Question:
The Swedish health authorities advice is to eat a maximum of one tablespoon of ground flax seeds per day and recommend heating it because of the cyanide risk.
In the brilliant book How Not To Die by doctor Michael Greger, it says that three tablespoons a day can prevent high blood pressure and prostate cancer. What is your opinion about the cyanide risk?
Jill Edwards, MS, DipACLM Response:
Thank you for bringing up the concern about ground flaxseed consumption, especially in light of the differing viewpoints from the Swedish health authorities and Dr. Michael Greger’s book “How Not To Die.”
Flaxseeds do contain compounds called cyanogenic glycosides, which can release hydrogen cyanide when the seeds are crushed (ground) and come in contact with water. The potential risk with these compounds is the reason some health authorities are cautious about the amount of raw flaxseed one should consume.
However, it’s important to clarify a few points:
Amount of Cyanogenic Glycosides in Flaxseeds: The actual amount of hydrogen cyanide released from flaxseeds is relatively small, especially when considering the levels that could produce harmful effects in humans. For most people, the body can effectively detoxify the small amounts of cyanide that are released from typical servings of flaxseeds.
Effect of Cooking: Heating processes, like baking, can reduce the cyanogenic glycosides in flaxseeds, thus lowering the potential risk. This is likely the basis for the recommendation from the Swedish health authorities to heat the flaxseed.
Benefits of Flaxseeds: Flaxseeds are rich in alpha-linolenic acid (a type of omega-3 fatty acid), lignans, and dietary fiber. Numerous studies have indicated the potential health benefits of flaxseeds, which include reducing the risk of heart disease, stroke, and cancer, as Dr. Greger mentions in his book.
Quantity: There is indeed research suggesting health benefits from consuming more than one tablespoon of flaxseeds a day. However, moderation is key. A diversified diet helps in not overly relying on one source for nutrients and potential health benefits.
In summary, while there is a theoretical risk of cyanide exposure from consuming ground flaxseeds, the actual risk to human health at typical consumption levels appears to be low, especially when one considers the demonstrated health benefits of flaxseed consumption. However, individuals with certain health conditions or those taking specific medications should always consult with their healthcare provider before making significant dietary changes.
It’s always essential to balance potential risks with the proven benefits, and in the case of flaxseeds, many health experts believe the advantages outweigh the theoretical risks when consumed in moderation.
References
Ganorkar PM, Jain RK. Flaxseed – a nutritional punch. Int Food Res J. 2013;20:519–525
Baker A, Garner MC, Kimberley KW, et al. Cyanide Toxicity of Freshly Prepared Smoothies and Juices Frequently Consumed. Eur J Nutr Food Saf. 2018;8(4):215-224.
Abraham K, Buhrke T, Lampen A. Bioavailability of cyanide after consumption of a single meal of foods containing high levels of cyanogenic glycosides: a crossover study in humans. Arch Toxicol. 2016;90(3):559-74.
Mishra S. Flaxseed: Bioactive compounds and health significance. IOSR J Humanities Soc Sci. 2013;17:46-50.
