Are Flaxseeds Toxic For Your Health?

by Stephlina D'cunha

A new-age superfood widely recognized for its several health benefits, flaxseeds can be a great addition to your diet. From keeping you away from cancer, managing cholesterol levels to controlling diabetes, the benefits are endless. But too much of anything can be disastrous.

With a galore of health benefits to offer, it may be quite hard to digest that flaxseeds, in fact, can have side effects as well. Susan Schenck, the author of the books The Live Food Factor and Beyond Broccoli, says, “The problem with flaxseeds is that they are toxic in more than moderate doses. Excessive consumption can result in abdominal distress, allergies, nausea and even menstrual problems.”

Flax & Its Side Effects: Hard To Believe But True!
Whether flaxseeds are harmful to health largely depends on the individual’s body chemistry and how much is too much for the individual based on their current health status.

Miss Schenck adds, “Flax contains factors antagonistic to the vitamin B group. Several studies demonstrate that flax contains toxins that have caused medical doctors to advice against its consumption for pregnant and lactating women. [1] Major toxins in flax are cyanogenic glycosides, also found in lima beans, sweet potatoes, yams, and bamboo shoots. These glycosides metabolize into yet another substance called thiocyanate (SCN–), which can create several problems in the body.”

Here we highlight four such adverse reactions you can get from eating too much flax:

1. Hampers Thyroid Function
“The thiocyanate produced through the metabolism of cyanogenic glycosides can over time suppress the thyroid’s ability to take up sufficient iodine. This can result in weight gain by suppressing the production and release of thyroid hormones,” quotes Susan. [2]

2. Causes Abdominal Problems
The laxative property of flaxseeds, which they are highly acclaimed for, is a boon for all those who suffer from constipation. However, for those who don’t, this very property can lead to diarrhea, vomiting, flatulence, gas and even belching. [3]

3. Increases Chances Of Bruising
The amount of omega-3 fats present in flaxseeds is highly regarded for its ability to treat swelling and inflammation in the body (specifically for arthritis). However did you know these healthy fats may be making you more prone to bruises if you eat too many flaxseeds? Yes, omega-3 fats can also slow the formation of blood clots and increase bleeding. Thus, people on blood-thinning medicines should consult their doctor before adding flaxseeds to their diet. [4]

4. Interferes With Menstrual Cycle
Flaxseeds may mimic the effects of estrogen and thereby conflict with your menstrual cycle. Women suffering from other hormone-related conditions such as PCOS or endometriosis should also be mindful when eating flaxseeds. [5]

In her book Beyond Broccoli, Susan quotes, “Nutrition expert Ann Louise Gittleman advises taking no more than three or four tablespoons of flaxseeds per day. She claims that baking or toasting the seeds deactivates the toxic cyanogenic glycosides but preserves the beneficial omega-3s when heated less than 300° F.”

For more interesting stories, visit our Health page. Read more about Diseases & Conditions here.

Read More:
Quick Fix: Flaxseeds For High Blood Pressure


1. Figueiredo MS, de Moura EG, Lisboa PC, Troina AA, Trevenzoli IH, Oliveira E, Boaventura GT, da Fonseca Passos MC. Maternal flaxseed diet during lactation programs thyroid hormones metabolism and action in the male adult offspring in rats. Horm Metab Res. 2011 Jun;43(6):410-6. doi: 10.1055/s-0031-1275285. Epub 2011 Mar 29. PubMed PMID: 21448850.

2. Pesce L, Kopp P. Iodide transport: implications for health and disease. Int J Pediatr Endocrinol. 2014;2014(1):8. doi: 10.1186/1687-9856-2014-8. Epub 2014 May 30. PubMed PMID: 25009573; PubMed Central PMCID: PMC4089555.

3. Hanif Palla A, Gilani AH. Dual effectiveness of Flaxseed in constipation and diarrhea: Possible mechanism. J Ethnopharmacol. 2015 Jul 1;169:60-8. doi:10.1016/j.jep.2015.03.064. Epub 2015 Apr 15. PubMed PMID: 25889554.

4. Necyk C, Ware MA, Arnason JT, Tsuyuki RT, Boon H, Vohra S. Increased bruising with the combination of long-chain omega-3 fatty acids, flaxseed oil and clopidogrel. Can Pharm J (Ott). 2013 Mar;146(2):93-6. doi:10.1177/1715163513481325. PubMed PMID: 23795184; PubMed Central PMCID: PMC3676193.

5. Sturgeon SR, Volpe SL, Puleo E, Bertone-Johnson ER, Heersink J, Sabelawski S, Wahala K, Bigelow C, Kurzer MS. Effect of flaxseed consumption on urinary levels of estrogen metabolites in postmenopausal women. Nutr Cancer. 2010;62(2):175-80. doi: 10.1080/01635580903305342. PubMed PMID: 20099191.

Related Articles

Join The Conversation