Availability of vitamin B6 from different food sources.

The present study was conducted to investigate the precaecal digestibility of vitamin B6 from selected food sources including eggs, bananas, white cabbage, corn, milk powder, fish, barley, soybeans, brown rice, wheat bran, brewer's yeast, rye and soybean meal. These foods were chosen for their relevance in human and animal nutrition and prepared as they are usually eaten by humans. As confirmed by further investigations the precaecal digestibility is a valuable measure for determining the availability of native B-vitamins. Therefore, pigs were fitted with an end-to-end ileo-rectal anastomosis for digesta passing straight from ileum to rectum, thus avoiding endogenous vitamin synthesis by the colon. Three weeks after surgery the digestibility experiments were carried out during which the animals were fed various experimental diets for a period of 12 days and digesta were collected quantitatively twice a day during the final 5 days of this period. The concentration of vitamin B6 in foods and chyme was determined by high pressure liquid chromatography. Precaecal digestibility of vitamin B6 from all tested food sources ranged from 51 to 91% in the following order: cabbage diet > banana diet > fish diet > milk powder diet > brewer's yeast diet > soybeans diet > soybean meal diet > egg diet/corn diet > barley diet > wheat bran diet > rye diet. Only boiled brown rice had a very low vitamin B6 availability of 16%. The digestibility of vitamin B6 from plant products (excluding the rice) was on average 10% lower when compared with animal products (71 versus 79%).