Human beings have used flaxseed for more than 4,000 years. The above mentioned benefits of flaxseed to human beings are not perfect. Flaxseed contains toxic substances such as cyanoglucoside, elements that fight against vitamin B6, and other anti-nutritional factors, such as cyanoglucoside, trypsin inhibitor, phytic acid, allergens, thyroxine and so on.

The anti-vitamin B6 component found in flax is one of the threats to human health. The American Heart Association's research in 1999 showed that low vitamin B6 in blood would increase the possibility of stroke and fatal coronary heart disease, and they were also worried about whether flax would have adverse effects on human pregnancy and reproductive system development. The reason is a compound called secoisolariciresinol diglucoside (SDG). Flax is the largest known source of SDG. Therefore, if you use flax during pregnancy and lactation, you should pay special attention. Moreover, the most successful method at present can not completely remove its toxicity.