Define Bioavailability of pyridoxine?

A recent review by Gregory confirms that bioavailability of vitamin B₆ in a mixed  diet is about 7570, with approximately 8% of this total contributed by pyridoxine a-d-glucoside, which is about half as effectively utilized as free B₆ vitamers or their phosphates. The amine and aldehyde forms of vitamin B6 are probably about 10% less effective than pyridoxine. Despite the involvement of PLP with many enzymes affecting amino acid metabolism, there seems to be only a slight effect of dietary proteins on vitamin B₆ status. Several studies have reported decrease in indicators of vitamin B6 status in women receiving oral contraceptives, but this probably reflects hormonal stimulation of tryptophan catabolism rather than any deficiency of vitamin . B₆  per se.