Tag Archives: flax

Getting omega-3’s: Science, texture and allergies

As I explained in a previous post, it’s important to have a reliable source of omega-3’s.

It took me some research and experimentation to find a cheap, hassle-free source of vegan omega-3’s that worked for me, so I wanted to share my findings. Since plant-based omega-3’s are in the form of ALA (alpha-linolenic acid), I’ll refer to vegan omega-3’s as ALA throughout this article.

What I was looking for

I wanted an easy source of ALA that I could add to my diet without a lot of change. I wanted to stick to a form that was fairly cheap, reasonably shelf stable, and which research supported as containing absorbable ALA. The ratio of omega-6’s to omega-3’s may be important, so I wanted a food that had few omega-6’s along with the omega-3’s. Finally, I have oral allergies which, while not life threatening, make many raw foods very unpleasant to eat, and possibly unsafe. I’d have to stick to a form of ALA-containing food that did not aggravate my allergies.

The contenders

I wanted a minimal dietary intervention, so while walnuts contain ALA, the ALA in walnuts is not very concentrated. You’d have to eat a lot of nuts to meaningfully boost your omega-3 levels, which would be a substantial dietary change. Similarly, tofu and soy products have ALA, soy ALA is also not very concentrated, and soy contains 10 times as much omega-6’s as omega-3’s.

The most concentrated sources of omega-3 fatty acids are flax seeds. About two teaspoons of flax seeds gives the American Heart Association’s recommended daily dose of omega-3 fatty acids.[4] Chia seeds are also a concentrated source. These are both promising candidates, so I focused on these.

ALA availability

The first challenge is that ALA from whole flax seeds is not absorbed in digestion. This means that even though there is a lot of ALA in flax seeds, your body will get very little ALA from them. Generally I found that nutrition information on the internet to be in agreement with the research here — to get ALA from flax seeds, you have to grind them or process them into flaxseed oil.

Interestingly, I found internet nutrition information to disagree with the research I could find on chia. Internet nutrition advice suggested that chia seeds, unlike flax, do not have to be ground for their ALA to be absorbable. However the only human study I found disagreed with this, and found that ALA was only absorbed from ground chia seeds, just like flax.

Ok, so we’ll have to grind them. No problem. A coffee grinder or a Vitamix will do the trick.


I wanted to incorporate flax or chia seeds into foods that I was already eating. Since it’s recommended to take flax and chia with lots of water, I wanted to use wet foods that I already eat frequently — oatmeal and lentil soup.

The problem is that when exposed to water, flax and chia seeds form a gel-like texture that I’ve heard compared poetically to pudding, or less poetically to mucous. While I find the texture of whole chia seeds pleasant when added to oatmeal or soup (although it took some getting used to), I find the texture of ground chia or ground flax much less appealing when added to wet foods. Unlike whole chia, there are no crunchy bits to break up the gel mush.

I’m curious if I’m alone here, because I couldn’t find much discussion online about avoiding gross textures with these seeds in their recommended wet form.

(I’ll note that some people suggest using flax meal as an egg replacer in baked goods, which avoids the texture issue. I don’t do much baking, I don’t want my daily omega-3 regimen to be so labor-intensive, so I didn’t find this to be a realistic strategy for me. If you bake a lot anyway, this could be a great strategy!)

Oral allergies

One last constraint, although one that only affects 1% of people: I have an oral allergy to raw flax seeds. (I have a similar sensitivity to chia, but I haven’t looked into it in as much depth.) This means that I can only consume flax and chia seeds that have been heated.

Roasted ground flax

I decided to try roasting flax seeds to solve the allergy problems, then grinding the roasted seeds to improve ALA digestibility. This was delicious, and surprisingly, did not have any effect on the texture of oatmeal or lentil soup. It adds a pleasant roasted flavor to these foods. So far so good. So does the research support this as a source of ALA?

Since ground flax seed is already established as an effective source of ALA, I was mostly concerned with whether or not roasting the flax seeds, grinding them, and then reheating them (in my case, adding them to oatmeal or soup) would compromise the ALA. Flaxseed oil is said to degrade when exposed to heat, so I was curious if the same would happen to my roasted flax seeds.

I found a great paper on roasted ground flax! The researchers roasted and ground flax seeds, then baked cookies with the roasted ground flax seeds. They then analyzed the cookies for ALA content, and found them to contain ALA as expected. (I’m in favor of any research paper that has a “Evaluation of cookies” section.) They even tested cookies that were stored at room temperature for 90 days to measure shelf stability. They found that the ALA degraded only slightly over 90 days at room temperature.[1]

Another study tested heating whole and ground flax seeds, as well as flaxseed oil at 178°C (350°F) for 90 minutes, and found the ALA in whole flax seeds to decrease by 3.4%, while the ALA in ground flax seeds and flaxseed oil lost 6-7% of ALA.[2] This is much better than I expected, especially considering that typical flaxseed roasting times are on the order of 15 minutes — 1/6th of the time used in the study. This study arguably supports cooking whole flax seeds and then grinding them, rather than grinding them first, although since we’re talking about a 3% difference, it doesn’t really matter.

These studies did not measure absorption, but a third study demonstrated that ALA from baked goods made from milled flax is absorbed in digestion.[3]

Considering all of this, I think there is good evidence that roasted ground flax seed is an effective source of ALA.


Spread 1 cup of flax seeds on a baking sheet, then bake for 10-15 minutes at 350°F, or until fragrant.

Flax seeds hot from the oven.

Grind the roasted seeds in a coffee grinder or high-speed blender.

The ground roasted flax seeds take about 30% more space than the seeds did before blending.

Ground flax.

The roasted flax should be shelf-stable at room temperature, either whole or ground.

You could also grind the flax first, and then roast it. Both should be effective sources of ALA, but note that ground (raw) flax is annoying to work with. It tends to clump together in the presence of any moisture, and its tendency to form a gel when wet makes it difficult to clean out of blenders, etc. If you have a strainer on your sink drain, the flax gel will stop it up. When possible, roast first.

Add 1 tsp to foods, twice a day (so 2 tsp / day total).

Flax-enriched oatmeal

Here are some pictures of roasted ground flax in oatmeal. I may have used 2-3 tsp of flax here to illustrate how it disappears.

Now you see it ...

Now you see it …

… now you don’t. (The same, after stirring.)

There you have it!

Super easy, and cheap. I roasted 2 cups of flax a while ago, and it’s lasted me months.



Just for kicks, I made a spreadsheet illustrating the various omega-3 approaches I considered.

You’re welcome.


[1] Rajiv J et al. Rheology, fatty acid profile and storage characteristics of cookies as influenced by flax seed (Linum usitatissimum). J Food Sci Technol. Oct 2012; 49(5): 587–593. doi: 10.1007/s13197-011-0307-2 (via Pubmed)

[2] Chen ZY et al. Oxidative stability of flaxseed lipids during bakingJ Am Oil Chem Soc. 1994; 71:629–632. doi: 10.1007/BF02540591 (via DeepDyve)

[3] Austria JA et al. Bioavailability of alpha-linolenic acid in subjects after ingestion of three different forms of flaxseedJ Am Coll Nutr. 2008 Apr; 27(2):214-21.

[4] There is no RDA for omega-3’s, so I have to use 3rd party recommendations here — in this case, from the American Heart Association. In fairness, the AHA recommends fish, which contain DHA and EPA, rather than ALA, which plant-based sources of omega-3’s provide. I think an algae-based DHA supplement may be wise for vegans, or arguably oysters, if that is consistent with your ethics.

Can flax seeds cause oral allergy syndrome?

While researching a post on vegan sources of omega-3’s, I noticed that there is almost no information on the internet about whether flax seeds can cause of oral allergy syndrome.

Oral allergy syndrome (OAS) occurs when an allergy (typically a pollen allergy) causes an allergic response to a similar protein in a plant food. Oral allergies vary in severity, although in my case they are just a cause of irritation — itching around the mouth and throat, and indigestion. Oral allergies are typically only triggered by raw foods, as heating often denatures the allergen, resolving the allergy.

Oral allergies are often diagnosed by having reactions to well-known common oral allergy foods (such as those on this list) that is resolved by cooking the foods. I have been diagnosed with oral allergy syndrome, and I react to bananas, almonds, melons, carrots, and occasionally pears or apples — these are all common OAS foods.

However I have identical symptoms to raw flax seeds, which I’ve never seen mentioned in lists of oral allergy foods. Is this really the same thing? If so, am I the only one? I wanted to research this to see if my flax sensitivity could be an oral allergy.

The research

I was able to identify only one study of flax seed allergic sensitivity that tried to distinguish true flax allergies from crossover oral allergy syndrome.[1] This was a French study made up of a mix of allergic (one food or respiratory allergy) and non-allergic people.

The study found only two cases of true flax allergy in the 1317 people, compared with 75 people who were sensitive due to cross-reaction (more or less equivalent to oral allergies). Since allergic people were overrepresented in this study, the rate in the general population would be even lower. The authors project that about 1 in 6000 people (in France) are allergic to flax seeds, whereas 0.5% to 1% of the population have cross-reactive sensitivity only to raw flax seeds.[1]

That is, not only can flax seeds cause oral allergy syndrome, but the vast majority of flax seed sensitivity is caused by OAS-like crossover allergies.

The takeaway

First, some caveats: Since so few cases of flax seed allergies have been studied, it’s hard to definitively say how that allergy presents. We could also expect the rate of flax allergies to vary between regions because of different levels of environmental and dietary allergens. This study was conducted in France, and I’m not aware of another study taking place elsewhere. Finally, while rare, there have been cases of life-threatening anaphylaxis caused by flax seeds, so please talk to a doctor if you might be allergic to flax seeds!

That said, this study suggests that flax seed sensitivity can be caused by oral allergy syndrome, and in fact the vast majority of people with flax seed sensitivity — 97% — have OAS-like crossover allergic reactions, rather than a true allergy.[2]

If you react to raw flax seeds, but can eat cooked flax without irritation, you’re not crazy. You are probably among the estimated 1% of people who have an oral allergy syndrome sensitivity to uncooked flax seeds.


[1] Fremont S, et al. Prospective study of sensitization and food allergy to flaxseed in 1317 subjects. Eur Ann Allergy Clin Immunol. 2010 Jun;42(3):103-11. PMID: 20648772.

[2] Authors project a 1 in 6000 rate of flax allergies compared to a 0.5 to 1% rate of flax cross-sensitivity.[1] Ratio = (0.5 / 100) / (1/6000) = 0.5 / (1 / 60) = 0.5 * 60 = 30. Percentage = 100 / 30 = 3.33% (96.66%). If we use the 1% rate, we get 1.66% (98.33%). 97% is a conservative intermediate.