Dear Mark: Is Flax Bad?

flax seedsDear Mark,

I’ve been researching flax and am ready to pull the plug on my dedicated flaxseed grinder. The kicker was seeing flaxseeds associated with prostate cancer. What?s your take?

Thanks to reader Clare for the thoughtful correspondence on flax. This is exactly why I love doing this blog. Research continues to unfold, and the conversation never fails to engage and inspire me.

As Apples know, I?ve been a flax supporter. Lately, I?ve been mulling that position. While I don?t think a single study?s results should rewrite the book on any issue, when a number of studies suggest that it may be linked to serious illness in some people, that?s enough to give me pause. And, well, it?s enough to incite me to do some digging ? and pondering. Flax is one of those cases lately.

The deal is this. Flax seed is rich in a form of omega-3 fatty acids called ALA (alpha-linolenic acid). Omega-3 fatty acids as a whole (group) are especially vital for the development and ongoing well-being of the nervous system and for the health of the cardiovascular system. They improve lipid profiles, thin blood, and combat inflammation like nobody?s business. (You know how I feel about that one, eh?) They can also help curb insulin resistance.

Research time and again supports the role of omega-3s (again, as a group) in overall health; however, some studies and reviews over the last few years have linked high ALA intake (from both flax oil and milled seed) with higher incidence of prostate cancer. ALA blood levels are higher in response to flax oil intake than they are with milled seed intake. (Eating whole seeds isn?t recommended unless you?re looking for some serious abdominal havoc.)

I?ve always maintained that other animal-based forms of DHA and EPA offer more health-related bang for your buck, and I stand by that point. The preponderance of research supports the particular power of EPA and DHA in the omega-3 fatty acids. One study suggests that fish intake (rich in both DHA and EPA) actually reduces the risk for prostate cancer.

The bottom line is ALA doesn?t do much that DHA and/or EPA can?t do and probably do better. As avid Apples know, I suggest that everyone take a fish supplement. In the past I?ve seen ALA as a decent secondary choice for vegetarians and as a useful addition to a healthy Primal eating strategy (e.g. a bit of ground flax seed on some berries). The human body isn?t terribly effective at converting ALA to either DHA or EPA, hence the need for added dietary intake or supplementation. (An interesting side nugget: women?s bodies are a little better at this conversion. Research has shown that young women convert 21% of ALA to EPA (compared to 8% in men) and 9% to DHA (compared to 0-4% in men). The difference, apparently, is linked to estrogen levels.)

Fish Oil Capsules

So, what?s my current suggestion in light of the potential prostate cancer link? If you?re a woman, the obvious point of the research isn?t relevant. Nonetheless, the underlying role of phytoestrogens in flax is nonetheless an important one. I?d say that healthy women can consume low to moderate amounts of flax without concern. Sure, a large amount of research suggests the protective effect of phytoestrogens against breast cancer (in healthy women), and this research includes flax. Nonetheless, a lot of a seemingly good thing isn?t necessarily better or even safe. My advice would be to use fish oil as your primary omega-3 source and keep the ALA on the lower side.

If you?re a man? Particularly an older man? I?d definitely suggest you make fish oil your principal source of omega-3s. Is it time to chuck the flax grinder all together? Based on the research, I?d at least put it into semi-retirement. (I?d suggest forgoing flax oil entirely.) In the meantime, we?ll stay on top of this one and let you know about any new developments on this front.

As always, thanks for your questions and comments. Keep ?em coming!

diglyesica, tellumo, spdrecrd Flickr Photos (CC)

Further Reading:

Omega 3 Fatty Acids Round Up:

Omega 3 to 6 Ratio

Omega 3 Daily Dose

Omega 3 Food Sources

Cooking Omegas

Modern Forager: The Vaunted Flax Seed

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

If you'd like to add an avatar to all of your comments click here!

111 thoughts on “Dear Mark: Is Flax Bad?”

Leave a Reply

Your email address will not be published. Required fields are marked *

  1. This post is somewhat refreshing to me. I have never really been a fan of adding Flax to my diet. Not because I thought it bad for you but more because I have never enjoyed it and have always had difficult fitting it in time, place and taste wise with my diet. I still make sure i get plenty of omega-3’s though! Flax was looked at as almost a mecca back in my bodybuilding days but if more research shows this to be bad thing then I will be glad yet again that I ignored the mainstream hype.

    1. The issue of flax is very complicated. I don’t see anything on the web that would preclude adding flax in moderate amounts to the diet.


    2. I am 64 years old and I’ve heard all the arguments for and against flax. I take prostate supplements because I get difficulty in emptying the bladder sometimes.
      But the most relief I get from prostate problems is when I take 2 tablespoons of ground flax seeds every day. My prostate and bladder usually get back in good shape after doing this for a few days.
      So all the studies back and forth don’t mean anything to me. I know what gives me relief and better health.
      Don’t forget the famous cancer cure from Dr. Budwig which consists of flax seeds/flax oil and cottage cheese. This is a proven cure, so the flax is doing something good here.

    3. Here is info from a flax seed study: “In male rats, lifetime 10% flaxseed exposure raised serum testosterone and estradiol levels and produced higher relative sex organ weights and prostate cell proliferation. In contrast, lifetime exposure to 5% flaxseed reduced adult relative prostate weight and cell proliferation, suggesting potential protection against prostatic disease, although sex hormone levels were unaffected. In conclusion, flaxseed can potentially alter reproduction, depending on the dose and timing of exposure.”

      So, at very high amounts for their entire life span, flax seeds increased both testosterone and estradiol and even at 5% of their diets for their entire life, no effects on hormones were found. Conclusion, people recommending men avoid flax oil “because it contains estrogens” don’t have a clue what they are talking about…

      (1) Brzezinski A & Debi A, Eur J Obstet Gynecol Reprod Biol, 85(1): 47, 1999)

      (2) Tou JC, Chen J, Thompson LU.J Toxicol Environ Health A. 1999 Apr 23;56(Cool:555-70.
      – See more at:

      1. I’m curious what’s the consensus here on rats compared to human physiology, in general.

        One of the tenets of Chinese medicine is to test things on humans.

    4. I am beginning to see that mainstream hype, is now geared towards blundering what is good for us. Each to their own as every human reacts differently to everything they put into their body’s. There’s never gonna be a quick fix for diets. Pure experimentation, and move on. Bottled water in a humid gym = chemical reactions with bottle = carcinogens. There’s no end to opposite opinions being mascaraed from a Chinese Whisper to what we call fact. The Internet confirms what we want to be true but may not be true in the end. I wasn’t aiming this at anyone you where the first post to see. No hard feelings I’m just an outsider

  2. I think flax is great but it must be used in the right way, the fact that when consumed as seeds (unground) they are a potent Estrogen metabolizes is something very interesting for men…I regularly add the seeds to yoghurt and shakes or even sprinkle some in burgers……I think its also best to mill your own batches of Flax and keep them in the fridge to ensure optimal freshness….

    1. Just so I understand correctly..flax seeds can help men lower estrogen levels? (And thus reduce the effects of it?)

      Or did I get this backwards?

      1. no….Flax increases estrogen, it has a lot of estrogen in it along with Soy which is why its so toxic to men, also soy and flax leach the body of Zinc and zink prevents prostate cancers 🙂

  3. Mark – thanks for this info. I have a couple of questions.

    1. I have about 1000mg of flax seed oil per day – is this a relatively low amount in the context of this discussion? All this talk of flax grinders makes me think my consumption is probably on the low side, but it would be good to get your view.

    2. I do get a lot of fish oil in my diet both via food and supplementation but had always understood that ALA offers something extra that is needed to complete the omega 3 picture. If this is not true I’ll happily ditch the flax oil and stick to the fish oil – one less bottle on the shelf!


  4. I’m not a fan of flax. Interesting, people with certain endocrine disorders can not tolerate flax, including myself. I’d stick with the fish oil or grass-fed meat.

  5. Thank you for the comment, Anna. We are working on a solution. I apologize for the inconvenience. In the meantime, Firefox seems to be displaying MDA just fine.

  6. As we age, the enzyme (delta-6 desaturase) that converts Omega-3 to EPA/DHA, decreases in activity.

    Thus with less anti-inflammatory EPA/DHA oils, the prostate, as well as other tissues, would become inflamed and dysfunctional.

    I am willing to bet that with increased ALA in the diet, not only prostate cancer, but, other cancers would exist too.

  7. How about the fibre content; is flax seed at least a valuable source of fibre? (Not that anyone following the PB diet needs to add fibre to the bountiful amount that veggies provide!)

    I don’t understand why whole unground seeds pose a potential problem. Would not Grok have nibbled on a few pinches of flax seeds as he found them? Aren’t they whole, unprocessed, natural goodness?

    I don’t know if my smoothies will ever be as good without the flax. 🙁

  8. Hi Mark,

    Can you let me know your thoughts on omega 3’s post workout? I had read somewhere that this is not optimal.


  9. Crystal,you said that people with certain endocrine problems cannot handle flax. Is that someone who is hypothyroid?

  10. Possibly Sue. There isn’t a lot of info. out there but it is common among hypoT./hypoA. people. It must have something to do with the conversion causing stress. Others think it’s a goitergen and should not be eaten.

    Some people are intolerant to flax worsening a nervous/emotional disorder—but what is described is actually low cortisol IMO.

  11. Hello Mark,

    Any opinion on chia seeds as an omega source, flax alternative?


  12. I use a high-quality liquid fish oil as my main supplement to combat inflammation and have really cut back on the flaxseeds (ground) after talking with my natural doctor. He suggested trying hemp seeds.

    I would also be interested in similar research (if it exists) on both chia and hemp seeds.

  13. Tony – The article doesn’t say there aren’t vegan sources; only that ALA is an option for vegetarians.

    Thanks for the link.

  14. Aaron, thanks for your response. Actually, Mark does say that there aren’t any vegan options for DHA and EPA:

    “I’ve always maintained that other animal-based forms DHA and EPA offer more health-related bang for your buck, and I stand by that point.”

    He says that DHA and EPA are “animal-based forms” of Omega-3s. This isn’t true and weakens his conclusion that fish oil is the best solution for those trying to get a healthy balance of Omega-3s.

  15. Tony – I’m still not sure how you get that Mark is saying vegan sources of DHA and EPA don’t exist. He is simply saying that he has always said that it is better to get Omega 3s via animals than flax. At least this is how I read it. Nevertheless I am pretty sure this is what was meant…

  16. Hey Aaron. In the passage I quoted above Mark specifically says that EPA and DHA are animal-based.

    “He is simply saying that he has always said that it is better to get Omega 3s via animals than flax.”

    No, he isn’t simply saying that fish oil is better than flax – what he’s saying is that he recommends fish oil as the best source of a good balance of omega 3s (out of all options, not just compared to flax). Without any mention of plant-based EPA and DHA this conclusion seems hasty at best.

    I know people find it obnoxious when vegans go on about their diets, but the reason we’re prone to preach is because the diet is so frequently unfairly maligned. I think it’s obvious that any reader will come away from the above article thinking that eating animals (in some form) is the only way to optimal health. This is a damn shame because it’s just not true, and while I’m sure it’s not Mark’s intent to knock veganism, by completely ignoring vegan DHA and EPA and coming to an ill-informed conclusion, that’s the effect his article has.

    1. Because someone might come along and read this later: I cannot go vegan unless I want to bleed out through my uterus. You can’t get real vitamin A from a vegan diet. I find that if I go low on vitamin A, my cycle gets all messed up. I am not the only one with this experience. A friend of mine on FB heard about my problem and tried vitamin A in her own health regimen and had the same results I did. And charity clinics in developing countries often use vitamin A to cure dysmenorrhea (sp?) in women of those countries. Not to mention it is vitamin A capsules, not golden rice, which are used to prevent blindness in children. (Kids under five can’t even convert beta carotene!)

      You also can’t get B12 in a vegan diet. You MUST supplement. If you *have* to get a nutrient from a pill in order to follow the rules of your diet, by definition your diet is not healthy. There’s a difference between just missing out on a nutrient because you didn’t eat enough of a food allowed in your dietary pattern, and *having* to supplement because the nutrient isn’t in any allowed foods at all.

      There isn’t anything unfair about maligning a diet that, followed properly, results in malnutrition. Vegans can only be vegans because you have an industrial support system that makes supplement pills for you. Follow it if you want. But we’re not the ones making inferior dietary decisions. It’s foolish to rely on machines for all of your intake of any nutrient, and even more foolish to cite farm animals not being fed species-appropriate diets as your excuse for not following a species-appropriate diet yourself.

      1. It’s true that with our hyper-sanitized food supply nowadays that vegans must supplement with B12. B12 of course, is a bacterium, not an animal product per se.

        Donald Watson, the gentleman who coined the term vegan, lived on a purely plant-based diet for over 55 years (most likely without B12 supplementation for all those years), and died at the ripe old age of 95. Not bad for someone subsisting on a diet that “results in malnutrition.”

        Omnivores must supplement with B12 as well, as they get older:

        “Many older adults, who do not have enough hydrochloric acid in their stomach to absorb the vitamin B12 naturally present in food. People over 50 should get most of their vitamin B12 from fortified foods or dietary supplements because, in most cases, their bodies can absorb vitamin B12 from these sources.”

      2. Want vitamin A on a vegan diet–just eat sweet potatoes or pumpkin
        and you’ll get plenty.

  17. The algae supplements come from Switzerland. Are they available in other countries?

    I think its a lot easier to achieve optimal health on a diet that includes meat. It could possibly be achieved on a vegetarian diet but with a lot more thought and possibly a lot more supplements.

  18. I stopped grinding flax a year or so ago based on the mixed research, some of it is pretty strong, same thing with soy, too much risk, there’s proof to suggest they are unsafe, that’s enough for me, other things like cod liver oil have down sides (pro oxidant, rancidity, heavy metals etc) but the research is more favourable, so i still consume it.

  19. Hey Sue, I don’t really know of any other vegan DHA and EPA supplements, but I do remember reading about others in development a few years ago when V-Pure came out. Although they’re based in Switzerland I think they deliver to the states. Supposedly they’re also working on an algae-based b12 supplement, more good news for vegans.

    “I think its a lot easier to achieve optimal health on a diet that includes meat.”

    I think in general this is true – planning a vegan diet in our meat-obsessed culture can take some time. However, there are lots of health problems associated with meat that vegans don’t deal with at all. Aside from the correlation with heart disease etc (which can be avoided if you eat the right meats), I am mainly thinking of accumulated toxins. Of course, you can buy free-range, grass-fed, no-antibiotics etc etc, but this can be difficult and costly. I’m guess what I’m trying to say is that for truly optimal health (which includes no toxins) it might be easier to just go vegan (also wayyyyy cheaper). There aren’t even really many supplements – b12 is the only one you absolutely need and then the omega-3s.

    Here is a thing from the V-Pure site, about “the dangers of fish oil.” Obviously, V-Pure has a business interest in convincing you of its claims, but then again, so do many proponents of fish oil.

    Again, I’m not trying to preach but it’s just SO frustrating when every single bit of advertising and health advice you see is a paean to the wholly destructive industrial meat industry.

    For a far more detailed rundown of EHA and DPA:

  20. This may have been answered already but I can’t find it…I have never found a fish oil that doesn’t “repeat” on me. I have tried (& returned) virtually every one that anyone even suggested would agree with me. I even tried just a liquid which was mixed in with my daily protein smoothie. Yuck & ick! The only one even remotely palatable has been Coromega–but it seems pretty low dosage. Any suggestions? I currently take a 1000 mg “organic” flaxseed oil cap. daily. I’m 63 & take no medications.

    1. I take Carlson’s Cod Liver Oil Professional Formula with light lemon flavour. I’m not saying it doesn’t ever “repeat” but I take it at night shortly before bed so it doesn’t bother me. I admit if I take it in the morning I can have an issue. Both of my 60 year-old parents take it in the morning, though, and never have a problem.

      I wouldn’t mix any CLO with food, even a smoothie– the taste always comes through. It doesn’t taste wonderful, but with a sip of water I down it like a pill and it’s not too fishy (like some other CLO I’ve tried). I’m a huge baby about taking anything that tastes bad, so if I find it palatable, I think anyone could handle it. Good luck!

  21. **OT, but can’t wait to read the chia post.

    recently had a green bar w/chia..then started reading up on someone making chia drinks, etc. The fiber content is out of this world..

    will check back soon.

  22. Ground flax seeds do NOT cause any sort of cancer. This is another paranoid headline-grabbing phenomenon based on dubious science from a tiny study or handful of studies. Who sponsored the research? Think about it- who the heck would pay to study a link between flax seeds and prostate cancer? It wouldn’t surprise me if it was another scare tactic by the meat or pharmaceutical industry. Reminds me of the garbage about too much Vitamin E, too much soy, and most recently drinking too much water. There will always be research that supports or attacks anything ever studied. Intelligent people read a cross section, take note who sponsored which studies, and act in accordance with the majority of independent science. The majority of independent science in regard to flax seeds is clear: they are an extremely beneficial food. Period.

  23. Peter, you said:
    “Ground flax seeds do NOT cause any sort of cancer”

    You can’t make such a statement, where is your proof that it doesn’t cause cancer. Flaxseeds contain phyto-oestrogens so it makes sense that there would be a study examining any links with cancer.

  24. Susan-

    In science, one doesn’t normally seek to prove that a substance DOESN’T cause something, (such as cancer); one normally attempts to prove that it DOES. The scary word “phyto-estrogens” literally means plant estrogens. Virtually every healthy food we eat — most vegetables, most fruits, grains, beans, nuts, seeds, and roots — all contain phytoestrogens. Perhaps you didn’t realize that. The preponderance of independent research in fact indicates that phytoestrogens actually PROTECTS tissues from the cancer-causing effects of xenoestrogens and other hormonal pollutants. I repeat my suspicion as to why flax seeds were singled out for such a misleading headline. What’s next- broccoli causes melanoma?

    And I repeat: who sponsored that so-called “research”?

    Anyone here know?


    Thank you. -P

  25. How come there’s no info on who did the study and what they did in the study? We need the proof before we can believe that this is true. To me it sounds like someone just made this up, why only flax and what about the other foods that have ALA in them? If it was the ALA that caused prostate cancer then why is flax the only food to be targeted?

  26. It’s always a relief to see a note of reason, in present case, from Peter and Michael. I spend a lot of time finding valid info for consumers, and have seen good double-blind clinical studies [not funded by special interests] which have shown that flaxseed consumption is definitely beneficial in opposing prostate and other cancers. Anyone who has a cause to prove can always find something to back it, of course. The amount of irresponsibility so often seen re: quoting an isolated study [which as Peter and Michael have pointed out was not even identified] is sad. It is doubly so when that’s done by someone who speaks as an authority. This is a position, which once chosen, demands objectivity and thoroughness due to influence on the uninformed. –Linda

  27. The study is mentioned above. Just click on the link just after the picture of the flax bottle.

  28. I would like to recieve your daily ‘informational’ updates, Thanks,

  29. I reviewed the study. The final sentence from the authors’ own abstract says it all:

    “It is quite uncertain at present whether the effect on prostate cancer is real.”

    Case closed.

    Thank you.


  30. O.k. One more point.

    And this flimsy, non-conclusive, ambiguous conclusion inspired HEADLINES warning people against flax seeds.

    Mark, with all due respect, how about a bit more homework next time before advising your readers to avoid an extremely healthy and essential nutrient source.



  31. Ok, I have read all of the pro’s and con’s and still have no idea whether I should continue having Flax seeds (3 tablespoons) with my cereal and my salads. I usually have one helping 3tbs per day. I am a male,76 years of age, in good health and take 1 each: 1000mg of Fish Oil Concentrate with Omega-3 Fatty Acids together with Vitamin B-6 (100mg); B-12(1000 mcg);
    Folic Acid (400 mcg); Vitamin D (1,000 IU); Magnesium (250 mg)and a Mature (Kirkland-same as Centrum Silver) Multi Vitamin daily.

    So, with all of the various discussions on this Blog, just where does a guy in my shoes fit into this picture, especially as regards to the possible affects to my prostate of using Flax Seed?? Thanks to anyone or everyone who is able to provide me with substantive info. Thanks

  32. Addendum to Floyd Holmes comment: I also eat salmon (wild) twice a week and red meat once a week.

  33. Uh…I thought it was pretty clear that flax seeds are a wonderful food. Let’s put it this way: I’m a 59-year-old male who researches nutrition daily, somewhat as a hobby and partly related to my work. I read at least a half-dozen health-related publications regularly. I reviewed the above study supposedly establishing a link between flax seeds and prostrate cancer.

    My conclusion? I am continuing to have crushed flax seeds almost daily with my meals.

    I read nothing whatsoever- except a sloppy interpretation of some research, and some paranoid gossip- that would make me concerned.

    Those of you who are now afraid of eating flax seeds- are you going to stop eating most fruits, vegetables, and grains as well? If you’re concerned about phytoestrogens, you absolutely should.



  34. I have been aware of this issue for many years now..that plain Flax seed oil is not beneficial to men and has phtoestrogen qualities and can cause issues with the prostate. BUT the kicker in this is “Plain” flax seed oil. “IF” the flax seed oil is with “Lignans” is has been stated to be okay for men. I believe that any flax seed oil taken should be organic and taken as oil “with Lignans for both men and women” always. The lignans help the nody remove excess estrogen.

  35. Another great form of Omega 3s are from Chlorella. Chlorella, spirulina and algaes are all excellent sources and also provide numerous other health benefits. Definitely worth taking.

  36. I was told that flax was also estronogenic (sp?)
    As having breast cancer back in 1999 I was told by a nutritinist to stay away from it as the cancer I had was estrogen dependent.I just found your website ,Thank’s

  37. I take 1 1000 mg flax seed oil capsule twice a day. The only “benefit” I have noticed so far is gas of such proportions it makes my ribs hurt. Anyone have helpful advice that does not include sharp objects?

    1. I bought organic flax seed oil,, I have to admit i’m highly allergic to this oil,,my nose plugged up so bad I couldn’t breathe,,,my liver totaly refused this,,I’ve read if it can cause allergies and yes it can,,i’m not allergic to much;;wheat and milk that I know causes me symtoms just wanted to share

  38. These are some comments about flaxseed oil that I have read that are quite interesting:

    “Have you seen this paper on ALA to DHA and EPA conversion?

    They claim that ALA from flax seeds is as effective as fish oil, while some previous studies questioned it’s effectiveness. If you have an access to the full text of the paper, could you comment on that? Thanks,


    Just peeked at the full text. The abstract is really incomplete!

    First of all, they gave flax at doses up to 3X the fish oil. Despite that, after 12 weeks they saw no increase in total erythrocyte n-3 with flax, while they did with fish oil. The flax actually caused a decrease in erythrocyte DHA, while the fish oil caused an increase. The flax did cause an increase in EPA and DPA.

    Well that pretty much removes any reservations I had about trashing flax oil as a supplement.”

  39. As I’m allergic to nearly every fish on the planet (including and especially the ones they use for fish oil supplements) I’ll stick with my Barlean’s Essential Woman capsules. 🙂

  40. Here’s the way I look at this flax seed issue and herbivory more generally. Evolutionary thinking should lead us to look at things from the plant’s perspective. Specifically, does the plant want its foliage or seeds to be eaten or not? If the answer is yes, it wants to be eaten, then it’s unlikely that natural selection would favor plant genes that sequester toxins to repel or injure foragers like Grok and others. Such plants can probably be eaten by us in large quantity without concern for toxicity.

    In contrast, if the plant does *not* want to be eaten, then selection is likely to equip the plant with defense like spines, resins, and other phytotoxins to repel or injure foragers. It is this latter type of plant, the type that is by far in the majority among all plant species, that we should be concerned about. In fact, much of plant breeding has focused on breeding out these nasty wild type traits and replacing them with more benign (and tasty) qualities.

    Only through study of plant natural history and biochemistry can we determine which plants are safe to eat in quantity. But since such work is not always feasible then the safest policy is to only eat lesser-known plant varieties in moderation, if at all. As far as flax goes, why take the risk considering that there are other Omega-3 sources available that we are pretty certain do not poison us?

  41. I take as little PUFA as possible. They are way too vulnerable for radical oxygen damage. I take a tablespoon of cod liver oil in the morning for the fish oils and vit A+D and use coconut oil for mostly anything else (and some butter for the K2).

    Would paleolithic man have eaten flax? I don’t think so. He would have eaten fat fish.

    Just remember that flax oil goes rancid very quickly when you don’t keep it refridgerated. You wil need lots of vit E to keep it fresh in your body.

    My guess is that the walls of my bodycells will be more resistant to ROS (radical oxygen species) if they contain more staturated fat.

  42. Worried about flax seed and cancer risks? Specific to this article, check out Cliff Beckwith details his experience with an existing prostate cancer, and how he addressed it with the use of flax seed and flax oil. Better yet, check out or preform a google search for “Johanna Budwig”. This 7 Time Nobel Prize Nominee was responsible for developing an alternative cancer therapy that is based largely around flax oil and cottage cheese consumption, most people include the seeds in their regimen for a good lignan source. PS, lignans are incredibly concentrated in flax seed and have AMAZING anticancerous benefits. My opinion, the study that site the “possible” increase in prostate cancer risks was poorly performed, poorly cited, and leaves much to be desired in order to carry any real weight. No question about it, EVERYONE should take fish oil daily! That said, flax has a whole host of benefits on it’s own (fiber, protein, lignans, EFA’s) and should be used daily as well!

  43. Flax seeds are an incredibly healthy food. In science, the burden of proof always lays with the person making the claim. For example, I can say that water is not beneficial, but the burden of proving that claim lays with me.

    Now there are two groups of people concerning flax, the large scientific and nutritional community that supports flax as a healthy food, and the newer studies suggesting that flax can increase the chances of cancer.

    Those who believe flax is healthy can easily prove their claim, there are basic nutritional standards flax meets and excels at. However, those suggesting flax can cause cancer have only the results of ambiguous studies on their side.

    Should this be an issue for further research, sure.

    Should someone stop eating flax, throw away their grinder, reach around and up, grab their prostrate and run away?

    I doubt it.

  44. Any more news on this topic of Flax and cancer? My husband just started taking because his acupuncturist suggested it. I would never let him use it because of the controversy.

  45. Likewise Shella. I’ve been taking Flax seed (Lindseed over here in the UK) for about a year now, putting them in my shakes in the morning & before training.

  46. was the study done with cold pressed flax oil? probably not, remember the bad rap on coconut oil? put those flax oil capsules you bought at wallyworld down the toilet and get only cold pressed/virgin for any oils you choose.after revisiting budwig/beckwith websites, there is no doubt in my mind that flax is hugely beneficial. Thanks jeff


    1. Please compost unwanted food and supplements, rather than putting it into the sewage system.

      1. sorry it was a matter of speach, I guess composting them might be good, but dont consume them, flax oil needs refridgeration

  47. I think people should just use common sense on this one. Just think primal if anything. How many flaxseeds do you think you are going to be able find/pick in the wild?…probably not that many. I would just do a little in the morning or on a salad ground up. I personally have stopped using the oil many months ago because of the same reasons mark explained…DHA and EPA simply have more benefits per calories and dollar amount.

  48. Some people (myself included) cannot tolerate fish oil. So, yes, I hear EVERYONE talking about the benefits of fish oil, but what can the rest of us do? I enjoy flax seeds in yogurt and smoothies (now started chia seeds), and enjoy flax oil on my salads.

  49. If you don’t want to use flax, use chia. It’s better for you anyway. Just shop around – as it gets trendy it’s also getting expensive. Costco sells the exact same brand as Shopper’s Drug Mart for exactly half the price. (Weber’s). Also don’t be fooled by the folks who tell you the white seeds are better for you than the dark ones. Not true.

    I use ground flax now and then to make a “muffin in a minute”, which has egg, oil (any kind) and baking powder and is great for sandwiches. bp may not be primal but on the rare occasions when I really want a big old ham and cheese with the trimmings, or chicken salad, it more than satisfies for practically no carbs.

  50. Indeed, let me add that at the link you provided, the only reference to “flax” is a link to another abstract, whose title is “Flaxseed Supplementation (Not Dietary Fat Restriction) Reduces Prostate Cancer Proliferation Rates in Men Presurgery.”

  51. I’m so confused now. It seems like the more I try to eat a healthier diet, the more I hear things like this that contradict what I originally thought. I eat 3/4 cup to 1 1/2 cups of flaxseed almost every day (as a pizza dough). Am I going overboard with the flaxseed? (I really hope not!)

  52. Salam
    Based on my observations, flaxseed increases my libido and gives me acne, which in my opinion means increase in testerone and not the other way around

  53. When I started putting flax seeds in my diet, I knew that it was a replacement for the traditional role of cod liver oil in the diet – I just didn’t want to eat cod liver oil! FF a few years, and I became absolutely convinced I needed fermented CLO for other benefits, not just the omega 3’s, and went that way, letting go of the flax.

    I think the heavy push for flax comes from the vegan contingent, just like the push for agave (although clearly agave syrup is far more processed than flax seeds). Before considering a return to flax, I’d want to know whether they were consumed the way we’re told to now (via oil or fresh crushed seeds, in daily sizeable amounts) by any traditional society. If the answer is no, I don’t need to go any further. If yes, I’d then start looking for the body of research on the matter.

    I thin kthere’s probably a reason why I can think of many references to the usefulness of flax (for linen) & linseed oil in history, but cannot ever think of a mention of anyone consuming flax seeds or flax seed oil, just off the top of my head.

    1. Not a vegetarian, but regarding flax not being in history: as far as I know, that’s right. But chia, that someone recommended a few posts back? That was historically eaten all over Central and South America. Besides the Omega 3’s, it also has a decent amount of protein, and the fact that it turns gelatinous in the presence of water is why the various peoples would use it as a trail food. It holds the water in your system and gradually releases it, keeping you hydrated. The Aztecs used it for sure. The traditional method is to soak it in lemon or lime juice with a lot of water, and then stir the resulting gel into a glass of water and drink it. My own experience is that if I drink a large glass early in the day, several hours later I really have to go, but I don’t feel dehydrated in between.

  54. I began using flax seed oil as an alternaive to fish oil. The main reason was to avoid MERCURY poisoning. Many cheaper fish oils can have traces of mercury, which btw, is cumulative in our bodies. There are some “mercury-free” fish oils. If making the switch back to fish oil, I would definitely recommend Mercury-free.

  55. I’m a vegetarian and I buy crushed flax seed from whole foods. I really will never believe that it has a connection to PC.

    In fact I read in a magazine that phytoestrogen does not make you into a woman. It does not give you man boobs. It has no feminizing effect at all.

    The phytoestrogens in soy was what they were talking about. The whole thing about soy giving you estrogen is a myth.

    “Phytoestrogen has no effect on estrogen levels or hormone levels or even testosterone.”

    Case in point: these scientists or researchers are making up things, and lying, in order to encourage a diet of flesh.

    Sounds gross right? Well just try to not dance to their tune. Be yourself and don’t be so easily influenced.

  56. I appreciate the vegetarians and vegans who posted here. Here’s a little bit on the vile lying meat industry:

    “The meat industry spends hundreds of millions of dollars lying to the public about their product. But no amount of false propaganda can sanitize meat. The facts are absolutely clear: Eating meat is bad for human health, catastrophic for the environment, and a living nightmare for animals” – Chrissie Hynde from The Pretenders, in the PETA website

    “You can’t tear flesh by hand, you can’t tear hide by hand. Our anterior teeth are not suited for tearing flesh or hide. We don’t have large canine teeth, and we wouldn’t have been able to deal with food sources that require those large canines” – Dr. Richard Leakey

    “Nothing will benefit human health and increase chances for survival of life on Earth as much as the evolution to a vegetarian diet.” – Albert Einstein

    ” [A]lthough we think we are one and we act as if we are one, human beings are not natural carnivores. When we kill animals to eat them, they end up killing us because their flesh, which contains cholesterol and saturated fat, was never intended for human beings, who are natural herbivores.” – Dr. William C. Roberts, M.D., editor of the authoritative American Journal of Cardiology

    “Since I stopped eating meat, I have noticed that my digestion is better, my thoughts are better, and I run instead of walking. […] I eat vegetables and all kinds of vegetarian food. I am a vegetarian. I am not a meat-eater.” – Vaslav Nijinsky, The Diary of Vaslav Nijinsky

    1. good points when answering carnivores who say humans were meant to eat all foods including meat

    2. Chrissie Hynde: That’s why we buy grass-fed meat — great for the environment, happy animals. This meat is also absolutely superb for human health.

      Dr. Richard Leakey: Stone knives have been around long enough for us to evolve around them. Eating raw and cooked meat drove our evolution to acquire our big brains.

      Albert Einstein: Brilliant guy but he’s a physicist, not a biologist. Plus, what is his reasoning for that statement?

      Dr. William C Roberts: Where’s the evidence that we are “natural herbivores”? Is it our lack of a four-part stomach that would allow us to efficiently digest cellulose for energy as well as micro-nutrients? How about the very few molars we have? Indeed, why do we have canines at all? A small stomach like we have necessitates a calorically-dense diet, which plants don’t provide. Besides, the argument is that humans are *omnivores*, not carnivores. Cholesterol? Our liver makes much more than we eat. Eat less, the liver makes more. Eat more, the liver makes less. Homeostasis!

      Vaslav Nijinsky: Greatly depends on total diet before and after the change. It’s very unlikely that the only change made was to cut out meat, so there’s no way to say that the absence of meat was the cause. Post hoc, propter hoc.

      I eat meat as well as massive amounts of vegetables, and I have never felt better since re-introducing meat. I’m not bashing vegetarianism, but the biological evidence points to modest consumption of meat as very beneficial.

  57. In regards to ground Flax Seed…I am an avid fan! I eat 3tbls daily. It’s helped me lose 40lbs in 3 years, I was a size 12 and now a size 4 and I firmly believe it’s due to Flax seed. I have a history of colon cancer in my family, my first colonoscopy was perfect.
    My husband has been battling Prostate Cancer for 3 years. After his diagnosis he began using ground flax until the “study” came out and he stopped and his PSA is rising again….he was doing better with the flax seed….I won’t stop using it.

    1. Linda you provide a way to test the claimed possible harmful effect of flaxseed through the study of PSAs for those men consuming flaxseed. BTW, nobody has pointed that zilch original research was carried out by the study that Mark cites. The authors of the study are just stating their opinion,

  58. I read an article today that says that whole flaxseeds are much better than the oil. Flax oil does not have fiber and it can actually cause cancer. Very interesting.

  59. Hi there. I’m doing research on flax seed and its benefits when I came across your article.

    Let me just state here: There is no clinical study up-to-date that proves flax seed consumption to cause prostate cancer or any cancer for that matter.

    The research, done by Harvard showed that a diet high in ALA derived from ANIMAL sources was associated with a higher incidence of cancer.

    As Flax seed is high in ALA an assumption was made that the consumption of flax seed would lead to a higher incidence in prostate cancer. It was not part of the experiment nor was it proven to be so. On the contrary there are studies that proves the opposite.

    Have a look at this article.

  60. Barry Sears seems to be “the man” who kicked off the fish oil craze (Go Barry!) – and as a biochemist concerned with rancidity and mercury etc. possibily in some fish oils, I believe he obtains and sells the purest fish oil around.

  61. I like the valuable info you provide in your articles. I will bookmark your weblog and check again here regularly. I’m quite sure I will learn many new stuff right here! Best of luck for the next!

  62. DHA and EPA: One of the many proofs that humans need to eat primal meat in order to remain healthy.

    DHA and EPA are the only forms of omega-3 that the body can use efficiently. These two forms are also found only in – MEAT. Plants have omega-3 but only in the ALA form, which the body cannot use well enough. Yes the body can convert ALA to EPA and DHA, but at too little amounts.

    It is essential to have a 1:1 ratio of omega 3 to omega 6. Plant foods are high in omega 6 and high in the useless omega 3. So if someone is eating a plant based diet, this person is basically only getting omega 6 fatty acids, which is pro-inflammatory.

    Humans are by nature, meat-eaters. Not herbivores, vegetarians or vegans.

    1. DHA and EPA are synthesized by algae, not animals, and their dietary necessity compared to ALA is not at all clear, e.g.

      “Substantial differences in intakes and in sources of Omega-3 polyunsaturated fatty acids existed between the dietary-habit groups, but the differences in status were smaller than expected, possibly because the precursor-product ratio was greater in non-fish-eaters than in fish-eaters, potentially indicating increased estimated conversion of ALA. If intervention studies were to confirm these findings, it could have implications for fish requirements.”

      And more to the point, if any of this was significant, we would see increased mortality for vegans/vegetarians, which isn’t borne out by real-world experience.

    ‘ asked on Just the Flax, Ma’am: There are a lot discussions and articles online about the supposed connection between flax seeds (ALA) and prostate cancer – suggesting that more flax consumed = increase chance of prostate cancer. I haven’t found this issue addressed on your website (sorry if I missed it). Can you comment? Thanks!

    The latest meta-analysis of prospective studies found that, if anything, alpha-linolenic acid (ALA, the omega-3 fat in flax) was protective against prostate cancer. Men consuming more than 1.5 g/day appeared to have significantly lower risk (the amount found in about a tablespoon of ground flax seeds).

    One of the reasons there’s been so much conflicting data is that ALA is found in great foods (dark green leafies) and less than great foods (meat), and so ALA intake is not necessarily a marker of healthy eating. What you want is a randomized controlled study of men with prostate cancer. Give half of them flax and see what happens. And that was done! (full text here)

    Researchers at the University of Texas Anderson Cancer Center took a bunch of men with prostate cancer about a month before they were to go into surgery. Half were put on a few tablespoons of ground flax a day and after surgery their cancerous prostates were examined. The proliferation rates of the cancer in the flax-eaters were only half that of the controls, confirming the test-tube studies done on prostate cancer cells suggesting that flax can indeed slow prostate tumor growth.’

  64. My dad ate a lot of ground flax. HE was doing it to help his colon. He used it for about 3-4 years, then ended up with Prostate Cancer. Luckily They found it at the early stages. Who knows if it was from the Flax seed. My dad is convinced it is so he quit taking it.

  65. My understanding of ground flaxseeds is that they contain lignan phytoestrogens, which are very different from phytoestrogens. On top of that, Flax Oil is very different from ground flax seeds in that it doesn’t have the lignan content that makes flax so beneficial.

    there’s an article here from Cornell University about phytoestrogens (and flax) and breast cancer and prostate is mentioned towards the end.

    I’m still open to any new findings and would love to find a definitive answer as I finally just got my Dad to start on ground flax, so the last thing I want to do is put him at risk.

  66. scyually, new resrearch shows flaxseed to be very beneficial in fighting prostate cancer…in fact it is considered by many researchers to be the strongest known anti prostate cancer food,…even more than broccoli

  67. actually, new research shows flaxseed to be very beneficial in fighting prostate cancer…in fact it is considered by many researchers to be the strongest known anti prostate cancer food,…even more than broccoli

  68. I’m a physician, and looking at the article you referenced, the studies were observational studies, and even as such, the data did not represent a strong link between flaxseed intake and prostate cancer.

    From the article:

    “It is quite uncertain at present whether the effect on prostate cancer is real. Even if it were real, the protective effect on fatal coronary heart disease would probably outweigh these possible negative effects, especially for men with an increased risk of heart disease.

    “In the United States, 6 times more men are diagnosed with coronary heart disease than with prostate cancer, and almost 8 times more men die of coronary heart disease than of prostate cancer (CDC/NCHS,

    “Furthermore, prostate cancer occurs at an older age: >40% of coronary heart disease patients are 50% of prostate cancer patients are >75 y old when diagnosed. “

  69. I know this might sound crazy and it’s not scientific at all, but I once took a heavy-duty flax-seed supplement for the Omega-3 content and had a really bad reaction. I was severely depressed for about 15 hours; it was the most frightening experience of my life, I felt truly awful. It was only when it was over that I thought it might be connected to the supplement I had taken that morning. Has anyone else had a reaction like this? I’m just curious.

  70. I would say this is a double edge sword.

    The positive side: studies show reduced risk of prostate, ovarian and breast cancer in people with high levels of lignans in the the body. This is because, Lignans bind testosterone which has potential to speed up tumor growth.

    The negative side: many men can not convert the ALA in flax seeds to EPA and DHA. Since a high ALA content is linked to prostate cancer, this is reason for concern.

    My understanding is that high insulin levels inhibits the conversion of ALA to EPA and DHA. Unfortunately over half of our population has high insulin levels. If you are overweight it’s a safe bet you have high insulin levels.

  71. Dr. Gerson realized the need for the right type of essential fatty acids. He experimented with many types of oils and found that in all cases, fats other than flax seed oil stimulated tumor growth and even the regrowth of tumors that had resolved.
    Flax seed oil is an omega 3 fatty acid containing linolenic and linoleic acids that inhibit the production of pro-inflammatory cytokines and lipid mediators and thus reduces inflammatory responses in the body. It attracts oxygen at the cell membrane assisting in transport of oxygen into the cell. It also helps carry vitamin A through the blood stream. Lignans come from part of the fiber of the seed and are high in protein. Although they can provide health benefits for certain conditions, high lignan flax oil is not allowed on the Gerson Therapy as it introduces too much protein.
    Seeds, including flax seeds, have an important substance in them called an enzyme inhibitor that keeps them dormant until they are in the right environment to sprout. This enzyme inhibitor can also inhibit human digestive enzymes and interfere with good digestion.

  72. OK, Flax is safe when combined with cottage cheese (A Sulfurous Protein). Flax is not safe and may be harmful if you eat it alone. All this was discovered quite a while ago by a renowned German biochemist called Dr Johanna Budwig.

    The key is the cottage cheese. With it you have a very safe statin and anti-cancer causing product. Without it you have a loaded gun.

    1/4 cup cottage cheese mixed with 2 TBsp ground flaxseed (kept in the refrigerator after grounding) Ground Flax loses its effectiveness quickly if not refrigerated.

    Google the free PDF “DIRECTIONS FOR BUDWIG’S WELLNESS PROGRAM” . It’s all spelled out there along with her statement on pg 2, “Such oils should be consumed together with foods containing the right proteins, otherwise the oils will have the opposite effect, causing more harm than good.”

    Look for Budwig’s books on Amazon, and also read the testimonials there as well. ’nuff said.

  73. It appears that the cited study had a publication bias:

    “A recent (2009) meta-analysis, however, found evidence of publication bias in earlier studies, and concluded that if ALA contributes to increased prostate cancer risk, the increase in risk is quite small.[21]

    In contrast, alpha-linoleic acid was recently shown to negatively regulate the growth of cancer cells, but not healthy cells, in vitro.[22]” [23]

    [21] Simon, JA; Chen, YH; Bent, S (2009). “The relation of alpha-linolenic acid to the risk of prostate cancer”. American Journal of Clinical Nutrition 89 (5): 1558S–1564S

    [22] Deshpande, R; Mansara, P; Suryavanshi, S; Kaul-Ghanekar, R (2013). “Alpha-linolenic acid regulates the growth of breast and cervical cancer cell lines through regulation of NO release and induction of lipid peroxidation”. Journal of Molecular Biochemistry 2 (1): 6–17.


    1. Hi Art. This is why I stated that Flaxseed without cottage cheese is a loaded gun. Those studies do not contain the mix. The cottage cheese makes the flax “water soluble” so you get all the benefits without any of the risks associated with those studies. The mix adds electrons and oxygen to your system. The lipids(flax) carry oxygen safely throughout the body removing the fake chemically created fats in salad dressing etc. from your system.

      “Dr Johanna preaches against the use of what she calls ‘pseudo’ fats. In order to extend the shelf life of their products, manufacturers use chemical processes that render their food products harmful to the body. These harmful fats go by a number of names, including ‘hydrogenated’, ‘partially hydrogenated’ and even ‘polyunsaturated’.
      The chemical processing of fats destroys the vital electron cloud within the fat. Once the electrons have been removed, these fats can no longer bind with oxygen, and they actually become a harmful substance deposited within the body. The heart, for instance, rejects these fats and they end up as inorganic fatty deposits on the heart muscle itself. Chemically processed fats are not water-soluble when bound to protein. They end up blocking the circulation, damaging heart action, inhibiting cell renewal and impeding the free flow of blood and lymph fluids. The bio-electrical action in these areas slows down and may become completely paralyzed.”

      There are plenty of people on the Budwig diet that are not getting prostrate cancer or enlarged prostrates. There are also plenty of studies saying quite the opposite of the studies you cite.

      Additionally the people at Lipitor aren’t too happy about this either.

      So it’s really up to the consumer. I use the mix every day, and if anything the swelling I used to feel in my prostrate totally disappeared as well as those annoying Actinic Keratosis (AK) red dots I used to get on my face. It’s up to you, but for me, I’ll believe the people that had miraculous cures from cancer rather than the pharma funded studies that keep the cancer doctors in business.

  74. Are you still so gung ho about fish oil considering new studies this year (2013) show a 70% increase risk in prostate cancer in men from consuming fish oil?

  75. This is confusing. I was told to avoid all animal based sources of omega 3s due to higher cancer risk. Newer studies published in the

  76. one small voice…but a suggestion of importance
    you should look at plant based sources of these particular group of vitamins
    as opposed to meat/fish based …there is a maqjor know difference between these two categories
    it is well documented

  77. I read the linked meta-analysis and some of the studies referenced in it, and they are talking about people who eat ALA from an average diet. Which means that their diet is full of garbage. The word margarine comes up a lot as a primary ALA source.

    Not buying it.

  78. Check out this article on flax and prostate cancer. It shows how flax dramatically improves the prostate according to several studies. I believe I’ve read that the studies implicating flax were bogus, but I’m going to do more research. Also, omega 3s can easily become unstable and make for rancid oil etc. Maybe that’s a negative factor for the prostate. I do remember briefly using some old flax oil on my salads, and my prostate started burning like crazy. Of course, I’ve also tried saw palmetto (?), a herb that supposedly protects the prostate, and I had a similar, but milder reaction … burning etc. Go figure.

  79. Thanks for sharing your knowledge with us and please share a more knowledgeable post like this thanks.

  80. Yeah, but newer research is now pointing to ALA (chia seeds, walnuts) as the better sources for prevention of dementia. I don’t get why though if the body has to do that conversion.

    Fish oil provides preformed EPA and DHA. Flax and chia seeds provide alpha linolenic acid (ALA) which can be converted by the body into EPA and DHA.

    This study showed that serum ?-linolenic acid was inversely associated with risk of disabling dementia (serum levels high = dementia low). The other omega-3 fatty acids (EPA and DHA usually from fish) were not correlated at all with disabling dementia.

    SO WTH???!!!!!!

    1. Diets with enough alpha-linolenic-acid protects against dementia. This is my main concern so now do I skip fish oil supplements and eat my chia pudding?? I still also try to eat fish couple times a week as suggested in following a Mediterranean diet. But then why is that info still valid in light of this study. Aren’t the fish oil studies still as equally valid as this one. Do we just need more studies now between the two?