Flax Seeds for Diabetes

Today's Blog--

Drug companies hope to capitalize on the fact that the consumption of certain plants appears to lower the risk of diabetes by isolating these plants’ active components for use and sale as pharmacological agents. Though not as profitable, why don’t we just eat the plants themselves?

One plant in particular that’s now been tested is flax. We’ve known for 20 years that having ground flax in your stomach can blunt the blood sugar spike from a meal, but it’s never been tested in diabetics–until now. World Health Organization researchers published an open-label study on the effect of flax seed powder supplementation in the management of diabetes.

Diabetic subjects took a tablespoon of ground flax seeds every day for a month, and, compared to the control group, experienced a significant drop in fasting blood sugars, triglycerides, and cholesterol, as well as the most important thing, a drop in A1C level. If one’s sugars are already well controlled, though, there may be no additional benefit.

How does flax help control blood sugars? Flaxseeds may improve insulin sensitivity in glucose intolerant people. After 12 weeks of flax, researchers found a small but significant drop in insulin resistance, perhaps related to the drop in oxidant stress due to the antioxidant qualities of flaxseeds.

The study profiled in my 3-min video Flaxseed vs. Diabetes showing a tablespoon of daily ground flax seeds for a month appears to improve fasting blood sugars, triglycerides, cholesterol, and hemoglobin A1c levels in diabetics was a non-blinded, non-randomized small study. If it was some drug they were testing, I’d never prescribe it based on this one study, but this isn’t a drug. It’s just flaxseeds. There are just good side effects, so even if this study was a fluke or fraud, flaxseeds have other benefits. In the worst case scenario the seed would still end up benefiting patients who aren’t quite ready or able to reverse their diabetes completely with a plant-based diet.

Flaxseeds are calorically dense, but even adding a half cup of ground flax a day may not lead to weight gain. When 4 tablespoons a day were tested for 3 months the flax group ended up with a slimmer waist than the flaxseed oil or control group. Because of the potential of raw flax seeds to interfere with thyroid function at high doses, though, I would only recommend 2 tablespoons a day. And I would not recommend flaxseed supplementation during pregnancy.

The flaxseed study reminds me of the Prunes vs. Metamucil for Constipation one, or any of those talking about various foods that may control blood sugar (Amla Versus Diabetes), weight (Fat Burning Via Flavonoids), cholesterol (Dried Apples Versus Cholesterol), or sexual dysfunction (Watermelon as Treatment for Erectile Dysfunction). Yes, these foods may help, but why not get at the root of the problem and try to reverse the condition altogether with a healthier diet overall?

The three best books on reversing type 2 diabetes with diet are Defeating Diabetes, co-authored by my favorite dietician, Brenda Davis, and from two of my medical mentors: Dr. Neal Barnard’s Program To Reverse Diabetes Now and Dr. Joel Fuhrman’s The End of Diabetes.

-Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.

Image credit: Jill A. Brown / Flickr


  • Catherine J Frompovich

    Thank YOU, Dr. Greger, for making important dietary and nutritional information known to the general public. That is a great service to humankind, I truly feel, since most MDs don’t know about the nutritional values in food, especially organically-grown plantfoods sans toxic chemicals.
    I wish there were more allopathic physicians who followed your parsing of the research. But then, as you point out, pharmaceutical companies wouldn’t be happy, now would they?
    As a “natural nutritionist” since the early 1980s, not an RD who normally would disseminate processed food industry information, I truly appreciate your take on the science about foods. Holistic health practitioners have been saying this type of information since the early 1900s. Thank goodness, it’s finally becoming mainstream.
    Again, thank you!

  • Frank X. Harris

    Hi, Dr. Gregor! Thanks for this info! Is there any data on whether it matters if you take a whole tablespoon in the AM or should it be taken in portions before each meal?
    Very best,

  • Dara Custance Schulbaum

    Hi Dr. Greger, I had the pleasure of seeing you speak in Indianapolis a couple weeks ago. Wondering if you might share anything at all about the best research re: nutrition for type 1 diabetes?

    • Veganrunner
    • Thea

      Dara: You might be interested to know that the book, Dr. Neal Barnard’s Program For Reversing Diabetes” has a chapter called, “A Revolution In Type 1 Diabetes”. It’s not a big chapter, but I think people with type 1 would benefit from reading it – and then reading the rest of the book. :-)

      Good luck.

  • Kate McConaughy

    Thank you!

  • bkkintegral

    Dear Dr. Greger,
    What kind of success might the following patient experience upon implementing a whole food, plant-based diet: an adult onset, yet, insulin dependent diabetes mellitus, hypertension (moderate to severe) and ischemic limb disease in a 53 year old male….all the usual lipid abnormalities, fasting blood sugar between 145-175? ILD is severe enough that 4 stents have already been surgically implanted. Previous MI as well.
    In short, this patient says he’s highly committed to do what I prescribe…interestingly, it wasn’t primarily the fear of losing his lower extremities, but rather, the loss of function of other extremity that has made him willing to go all the way now.


  • isisgagnongrenier

    Hello Dr. Greger,

    Thank you for your work, it is one of the most impressive I’ve seen in my life. I have been looking at almost a third of your videos in the past 2 years, consulting the sources cited, and I LOVE it!

    I am surprised by the affirmation : “And I would not recommend flaxseed supplementation during pregnancy.”

    I searched in vain for an explanation. Being a type MODY 3 diabetic, living off insulin for 6 years now, eating vegan, without refined sugars, and drinking lots of medicinal herbal teas, it is still a challenge for me to keep my blood glucose below 7mmolL all the time. Flaxseeds is one of the many plants that help me in this challenge.

    I am pregnant today, and many of my usual hypoglycaemic plants are nocive for the development of my baby, which is even more challenging as I wish, if possible, to keep off insulin during my pregnancy. My question : why don’t you recommand flaxseeds during pregnancy, and is there a safe upper limit? For example, a tablespoon every two days?

    Thank you very much, have a nice day!

  • cibi

    Have you read any of the studies on black seed (nigella sativa), also called black cumin seed and its oil? It seems like another useful seed, and I’ve read some of
    the studies which make it sound very promising for increasing one’s
    health. However, as I am no expert, could you and/or your assistants do
    the research in order to help us know what is credible and reputable?
    Thank you! ♥

    • Joseph Gonzales R.D.

      I see one study on blood pressure and black cumin seed oil and the results seem promising. Another study looked at ever more biomarkers related to CVD health, but did not find statistical significance due to small sample size. I recommend incorporating of a plant-based diet, as there are protective compounds found in plant foods, not just black cumin seeds. I have never had a black cumin seed.

  • alexandernorlen

    I live in Sweden and have the following issue: I use nutritionfacts as the main source of nutritional knowledge (thank you for being awesome). My mother has a habit of using the Swedish National Food Agency as hers (I guess many swedes do). If you do a google search on “livsmedelsverket linfrö” (translates to “Swedish National Food Agency flax seeds”) you find their latest recommendation which has the unfortunate title “Cyanogenic Glycosides and Hydrogen Cyanide – Flax Seeds” (http://www.livsmedelsverket.se/livsmedel-och-innehall/oonskade-amnen/vaxtgifter/cyanogena-glykosider-och-vatecyanid/). Judging by the other results that show up in the same google search (the words poisonous, toxic and death are in the top titles) people in general are pretty scared here in Sweden. In their recommendation they say “The amount of hydrogen cyanide that can be released by the most common usage of whole flax seeds, one to two table spoons a day, is considered risk free”. But they advise against eating ground flax seeds completely because “We don’t have enough knowledge yet on the amount of ground flax seeds you can eat without jeopardising your health”. On a side note: there are no mentions of possible benefits of eating flax seeds, other than “Flax seeds produce a mucus that makes food pass more easily through the intestines.”

    So my question or request is simply: I can’t find a post on nutritionfacts about the toxicity of flax seeds. Could you please clarify what we know and how the risks compare against the benefits. It’s very easy to scare most people from eating ground flax seeds by using the word cyanide. If we shouldn’t be scared, a good reliable source that clarifies this issue is needed :) Thank you

  • James love

    “Because of the potential of raw flax seeds to interfere with thyroid function at high doses, though, I would only recommend 2 tablespoons a day. And I would not recommend flaxseed supplementation during pregnancy.”

    I’ve been having 4 tablespoons per smoothie. Where is the evidence that flax seeds have the potential to interfere with thyroid function?

    Thank you!