacity and oxidative stability. J Food Sci Technol. 2018 Oct;55(10):4159-4166. doi: 10.1007/s13197-018-3345-1. Epub 2018 Jul 23. PMID: 30228414; PMCID: PMC6133840.
6. Ndidi US, Ndidi CU, Olagunju A, Muhammad A, Billy FG, Okpe O. Proximate, Antinutrients and Mineral Composition of Raw and Processed (Boiled and Roasted) Sphenostylis stenocarpa Seeds from Southern Kaduna, Northwest Nigeria. ISRN Nutr. 2014 Mar 16;2014:280837. doi: 10.1155/2014/280837. PMID: 24967265; PMCID: PMC4045307.
7. Peng M, Lu D, Liu J, Jiang B, Chen J. Effect of Roasting on the Antioxidant Activity, Phenolic Composition, and Nutritional Quality of Pumpkin (Cucurbita pepo L.) Seeds. Front Nutr. 2021 Mar 10;8:647354. doi: 10.3389/fnut.2021.647354. PMID: 33777995; PMCID: PMC7988230.
8. Nieman DC, Cayea EJ, Austin MD, Henson DA, McAnulty SR, Jin F. Chia seed does not promote weight loss or alter disease risk factors in overweight adults. Nutr Res. 2009 Jun;29(6):414-8. doi: 10.1016/j.nutres.2009.05.011. PMID: 19628108.
9. Fernandez I, Vidueiros SM, Ayerza R, Coates W, Pallaro A. Impact of chia (Salvia hispanica L.) on the immune system: preliminary study. Proceedings of the Nutrition Society. 2008;67(OCE1):E12. doi:10.1017/S0029665108006216