OCCURRENCE IN FOODSTUFFS 



Beers and pale ales contain 0*45 to 0-82, strong ales 1-35 to 2-7, 

 and stouts 0-62 to i-i mg. per 100 ml.,^^ so that each pint provides 

 approximately 5 mg. The daily requirement of nicotinic acid can 

 therefore be provided by about two pints of beer. 



Seven samples of tea, examined by the method of Wang et al. were 

 found 2^ to contain 5-6 to 9-4 mg. of nicotinic acid per 100 g., and most 

 of this dissolved in boiling water when the tea was infused. Assum- 

 ing that twenty-four cups can be prepared from J lb. of tea, the daily 

 requirement would be supplied by about twenty-four cups. 



Raw coffee beans contain i-6 to 4-4 mg. of nicotinic acid per 100 g. 

 and roast coffee 9-5 to 26 mg. per 100 g., dark roast coffee containing 

 more than light roast. ^^ The increase is explained by decomposition 

 of trigonelline during roasting. Almost the whole of the nicotinic acid 

 is extracted in making a cup of coffee and an average cup of white 

 coffee contains i to 2 mg., that is, one-tenth to one-fifth of the amount 

 required per day. An attempt to assay coffee biologically by means 

 of chicks was unsuccessful, owing to the presence of toxic substances, 

 whilst the feeding of a charcoal eluate of coffee extract to blacktongue 

 dogs produced symptoms of biotin deficiency.^^ On addition of biotin, 

 the dogs responded normally to nicotinic acid. 



Honey, pollen and royal jelly contain o-ii, 10 and 11 mg. of nico- 

 tinic acid per 100 g. respectively. ^^ 



Efifect of Processing Food on Nicotinic Acid Content 



Less work has been carried out on the effect of cooking and storage 

 on the nicotinic acid contents of food than with other members of the 

 vitamin B complex, possibly because it is considerably more stable to 

 heat than aneurine and more stable to light than riboflavine. Never- 

 theless, in calculating the dietary intake of nicotinic acid, the losses 

 caused by extraction of the vitamin into the water used in cooking 

 fruit and vegetables must be taken into consideration. This may be 

 up to 30 % of the amount present in the food.^^ Cooking water was 

 found to contain 2 to 40 % and the liquid in canned vegetables 30 to 

 40 % of the total nicotinic acid. As already mentioned above, roast 

 coffee may contain several times the^amount of nicotinic acid present 

 in the raw bean, owing to decomposition of trigonelline. Raw milled 

 rice lost 60 % of its nicotinic acid on washing and cooking, whereas 

 parboiled milled rice, that is, rice steamed in the husk, lost only 

 12 %.2« 



Roast beef retained nearly all the nicotinic acid present in the raw 

 meat.^^ Beef extract is a rich source of nicotinic acid,^^ as well as of 

 riboflavine (see page 166), and seven samples of commercial meat 

 extracts and meat juices contained 34*5 to 102-5 n^g. of nicotinic acid 



235 



