The effects of dietary flaxseed on the Fischer 344 rat: I. Development, behavior, toxicity and the activity of liver y-glutamyltranspeptidase.

Key findings

This early (2004) study assessed the safety of flax on (i) growth curves; (ii) physical, behavioural and developmental milestones to gauge the impact on overall development; (iii) the levels of plasma glucose to assess glucose homeostasis; (iv) plasma levels of alanine aminotransferase (ALT) and g-glutamyltranspeptidase (gGT) which are indicators of liver damage; and (iv) the activity of the enzyme g-glutamyltranspeptidase (gGT) in the liver which have shown to be markedly elevated in premalignant and malignant liver lesions. The levels of alanine aminotransferase and g-glutamyltranspeptidase (gGT) were the same as those of regular chow-fed rats. The activity of gGT was increased in the livers of flax chow-fed rats. Flax, by increasing the activity of gGT in the liver, may increase GSH, thereby being protected against injury. The results show flax consumption to be without effect on growth, development and behaviour of the Fischer 344 rat and to show no signs of toxicity or liver damage in males or females.

ABSTRACT

The effect of exposure to, followed by consumption of, 10% flax chow from the 18th day of gestation to the 86th day after birth was examined in male and female Fischer 344 rats. Growth curves of the flax chow-fed rats were identical to those of regular chow-fed rats, as were such developmental milestones as pinna development, growth of hair and eye opening. Acoustical startle and the righting reflexes, developmental behavioural indices, were also the same. Blood glucose levels were comparable in flax chow-fed and regular chow-fed rats at all stages of development, indicating that flax is without effect on glucose balance. There were no signs of toxicity in the flax chow-fed rats since their plasma levels of alanine aminotransferase and g-glutamyltranspeptidase (gGT) were the same as those of regular chow-fed rats. The activity of gGT displayed an increase in the livers of flax chow-fed rats after puberty, more so in the male—four-fold than in the female,1.38-fold. This is suggestive of an estrogenic effect which implicates an effect of an estrogenic flax lignan. An hepatobeneficial effect of the flax-induced increase in liver gGT is discussed. In summary, dietary 10% flax chow is without long-term effect on growth, development and behaviour, is non-toxic and may be hepatoprotective.