The following facts became clear in human experiments.
1. When the diet is changed from an ordinary to a vegetable diet, the vitamin B
6 content of the feces increases, the amount of PIC excreted in the urine increases and the quantity of the vitamin synthesized increases. The addition of cellulose to the vegetable diet results in a further intensification of this effect.
2. When the diet is changed from an ordinary to a meat diet, the fecal vitamin B
6 content, urinary PIC level and the amount of the vitamin synthesized decrease but with the addition of cellulose, these clearly show an increase.
3. Together with the increase in synthesized vitamin B
6 with the vegetable diet or cellulose supplementation, there is always an increase in urinary PIC, showing that the absorption of the vitamin B
6 synthesized in the intestines is more marked than in the cases of thiamine and riboflavin.
4. It is suggested that the greater synthesis of vitamin B
6 with the vegetable diet, as compared to the meat diet, is mainly due to cellulose.
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