DISTRIBUTION OF B VITAMINS 23 



vitamin E 51 ; this is in contrast to hen's eggs which are a poor source of 

 E vitamins. The occurrence of E vitamins in the germs of seeds (and in 

 some eggs) makes their distribution resemble that of the B vitamins more 

 than that of ascorbic acid, but the available evidence indicates that they 

 are absent and nonfunctional in many lower forms of life. 



Vitamins K. The distribution of the K vitamins is particularly inter- 

 esting in that they are produced by bacteria, are widespread in the 

 chloroplasts of green plants 52 and are known to function in higher animals. 

 However, one bacterium out of ten produced no demonstrable amount of 

 vitamin K, and yeast contains little or none. 33 Substances with vitamin K 

 activity have no effect on the growth, respiration or fermentation of 

 yeast. 54 The studies of Dam and co-workers 54 have shown that vitamin K 

 is -present in all chlorophyll-bearing plant organs and that it is absent or 

 present in low amounts in plant organs which normally do not carry 

 chlorophyll throughout development. Chloroplast preparations were found 

 to be about 60 times as rich as cytoplasm preparations. Seeds contain very 

 little. Photosynthesizing algae and bacteria were found to contain vitamin 

 K. 54, 55, 56 Mushrooms were found to contain roughly 1/40 of the amount 

 in green leaves. 



The absence or near absence of K vitamins from seeds, yeast, certain 

 bacteria, nonchlorophyll-bearing higher plant organs and most animal 

 tissues makes it appear that their occurrence is not universal. Certainly 

 their distribution offers a strong contrast to that of the B vitamins. 



Quantitative Relationships Pertaining to the Distribution of B Vitamins 



Some of the quantitative relationships with respect to the distribution 

 of the B vitamins are worthy of note, in spite of the fact that available 

 data are not all dependable. Our present discussion of these relationships 

 will be limited to six substances: thiamine, riboflavin, nicotinic acid, 

 pantothenic acid, biotin and inositol. The available data with respect 

 to pyridoxal, etc., are not sufficiently reliable because of the difficulties 

 involved in assay and in releasing these forms quantitatively from tissues 

 without destruction. The available folic acid values are too low by a 

 variable and unknown amount due to the fact that when most of the 

 comparable assays were made, enzymes capable of freeing it completely 

 from tissues were not known. 57 Data regarding p-aminobenzoic acid and 

 choline which might be used for comparative purposes are not available. 



From the data compiled in Table 1 it may be noted first that in terms 

 of the absolute amounts, inositol is always the most abundant and biotin 

 the least abundant. In 17 out of 24 cases, the following order is main- 

 tained: (1) inositol, (2) nicotinic acid, (3) pantothenic acid, (4) ribo- 



