T Nation

Whole Flaxseed and Decreased Testosterone

Note: This posting is about whole flaxseed, repeat “whole flaxseed”, and the lignan it contains. Flaxseed oil does not contain lignan.

I just came across a report from Reuters concerning a very preliminary study at Duke University concerning the use of whole flaxseed to combat prostate cancer - presumably because, and I quote from the article, “flaxseed contains a fiber compound called lignan that may slow tumor growth by binding to the male hormone testosterone, which is believed to contribute to the progression of prostrate cancer.” Here’s a partial description of the study, again from the Reuter’s article. “The Duke study involved 25 cancer patients who were awaiting the removal of their prostrate. Each member of the trial group consumed each day three tablespoons of ground flaxseed mixed into cereal, yogurt, applesauce or juice. [The researcher] found that men who were on a low-fat, flaxseed-supplemented diet for an average of 34 days experienced decreased levels of testosterone, lower tumor cell proliferation rates and higher levels of cancer cell death.”

Personally I've seen more and more references and articles pushing flaxseed because of its high fiber content and its apparent ability to reduce the risk of cardiovascular disease and cancer. I had been considering trying the stuff, but "decreased levels of testosterone?" Not exactly what I'm looking for! Has anybody else heard of this study or of this undesireable side-effect (undesireable at least from the T-man point of view) of whole flaxseed? How about you T-mag science writers? Any buzz about this at the conferences? Inquiring minds want to know!

The decrease in test is from the low-fat diet. I’ve been reading a lot about Udo Erasmus lately, & that’s one of the things that he found out. He also says that it’s the flaxseed oil, not whole flaxseed that’s good. You’ve got to grind it up.

So when buying the oil what should I get? The high-lignan or the regular?

Yeah - “flaxseed oil” is definitely good stuff, hence my note at the top of the original post. And agreed, the low-fat diet may account for some or all of the T-decrease. (In fact I hope it does account for all of the decrease.) But the researchers - at lease as I interpret the article - conjecture that lignan can bind free T. It’s the effects of the lignan that I’m trying to a handle on. Grinding up whole flaxseed and using that as my source of flaxseed oil would be great as it would also provide a big does of fiber - but if the lignan is going to snatch up precious nanograms of free T, I ain’t gonna do it.

I thought that fibre was only good for regularity and didn’t have any other value because the body doesn’t have any enzymes to digest it. I wonder if this lignan is different though. I’m sure that the decrease in T is from the low-fat diet.

I remeber reading something like that. The onlty other thing I can think of to prevent is to eat some cholesterol along with your meals. It makes sense to have low Testosterone if the only fat source is highly unsaturated flax oil. Make sure to get some animal fat in your diet.

I dimly remember lignans being in a list of things like aspirin to avoid because it (if I remember correctly, which I probably don’t)interferes with the inflammatory response we want right after a work out. I can’t recall where I read that, but it may have been in a supplement report of some kind here at t-mag. I’ll make a quick check to see if I can find where I read that. I wondered whether to buy regular flax seed oil or the lignan-enriched stuff. Now it looks like a no brainer. Thanks for passing this along.

I learn more here at T-mag everyday. I read this post last night. I just grabbed a handful of flax oil caps from the cupboard and as I was putting the bottle back, I noticed the big “Lignan-enriched” on the front of the bottle. Damn! I just bought two bottles of this crap the other day because it was 20% off. I checked the omega’s, but didn’t know about lignan at the time. At least it was discounted!

Guys, what’s your opinion of this study? I just bought an assload of Barlean’s flax oil (“lignan rich” and loaded with particulate) and would like to know if I should take it back and get regular flax. One study shouldn’t be the basis for an anti-lignan hysteria, and I’d like to hear some more info. Thanks in advance.

—Demo Dick

Dose, timing, and duration of flaxseed exposure affect reproductive indices and sex hormone levels in rats.

Tou JC, Chen J, Thompson LU.

Department of Nutritional Sciences, University of Toronto, Ontario, Canada.

Flaxseed ingestion produces large amounts of mammalian lignans. Since lignans have weak estrogenic/antiestrogenic properties, the objective of this study was to determine in rats whether exposure to 5% or 10% flaxseed affects sex hormone levels and reproductive indices when given at different developmental stages. Rats were exposed to either a basal diet (control), 5%, or 10% flaxseed diet starting at weaning on postnatal day (PND) 21 or continuously from gestation to PND 132 for lifetime exposure. Compared to the control, exposure to 5% or 10% flaxseed after weaning produced no marked reproductive effects, whereas lifetime flaxseed exposure caused significant changes that differed depending on the dose. In female rats, lifetime exposure to 5% flaxseed affected the reproductive tract as indicated by delayed puberty onset. In contrast, lifetime exposure to 10% flaxseed caused earlier puberty onset, higher relative ovarian weight, higher serum estradiol levels, and lengthened estrous cycles. 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

I think that the low fat diet and lowering of cholesterol could have contributed. Also the decline in T, while statistically significant, was really small and wouldnt make a difference to muscle mass or strength.

Health aspects of partially defatted flaxseed, including effects on serum lipids, oxidative measures, and ex vivo androgen and progestin activity: a controlled crossover trial.

Jenkins DJ, Kendall CW, Vidgen E, Agarwal S, Rao AV, Rosenberg RS, Diamandis EP, Novokmet R, Mehling CC, Perera T, Griffin LC, Cunnane SC.

Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Ontario, Canada.

BACKGROUND: Currently there is considerable interest in the potential health benefits of oil seeds, such as soy and flaxseed, especially in relation to cardiovascular disease and cancer. OBJECTIVE: We therefore evaluated health aspects of partially defatted flaxseed in relation to serum lipids, indicators of oxidative stress, and ex vivo sex hormone activities. DESIGN: Twenty-nine hyperlipidemic subjects (22 men and 7 postmenopausal women) completed two 3-wk treatment periods in a randomized, crossover trial. Subjects were given muffins that contributed approximately 20 g fiber/d from either flaxseed (approximately 50 g partially defatted flaxseed/d) or wheat bran (control) while they consumed self-selected National Cholesterol Education Program Step II diets. Both muffins had similar macronutrient profiles. Treatment phases were separated by > or = 2 wk. RESULTS: Partially defatted flaxseed reduced total cholesterol (4.6+/-1.2%; P = 0.001), LDL cholesterol (7.6+/-1.8%; P < 0.001), apolipoprotein B (5.4+/-1.4%; P = 0.001), and apolipoprotein A-I (5.8+/-1.9%; P = 0.005), but had no effect on serum lipoprotein ratios at week 3 compared with the control. There were no significant effects on serum HDL cholesterol, serum protein carbonyl content, or ex vivo androgen or progestin activity after either treatment. Unexpectedly, serum protein thiol groups were significantly lower (10.8+/-3.6%; P = 0.007) at week 3 after the flaxseed treatment than after the control, suggesting increased oxidation. CONCLUSIONS: These data indicate that partially defatted flaxseed is effective in lowering LDL cholesterol. No effects on lipoprotein ratios, ex vivo serum androgen or progestin activity, or protein carbonyl content were observed. The significance of increased oxidation of protein thiol groups with flaxseed consumption requires further investigation.

Thanks John! I kind of suspected the negative effects may have been overstated, or at least over-implied. This saves me a trip to my health food store (where the men are emaciated and the women don’t shave).

Thanks, JMB! That’s the sort of feeback I was hoping to scare up by asking the question.

Yeah I knew it was the low-fat diet!