9 Burt, J. V., and A. A. Hertzler. Parental influence on the child's food preferences. Journal of Nutrition Education 10:127-28, 1978.

10 Sanjur, D., and A. D. Scoma. Food habits of low-income children in northern New York. Journal of Nutrition Education 2:85-95, 1971.

11 McCarthy, D. Children's feeding problems in relation to food aversions in the family. Child Development 6:277-84, 1935.

12 Glaser, A. Nursery school can influence food acceptance. Journal of Home Eco­nomics 56:680-83, 1964.

Zinc in human milk is more readily ab­sorbed than that in infant formulas or cow's milk (Pediatrics 68:394-96, 1981). There is now evidence showing that this is reflected in the nutritional status of the breastfed infant. Collipp et al. (Clinical Pediatrics 22:512-13, 1983) recently com­pared the hair zinc levels (an indicator of zinc status) of 24 breastfed infants to that

13 Birch, L. L. The relationship between children's food preferences and those of their parents. Journal of Nutrition Educa­tion 12:14-18, 1980.

14 Jefferson, S. C., and A. M. Erdman. Taste sensitivity and food aversions of teenagers. Journal of Home Economics 62:605-8, 1970.

15 Desor, J. A., and o. Maller. Preference for sweet and salty in 9- to 15-year-olds and adult humans. Science 190:686-87,1975.

16 Slaby, R. G., and K. S. Frey. Development of gender constancy and selective attention to same-sex models. Child Development 46:

ZINC AND INFANT FEEDING

of 35 formula-fed ones. Ages ranged from one to six months in both groups. The mean hair zinc level of one-month-old in­fants who were formula fed was lower than that of newborn babies. Among the breast fed group, mean hair zinc levels of one-month-old babies did not differ from newborn ones, but a decline was apparent among those two months of age. The de-

849-56, 1975. 17 Hartup, W. W. Some correlates of parental

imitation in young children. Child Develop­ment 33:85-96, 1962.

18 Grusec, J. E., and D. B. Brinker. Reinforce­ment for imitation as a social learning deter­minant with implications for sex-role devel­opment. Journal of Personality and Social Psychology 21:149-58,1972.

19 Perry, D. G., and L. C. Perry. Observa­tionallearning in children: Effects of sex of model and subject's sex role behavior. Jour­nal of Personality and Social Psychology 31:1083-86, 1975.

cline in hair zinc, from newborn levels, was not as great in the breastfed as the bottIe-fed group throughout the six­month period. This study confirmed ob­servations from earlier studies showing that hair zinc levels drop during the first year of life, but with breastfeeding this drop is less precipitous.

MEAT CONSUMPTION AND CALCIUM STATUS

The influence of dietary protein on calcium status has been the subject of nu­merous investigations since 1920. When protein consumption increases, so does the excretion of calcium in the urine. For a long time it was generally believed that an increased protein intake enhanced intestin­al calcium absorption, which, in turn, caused urinary calcium to be higher with­out any detriment to overall calcium sta­tus. However, research during the last de­cade, particularly that conducted by Linkswiler and co-workers (Federation Proceedings 40:2499-33, 1981), showed that a large proportion of the increase in urinary calcium accompanying higher pro­tein intake could not be accounted for by increased calcium absorption. A negative calcium balance usually occurred among the subjects in those investigations when protein intake increased. This raised con­cern about whether the high levels of pro­tein in U.S. diets might be compromising calcium status.

Purified protein was used in most of the investigations examining the relationship between urinary calcium and dietary pro­tein. Protein in the diet is, of course, not purified, and one of its major sources is meat. In 1978, Spencer and co-workers (American Journal of Clinical Nutrition 31:2167-80,1978) studied the effect of meat (beet) on urinary calcium and found that

140 JOURNAL OF NUTRITION EDUCATION

in all but two subjects, urinary calcium did not increase with increases in meat intake. In those two subjects the increase was tem­porary. Spencer attributed these results to the phosphorus content of meat because phosphorus per se is known to reduce urin­ary calcium. As the meat in the subjects' diet increased, so did the phosphorus, which could have counteracted the hyper­caluric effect of the protein.

Linkswiler and co-workers (Journal of Nutrition 1ll:553-62, 1981) followed up the Spencer study by simultaneously in­creasing dietary phosphorus and purified protein. They found that increasing phos­phorus greatly reduced but did not com­pletely override the effect of increasing protein.

Spencer and co-workers have recently conducted another study (American Jour­nal of Clinical Nutrition 37:924-29, 1983) in which they studied the effect of meat (beet) on calcium metabolism of seven adult males. With three of the seven sub­jects, the study was short term (18-30 days) and with four it was long term (78-132 days). The quantity of meat in their diets was varied to yield two levels of dietary protein, one termed "normal" (I g/kg body weight) and one termed "high" (2 g/kg body weight). Regardless of the length of the study, urinary calcium, fecal calcium, and calcium absorption during the high

protein intake did not differ significantly from that observed during the normal in­take.

These results agree with those of Spen­cer's early study showing little to no effect of increased meat consumption on urinary calcium. They conflict, however, with findings reported by Licata (American Journal of Clinical Nutrition 34:1779-84, 1981) who found a dramatic increase in ur­inary calcium when meat intake was raised, so protein intake increased four-fold. Spencer speculated that the difference in the results of these two studies may have occur­red because Licata increased protein four­fold above a "low" initial level while she and her co-workers increased it only two-fold above a "normal" initial level.

Obviously we still do not have a defini­tive answer as to whether high consump­tion of meat compromises calcium status. It is clear that the results of studies using purified protein cannot be extrapolated di­rectly to the effect of meat and that the phosphorus in meat likely counteracts to some extent the effect of meat's protein or urinary calcium. But does eating a quanti­ty of meat that provides 1 g or more of pro­tein per kg daily create a risk of compro­mising calcium status that does not exist when smaller quantities of meat, or none at all, are eaten? This remains to be answered by future research.

VOLUME 15 NUMBER 4 1983