What are the facts on flax?

(Nathan Bailey) #1

I’m a newbie into the second week of my new ketogenic lifestyle and am still trying to nail down a meal plan that provides all the nutritional requirements.

One aspect that I was concerned about was a shortage of fiber in my diet as previously I was eating 30g a day or more…mainly from homemade whole wheat bread.

I thought my fiber filled days were over until I found the “muffin in a minute” on a variety of low carb recipe sites. I had found the answer…until I got curious about what the amount of flax meal I was eating daily was doing to my nutrition.

My google search led me to a pile of contradictions. From it being a super food to it should be avoided at all costs. What really caught my eye was the information about its effect on testosterone and how it mimics estrogen. With some saying it is a weak estrogen that blocks receptors resulting in less estrogen uptake. And others saying it causes a higher level of estrogen while reducing testosterone.

As a male entering middle age who wants to keep what little hair I have left and get rid of the “man boobs” covering what used to be pecs; I would like to keep my testosterone estrogen ratio in a normal range.

Can anyone clear the air on this subject and point to a peer reviewed study that looks at flax consumption while on a high fat, moderate protein, low carb diet? Particularly its effect on testosterone and estrogen.


(Lisandra Mathews) #2

Ive avoided flax and chia seeds since I came across Maria Emmerich’s article about avoiding flax. She makes a good case and she also provides links to her sources- that may get help you dig deeper.




(jketoscribe) #5

I thought it would be a great idea to have a flax muffin every day, for the fiber and as a bread substitute, when I first started keto. A few weeks in I started bleeding (female) and the bleeding progressed from light spotting to heavy (almost hemorrhagic) bleeding over the course of 8 weeks. I called my doctor who chalked it up to menopause (when you are a female of a certain age, suddenly everything can be blamed on menopause) and it was rather upsetting to find my doctor did not take this seriously. So I consulted Dr. Google, and found, to my surprise, that the phytoestrogens in flax can b responsible for excessive bleeding in women. That day was the last day I had my flax muffin, and within 48 hours the bleeding stopped. I was severely anemic by that point. Was it a coincidence that the bleeding stopped when I stopped ingesting flax? Perhaps. But just as likely it was not a coincidence.

Take it as a precautionary tale. After that experience, I have no question there is bioactive hormone in flax. Not everyone agrees as to whether it’s beneficial or harmful, but as for me, I’m taking the possibility of harm seriously. I still use flax occasionally and in very small amounts, but I’m not taking any chances with daily intake or in the amounts you are proposing.

You might want to do some research on whether you really need fiber to maintain regularity at all. There’s a lot of evidence to the contrary. Good hydration and adequate electrolytes should be sufficient to keep things moving along.


Just low-carbing can cause very heavy bleeding in some women. It sure seemed to in me! And I was not having any flax or other suspicious foods at the time. The situation has started to improve some (after many months), and, ironically, I’m now eating a little flax on a somewhat regular basis.

Your situation might or might not have been related to your flax consumption, but I’ll admit that the quick resolution after stopping makes it mighty suspect.

(Nathan Bailey) #7

Thank you all for your input.

Here is a link to the most extensive paper on flax in the diet I could find:

I’m still working my way through it. Although it was sponsored in part by the flax council of Canada it appears to be an analysis of multiple sources/studies and as such hopefully limited in bias.

My understanding so far is that the effect of flax changes depending on amount and timing of consumption.

Regarding testosterone the only mention I have come across so far is:

“The only study conducted on flaxseed consumption in men resulted in no effect on testosterone levels in healthy males consuming 13.5g flaxseed flour/d for six weeks (Shultz et al., 1991).”

I was raised by a couple of medical practitioners that always preached “everything in moderation”. That would appear to ring true here.


(Nathan Bailey) #8

I guess I should also add that constipation is not an issue for me. The bowels are moving just not putting out the firm stool I am used to. It’s the looseness that concerns me.

(jketoscribe) #9

Although it was sponsored in part by the flax council of Canada it appears to be an analysis of multiple sources/studies and as such hopefully limited in bias.

I’m not a huge fan of Dr. Marion Nestle, but she has a lot to say on the subject of industry bias: https://www.foodpolitics.com/tag/conflicts-of-interest/

I take any study about nutrition sponsored by a producer with a HUGE grain of salt.

(Nathan Bailey) #10

So far in what I have read the author has cited from previous studies and has not put forward any conclusions.

But yes, all things should be taken with a grain or two.


I consume 2 tablespoons a day every day. The same things are found in a range of legumes and veggies that people have been eating for centuries. You can’t avoid death.

(jketoscribe) #12

Listening to episode 1306 Living La Vida Low Carb podcast interview with Dr. Anthony Jay who has written a book about the dangers of artificial estrogens. He points out that flax is very high in phyto-estrogens (second only to soy) and artificial estrogens are especially toxic to people with impaired gut microbiomes.


Interesting… I’ve been bleeding (accompanied sometimes by cramps) for over a week now, and as Ive been on b.c. for a few years (it’s the only thing that has kept me on a regular cycle since I started as a child) my period is supposed to be next week. I just started taking flax/fish oil blend just after starting keto about three weeks. I am seeing that many women experience menstrual changes, but haven’t really seen anyone else describe my issue. I suppose I should try stopping the daily flax oil dose jic. It’s a pain I gotta go shopping for fish oil supplement again.
I just have so many things I don’t know yet, like should I go off my b.c. and let keto try to fix my hormones (my hormones not on b.c. like to be completely backwards all the time)
I will stop daily flax for now and see if my continual bleeding stops. I’ll probably start it up again later to test if it was a fluke.

(jketoscribe) #14

I’m not sure I would take flax oil. Not just the phytoestrogens, but also question whether it might be inflammatory in general.

I saw something interesting called “seed cycling” on the internet. Some people actually use seeds like flax, pumpkin, sesame, and sunflower in a particular rotation to act as hormones and regulate periods and fertility. More evidence that the phytoestrogens ARE bioactive and should be paid attention to.