Experimental and human studies describe the adverse effect of
iron or
vitamin B6 deficiencies on
polyunsaturated fatty acid metabolism.
Iron is present in end
proteins of the delta6-desaturase
enzyme complex, and
vitamin B6 deficiency can affect the transmethylation reaction of
proteins. Plasma
polyunsaturated fatty acid content was estimated in apparently healthy subjects of the general population with no consumption of fish and low
vitamin B6 serum levels (< 3 microg/l; n = 21) or with low
iron serum levels (men: < 12 micromol/l; women: < 10 micromol/l; n = 16) and compared to a control group (n = 22) with normal
vitamin B6 and
iron serum levels (in reference range). The activities of the delta6-desaturase
enzyme complex were calculated as product/precursor (conversion indices). In groups of subjects with low
vitamin B6 and low
iron levels, delta6-desaturase activity together with delta5-desaturase activity (conversion of alpha-linolenic/18:3,n-3/ into
eicosapentaenoic acid/20:5,n-3/) as well as the conversion index of
docosahexaenoic acid formation (22:6,n-3) from 22:5,n-3 (second delta6-desaturase activity) were significantly reduced. The inhibition effect on
fatty acid synthesis was more pronounced in subjects with low
iron levels than in those with low
vitamin B6 levels. The conversion indices correlated significantly positively with
vitamin B6 or
iron levels.