I I I I I I I I II I I III III — — ,, 7, I I I' I I I I I I 'I I I I I I I I l I II 'I I I I I I II THE MAGNESIUM METABOLISM AND ITS RELATION TO CALCIUM RETENTION OF TWO NORMAL PRESCHOOL CHILDREN ON HIGH ANO MEOIOM PROTEIN [OIETs ' THESIS FOR THE DEGREE 01? M. R Linnea C. Bennett 1933 0" . II NII'III £ HIM .00! "D! .1 . Q > I I O C . 'r $ O o. 9 o O - U .4!" - . . I II ,1 __ I -. O u . O _| '0. v ? “ , r, . 7- '. nJi‘. ‘0 Q U o .‘. v ' o THE MAGNESIUE KELAfiOLISL AID ITS ELLATIOH TC CALCIUL RQTLfiTIOH OF EEO NOENAL PEQSCHOCL ‘HILDHLN ON HIGH AND KEDIUM PROIL N DIETS A Thesis Submitted to the Faculty of Michigan State College of Agriculture and Applied Science in Partial Fulfillment of the Requirements for the Degree of Master of Science Vs By: r .45 Linnea Cl Qennett Department of Foods and Nutrition Division of Home Economics 1955 THESIS Acknowledgement The writer Wishes to express appreciation to Dr. Marie Dye and Dr. Jean Hawks for their untiring interest and helpful suggestions and criticisms during the entire study. 95478 I. II. III. IV. VI. Table of Contents Introduction . . . . . . . . . . . . . . . . Review of Literature . . . . . . . . . . . . Plan of Study . . . . . . . . . . . . . . . Discussion of nesults . . . . . . . . . . . l. Variations.in magne31um intake. 2. Daily variations in the magnesium balances. 5. Differences in magnesium netabolism of the W0 children on each diet. 4. Conparison of the reactions of the two children. 5. Variations in the Hg:Ca retention ratios. Sumnary. . . . . . . . . . . . . . . . . . . Bibliography . . . . . . . . . . . . . . . . ‘_1 CA N) H DC) 0 I. II. List of Tables Page Sunrary of Kagnesium Balances in Infants . . . 12 A Comparison of the Height and Reight of the Children Vlith the :OOdbuI‘y Tables 0 o o o o o o 14 III. Composition of Medium Protein Diet . . . . . . 16 IV. V. VI. Composition of High Protein Diet . . . . . . . 17 .Tests of the Accuracy of the Kethod on Known Solutions with and without Analyzed Urine and Calcium Solutions . . . . . . . . . . . . . . . 19 Comparison of Calculated with Analyzed Values for Nagnesium Content of Food . . . . . . . . . 21 VII. Daily Kagnesium Balances on the Medium Protein Diet 0 O O O O O O O O O O O 0 O O O O O O O O 25 VIII.Daily Nagnesium Balances on the High Protein IX. X. XI. Diet . . . . . . . . . . . . . . . . . . . . . 27 Average Daily Kagnesium Balances by Three Day Periods on Kedium Protein Diet . . . . . . . . 51 Average Daily Magnesium Balances by Three Day Periods on High Protein Diet . . . . . . . . . ()3 [.4 Percentage of the Kagnesium Intake Excreted . 57 III. Daily Magnesium Balances on the Kedium ' Protein Diet Calculated per Kilogram Body LeightJMB XIII.Daily Magnesium Balances on the High Protein Diet Calculated per Kilogram of Body ieight. . .59 _ XIV. Daily Intake and Retention Ratios of Magnesium to Calcium on the Eedium Protein Diet . . . . .41 .IIII If .IIIIIOIIIAIT. Page XV. Daily Intake and Retention Ratios of hagnesium to Calcium on the High Protein Diet . 42 XVI. Comparison of Balances of the Two Children . . 45 Charts I. Intake, Absorption and Retention by 5 Day Periods on Medium and High Protein Diets . . . . 54 II. Comparison of Daily Variations of Fecal magnesium with Amount of Feces Excreted . . . . 55 THE MAGNESIUM METABOLISM AND ITS RELATION TO CALCIUM RETENTION OF T20 NORMAL PRESCHOOL CHILDREN ON MEDIUM AND HIGH PROTEIN DIETS Introductign 'While numerous mineral metabolism studies have been conducted on adults and animals, there have been relatively few on preschool children. The majority of the metabolic investigations on humans deal with only two or three of the necessary ash constituents. Very little work has been done on magnesium. Most of the studies on human beings are not comparable because of the variations in age and physical con- dition of the subjects, and length of the experimental period. A search of the literature reveals very little informa- tion concerning the magnesium requirement and metabolism of normal dhildren. For this reason no standards have been set for the daily amount required to maintain positive magnesium balance as has been done with some of the other minerals. This study deals with the magnesium metabolism of two normal preschool children on medium and high protein diets, and is a part of an extensive investigation planned and carried out to study the daily variations on the metabolism of these two children. The objectives of this study are: to determine the daily variations in the magnesium absorption and retention; - 2 - to determine if the children reached an equilibrium after being on a constant diet for a considerable period; to compare the individual variations in the metabolism of the two children; to observe whether the different levels of protein intake affects the magnesium metabolism; and to study the relationship of magnesium metabolism to the calcium metabolism. Review of Literature Magnesium investigations have been made to study the paths of excretion of this mineral and its relationship to calCium excretion. Nelson and Burns (18) conducted an investigation on the urinary excretion of magnesium and calcium in 25 normal adults and found that 17 of the sub- jects excreted calcium in larger amounts than magnesium while the output of magnesium was greater in the other 8 subjects. The amount of CaO excreted varied from 0.099 to 0.488 gm. and the Ego from 0.118 to 0.416 gm. They stated that the predominance of one element or the other was practically constant in the individual and appeared to be independent of the character of the food ingested. Givens (7) also found that, as a rule, more calcium than magnesium was excreted in the urine of 9 healthy man who had been instructed to select their foods with regard to the calcium and magnesium content. On a diet of natural foods containing more magnesium than calcium, the urinary .. 5 .. excretion of calcium ranged from 0.05 to 0.24 gm. and the magnesium 0.05 to 0.15 gm. On a diet having more calcium than magnesium, the limits were 0.15 to 0.47 gm. of calcium and 0.05 to 0.25 gm. of magnesium. Contrary to Nelson and Burns (18), he concluded that the variations in the excretion of these elements were influenced by the diet and by the tissue reserves. He found that the administra- tion of milk was more efficacious than a comparable quan- tity of calcium salts in producing increased urinary excre- tion of calcium and that magnesium citrate apparently dfli not affect the excretion of magnesium. By varying the calcium and magnesium ratio through the addition of magnesium citrate and calcium lactate to the experimental diet, Bogert and McKittrick (1) studied the interrelations between calcium and magnesium metabolism of four normal women. They found that the addition of 6 gm. of magnesium citrate per day increased the urinary and fecal magnesium in all cases. Urinary and fecal calcium was in- creased in 5 out of 4 cases and the total calcium excretion in all cases. Increased excretion of calcium in the urine and feces in all subjects resulted When 6 gm. of calcium lactate per day was added to the diet and the magnesium output also increased. Underhill, Honeij and Bogert (25) conducted an eXperi- ment on the effect of varying the ratio of the calcium and magnesium intake on the retention of these two minerals in [If I .ll. - 4 - 'two normal adults. The calcium intake averaged 0.414 gm. for the low level and 1.416 gm for the high one. The 'magnesium intake was 0.297 gm. on the low intake diet and ' 0.549 gm. on the high level. On a low magnesium and low calcium diet for four days, both.subjects were in negative calcium and positive magnesium balances. During the following period of high calcium and low magnesium intake, one subject was in negative calcium and positive magnesium balance while the other subject's balances were just the reverse. Both subjects were in negative balance on the third 5 day period When both minerals were low. The high magnesium and low calcium.intake produced the greatest magnesium retention in both.individuals, while the calcium ’balance was the least for both subjects of any period. They also found that, While the food calcium and mag- nesium may be practically constant, there may be a decided variation in the ratio of these elements in the urine and in the feces and especially in the urine. This was due t0‘ the extent of the retention of one or the other of the elements.. Carswell and Winter (5) conducted an experiment on two men, one subject being on the experiment for 20 days and the other for 24 days, to determine the effect of the use of magnesium as a therapeutic measure.. During a control period both subjects were in positive balance, while the magnesium balance for one subject was positive and for the _ 5 - other it was slightly negative. The intake of CaO was 1.74 gm. and the rgog intake was 5.59 gm. daily and remained constant throughout the eXperiment. To observe the effect of ragnesium, 8 gm. f magnesium lactate were added daily. The addition of magnesium caused definite decrease in -‘ urinary calcium in one subject, wnile th (1'3 -re was slight retention in the other. The magnesium retention in the first subject was slight while in the latter it was marked. These Workers concluded that if the phosphorus intake was adequate, the magnesium appeared to favor calcium storage instead of calcium loss. d prerimental work with animals substantiates the s importance of adequate phosnhorus in the diet when studyin the interrelationshin of calcium ani magnesium. In a study \ on the effect of a high magnesium intake on t \ 18 calcium retention of swine, Hart and Steonbock (10) found that the addition of soluble phosphates decreased the increased calcium excretion brought on by the addition of magnesium salts to the diet. However, Huffman and his co-workers (14) obtained beneficial results When 5 to 5 per cent magnesium salts, either as phosphates or carbonates, were added to a ration of whole milk and grain and fed to dairy calves. The cal- cium and phosphorus retentions were unaffected or improved. In eXperimental work with rats, Haag and Palmer (9) studied the effect of variations in the proportions of -6- calcium, magnesium and phosphorus contained in the diet. They varied the proportions of these minerals in rations that were adequate in other respects. On a diet low in calcium and high in phosphorus or high calcium and low phosphorus the addition of high magnesium, 0.80 to 0.88 per cent, depressed calcium retention less frequently than when both these elements were low. They concluded that the deleterious effect of high magnesium was condi- tioned by the intakes of calcium, phosphorus and vitamins. They stated, "The interrelations existing between mineral elements are important factors for consideration in studying the Specific role of a mineral element in animal nutrition." In a study on the growth and nutrition of dairy calves McCandlish (16) found that the addition of grains to a ration consisting solely of milk impaired the growth of calves and eventually brought on death. He concluded that death was caused by the depletion of the body stores of calcium since the grains contain more magnesium than calcium and that calcium was drawn from the bones to counteract the effect of magnesium. The addition of al- falfa hay to the ration bf milk and grains brought the animals back to good growing conditions. The beneficial effect was not attributed to any one constituent in hay. The effect of high and low protein rations on the metabolism of various minerals in dairy cows was studied by Monroe (17). He found that the magnesium balances of - 7 _ the high protein fed animals showed no marked difference frcm.the corresponding balances of those on the low protein ration. The cows receiving the high protein diet stored calcium while those on the low ration were in negative balance. It was suggested that this difference was due to the larger amounts of clover hay contained in the high protein ration. Studies of factors which may influence mineral metabolism in humans have been made by several workers. A few of these investigations include the metabolism of magnesium. Hobbler (13) varied the fat content of cows' milk fed to an infant and obtained 82 per cent magnesium retention on a 2J5per cent fat intake, negative balance on a 4 per cent level and 52 per cent retention on a 5.4 per cent intake. The retention of magnesium varied. in- versely with the calcium retention. Sawyer, Bauman and Stevens (19) conducted an experi- ment on two boys, 5 and 8 years of age, to determine the effect of a high fat diet as compared to a normal diet on mineral metabolism. On the normal diet, the average mag- nesium intake was 0.436 gm. which gave an average retention of 0.064 gm. The high fat diet provided 0.514 gm. of mmg- nesium, but the retention on this diet gave an average negative balance of -0.525 gm. Shohl and Sato (22) were interested.in the effect of acids and alkalis on the salt retention of infants. For _ 8 - subjects, they used three artificially fed infants 7, 9 and 7 months old. A normal diet was fed for a period flaen hydrochloric acid was added. This was succeeded by a nor- mal diet and then sodium bicarbonate was given. The magnesium intake on the first two periods was 0.123 gm. When only the normal diet was given there was a 37 per cent retention which drOpped to 20 par cent when hydrochloric acid was added. The third period which.was normal and provided 0.072 gm.magnesium gave a negative balance of ~3.0 per cent. The addition of -1a3103 increased the retention of magnesium to 74 per cent. The acid did not affect the excretion of magnesium in the urine but the fecal excretion increased. The Nahbog decreased magnesium excretion in both urine and feces. The authors stated.that the explana- tion for the effect of acids and alkalis on mineral metabo- lism is often obscure and until facts have been firmly es- tablished do not warrant speculation. Chaney (4) studied the effect of orange juice on fire mineral retention of two girls age 10 and 11 years. There were two experiments, the second being a duplicate of the first. During the period When the basal diet alone was given, the average intake of magnesium per day was 0.25 gm. and the output 0.18 gm. with a retention of 0.07 gm. or 28 per cent. The addition of 600 to 700 cc. of unstrained orange juice increased the intake to 0.34 gm. per day and the output to 0.22 gm. with a retention of 0.12 gm. or 35 _ 9 - per cent. The author found that the retention of calcium and phOSphorus was more marked than that of magnesium since the body output of these two minerals was actually diminished with the addition of orange juice. Bogart and Trail (2) made a study of the influence of yeast and butterfat on the assimilation of certain minerals in four adult subjects. The addition of yeast brought the calcium balance from -0.056 gm. to 0.006 gm. and in the case of magnesium the retention was increased from 0.005 to 0.053 gm. After the administration of yeast the subjects were given the basal diet for a period and the balances for both minerals were negative. Then butter- fat was substituted for the vegetable fat producing a change in the retention of both minerals. The average magnesium balance increased from -0.007 to 0.037 gm. and the calcium from -0.084 to 0.013 gm. ‘In a study to determine what the proportion of mineral elements should be in milk modifications for infants, Shohl, Wakeman and Shorr (23) used for their subject an infant with rickets of prematurity. During the first experimental period the infant was fed skimmed cow's milk and cane sugar with salts added so as to make the concentration of each mineral element approximately double that of cow's milk. In the second period the same food was fed without the salt addi- tions. Results from this one study Showed that a baby on a skimmed milk diet after the salt constituents were increased _ lO - from 0.18 to 0.36 gm of Mgo retained 0.01 gm as compared to 0.00 gm. when no additional salts were given. The use of MgSO4 for treatment of the convulsions of tetany in infants led Courtney and.Fales (5) to study the rate at which MgSO4 is eliminated after subcutaneous injec- tion. If the doses required more than 24 hours for their excretion then daily repetition of the injection would lead to an accumulation of Hg in body with possible toxic results. FouPinfants with tetany were treated with subcutaneous in- jections of 4tx>10 cc. of MgSOé solution, whose concentra- tion was 8 gm. of anhydrous MgSO4 per 100 cc. They found that the infant organism can incorporate within 2 success- ive days as mush as one or two tenths of a gram of MgO from the MgSO4 and.that amounts in excess of this are immediately excreted by the kidneys. There appeared to be no danger of the cumulative effect of magnesium if the dose was not given more frequently than once in 24 hours. Hamilton, Bengt and Moriarty (8) studied the mineral retention of a premature infant for two months, keeping the subject on a metabolism bed for 31 out of 53 days, each period being 6 days in length. They drew no conclusions in regard to the magnesium metabolism since the mean for all the periods was negative. They stated that on this prema- ture infant study there was a progressive loss of lime salts from the bones, an increase in body fluids and a change in either the composition or the relative mass of - 11 _ cellular tissue. A portion of the data on nfineral metabolism studies on infants in this country and abroad that include the analysis of magnesium have been compiled by Hawks (11) (Table I ). The magnesium is calculated as grams of MgO per 24 hours. A comparison of the Ego intake and output of breast fed infants was made with artificially fed in- fants. The average intake of magnesium per 24 hours of artifically fed infants was higher than in breast fed in- fants, being 0.160 and 0.057 gm. MgO respectively. The retention of MgO per 24 hours for natural fed infants was 0.022 gm. while the infants on the higher intake retained 0.030 gm., The percentage retention was 38 per cent on the low intake as compared to 12.5 per cent on the high level. This summarization of a number of studies supports the work of Shohl, Wakeman and Shorr (23) that by increasing the intake the amount of the salt retained is increased. From the above studies on magnesium metabolism it appears that the retention of this mineral increases with increased intake. Factors such as alkali, yeast, butter- fat and orange juice influence magnesium retention favorably, while acids and high fat diets decrease it. There iS'a close relationship between magnesium, calcium and phosphorus, and the conclusion reached from present data is that adequate amounts of calcium and phosphorus are necessary to counteract the depressing effect of high magnesium intake. Sbflunhi 3'f or vieNLSIUH B LLTCuS In TEFLHTS* Grams Mgp_per 24 hmzrs in breast fed infants Outputgfz Author Intake Urine Feces Retention Remarks Blauberg 0.05 0.01 0.02 0.02 Klotz 0.04 0.01 0.01 0.02 ““ doobler 0.05 0.01 0.02 0.02 Lindbergg, 0.05 0.01 0.02 0.02 0.07’ 0.02 0.03 0.02 Kuhl 0.07 0.02 0.02 0.03 __ ialmbergfi 0.07 0.02 0.03 0.02 Average 0.057 0.014 0.022 0.021 Grams th per 24 hours in artificially fed infants C.l5 .03 0.07 0:05 haw milk Cronheim 0.16 0.03 0.11 0.03 Boiled milk 0.18_ 0:02' 0.12 0.04 '__ Birk 0.19 0.02 0.14 0.03 Phosphorated cod liver oil Bruck 0.13 0.02 0.03 0.08 0.20' 0.05 0.10 0.07 Shohl 0.2 c.03 0.13 0.04 H01 added & 0.12 C.04 0.08 0.00 .Sato 0.12 0.Cl 0.02 0.08 NaHCQg added 0336 0.35 0.01 Hinerals doubled Shohl 0.18 0.18 0.00 Hoobler 0.11 0.04 0.04 0.03 0.06 0.02 0.05 —0.01 Brahm 0.08 0.02 0.03 0.03 Irradiated cod liver oil COurtney & Fales 0.13 0.C2 0.09 0.02 Average 0.158 0.02‘ 0.102 0.034 % Compiled by Hawks (ll) Unpublished data. - 15 _ Plan of Study A comprehensive study of the metabolism of two pre- school boys is being made by the food and nutrition depart- ment of the Home Economics Division. There are three parts to the extensive experiment; a 15 day preliminary period, a period of 30 days when the children received a constant diet containing 3 gm. of protein per kilogram body weight, and a 15 day period when the protein intake was 4 gm. per kilogram. This paper is a report of a part of the larger study. It deals with the magnesium metabolism during the last 6 days of the medium protein period and.the entire 15 days of the period.wren the high level of protein was used. Only a brief summary of the method of conducting the experiment will be given since full details have been given in previous studies (12) (15). The 2 four year old boys, W.W. and D.A. were healthy, normal subjects Who had received excellent care and had good health habits. Table II shows that they did not deviate to any great extent from.the computed standard for age, weight and height according to Woodbury (26). The eXperimental diets for the children were planned to be adequate as to calories, protein, calcium, phOSphorus and iron, and were thought to be adequate for the other minerals. The calculated composition of the diets may be WEIGHT OF THE CHILDRLN 01TH TEL TABLE II - 14 - A COKPARISCN OF‘THE HEIGHT AND ~7— Height Weight floodbury's ' Woodburyrs Standard Standard SUb“ Ob. 8H” Ob- jgpt Age served Normal ation served Normal Variation Mo (In? IInI 7%) (DDS) (LBS) (7:) D.A. 57 42.88 42.0 2.08 38.38 39.5 -2.81 fi;?. 55 43.7 44.0 -0.56 41.75 41.5 0.60 - 15 - found in tables III and IV. The food was prepared in three day periods and included a sample for analysis. The feces were collected daily, each day being marked off alternately with carmine and charcoal. Urine was collected in 24 hour samples. 0f the three general methods for the determination of magnesium in biological material, namely gravimetric, titrimetric and colorimetric, the titration method of Tisdall and Kramer (24) was selected, because it was rapid and accurate, and required only a small amount of material. Any inaccuracies in this method as compared to the gravimetric are probably not as great as the errors encountered in the collection of biological material. Weighed amounts of dried food and feces were ashed in platinum dishes in a muffle furnace at a dull red heat. The ash was taken up with 1:4 HCl, evaporated to dryness to dehydrate any silica present and again taken up with 1:4 HCl and made up to volume. Two hundred cc. of urine were digested on a steam bath with 5 to 10 cc. of concentrated HNOs and then ,ashed in a muffle furnace at dull red heat. This ash was taken up with 5 per cent HN03 and made up to volume. The magnesium analyses were made on the filtrates from the calcium determinations. One cc. of a 10 per cent (solution bf (NH4)2 HPO4 and 5 cc. of concentrated NH4OH were added to the filtrate, mixed thoroughly and allowed _16- TABLE III COMEQSITION 0F HEDIUM PROTEIN DIETwé ‘“ "‘ Ex- ‘Ex- Cal- Pro- Cal- Phos- Mag- cess cess Food ‘Neight cries tein cium phoru nesium Acid Base ‘Milk ‘(gm) #782) (Cm) (gm) (co) (co) (Whole) 720 496.8 23.8 0.8640 0.6696 0.0864 13.0 (uncooked Farina 18 64.8 2.0 0.0038 0.0225 0.0045 1.7 ’0range . auice 180 64.8 0.0522 0.0288 0.0198 11.1 ee _(;aw) 45 52.2 10.1 0.0059 0.1084 0.0115 5.2 FEfif" (raw) 45 66.6 6.0 0.0297 0.0810 0.0050 5.0 Istrsrneay Prunes 90 113.4 0.5 0.0144 0.0279 0.0495 14.6 'Tgtrained Apple sauge 90 88.2 0.3 0.0054 0.0099 0.0072 3.1 Lettuce 14 2.2 0.2 0.0060 0.0059 0.0024 1.0 Tstrained Carrots 72 29.5 0.8 0.0403 0.0331 0.0151 7.8‘ (strained - Tomatoes 90 18.9 1.1 0.0099 0.0234 0.0090 5.1 Butter 18 138.4 0.2 0.0027 0.0031 0.0002 (coEked) Potato 63 71.8 1.4 0.0145 0.0372 0.0176 4‘01 Sugar 18 72.0 Bread 72 173.5 7.0 0.0360 0.1260 0.0360 5.3 008 Liver ‘0— Oil 4.5 40.5 Total 1493.6 1.0968 0.2640 * Allowance for D.A. W.W. received 1.1 times this amount. / Figures from tables, Sherman, Chemistry of Food and Nutrition.(20) 17 - TABLE IV COMPOSITION OF HIGH PROTEIN DIETw/ a; ——-——-—r— Ex- ax- Cal- Pro- Cal- Phos- Mag- cess cess Food Weight ories tein cium phorus nesium Acid Base Milk' (gm) (gm (gm) gs) cc. cc. (whole) 425 295. 14.0 0.5100 0.5955 0.0510 7.7 MiIk (skim) 425 157.3 14.5 0.5185 0.4080 0.0510 7.7 (uncooke ) Farina 18 64.8 2.0 0.0038 0.0225 0.0045 1.7 Orange juice 200 72.0 0.0580 0.0320 0.0220 12.4 ee (raw) 90 104.4 20.2 0.0117 0.2159 0.0225 10.4 (uncookeab Baa 90 133.2 12.0 0.0594 0.1620 0.0099 9.9 (straifie Prunes 90 113.4 0.5 0.0144 0.0279 0.0495 14.6 (straine Apple gauce 90 88.2 0.3 0.0054 0.0099 0.0072 3.1 Lettuce 14 2.2 0.2 0.0060 0.0059 0.0024 1.0 (Straine Carrots 70 28.7 0.8 0.0392 0.0322 0.0147 7.6 (strained Tomatoes 100 21.0 1.2 0.0110 0.0260 0.0100 5.5 Butter 20 153.8 0.2 0.0030 0.0040 0.0002 (cooked) Potato 50 57.0 1.2 0.0115 0.0295 0.0140 3.2 Sugar 10 40.0 Bread 60 144.6 5.8 0.0300 0.1040 0.0300 Cod Liver Oil 4.5 40.5 _ e:e Total 1756.52Hfl4.3 72.9 1.2819 1.4761 0.2889l4l.O 48.2 * Allowance for D.A. w;w. received 1.1 times this amount. / Figures from tables, Sherman, Chemistry of Food and Nutrition.(20) - 18 - to stand one hour or longer. The solution was then filtered through.No.40 Rhatman filter paper. The original method was modified somewhat at this stage. Instead of renoving all the precipitated MgNH;ITM to the filter paper, the beaker and any remaining precipitate were washed three times with 30 volume per cent alcohol. The precipitate and filter paper were washed an additional three times with the alcohol to insure the removal of all of the ammonia and then trans- ferred to the original beaker. 30 cc. of warm water and ex- actly 5 cc. of N/lO H01 were added and thoroughly mixed. Brom creosol green was used as indicator instead of cochi- neal. The excess HCl was titrated with.N/10 NaOH. Fiske's (6) method was used to insure accuracy in obtaining the end point. A comparison was made with a standard buffer solution at the correct end.point,1fii4.6 containing comparable amounts of indicator and filter paper as the unknown solution. The amount of magnesium in the sample was corputed on the number of cc. of N/lO HCl neutralized by the magnesium. A preliminary test showed that the method selected was satisfactory. (Table V). Analysis of known solutions of MgO and Mg804 gave average recoveries of 98.3 per cent and 98.6 per cent respectively. The recovery of magnesium from a known solution of calcium and magnesium salts averaged 97.7 per cent. When urine, previously analyzed for its magnesium content was added to the known salt solution, 96.2 per cent of the magnesium was recovered. From maese - 19 - TABLE V TESTS OF THE ACCURACY OF Bfii KETHOD ON KNO N SOLUTIONS, WITH AND WITHOUT AEALYZED URINE AND CRLCIUF SOLUTIOYS Number—of- ‘ — Deter- Magnesium Series V§ample minations Present Magnesium Recovered:_ (Milligrams)(Milligrams) (Per cent) 1 Egg 4 3.098 3.072 99.2 N30 ‘ 8 3.059 2.994 97.9 .___..1=.~__‘al_l V.l K5894 7 3.293 3.263 99.1 h1g0 +- — ' ICaO + W 9 ' .14 MgSO4 2 3.263 3.248 99.6 20 cc. III 5 Urine 3 0.164 12530 +- 6 197cc.Urine 2 3.154 3.023 95.9 EYE->304- + ‘;=Z 10 cc.Urine 3 3.345 3.223 96.3 _ 20 _ results it may be assumed that the method used in this study is within the limits of accuracy as given by Tisdall & Kramer. (2 ). With.the limited quantity of biolOQical materials available for analysis, the method gives satis- factory results. Discussion of Resu1t§_ In this study of the magnesium metabolism of two normal children, the magnesium content of the food will be discussed first, then the output of this mineral, and following this the retention and absorption of it on the two diets. A comparison of the magnesium content of the food on the two protein levels as determined by analysis and the values as calculated according to the food composition tables of Sherman (20) show several interesting facts. (Table VI). It is first noted that the analyzed resilts are lower than those of the calculated values, the average variation for the period during which.the medium level was 7.3 per cent and 7.9 per cent for the period with higher intake. HoweVer, the food was analyzed in three day periods and therefore represents an aliquot of a fairly large sample, and the magnesium content may be eXpected to represent the average of this mineral in these feeds. Even these three day analysis show slight variation, usually not more than 4 or 5 mg. The greatest variation COKPHHISOQ W 1TH .-'~.I~I:~.LYV if) VILLTL T‘\ >4 ~. ) ..J~_' _ 21 _ TABLE VI OF I a”: E; IU; CF CaLCULnTnD '4; cc 2T 1:}: 1‘ CF rcoufiA Magnesium Intake Diet Period Analyzed Calculated Variation Ledium 4(3 days), gm) (gr) (Per cent) Protein 1 0.2428 0.2640 8.0 2 0.2464 0.2640 6.7 Average 0.2446 0.2640 7.3 High Protein 1 0.2662 0.2889 7.9 2 0.2623 0.2889 9.1g_ 3 0.2676 0.2889 7.4 4 0.2631 0.2889 8.9 5 0.2711 0.2 89 6.1 Average 0.2 61 0.2889 7.9 * Intake for D.A. W.W. received 1.1 times these amounts. fLFigures from table, Sherman, Chemistry of Food and Nutrition.(20) - 22 _ was found between the 4th and 5th periods of the high protein diet, a difference of 8 mg. or an increase of 3.4 per cent. Possible eXplanatiors for this difference in variations in the composition and method of preparation of the food. However, these differences are slight and probably represent an uncontrollable variation. The magnesium content of the high protein diet for subject D.A. averaged 0.266 gm. for the entire period which was 0.022 gm. or 9 per cent higher than the intake on the medium level. The amounts for W.W. are 1.1 higher than for D.A. since he weighed 1.1 times as much. The increase in the amount of magnesium was to be expected as the calcium intake also increased on the high level. Givens (7) stated that it was practically impossible to increase the dietary calcium without also increasing the magnesium. Table VII gives the daily amounts of magnesium con- sumed and excreted by the two subjects on the medium protein diet. 'While the diet was fairly constant in mag- nesium content, both subjects showed considerable variation in the total amount of magnesium excreted. The urinary excretion for D.A. was practically constant while W.W. showed slightly more daily variation. The range of varia- tion in the urinary excretion of magnesium for D.A. was from 0.081 to 0.089 gm. and for W.W. it was 0.090 to 0.119 pan The fecal magnesium for D.A. varied from 0.115 to - 23 - TABLE VII DAILY Ifs‘lGl‘ThSIUIz'I BAIAZ‘ICLS 01E ’l’Hh iiljDIUI'j PIZOTE‘I’Il-I DIET Output Retention Absorption Percentw Percent- Sub- age of age of ject Day Intake Feces Urine Total Total Intake Total Intake (ng (am) (at?) (am (an) (gm) D.A. 1 0.243 0.1 0 0.085 0.265-0.022 0.063 25.9 2 0.243 0.115 0.085 0.200 0.043 17.7 0.128 52.7 3 0.243 0.145 0.087 0.232 0.011 4.5 0.098 40.3 4 0.247 0.158 0.089 0.247 0.000 0.089 36.0 5 0.247 0.148 0.087 0.235 0.012 4.8 0.099 40.0 6 0.247 0.160 0.081 0.241 0.006 2.4 0.087 35.2 Aver- ‘ W.W. 1 0.265 0.162 0.112 0.274-4L009 0.103 38.9 2 0.265 0.116 0.108 0.224 0.041 15.5 0.149 56.2 3 0.265 0.170 0.104 0 274-(L009 0.095 35.8 4 0.271 0.151 0.113 0.264 0.007 2.6 0.120 44.3 5 0.271 0.162 0.119 0.281-0.010 0.109 40.2 6 0.271 0.138 0.090 0.228 0.043 15.9 0.133 49.1 Aver- age 0.268 0.150 0.108 0.258 0.010 3.7 0.118 44.0 - 24 - 0.180 gm. This extreme variation occurred at the beginning of the period. No explanation of this high output is available since both subjects had been receiving this‘ggg; stant diet for 24 dgys prior to the start of this study. Following these two high days, the fecal magnesium varied less, the range being within 0.015 gm. W.W.,also, showed a day-to-day variation in the fecal magnesium, the output ranging from 0.116 to 0.170 gm. per day. Both subjects showed a decided tendency towards alternating high and low Idaily fecal excretions of this mineral. The total output varied from day to day which was to be expected since the urinary excretion was practically constant while the amount of magnesium in the feces changed from day to day. The daily fluctuations in the total output of magnesium would, of course, cause variations from day to day in the amount of magnesium absorbed--that is the total daily intake less the amount excreted in the feces that day. The ab- sorption values for D.A. ranged from 0.063 to 0.128 gm. and, since the amount absorbed varies according to the fecal out- put of the mineral, this extreme variation followed the fecal variation and occurred at the beginning of the medium protein period. While this occurred at the beginning of the period, it cannot be due to a change in diet, for the child had been on the same one for the 24 preeeeding days. After these first two days it became practically constant. W.W. did not show as extreme variation, but the day-to-day - 25 - variations were greater and indicate an individual varia- tion in the magnesium absorbed on a constant-diet. The smallest amount of magnesium absorbed by W.W. was 0.095 gm. and the largest amount was 0.149 gm. The average amount of magnesium absorbed for the entire medium protein period for D.A. was 0.094 gm. or 58.4 per cent of his average intake of 0.245 gm. w.W. absorbed 0.118 gm.or 44.0 per cent of his average intake of 0.268 gm. A daily variation in the retention of magnesium would, of course, follow daily variations in the absorption values since the amount of magnesium retained is the amount ab- sorbed less the amount excreted in the urine. Because D.A.'s absorption on the first day was lower than the amount ex- creted in the urine he had a negative balance of -0.022 gm. that day, showing that he lost magnesium from his tissues. Following this first day he was either in equilibrium or in positive balance. The largest amount retained was 0.045 gm. W.W. was less constant than D.A. in his retention of magnesium. He alternated negative and positive retention days, while D.A. had only'one negative day. W.W.'s reten- tien values ranged from -0.010 to 0.045 gm. 'When the averages for the medium protehiperiod are considered, D.A. received 0.245 gm. of magnesium, and of this am0unt he absorbed 0.094 gm. or 58.4 per cent. Of the amount absorbed he retained 0.008 gm which is 5.3 per cent of the intake or 8.5 per cent of'the amount absorbed. _ 26 _ 0f the 0.268 gm. received daily, W.W. absorbed 0.118 gm. or 44.7 per cent and retained 0.010 gm. or 5.7 per cent, which is 8.5 per cent of the absorbed magnesium. Calculated on the percentage basis, W.W. absorbed more magnesium than D.A. but the two subjects retained the same preportion 0f the absorbed magnesium. The magnesium balances on the high protein diet are given in Table VIII. D.A.'s intake was 0.266 gm. during this period as compared to 0.245 on the preceeding diet. W.W. received 0.295 gm. of magnesium in place of 0.268 on the medium protein diet. The day'by day variations in the excretion of mag- nesium through the urine and feces are similar to those on the last 6 days of the medium protein diet, constant for 50 days. It is to be expected that variations would occur in the change from the medium to the high protein diet while the body was becoming adjusted, and by referring to Tables VII & VIII and Charts I a II this is readily seen. W. T. again showed a greater fluctuation in the excretion of magnesium through the urine; his excretion ranged from 0.086 to 0.154 gm. per day as compared with 0.085 to 0.111 gm. per day for D.A. The amount excreted does not be be- come more constant at the end 0f 15 days than at the be- genning. The fecal excretion varied considerably from day to day on tnis diet. When the amount of magnesium excreted n.He HmH.o H.m bHo.o msm.o moa.o maa.o *4 mam.o owaaeae m.mm st.o a.» mmo.o. eem.o ena.o mea.o adm.o ma m.sm nHH.o 9.0 Hoo.o mam.o maa.o emH.o mam.o ea e.Hm boo.o meo.o- aen.o nHH.o emm.o amm.o ma .1 i 41:14.]- J 44. BMHQ amBomm mem HHH> lama/am. 'HIHI was. zo mflowgqmm Sammzwdz MAM—”dd - 28 - by the way of the intestinal tract is compared with the amount of feces excreted for that day, it is observed that if the total amount of wet feces was high the mag— nesium excreted was also larger in amount. (Chart II) In spite of the fact that the children were on a constant diet, there was considerable variation-in the amount of feces excreted daily, and generally the amount of fecal magnesium increased or decreased with the increased or decreased amount of feces. These extreme daily varia- tions may be due to insufficient information as to what constitutes a daily metabolic cycle. That both subjects had to adjust themselves to the higher protein intake is shown by the absorption figures for the first three days of this period. The percentage of the intake absorbed by D.A. was considerably lower for these three days than for the preceeding 5 days of the medium pro- tein diet as well as for the succeeding days of the high protein level. There were fmlr days on this diet when D.A. apparently excreted more magnesium than he absorbed. These days were all at the beginning of the new diet and are due, no doubt, to the adjustment joythe higher protein intake since he was in equilibrium or storing magnesium previous to the change. The absorption figures for W.W. on the first 5 days of this diet shows extreme fluctuation from one day to the next. This was also true for the 6 days of the medium protein diet, - 29 - which had been constant for 24 days previously. However, after the third day, he evidently became adjusted to the dietary Change since the absorption figures were higher, although showing daily variations. Both subjects absorbed slightly more magnesium on the high protein diet. D.A.'s average absorption increased from 0.094 to 0.119 gm. and W.W. from 0.118 to 0.121 gm. Calculated on the percentage basis, W.W. absorbed less of the intake on the high level which was 41.5 per cent as compared with 44.0 per cent on the first diet, while D. A. increased his percentage of absorption from 58.4 to 44.7 per cent. With an increase in absorption on.the second diet, an increase in retention would be expected and this was found to be the case with both subjects. During the first 5 days, D. A. apparently excreted more magnesium than he absorbed since 4 out of the 5 retention figures were negative. How- ever, after this period of adjustment, D.A. retained mag- nesium throughout the remainder of the period, the amount varying from 0.011 to 0.127 gm. W.W. showed somewhat similar reaction to the change in diet, although his period of adjustment was shorter in length than for D.A. He had only two negative retention days at the beginning of the period, as compared to 4 nega- tive days for D.A. Although W.W.'s retention on the medium protein diet was less consistent than for D.A., he apparent- ly became more quickly adjusted to the change in diet. After the initial adjustment period both subjects stored - 50 - magnesium every day until the end of the experiment, with the exception of the 15th day for W.W. which was negative. W.W.'s retention on this diet ranged from 0.001 to 0.067 gm. The average retention figures for the high protein level are greater for both subjects than on the medium pro- tein diet. D.A.'s average retention increased from 0.008 to 0.024 gm. and there was an increase from 0.010 to 0.015 gm. for W.W. 0f the amount absorbed, D.A. retained 20.1 per cent as compared to 8.5 per cent on the medium level. The percentage retained of the amount absorbed for U.W. in- creased from 8.5 per cent to 12.4 per cent when the diet was changed. The higher magnesium intake appeared to favor increased magnesium retention. then the magnesium retabolism data are calculated on tie 5 day period basis, as given in Tables IX & X, there is practically no difference be+ween the two periods on the medium protein diet in the excretion of the mineral in the urine and feces for both subjects. There is, also, only a very slight variation in the absorption values for the 5 day periods for the subjects, but there is a significant. difference in the retention values for the two 5 day periods. The first 5 day period is the higher for D.A. while W.U. has the higher retention the last three days. There is more variation in the output for the different :5 day periods on the high protein level for both subjects and” in general, the trend is similar to the daily variations. D o a o 0 a 0 \~ 1' o o o ~ 0 u o o o 0 O a a a a 1%, H 1‘ 4a 11 pH « emHo ZHaeoma apHmm; a. mQOHmma sad n em mMoeaaam abumaawaa VaHam acamm>a RH mqm¢e - 32 - As the subjects are maintained on the higher magnesium and protein intake, there is less magnesium excreted for each succeeding period with the single exception of W.W.'s last 5 day period. With a progressive decrease in the excre- tion there is a correSpondingly progressive increase in the amount of magnesium absorbed and retained. Computing the balances on the 5 day period basis, the negative and positive days offset each other and there is only one negative period for each subject throughout the entire 21 days. The two subjects have different negative periods, D.A.'s being the first period on the high protein intake while W.W.'s is the last 5 day period. When the averages for the two levels are compared, it will be seen that both subjects absorbed more magnesium on the high protein diet. However, computed on.the percentage basis, W.W. absorbed less of the magnesium on the higher in- take.while D.A. increased his absorption. The retention was considerably higher for the high level, D.A.'s markedly so. His retention increased from 5.5 per cent of the intake to 9.0 per cent when on the higher protein and magnesium diet. h.h.'s retention in- creased from 5.7 to 5.1 per cent. 0f the amount of mag- nesium absorbed that was retained, D. A. retained 8.5 per cent on the low level and 20.1 per cent on the high level, while W.W.'s retention increased to 12.5 per cent on the high intake as compared to 8.4 per cent on the medium pro- tein diet. A graphic representation of the intake, absorption and retention of magnesium on the 5 day period basis is given in Chart I. This shows that the first 5 day period follow- ing the change in diet was a period of adjustment, since the amount absorbed decreased and the retention dropped to almost equilibrium for wsn. and became negative for D.A. Following this period of adjustment there is increasing absorption and retention for each period.with the exception of the last period for $93. when the amount absorbed de- creased to approximately 33/4 of the preceeding period and the retention became negative. .A reference to all the available data recorded during the_study brings forth no information that might eXplain W.W.'s reaction during this last period. The acid-base values of the two diets, calculated in cubic centimeters of N/10 acid or base, are given in Tables III & IV. It will be seen that the high protein diet was slightly less basic than the medium protein diet, having 7.2 cc. of N/lO excess base as compared to 15.5 cc. on the medium protein level. The fact that the high protein diet was less basic may have been a factor in favoring magnesium retention on this level. This result is not in agreement with that of Shohl and Sato (22) who obtained .greater magnesium retention when NaHCOg was added to the diet of infants than when H01 was added. Monroe (17) did 0 Chart I INTAALL, xaijSCziz-TICN .LI‘ED ELTELZTTI OT 0’7 3337;521:11U35 LY 5 [MY FIJILIODLS / hedium.\, High \ 7\ > soo ' ' 50 150 . c. D._n. absorption 100 Nedium §_4__ High V so 50 we 2178']. o 3 131,1 Intake - D.A. D. A. Retention < Medium _\,_< High x 300 mg . . [150 IT'S 250 100 .-. w. W, Absorption 100 H" £717 X J“) 50 n? \/ {.73 50 fled. High Intake - W.W. *. N.W. Retention mmeumsma maoaa a0 expose new; ernigsc, [75K ,: .§.; 90% madam SH hep sea cowpepoxe Meoem .E.$ new maeamwaflfia an hep pea Siamecaee Heoem 5 5 .¢.Q new madam me had hem compoaome fimoem .<.m mom mamhwfififlfia QH hep hem Edwmenmmfi Heoem BS <5 not obtain any marked difference in the effect of high and low protein diets on the magnesium balances in his animal experiments. The paths of excretion of the mineral in the two subjects are given in Table XI. The urinary excretion for D.A. on the two diets remained the same, while the fecal magnesium decreased from 61.6 per cent to 55.5 per cent. The total excretion was lowered from 96.7 to 91.0 per cent. The paths of excretion for W.W. were somewhat different. There was a decrease in the urinary excretion from 40.5 per cent on the first diet to 56.2 per cent on the second. The fecal magnesium increased from 56.0 to 58.7 per cent on the higher intake. The total excretion decreased from 96.5 to 94.9 per cent which was less marked than in the case of D.A. Since calorie and protein requirements are based on body weight, there may be a similar relationship between body weight and mineral requirement. The magnesium balances for the two periods calculated per kilogram of body weight, are recorded in Tables XII and XIII. The intake per kilogram was constant for the two periods on the medium protein diet for both subjects. It was constant, also, for D.A. on the high level. Because W.W.'s weight fluctuated from period to period on the high level, the amount of magnesium per kilogram varied from 0.015 to 0.016 gm. There was very little variation in the output and.ab- sorption of magnesium on the medium level while the high PERCENTAGE OF THE MAGNESIUM _‘__vv TABLE XI - 57 - Medium Protein INTAKE EXCHETLD High Protein Subject Feces Urine Total D.A. 61.6 55.1 96.7 55.5 55.7 91.0 HAW. 56.0 40.5 96.5 58.7 56.2 94.9 - 59 - TABLE XII MA GN ES IULI BALAH CE .5 ON THE MEDIUM PROTEIl‘.r DIET CALCULATED PER KILOGRE’Z 03180133! WEIGHT: T“ T==_ Output Sub- Reten- Absorp- jectuPeriod Weight Intake Feces Urine Total tion tion (kg.7 (ng ’TEmI' (gm) (ET (gm) IIIgm) D.A. 1 17.4 0.014 0.008 0.005 0.015 0.001 0.005 2 17.4 0.014 0.009 0.005 0.014 0.000 0.005 22:?" 17.4 0.014 O£D85 0.005 oxnss oxxns 0.00a5 w.w. 1 18.8 0.014 0.008 0.005 0.014 0.000 0.005 2 19.0 0.014 0.008 0.005 0.014 0.001 0.005 Aver- age 18.9 0.014 0.008 0.006 0.014 O.CI)05 0.006 MAGNESIUM BALANCLS GR TABLE XIII THE HIGH PROTEIN DIZT CKLCULATED PER KILCGRAM OF BODY WEIGHT r Output Ab- Sub- Reten- serp- ject Feriod Weight Intake Feces Urine Total tion tion (kg) ng) (gm Ten) ngmT Fen) (emf D.A. 1 17.5 0.015 0.01 0.005 0.01 ‘—0.001 0.004 2 17.4 0.015 0.009 0.006 0.015 0.000 0.006 5 17.5 0.015 0.008 0.005 0.015 0.002 0.007 4 17.5 0.015 0.007 0.005 0.012 0.005 0.007 5 17.5 0.015 0.007 0.005 0.012 0.005 0.008 Aver- age 17.5 0.015 0.008 0.005 0.015 0.002 0.007 W.W. 1 18.8 0.016 0.010 0.005 0.015 0.001 0.006 2 18.8 0.015 0.009 0.005 0.014 0.001 0.006 5 19.0 0.016 0.009 0.005 0.014 0.002 0.007 4 19.1 0.015 0.007 0.006 0.015 0.002 0.008 5 19.1 0.016 0.010 0.006 0.016 0.000 0.006 Aver- gge 19.0 0.015 0.009 0.005 0.014 0.001 0.006 - 4o - level shows greater fluctuations for these values through- out the five periods for both subjects. The absorption and retention figures for D.A. are higher on the high protein diet, while for W.W. the absorption figure remains the same with the dietary change, but the retention per kilo- gram is greater on the higher intake. The per cent of ab- sorbed magnesium for D.A. on the medium protein diet was 59.5 and 42.9 for W.T. On the high protein diet this figure increased to 46.5 for 0.5. and was reduced to 40.0 for W.W. Because of the interrelationship of magnesium and calcium, the ratios of these two minerals, on the two protein levels, are tabulated in Tables XIV and XV. The importance of this interrelationship between these two elements has been studied by a number of workers (1) (5) (7) (9) (10) (14). According to the standards recommended by Sherman and Hawley (21), the amounts of calcium provided in these constant diets were adequate. These workers recommended not less than 1 gm.of calcium per child per day to support optimal rate of storage. The calcium intake on the medium protein diet was 0.991 gm. for D.A. and 1.090 gm. for W.W.‘ The high level furnished D.A. with 1.191 gm. and 1.510 gm. for Wifi.‘ Recent investigations (5) (9) (10) (14) indicate that the amount of phosphorus in the diet is an important factor in the metabolic relationship of calcium and.magnesium. TABLE XIV DAILY IN T ME 11111? BE; THY]? ION ELTWIOS OF RCAGNESIUL-T TO CALCIUZ’I“ ON TB; R'LDIUM PHOTL‘IN BIND ___ Intake Retention Sub- ' ect Day Mg Ca Mg : Ca ligfi Ca RigiCa (in? (an) 15m) (am) D.A. 1 0.245 0.987 1:4.1 -0.022 -0.147 2 0.245 0.987 1:4.1 0.045 0.298 1:6.9 5 0.245 0.987 1:4.1 0.011 0.088 1:8.0 4 0.247 0.995 1:4.0 0.000 0.101 p__ 5 0.247 0.995 1:4.0 0.012 0.171 l:l4.5 6 0.247 0.995 1:4.0 0.006 -0.009 'Aver- age 0.245 0.991 1:4.0 0.008 0.084 1:10.5 W.W. 1 0.265 1.086 1:4.1 -0.009 -0.109 g _2 0.265 1.086 1:4.1 0.041 0.296 1:7.2 5 0.265 1.086 1:4.1 ~0.009 -0.221 4 0.271 1.094 1:4.0 0.007 0.077 l:ll.0 5 0.22; 10094 1:400 ‘00010 00001 5 0.271 1.094 1:4.0 0.045 0.252 1:5.9 Aver- ‘— a-e 0.268 1.090 1:4.1 0.012J 0.049 1:4.9 * Figures from Tables, Hiller, Unpublished Thesis (12). .emeHHoo euwpm newasoaz ..paem sofipfinpsz a mpoom .mumm penmfiansacb Seem when m umea pom m055Mam .ANHV mamena penmfiHQSQQD .aeHHHm .meapwe 502% when m pmham pom newsman * m.o ”a m~o.o 5H0.o 5.eua oan.a nom.o meahmpa 5.5a H enm.o nmo.o 5.4 H mem.fl 55m.o ma mma.o- Hoo.o m.e a mem.a omm.5 4H 1 scapeopom maepeH lg BHHQ ZHMBomm mmHm mug zo *SDHOA¢O OB EDmezo<2 mo mOHedm >N mam¢a 25Hazaammlmz< maanswer from the present data. The intake of magnesium on the medium protein diet is sufficient to maintain positive balances. However, it appears that 0.250 to 0.270 gm. represents about the mini- mum requirement for these 2 four year old subjects, since there are occasional negative balances on these amounts. While further studies are needed to establish the quantity of magnesium needed by 4 to 5 year children, these results may be useful until further data are available. Summary This investigation was made to study the daily varia- tions in the magnesium metabolism of two normal preschool children on a 6 day medium protein diet and a 15 day high protein diet. . 1. There was considerable daily variation in the amount of magnesium absorbed and retained, possibly due to the lack of information as to What constitutes a daily metabdfic cycle, and to the difficulty in collecting daily fecal samples. 2. 0n the medium protein diet D.A. and W.W. stored daily 0.008 and 0.010 gm. respectively. On the basis of per kilo- gram of body weight these same values were 0.0005 gm. for - 47 - both subjects. 5. There was greater retention of magnesium.on the high protein diet for both.subjects, D.A. storing 0.024 gm. and U.W. 0.015 gm. In grams per kilogram body'weight D.A. re- . tained 0.002 gm. and w.W. 0.001 gm. 4. The two children did not react the same to the two diets. D.A. was more constant in his retention on the medium protein diet than W.W., but W.fi. became adjusted more quickly when the diet was changed. 5. With the increased protein and magnesium intake there was, with the exception of one period for W.W., a gradual increase in the amount of magnesium absorbed and retained for each 5 day period for both subjects after the adjust- ment period. ' L 6. Several factors may be responsible for the increased retention during the last period of 15 days. It may have been the increased protein intake, the increase in the amount of magnesium, the increased calcium and phosphorus intake, or since the high protein diet was slightly less basic, it may have favored increased magnesium retention. 7. The average retention ratios of Kg:Ca for D.A. and W.W. on the medium protein diet were 1:10.5 and 1:4.9 respectively. On the higher protein diet these ratios were lower, namely 1:5.8 for D.A. and.1:0.8 for W.W. 8. It appears from this experiment that 0.250 to 0.270 gm. magnesium represents about the minimum requirement for 4 to 5 year old children. _ 48 - Bibliography (1) Bogert, L. J., and McKittrick, E. J., "Studies in Inorganic Ketabolism. Interrelations Between Calcium and magnesium Metabolism." J. Biol. Chem. 54, 565 (1922). (2) Bogert, L. J.' and Trail, R. K., "Studies in Inorganic Hetabolism. The Influence of Yeast and Butterfat Upon Kagnesium and Phosphorus Assimilation." J. Biol. Chem. 54, 755 (1922). (5) Carswell, H. E., and Winter, J. 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S., "The Effect of Vari- ations in the Proportions of Calcium, magnesium, and Phosphorus Contained in the Diet." J. Biol. 9235; 76, 547,(1928). (10) Hart, E. B., and Steenbock, H., "The Effect of a High Kagnesium Intake on Calcium Retention in Swine." J. Biol. Chem. 14, 75,(1915). (ll) Ebwks, J. E., Unpublished Data. (l2) Hiller, V. E., "Variations in the Calcium Metabolism of Preschool Children." Unpublished Thesis, Nichioan State College, 1952. (l5) Hoobler, B. R., "The Role of Mineral Salts in the metabolism of Infants." Am. Jour. Dis. Child, 2, 107, (1911). (14) Huffman, Robinson, Winter and‘Larson, "The Effect of Low Calcium--High magnesium Diets on Growth and Metabolism of Calves." J. hutr. 2, 471 (1950). (15) Kilpatrick, A., ”Variations in Phosphorus ketabolism ' of Preschool Children." Unpublished Tiosis, Michigan State College, 1952. (16) (17) (18) (19) (20) - 50 - KcCandish, A., "The Addition of Hay and Grain to a Milk Ration for Calves." J. 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F., and Kramer, B,, "Methods for the Direct Quantitative Determination of Sodium, Potassium, Calcium and Magnesium in Urine and Stools." J. Biol. Chem: 48, l, (1921). - 51 - (25) Underhill, F. B., Honeij, J. A., and Bogert, L. J., "Studies on Calcium and magnesium Metabolism in Disease." J. Exp. ted. 52, 41, (1920). (26) Hoodbury, Height - height - Age mables, Supplement to Issue of tether and Child. (July), 1952. American Child Health Association. ROOM use ONLY :14 uIunullHungu;usuuwwmmuujwujfluluH