19@] XUTRITION REVIEWS 5

Alcaligenes fecalis, Bacillus mesentericzis, and Bacillus vulgatzu. For B. vnescntericzcs it was found necessary to supply biotin ini- tially and for P. vzilyaris, nicotinic acid, because these organisms apparently are unable to synthesize these factors. The two organisms were able to synthesize appre- ciable quantities of the remaining vitamins that were studied, however, and the other four species of bacteria likewise produced appreciable quantities of the four vitamins when incubated at body temperature. Cal- culated on the basis of the amount of vita- min produced per gram of fresh cells, E. coli, normally a dominant organism in the human intestinal flora, produced the most riboflavin, A. fecalis the most thiamine, and B. i d g a t i t s the most nicotinic acid. The quantities of biotin produced were small in all instances.

It was also shown that most of the vita- mins were contained within the bacterial cell. Even after long continued gron th only about a third of the vitamin content was leached from the bacteria into the media. Studies of the rate of vitamin production by B. aerogenes showed that the initial qynthesiq was rapid, so t!iat not much more n-as pro- duced in forty-eight hours than in fourteen and one-half hours of incubation. The failure of the synthesized vitamins to escape freely into the surrounding medium may explain the apparent inadequacy of such a soIirce for most of the larger animals, in- cluding man.

The authors conservatively conclude that the species of bacteria studied synthesized some of the B-vitamins in greater amounts than n-ere used in their metabolism, and that the excess accumulated in the cultures. While much more work must be done before a complete picture is obtained of the func- t>ions and practical significance of intestinal bact.eria, it is evident that, the vast numbers of int.estina1 bacteria living with us through- out life may a t times play m important part in our welfare. Under cert,ain conditions it is possible that the effects of diet in con- trolling t.he nature of our intestinal flora may assume practical importance well be- yond the immediate provision of specific nL1trient.s. Further studies of the kind reported by the Yale investigators should help elucidate some of the puzzling prob- lems of nutrition, for esample, t.he fact that healthy babies thrive on cow’s milk, suitably modified, and have shown no signs of nicotinic acid deficiency in spite of the low content of nicot,inic acid in milk, an amount coneiderecl by nutrition esperts to be less than desirable. Are t,he intestinal bacteria responsible for this ability to get along with what seems t,o be a meager supply of an important dietary essential? The vien- that int.est.ina1 bacteria may be distinctly bene- ficial, cont.rary to the classical views of RIet.chnikoff, thus looms as a, definite possibiliby -.

VITAMIN D AND TOOTH DECAY

No subjeet in nutrition is more contro- versial, or more in need of clarification, than our ideas of the cause and prevention of tooth decay. The observations of XcBeath and Verlin recently reported in the Journal of the American Dental Association ( J . Am. Dental dssn. 29, 1593 (1942)) offer addi- tional evidence of the effect. of different forms and quantities of vitamin D on this widespread disease in which nutrition un-

doubtedly plays a major role. These Kew York investigators studied the beneficial effects of different amounts of vitamin D in the form of irradiated ergosterol (as prepa- rations of TTiosterol) or of cod liver oil (as preparations of cod liver oil concentrate) on the development, of dental caries in children, aged ten to twelve years, over a period of seven months, These children resided in cottages, the food materials for each kitchen

G SUTRITION REVIEU-S [Nocenibtr.

u-ere obt,ained from a central storeroom, and the diet, for the entire school n-as planned by an experienced dietitian; thus, the diets n-ere considered to be uniform and aclecluat,e. The children were divided into four groups, consist,ing of about 40 persons in each; there n-as also a control group of chilciwn \vho received no supplement. The supplements administered were, respectively, 400 u1iit.s (V. S. P.) of vitamin D as cod liver oil con- centrate, 800 units of the same, and 800 and 3200 units of vitamin D as viosterol in oil. Each of the preparations n-as incorporated in sweet,ened chocolate flavored .syrup ; this syrup, fortified n-ith vitamin D, i'i'as diluted u-ith milk, and served as chocolate flavored milk. .Appa,rently t,here x i s no difficulty in having the children consume this beverage regularly, an item of interest because dairies selling chocolate flavored milk rarely find customers who I d 1 drink the product regularly. The vit>aniin D potency of the prepa,rations n-as assayed both before and aft,er mising witah the syrup, and periodic checks were made on the bever- age as consumed. Several dentists co- operated in the examination of t>he t'eeth of the children bot,li a t the beginning (Septem- ber, 1940) and a t the end (May, 1941) of the esperiment. The results were recorded in terms of t,he number of carious t,ooth sur- faces, and the differences found were ta,ken as a mea.sure of the effect of the vitamin D supplements in the prevention of tooth decay. In all children esamined there was some increase in denta.1 caries, but there were large differences in the response of t'he several groups.

The children in the control group, receiv- ing no extra vitsamin D, showed on the aver- age an increase of 4.50 carious surfaces for each child. The children receiving 400 unit>s of vitamin D from cod liver oil showed a n average increase of 2.48 carious surfaces per child; those receiving 800 units of vitamin D from cod liver oil, 1.65. The children re- ceiving vitamin D from viosterol showed, for those receiving 800 units, an increase of

2.48 and, ior those receiving 3200 units, it11

increase of 2.2 i carious surfaces per chiltl. The result,<, like many previous findings in this country and abroad, are indicative ot the fact that vitamin D has a beneficial effect in the maintenance of normal tooth stiuc- ture and in the prevention of the estcnsion of dental caries, under the conditions of the experiment. Better results were obtained with 800 units of vitamin D from cod limr oil than from 400 units, but even with the larger close there was not complete protec- tion. T'itamin D in the form of ergostcrol also afforded some protection, but the benefits resulting from 800 units wcre no better than those obtained with 400 units from cod liver oil. The reported effects of 3200 units from ergosterol were not as good as those obtained with 800 units of vitamin D froni cod liver oil, though the diffcrencec between the results for these two groups mere not statiqtically significant.

The observationq of McBeath and Yerlin not only represent a contribution to our knowledge of diet in relation to tooth pro- tection but they also have a bearing on ciir- rent views about the relativc values oi vitamin D fioni animal sources (vitamin D3) and vitamin D from plant sources (vitamin D?), and on the requirement for vitamin D. A consideration of the nature of the esperiments of McBeath and Verlin and of the results of other investigators lead? to the opinion that the present results should not be considered as an adequate basis for the claims, (1) that vitamin D3 is markedly superior t o vitamin D2, unit for unit, for the human being or (2) that the childhood re- quirement for vitamin D is 800 U.S.P. units daily, unless and until these observa- tions are corroborated and extended by investigators in other institutions. It, is particularly urgent that such studies should include large numbers of children and long intervds of time. There are so many fac- tors involved in human nutrition that the need for independent verifimtion of most observations is esqential. Especially is thi.

19421 NUTRITIOS REVIEKS 7

true of experiments dealing with the health of the teeth.

It is apparent from the observations of McBeath and Yerlin that 800 unit. of D3 is superior to 800 units of D,, hut there is evidence in the literature to the effect that clifferences in physiologic a.ipect< of these two types of vitamin D are, in the hiiman being, sery small. There is also Gome evi- dence tha t intakes of 1500 unit.; of vitamin D, in younger children, :ire riot juqt as effective as 400 units, even though the vitamin is equally disperwl in a large volume of milk. Hence, the coinpariron of results with 3200 units of vitamin D2 and those with 800 units of D? or D2 may not he valid.

There are several reason. uhy the r e 4 t s of IIcBeath and Veilin cannot he inter- preted RS indicating that the requirement for grouing children is 800 I-.P.P. unit.; of vitamin D daily. In the age gi oiip .tudiecl, ten to tTicl\Te years, thcie i\ theoieticallv the grrateit growth need for calcium, niid hencc. the vitamin D requiiwiient n t this age may be greater than it i. at other ape'. Better rcwlts vere obtained ui th 800 unit. than with 400 units of D2, but complete pro- tection n a s not afforded \iith the higher intake. The development of dental caries require? time and so does the treatment, if it iq to be effective. Higher dosages of vita- min D may decrease the latent period before the further development of tooth decay is arrested. The possibility remains, there- fore, that with a longer period of olxervation the results might hare been con~iderahly cliflerent. There is also a question about the

adequacy of the diet consumed by the children in tlie different cottages. The dietetic control was exerted from a distance, introducing the possibility that there may have been differences in cooking, food selec- tion by the children, and the like. As Osborne and Mendel pointed out many years ngo, it is necessary to take extra- ordinary pains to see that the only variable betn-een groups is the one factor being studied.

With controlled diets, nutritionally excel- lent in all respects so far a- known nutrients are concerned, except for tlie ah5ence of vitamin D, Jeans and his associates at Iowa City have reported that the daily conquinption of 350 units of vitamin D, in '750 nil. of milk, by children up to ten years of age, resulted in excellent retention of calcium and complete protection from dental caries. Differences in the amount of sun- light in different localities, tlie presence of T-ni.iable, small amounts of fluorine in the drinking nater, the amount of sugar in the diet, and mnny other factors no doii1,t are involved in the development of dental caries and hence should be controlled as far as poqsible in experimental studies. Small wonder that there is no general consensus of opinion as to the cause and control of tooth decay. The experiments of hIcReath and T-erlin, hon-ever, represent a contribution to our knowledge of the subject and their ob- qervations are a challenge to other workers in this field. There are few problems in public health that offer so much promise of value from carefnlly planned research as the study of dental carieb.

MUSCLE DYSTROPHY AND VITAMIN E DEFICIENCY

A detailed study of the tiwie. of young for several generations on a vitamin E defi- mice born of vitamin E-deficient mothers has cient diet, were examined after careful fixa- been made b y Pappenheimer (-1ni . J . Path. tion (Bouin's fluid) and staining. 18, 169 (1942)). Tiyo hundred ninety- JIice do not exhibit the usual signs of thrce newborn pounq, one to thirty-five paralysis and muscle lesions like other days of age and from mothers maintained experimental animals. I-pon histologic ey-