Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
8 Sep

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

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. 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.

    Pieter wrote on June 28th, 2011
  2. 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.

    Paula wrote on July 31st, 2011
  3. 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!

    Thea Tooker wrote on September 24th, 2011
  4. 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.

    Peter wrote on November 23rd, 2011
    • 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.

      Zeria wrote on February 27th, 2012
    ‘ 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.’

    Lance Strish wrote on January 16th, 2012
  6. 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.

    Lindsey wrote on February 7th, 2012
  7. 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.

    Jenny wrote on April 26th, 2012
  8. 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

    elliot wrote on June 11th, 2012
  9. 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

    elliot wrote on June 11th, 2012
  10. 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. “

    wmhogg wrote on October 6th, 2012
  11. 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.

    Bridget wrote on November 11th, 2012
  12. 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.

    Ms. Immortal wrote on January 10th, 2013
  13. 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.

    Craig wrote on January 21st, 2013
  14. just use hemp oil instead. even tastier. :-)

    Stefan wrote on March 21st, 2013
  15. 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.

    Neo wrote on May 9th, 2013
  16. 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.


    Art wrote on May 18th, 2013
    • 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.

      NEO wrote on June 10th, 2013
      • Neo, I am sensitive to dairy (runny nose, sore throat etc…) what can I do instead of cottage cheese? Is soaking ok?

        Justin Goldberg wrote on April 17th, 2016
  17. 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?

    Steve wrote on July 27th, 2013
  18. 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

    Jerry wrote on February 28th, 2014
  19. 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

    L.RF wrote on June 8th, 2015
  20. 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.

    some guy wrote on March 1st, 2016
  21. Any thoughts on the newest studies showing that lignans can help reverse prostate cancer?

    Also I’ve been trying to register on the forum for months with no luck, it says the captcha failed and I can’t register twice; I’ve never registered.

    Justin Goldberg wrote on April 17th, 2016
  22. 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.

    Bill wrote on May 22nd, 2016

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