JANETL.GREGER;SUSAN c. ZAIKIS, R. PAUL ABERNATHY, OLIVIA A. BENNETT ANDJACQUELYN HUFFMAN Foods and Nutrition Department, Purdue University, West Lafayette, Indiana 47907 ABSTRACT The effect of feeding two different levels of zinc (Diet Z11.5 and Diet Z14.7) on zinc, nitrogen, copper, iron, and manganese balances was determined in 11 girls, 12.5 to 14.2 years, during a 30-day period. Diet Z11.5 provided 11.32 or 11.64 mg zinc daily, levels similar to that determined previously to be consumed by average adolescent females. Diet Z14.7 provided 14.52 or 14.84 mg zinc daily. These levels were just slightly less than the Recommended Dietary Allowance for zinc. When fed Diet Z14.7, subjects lost significantly more zinc in their feces than when fed Diet Z11.5. Regression analyses were applied to the zinc balance data from this study and a previous study with adolescent females. By extrapo lation, a dietary intake of 11 mg zinc daily was estimated to compensate for fecal and urinary zinc losses of the average girl in these studies. The standard error of the estimate was 2.18 mg zinc daily. Nitrogen excretion and retention were unaffected by the variations in zinc intake. Copper excretion in the feces was significantly increased when subjects were fed Diet Z14.7 rather than Diet Z11.5. Manganese and iron fecal losses were also significantly correlated to zinc fecal losses. J. Nutr. 108: 14491456, 1978. INDEXING KEY WORDS zinc •adolescents •copper •nitrogen iron •manganese •balance In a previous metabolic study with adolescent girls, Greger et al. (1) found that the majority of girls did not achieve positive zinc balance when fed 7.4 mg zinc daily. When these adolescent girls were fed 13.4 mg zinc daily, zinc retention was greater but still not all the girls were in positive zinc balance. Engel (2, 3) and his associates have demonstrated that pré-adolescent girls require about 6 mg zinc daily to achieve positive zinc balance. Generally adults remain in positive zinc balance when .1 -K. . , ., , . _, they consume 12 mg zinc daily (4-7). Thus i-Vip rlarn imi > me Gara
frnm rrom
that adolescents .1
j
,
tnan pre-adolescent
tVi^c^ tnese
cHirHix: Studies
currrroct suggest
require more zinc daily ,
L/IJ
children,
i_ t ti_ • •
but their zinc
requirements in comparison to adult needs are unclear. Altering dietary zinc levels have been demonstrated to affect the utilization of several nutrients by test animals. Somers and Underwood (8) and Hsu and Anthony ( 9 ) have observed zinc deficient lambs and rats retain less nitrogen than control animais. However, Meiners et al. (10) and Greger et al. (1) were unable to demonf*ce'ved*?.'P«»«««»» FebruaryIT ma. »Purdue University Experiment Station Paper7000.
Journal
"Supported in part by Cooperative State Research Service. U.S. Department of Agriculture, Grant No.
sie-is-ioi
t Present
address:
Nutritional
Sciences Dept.,
versity of Wisconsin,Madison.Wisconsin. 1449
uni-
Downloaded from https://academic.oup.com/jn/article-abstract/108/9/1449/4770524 by East Carolina University user on 13 January 2019
Zinc, Nitrogen, Copper, Iron, and Manganese Balance in Adolescent Females Fed Two Levels of Zinc1'2
1450
GREGER ET AL.
METHODS
Subjects.3 Eleven girls, between 12.5 and 14.2 years of age, agreed to participate in a 30 day metabolic study. Parental ap proval was also obtained. All subjects were given a routine physical examination by a physician with a urine analysis prior to their participation in the study. Their mean height was 158 ±7 (so) cm; their mean weight was 52.5 ±13.6 kg. Six of the subjects had already experienced menarche. These subjects were selected from a group of 80 adolescent girls sur veyed three times during the preceding 2 years. There were no significant differences between the group participating in the metabolic study and the total group that was surveyed in regard to serum zinc, copper, magnesium and iron levels or hair zinc and copper levels. Expérimental design. The subjects were split randomly into two groups. During period 1, the first 14 days of the study, froup A was fed 11.32 mg zinc daily (Diet 11.5) and group B was fed 14.52 mg zinc daily (Diet Z14.7). Excreta were collected from day 5 until day 14. During period 2, the last 16 days of the study, group A was fed 14.84 mg zinc daily (Diet Z14.7) and group B was fed 11.64 mg zinc daily (Diet Z11.5). Excreta were collected from day 19 to day 28.
Experimental diet. A 6-day cycle menu containing foodstuffs typical of adolescent food patterns was served throughout the study (appendix 1). The diet included two snacks and three meals daily. The diet was calculated by computer using U.S. Department of Agriculture food composi tion tables (18) and nutrition information supplied by companies to contain 100% of the Recommended Dietary Allowances (RDA) (16) for 11 to 14 year old girls of protein, vitamins A, B-6, and C, thiamin, riboflavin, niacin, calcium, and iron. When a similar menu was fed previously in a metabolic study, the level of magnesium was found to be low ( 19). Hence the girls were given 25 mg of magnesium in the form of magnesium gluconate at each meal. The lunch menus met the standards of the School Lunch Program except milk was omitted and calcium gluconate supple ments were given. This was done so the protein content of the diets could be kept between 100% to 110% of the RDA. As is allowed by the School Lunch Program, defatted, rehydrated soy4 was substituted for 30% of the meat in lunch menus (20). The energy content of the diet was ad justed between 2,200 and 2,600 kcal so that all girls maintained their weights through the use of candies, popsickles and beverages that contained no measurable amounts of protein or zinc. Deionized water was allowed ad libitum. No other food or beverages were allowed ad libitum. The nitrogen and mineral content of the diet as determined by laboratory analyses for the experimental periods is shown in table 1. The higher dietary levels of zinc were achieved by adding 4.4 or 7.6 mg zinc in a zinc sulfate solution5 to the lemonade served at lunch to subjects. The magnesium and zinc content of the diet, shown in table 1, include the supplements. Analyses. All samples were collected and stored in acid-washed plastic containers. Meals were composited on a daily basis but fecal and urine samples were pooled ' All procedures were approved by Purdue Univer sity's committee on the use of human subjects. ' Textured vegetable protein, Archer Daniels and Midland Co.. Decatur. Illinois. s Donated by Mericon Industries, Inc., PeorÃ-a, Illinois.
Downloaded from https://academic.oup.com/jn/article-abstract/108/9/1449/4770524 by East Carolina University user on 13 January 2019
strate any effect by moderate alteration in dietary zinc levels on nitrogen utilization in pre-adolescent and adolescent females. Van Campen (11, 12) has demonstrated in vitro that zinc and copper are mutually antagonistic during the absorption process. Moreover, high dietary zinc levels have been demonstrated to repress the level of copper in certain tissues of rats (13-15). The effect of alterations in dietary zinc levels on the utilization of trace elements by humans has received little attention. Utilization of dietary zinc, nitrogen, cop per, iron and manganese by adolescent girls fed two levels of zinc was assessed in this study. One level of zinc fed was only slightly less than the Recommended Di etary Allowance for zinc (16). The other level of zinc was similar to the mean level of zinc consumed by adolescent females surveyed previously (17).
ZINC BALANCE IN ADOLESCENTS
TABLE 1 Analyzed diet composition1 1(n -9)Period 9)nutrient/day11.32±
2(n =
Zinc (mg)Diet 5DietZII. 0.7914.52 1.0714.84 Z14.7Nitrogen 0.797.9 ± 1.078.1 ± (g)Calcium 0.61,049 ± 0.51,058 ± (mg)Magnesium ±50271 ±112281 (mg)Copper ±221.2 261.3± (mg)Iron 0.129 ± 0.231 ± (mg)Manganese 13.2 ± 33.2 ± (mg)Period ± 1.411.64± ± 1.7 * Mean±8D.
TABLE 2 Excretion and retention of minerals by adolescents fed two levels of zinc1 TreatmentNumber
Z11.51110.20±1.22>0.46 Z14.71113.56
subjectsZincFecal of losses(mg/day)Urinary ±2.920.48 losses(mg/day)Apparent ±0.470.81 retention'(mg/day)NitrogenFecal ±1.231.10 (g/day)Urinary losses losses(g/day)Apparent
±0.140.66 ±2.981.12
±0.255.91
±0.225.78
±0.981.02
±0.951.10±1.000.90
retention1(g/day)CopperFecal ±0.970.79 losses(mg/day)Urinary ±0.10«28
±0.1626
lossesOig/day)Apparent ±10.42
±10.31
retention*(mg/day)IronFecal ±0.1027.99
±0.1730.60
±1.670.33
±6.500.24
losses(ng/day)Urinary losses(mg/day)Apparent ±0.261.40 retention*(mg/day)ManganeseFecal ±1.562.77
±0.05-0.97 ±6.093.04
losses(mg/day)Apparent ±0.250.44
±0.580.17
retention4(mg/day)Diet ±0.25Diet
±0.58
1Mean±8D;n - 11. ' Difference significant at P < 0.005 level. 'Difference significant at P < 0.041 level. 'Ap parent retention *=Intake-Fecal loss-Urinary loss.
fied value was 10.3 ±1.0 jug manganese/g tissue ), 105 ±2 mg nitrogen/g tissue ( cer tified value was 106 ±6 mg nitrogen/g tissue), and 267 ±11 mg iron/g tissue ( certified value was 270 ±20 mg iron/g tissue ). All statistical analyses were done by computer utilizing SPSS programs (25). Paired "t" tests were used to evaluate dif ferences due to treatment (26). RESULTS AND DISCUSSION
While subjects lost significantly more zinc in their feces when fed Diet Z14.7 rather than Diet Z11.5, their urinary losses of zinc remained constant (table 2). Simi larly, other investigators have observed
Downloaded from https://academic.oup.com/jn/article-abstract/108/9/1449/4770524 by East Carolina University user on 13 January 2019
for each 9-day period. Brilliant blue was used as a fecal marker. The mineral content of samples were determined by atomic absorption spectrophotometry. Food and fecal samples were ashed as described by Osis et al. (21). Urine samples were concentrated for zinc, copper, iron and manganese analyses by refluxing with nitric acid in acid^-washed flasks and then diluting the samples to one-third their original volume. The con centration of manganese in these prepared samples was still below 0.02 mg/day and hence could not be determined accurately. Complete menses were collected from only three subjects during this study. The rest of the subjects either had not experi enced menarche yet or did not have a com plete menstrual cycle during the study. Menses were stored, dry ashed as described previously (22), and analyzed for zinc and iron by atomic absorption spectrophotometry. Nitrogen was determined in food, urine, and fecal samples by the boric acid modifi cation of the Macro-Kjeldahl method (23). Creatinine was determined in urine sam ples by a picrate method ( 24 ). Bovine liver samples, obtained from the National Bureau of Standards, were ana lyzed for zinc, manganese, and nitrogen in the same manner as food and fecal sam ples. The investigators performing the analyses did not know the certified con centrations of substances in the liver. Liver samples were determined to contain 131.6 ±10.2 (SD) /ig zinc/g tissue (certified value was 130 ±10 ^g zinc/g tissue ), 10.2 ±1.0 /ig manganese/g tissue (certi-
1451
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CITED
Downloaded from https://academic.oup.com/jn/article-abstract/108/9/1449/4770524 by East Carolina University user on 13 January 2019
16. Food and Nutrition Board. (1974) Recom mended Dietary Allowances. Eighth Revised Edition. Washington, D.C. National Academy 1. Greger, J. L., Abernathy, R. P. & Bennett, Sciences. O. A. ( 1978 ) Zinc and nitrogen balance 17. Greger J. L., Higgins, M. M., Abernathy, R. in adolescent females fed varying levels of P., Kirksey, A., DeCorso, M. B. & Baligar, P. zinc and soy protein. Am. J. Gun. Nutr. 31, 112-116. (1978) Nutritional status of adolescent girls in regard to zinc, copper and iron. Am. J. 2. Engel, R. W., Miller, R. F. & Price, N. O. Clin. Nutr. 31, 269-275. (1966) Metabolie patterns in préadolescent 18. Watt, B. K. & Merrill, A. L. (1963) Com children: XIII Zinc balance. In. Zinc Metab position of Foods—Raw, Processed, Prepared. olism (A. S. Prasad, éd.), pp. 326-337, Rev. U.S.D.A. Agriculture Handbook No. 8. Springfield, Charles C Thomas. 19. Greger, J. L., Baligar, P., Abemathy, R. P., 3. Price, N. O., Bunce, G. E. & Engel, R. W. Bennett, O. A. & Peterson, T. (1978) Cal ( 1970 ) Copper, manganese and zinc balance cium, magnesium, phosphorus, copper, and in préadolescent girls. Am. J. Clin. Nutr. 23, 258-260. manganese balance in adolescent females. Am. J. CÃ-n. Nutr. 31, 117-121. 4. Spencer, H., Osis, D., Kramer, L. & Noms, C. 20. United States Dept. of Agriculture. (1971) ( 1972 ) Studies of zinc metabolism in man. Textured vegetable protein products to be In: Trace substance in Environmental Health (D. D. Hemphill, ed.), Vol. V, 193-203, used in comoination with meats for use in lunches and suppers served under child feed University of Missouri, Columbia. ing programs. FNS. Notice 219. 5. White, H. S. & Gynne, T. M. ( 1971 ) Utili 21. Osis, D., Kramer, L., Wiatrowski, E. & zation of inorganic elements by young women eating iron-fortified foods. J. Am. Diet. Assoc. Spencer, H. (1972) Dietary zinc intake in 59, 27-33. man. Am. J. Clin. Nutr. 25, 582-588. 22. Greger, J. L. & Buckley, S. (1977) Men 6. Tipton, I. H., Stewart, P. L. & Dickson, J. strual loss of zinc, copper, magnesium, and (1969) Patterns of elemental excretion in iron by adolescent girls. Nutr. Rep. Int. 16, long term balance studies. Health Phys. 16, 639—647 455-462. 23. Scales, F. M. & Harrison, A. P. (1970) 7. Hess, F. M., King, J. C. & Margen, S. (1977) Zinc excretion in young women on low zinc Boric acid modification of the Kieldahl intakes and oral contraceptive agents. J. Nutr. method for crop and soil analysis. T. Ind. Eng. 107, 1610-1620. Chem. 12, 350-354. 8. Somers, M. & Underwood, E. J. (1969) The 24. Interdepartmental Committee on Nutrition influence of zinc deficiency in ram lambs upon for National Defense. (1963) Manual for Nutrition Surveys. Second edition. Bethesda, the digestibility of dry matter and the utili Md. 135-136. zation of nitrogen and sulfur in the diet. Aust. J. Agri. Res. 20, 889-905. 25. Nie, N., Hull, C. H., Jenkins, J., Steinbrenner, 9. Hsu, J. M. & Anthony, W. L. (1975) Ef K. & Bent, D. (1975) Statistical Package for Social Sciences. New York. McGraw-Hill, fect of zinc deficiency on urinary excretion of nitrogenous compounds and liver amino acidInc. 26. Steel, R. G. D. & Tome, J. H. (1960) catabolizing enzymes in rats. J. Nutr. 105, 26-31. Principles and Procedures of Statistics, p. 78, McGraw-Hill, Inc., New York. 10. Meiners, C. R., Taper, L. J., Korslund, M. K. & Ritchey, S. J. (1977) The relationship 27. McCance, R. A. & Widdowson, E. M. (1942) The absorption and excretion of zinc. Bioof zinc to protein utilization in the pré chem. J. 36, 692-696. adolescent child. Am. J. Clin. Nutr. 30, 879882. 28. Schraer, K. K. & Calloway, D. H. (1974) 11. Van Campen, D. R. (1970) Copper inter Zinc balance in pregnant teenagers. Nutr. Metabol. 17, 205-212. ference with the intestinal absorption of zinc-65 by rats. J. Nutr. 97, 104-108. 29. Robinson, M. F., McKenzie, J. M., Thomson, 12. Van Campen, D. R. & Scaife, P. U. (1967) C. D. & van Rij, A. L. (1973) Metabolic Zinc interference with copper absorption in balance of zinc, copper, cadmium, iron, rats. I. Nutr. 91, 473-476. molybdenum, and selenium in young New Zealand women. Br. J. Nutr. 30, 195-205. 13. Murthy, L., Klevay, L. M. & Petering, H. G. 30. Sandstead, N. H. (1973) Zinc nutriture in ( 1974 ) Interrelationships of zinc and copper nutriture in the rat. J. Nutr. 104, 1458-1464. the United States. Am. J. Clin. Nutr. 26, 1251-1260. 14. Magee, A. C. & Matrone, G. (1960) Studies 31. Committee on Maternal Nutrition Food and on growth, copper metabolism and iron me Nutrition Board. (1970) Maternal Nutri tabolism of rats fed high levels of zinc. J. Nutr. 72, 233-242. tion and the Course of Pregnancy. Washing ton, D.C. National Academy of Sciences, 147. 15. Chu, R. C. & Cox, D. H. (1972) Zinc, 32. Bowering, J., Sanchez, A. M. & Irvin, M. E. iron, copper, calcium, cytochrome oxidase, and (1976) A conspectus of research on iron phospholipid in rats of lactating mothers fed requirements of man. J. Nutr. 106, 985-1074. excess zinc. Nutr. Rep. Int. 5, 61-66.
frnm rrom
that adolescents .1
j
,
tnan pre-adolescent
tVi^c^ tnese
cHirHix: Studies
currrroct suggest
require more zinc daily ,
L/IJ
children,
i_ t ti_ • •
but their zinc
requirements in comparison to adult needs are unclear. Altering dietary zinc levels have been demonstrated to affect the utilization of several nutrients by test animals. Somers and Underwood (8) and Hsu and Anthony ( 9 ) have observed zinc deficient lambs and rats retain less nitrogen than control animais. However, Meiners et al. (10) and Greger et al. (1) were unable to demonf*ce'ved*?.'P«»«««»» FebruaryIT ma. »Purdue University Experiment Station Paper7000.
Journal
"Supported in part by Cooperative State Research Service. U.S. Department of Agriculture, Grant No.
sie-is-ioi
t Present
address:
Nutritional
Sciences Dept.,
versity of Wisconsin,Madison.Wisconsin. 1449
uni-
Downloaded from https://academic.oup.com/jn/article-abstract/108/9/1449/4770524 by East Carolina University user on 13 January 2019
Zinc, Nitrogen, Copper, Iron, and Manganese Balance in Adolescent Females Fed Two Levels of Zinc1'2
1450
GREGER ET AL.
METHODS
Subjects.3 Eleven girls, between 12.5 and 14.2 years of age, agreed to participate in a 30 day metabolic study. Parental ap proval was also obtained. All subjects were given a routine physical examination by a physician with a urine analysis prior to their participation in the study. Their mean height was 158 ±7 (so) cm; their mean weight was 52.5 ±13.6 kg. Six of the subjects had already experienced menarche. These subjects were selected from a group of 80 adolescent girls sur veyed three times during the preceding 2 years. There were no significant differences between the group participating in the metabolic study and the total group that was surveyed in regard to serum zinc, copper, magnesium and iron levels or hair zinc and copper levels. Expérimental design. The subjects were split randomly into two groups. During period 1, the first 14 days of the study, froup A was fed 11.32 mg zinc daily (Diet 11.5) and group B was fed 14.52 mg zinc daily (Diet Z14.7). Excreta were collected from day 5 until day 14. During period 2, the last 16 days of the study, group A was fed 14.84 mg zinc daily (Diet Z14.7) and group B was fed 11.64 mg zinc daily (Diet Z11.5). Excreta were collected from day 19 to day 28.
Experimental diet. A 6-day cycle menu containing foodstuffs typical of adolescent food patterns was served throughout the study (appendix 1). The diet included two snacks and three meals daily. The diet was calculated by computer using U.S. Department of Agriculture food composi tion tables (18) and nutrition information supplied by companies to contain 100% of the Recommended Dietary Allowances (RDA) (16) for 11 to 14 year old girls of protein, vitamins A, B-6, and C, thiamin, riboflavin, niacin, calcium, and iron. When a similar menu was fed previously in a metabolic study, the level of magnesium was found to be low ( 19). Hence the girls were given 25 mg of magnesium in the form of magnesium gluconate at each meal. The lunch menus met the standards of the School Lunch Program except milk was omitted and calcium gluconate supple ments were given. This was done so the protein content of the diets could be kept between 100% to 110% of the RDA. As is allowed by the School Lunch Program, defatted, rehydrated soy4 was substituted for 30% of the meat in lunch menus (20). The energy content of the diet was ad justed between 2,200 and 2,600 kcal so that all girls maintained their weights through the use of candies, popsickles and beverages that contained no measurable amounts of protein or zinc. Deionized water was allowed ad libitum. No other food or beverages were allowed ad libitum. The nitrogen and mineral content of the diet as determined by laboratory analyses for the experimental periods is shown in table 1. The higher dietary levels of zinc were achieved by adding 4.4 or 7.6 mg zinc in a zinc sulfate solution5 to the lemonade served at lunch to subjects. The magnesium and zinc content of the diet, shown in table 1, include the supplements. Analyses. All samples were collected and stored in acid-washed plastic containers. Meals were composited on a daily basis but fecal and urine samples were pooled ' All procedures were approved by Purdue Univer sity's committee on the use of human subjects. ' Textured vegetable protein, Archer Daniels and Midland Co.. Decatur. Illinois. s Donated by Mericon Industries, Inc., PeorÃ-a, Illinois.
Downloaded from https://academic.oup.com/jn/article-abstract/108/9/1449/4770524 by East Carolina University user on 13 January 2019
strate any effect by moderate alteration in dietary zinc levels on nitrogen utilization in pre-adolescent and adolescent females. Van Campen (11, 12) has demonstrated in vitro that zinc and copper are mutually antagonistic during the absorption process. Moreover, high dietary zinc levels have been demonstrated to repress the level of copper in certain tissues of rats (13-15). The effect of alterations in dietary zinc levels on the utilization of trace elements by humans has received little attention. Utilization of dietary zinc, nitrogen, cop per, iron and manganese by adolescent girls fed two levels of zinc was assessed in this study. One level of zinc fed was only slightly less than the Recommended Di etary Allowance for zinc (16). The other level of zinc was similar to the mean level of zinc consumed by adolescent females surveyed previously (17).
ZINC BALANCE IN ADOLESCENTS
TABLE 1 Analyzed diet composition1 1(n -9)Period 9)nutrient/day11.32±
2(n =
Zinc (mg)Diet 5DietZII. 0.7914.52 1.0714.84 Z14.7Nitrogen 0.797.9 ± 1.078.1 ± (g)Calcium 0.61,049 ± 0.51,058 ± (mg)Magnesium ±50271 ±112281 (mg)Copper ±221.2 261.3± (mg)Iron 0.129 ± 0.231 ± (mg)Manganese 13.2 ± 33.2 ± (mg)Period ± 1.411.64± ± 1.7 * Mean±8D.
TABLE 2 Excretion and retention of minerals by adolescents fed two levels of zinc1 TreatmentNumber
Z11.51110.20±1.22>0.46 Z14.71113.56
subjectsZincFecal of losses(mg/day)Urinary ±2.920.48 losses(mg/day)Apparent ±0.470.81 retention'(mg/day)NitrogenFecal ±1.231.10 (g/day)Urinary losses losses(g/day)Apparent
±0.140.66 ±2.981.12
±0.255.91
±0.225.78
±0.981.02
±0.951.10±1.000.90
retention1(g/day)CopperFecal ±0.970.79 losses(mg/day)Urinary ±0.10«28
±0.1626
lossesOig/day)Apparent ±10.42
±10.31
retention*(mg/day)IronFecal ±0.1027.99
±0.1730.60
±1.670.33
±6.500.24
losses(ng/day)Urinary losses(mg/day)Apparent ±0.261.40 retention*(mg/day)ManganeseFecal ±1.562.77
±0.05-0.97 ±6.093.04
losses(mg/day)Apparent ±0.250.44
±0.580.17
retention4(mg/day)Diet ±0.25Diet
±0.58
1Mean±8D;n - 11. ' Difference significant at P < 0.005 level. 'Difference significant at P < 0.041 level. 'Ap parent retention *=Intake-Fecal loss-Urinary loss.
fied value was 10.3 ±1.0 jug manganese/g tissue ), 105 ±2 mg nitrogen/g tissue ( cer tified value was 106 ±6 mg nitrogen/g tissue), and 267 ±11 mg iron/g tissue ( certified value was 270 ±20 mg iron/g tissue ). All statistical analyses were done by computer utilizing SPSS programs (25). Paired "t" tests were used to evaluate dif ferences due to treatment (26). RESULTS AND DISCUSSION
While subjects lost significantly more zinc in their feces when fed Diet Z14.7 rather than Diet Z11.5, their urinary losses of zinc remained constant (table 2). Simi larly, other investigators have observed
Downloaded from https://academic.oup.com/jn/article-abstract/108/9/1449/4770524 by East Carolina University user on 13 January 2019
for each 9-day period. Brilliant blue was used as a fecal marker. The mineral content of samples were determined by atomic absorption spectrophotometry. Food and fecal samples were ashed as described by Osis et al. (21). Urine samples were concentrated for zinc, copper, iron and manganese analyses by refluxing with nitric acid in acid^-washed flasks and then diluting the samples to one-third their original volume. The con centration of manganese in these prepared samples was still below 0.02 mg/day and hence could not be determined accurately. Complete menses were collected from only three subjects during this study. The rest of the subjects either had not experi enced menarche yet or did not have a com plete menstrual cycle during the study. Menses were stored, dry ashed as described previously (22), and analyzed for zinc and iron by atomic absorption spectrophotometry. Nitrogen was determined in food, urine, and fecal samples by the boric acid modifi cation of the Macro-Kjeldahl method (23). Creatinine was determined in urine sam ples by a picrate method ( 24 ). Bovine liver samples, obtained from the National Bureau of Standards, were ana lyzed for zinc, manganese, and nitrogen in the same manner as food and fecal sam ples. The investigators performing the analyses did not know the certified con centrations of substances in the liver. Liver samples were determined to contain 131.6 ±10.2 (SD) /ig zinc/g tissue (certified value was 130 ±10 ^g zinc/g tissue ), 10.2 ±1.0 /ig manganese/g tissue (certi-
1451
1452
GREGER ET AL.
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*3
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1455
ZINC BALANCE IN ADOLESCENTS
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16. Food and Nutrition Board. (1974) Recom mended Dietary Allowances. Eighth Revised Edition. Washington, D.C. National Academy 1. Greger, J. L., Abernathy, R. P. & Bennett, Sciences. O. A. ( 1978 ) Zinc and nitrogen balance 17. Greger J. L., Higgins, M. M., Abernathy, R. in adolescent females fed varying levels of P., Kirksey, A., DeCorso, M. B. & Baligar, P. zinc and soy protein. Am. J. Gun. Nutr. 31, 112-116. (1978) Nutritional status of adolescent girls in regard to zinc, copper and iron. Am. J. 2. Engel, R. W., Miller, R. F. & Price, N. O. Clin. Nutr. 31, 269-275. (1966) Metabolie patterns in préadolescent 18. Watt, B. K. & Merrill, A. L. (1963) Com children: XIII Zinc balance. In. Zinc Metab position of Foods—Raw, Processed, Prepared. olism (A. S. Prasad, éd.), pp. 326-337, Rev. U.S.D.A. Agriculture Handbook No. 8. Springfield, Charles C Thomas. 19. Greger, J. L., Baligar, P., Abemathy, R. P., 3. Price, N. O., Bunce, G. E. & Engel, R. W. Bennett, O. A. & Peterson, T. (1978) Cal ( 1970 ) Copper, manganese and zinc balance cium, magnesium, phosphorus, copper, and in préadolescent girls. Am. J. Clin. Nutr. 23, 258-260. manganese balance in adolescent females. Am. J. CÃ-n. Nutr. 31, 117-121. 4. Spencer, H., Osis, D., Kramer, L. & Noms, C. 20. United States Dept. of Agriculture. (1971) ( 1972 ) Studies of zinc metabolism in man. Textured vegetable protein products to be In: Trace substance in Environmental Health (D. D. Hemphill, ed.), Vol. V, 193-203, used in comoination with meats for use in lunches and suppers served under child feed University of Missouri, Columbia. ing programs. FNS. Notice 219. 5. White, H. S. & Gynne, T. M. ( 1971 ) Utili 21. Osis, D., Kramer, L., Wiatrowski, E. & zation of inorganic elements by young women eating iron-fortified foods. J. Am. Diet. Assoc. Spencer, H. (1972) Dietary zinc intake in 59, 27-33. man. Am. J. Clin. Nutr. 25, 582-588. 22. Greger, J. L. & Buckley, S. (1977) Men 6. Tipton, I. H., Stewart, P. L. & Dickson, J. strual loss of zinc, copper, magnesium, and (1969) Patterns of elemental excretion in iron by adolescent girls. Nutr. Rep. Int. 16, long term balance studies. Health Phys. 16, 639—647 455-462. 23. Scales, F. M. & Harrison, A. P. (1970) 7. Hess, F. M., King, J. C. & Margen, S. (1977) Zinc excretion in young women on low zinc Boric acid modification of the Kieldahl intakes and oral contraceptive agents. J. Nutr. method for crop and soil analysis. T. Ind. Eng. 107, 1610-1620. Chem. 12, 350-354. 8. Somers, M. & Underwood, E. J. (1969) The 24. Interdepartmental Committee on Nutrition influence of zinc deficiency in ram lambs upon for National Defense. (1963) Manual for Nutrition Surveys. Second edition. Bethesda, the digestibility of dry matter and the utili Md. 135-136. zation of nitrogen and sulfur in the diet. Aust. J. Agri. Res. 20, 889-905. 25. Nie, N., Hull, C. H., Jenkins, J., Steinbrenner, 9. Hsu, J. M. & Anthony, W. L. (1975) Ef K. & Bent, D. (1975) Statistical Package for Social Sciences. New York. McGraw-Hill, fect of zinc deficiency on urinary excretion of nitrogenous compounds and liver amino acidInc. 26. Steel, R. G. D. & Tome, J. H. (1960) catabolizing enzymes in rats. J. Nutr. 105, 26-31. Principles and Procedures of Statistics, p. 78, McGraw-Hill, Inc., New York. 10. Meiners, C. R., Taper, L. J., Korslund, M. K. & Ritchey, S. J. (1977) The relationship 27. McCance, R. A. & Widdowson, E. M. (1942) The absorption and excretion of zinc. Bioof zinc to protein utilization in the pré chem. J. 36, 692-696. adolescent child. Am. J. Clin. Nutr. 30, 879882. 28. Schraer, K. K. & Calloway, D. H. (1974) 11. Van Campen, D. R. (1970) Copper inter Zinc balance in pregnant teenagers. Nutr. Metabol. 17, 205-212. ference with the intestinal absorption of zinc-65 by rats. J. Nutr. 97, 104-108. 29. Robinson, M. F., McKenzie, J. M., Thomson, 12. Van Campen, D. R. & Scaife, P. U. (1967) C. D. & van Rij, A. L. (1973) Metabolic Zinc interference with copper absorption in balance of zinc, copper, cadmium, iron, rats. I. Nutr. 91, 473-476. molybdenum, and selenium in young New Zealand women. Br. J. Nutr. 30, 195-205. 13. Murthy, L., Klevay, L. M. & Petering, H. G. 30. Sandstead, N. H. (1973) Zinc nutriture in ( 1974 ) Interrelationships of zinc and copper nutriture in the rat. J. Nutr. 104, 1458-1464. the United States. Am. J. Clin. Nutr. 26, 1251-1260. 14. Magee, A. C. & Matrone, G. (1960) Studies 31. Committee on Maternal Nutrition Food and on growth, copper metabolism and iron me Nutrition Board. (1970) Maternal Nutri tabolism of rats fed high levels of zinc. J. Nutr. 72, 233-242. tion and the Course of Pregnancy. Washing ton, D.C. National Academy of Sciences, 147. 15. Chu, R. C. & Cox, D. H. (1972) Zinc, 32. Bowering, J., Sanchez, A. M. & Irvin, M. E. iron, copper, calcium, cytochrome oxidase, and (1976) A conspectus of research on iron phospholipid in rats of lactating mothers fed requirements of man. J. Nutr. 106, 985-1074. excess zinc. Nutr. Rep. Int. 5, 61-66.
