Flaxseed - A Summary

Flaxseed continues to be an increasingly popular ingredient, frequently added to meals and snacks due to its pleasant taste and health properties^[1-8].

Flaxseed is a rich source of protein, fibre, vitamins and the essential omega-3 fatty acid alpha-linolenic acid (ALA), which can be converted to EPA and DPA by the body^[9]. Read here for more information.

Flaxseed, Phytoestrogens and Testosterone

Phytoestrogens are derived from plants and have a chemical structure that is similar to that of human oestrogen. Phytoestrogens are naturally present in many common foods such as vegetables, seeds, berries, wine and tea^[10]. There are a variety of structurally different compounds including lignans which are found in flaxseed and grains^[10]. Phytoestrogens can bind to the oestrogen receptor in humans and can act either like weak oestrogen promoters or inhibitors^[11].

Lignans play a role in plant growth and act as antioxidants in human metabolism. They are converted into weak oestrogenic compounds in the intestines via the gut flora which renders lignans inactive^[12]. Therefore, lignans present no effect on the body’s oestrogen levels^[12]. However, in chronic intestinal illness, the flora may have suboptimal binding abilities, potentially leading to a slight increase in oestrogen levels^[13].

Concern has been raised that the ingestion of phytoestrogens could alter the uptake of testosterone in males. However, these claims are unfounded and based on poorly designed studies on rodents that were administered large quantities of extracted phytoestrogens^[14]. There have been no reported medical cases of testosterone disturbance due to phytoestrogens in humans derived from dietary intake^[15] and the consumption of phytoestrogens from flaxseed does not appear to affect sex hormone metabolism.

Cyanide compounds in foods

Cyanide is naturally present in the environment and plants that are able to liberate hydrogen cyanide (HCN) are referred to as ‘cyanogenic’^[16]. Nearly 3,000 plant species have been reported to be cyanogenic: the most common include almonds, soya and flaxseed^{[16, 17]}, where they occur naturally^[17].

You’re more likely to ingest these trace amounts of cyanide when such foods are consumed raw and dry, as heat and water degrade these compounds. When flaxseed is eaten raw, the body has a natural capacity to break down cyanide compounds which are expelled through urine and breath^{[16, 18]}. without any harm to health^{[16, 18]}.

References

1. Hargis PS & Van Elswyk ME. Manipulating the fatty acid composition of poultry meat and eggs for the health conscious consumer. World's Poultry Sci J. 1993; 49(3):251-64.
2. Prasad K. Flaxseed and cardiovascular health. J Cardiovascular Pharma. 2009; 54(5):369-77.
3. Biswas AK, et al. Dietary fibres as functional ingredients in meat products and their role in human health. Int J Livestock Production. 2011; 24:45-54.
4. Rabetafika HN, et al. Flaxseed proteins: food uses and health benefits. Int J Food Sci and Tech. 2011; 46(2):221-8.
5. Kitts DD, et al. Antioxidant activity of the flaxseed lignan secoisolariciresinol diglycoside and its mammalian lignan metabolites enterodiol and enterolactone. Mol Cell Biochem. 1999; 202(1-2):91-100.
6. Cunnane SC, et al. Nutritional attributes of traditional flaxseed in healthy young adults. Am J Clin Nutr. 1995; 61(1):62-8.
7. Oomah BD. Flaxseed as a functional food source. J Sci of Food and Agri. 2001; 81(9):889-94.
8. Toure A & Xueming X. Flaxseed lignans: source, biosynthesis, metabolism, antioxidant activity, bioactive components, and health benefits. Comp Rev in Food Sci and Food Safety. 2010; 9(3):261-9.
9. Harper CR, et al. Flaxseed oil increases the plasma concentrations of cardioprotective (n-3) fatty acids in humans. J Nutr. 2006; 136(1):83-7.
10. Gaya P, et al. Phytoestrogen metabolism by adult human gut microbiota. Molecules. 2016; 21(8):1034.
11. Valdés L, et al. The relationship between phenolic compounds from diet and microbiota: impact on human health. Food & Funct. 2015; 6(8):2424-39.
12. Aldred EM, et al. Chapter 21 - Phenols. In: Aldred EM, et al., editors. Pharmacology. Edinburgh: Churchill Livingstone; 2009. p. 149-66.
13. Imran M, et al. Potential protective properties of flax lignan secoisolariciresinol diglucoside. Nutr J. 2015; 14(1):71.
14. Probst F, et al. Testosterone-to-oestradiol ratio is associated with female facial attractiveness. Q J Exp Psychol (Hove). 2016; 69(1):89-99.
15. Barrett J. Phytoestrogens. Friends or foes? Environ Health Perspect. 1996; 104(5):478-82.
16. Jaszczak E, et al. Cyanides in the environment-analysis-problems and challenges. Environ Sci Pollut Res Int. 2017; 24(19):15929-48.
17. Abraham K, et al. 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.
18. Moknatjou R, et al. Roasting effect on total cyanide, α-tocopherol and oil characteristics of the brown and yellow types of the flaxseed (Linum Usitatissimum L.). Int J Biosci (IJB). 2015; 6(5):273-82.