THE ABSORPTION OF CALCIUM SOAPS AND THE RELATION OF DIETARY FAT TO CALCIUM

UTILIZATION IN THE WHITE RAT

BY OSCAR F. BOYD, CARLOS L. CRUM, AND J. F. LYMAN

(From the Laboratory of Agricultural Chemistry, The Ohio State University, Columbus)

(Received for publication, September 17, 1931)

The influence of dietary fat on calcium soap formation and calcium absorption in the intestine has received considerable study with somewhat conflicting results. Cronheim and Miiller (7), Bahrdt (3), Rothberg (18), and Birk (4) found that as the amount of fat in the diet increases above a moderate level calcium soaps in the stools also increase. When fatty acid utilization is low, as is the case with ethyl palmitate or palmitic acid, the loss of calcium soap is increased (Givens (9)). Bosworth, Bowditch, and Giblin (5) concluded that the presence of soluble ionized calcium in the intestine determines the extent of soap formation; while loss in the feces depends not only upon the amount of calcium soaps formed but also upon their nature, calcium oleate being much more soluble in the normal intestinal fluids than is calcium palmitate or calcium stearate. Telfer (22) also believes that the higher calcium content of cow’s milk as compared with human milk is the factor that leads to the greater loss of calcium soaps in the stools of bottle-fed infants. Holt, Courtney, and Fales (13), on the other hand, con- cluded that a high calcium intake does not necessarily cause a large loss of fat in the feces. They found better assimilation of calcium by infants when the fat of the diet was generous than when it was more restricted.

Whether calcium soaps are lost in the feces in large quantities undoubtedly depends upon other factors in addition to the amount and nature of the calcium compounds and fats of the diet. One such factor is the acidity of the intestinal contents. Telfer (21) points out that free fatty acids dissolve calcium phosphate with

29

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from

30 Utilizat’ion of Calcium Soaps

the precipitation of calcium soaps. If fats and phosphates both are low, calcium carbonate may be excreted in an alkaline stool. The form in which calcium is eliminated from the intestinal tract, therefore, is associated with the pH of the intestinal contents as a consequence of the effect of acidity upon solubilities.

The beneficial effects of dietary fat upon calcium assimilation as found by Holt and Fales (14) and the curative effect of vitamin- free fat upon rickets as found by Zucker and Barnett (24) probably depend, partly at least, upon a more favorable pH of the intestinal contents, produced by the fatty food. Boyd and Lyman have shown that the utilization of calcium soaps, particularly of calcium oleate, may be high, 70 to 80 per cent of the latter that is ingested being absorbed (6).

Haldane, Hill, and Luck (10) found that calcium chloride inges- tion causes a loss of blood bicarbonate and a great increase in calcium carbonate of the feces. This observation has been verified by Gamble, Ross, and Tisdall (8) and by Atchley, Loeb, and Benedict (2). It thus appears that the chloride ion of calcium chloride is more rapidly absorbed than is its associated calcium ion. The calcium ions, therefore, associate with fatty acid, phosphate, or carbonate ions to form compounds that are but slightly soluble in the intestinal fluids. The particular compounds of calcium that form in any given experiment evidently will depend upon the products then present in the intestinal contents. Telfer (20) has stated these conditions thus: If fatty acids are in excess, the calcium is excreted as soap; if alkalinity predominates, calcium phosphate is formed; if both fats and phosphate are low in the diet, calcium may be excreted as carbonate. These facts can be put in another form : The lower fatty acids readily dissolve calcium carbonate and calcium phosphate. In the presence of higher fatty acids and their soluble soaps a secondary reaction may then result in the formation of insoluble calcium soaps and the liberation of carbonic and phosphoric acids (Telfer (19)). Stated in still another way, this is merely the effect of hydrogen ion concentra- tion upon the solubility of salts of a strong base with weak acids.

Another well recognized factor in fat and calcium assimilation is the bile. It is well known that in the absence of bile from the intestine large quantities of fatty acids and calcium soaps are eliminated in the feces from fat-containing diets. That bile, and

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from

0. F. Boyd, C. L. Crum, and J. F. Lyman 31

solutions of bile salts in water, dissolve fatty acids and calcium soaps has been amply demonstrated (Verzk and Kdthy (23), Adler (l), Oelsner and Klinke (16)).

Our experiments are divided into two groups. The first group deals with the absorption of calcium soap; the second with the effect of dietary fat upon the assimilation of calcium.

Utilization of Calcium Soaps

Method-The general plan was to feed pure calcium soaps in a synthetic food mixture otherwise free, as far as practicable, from calcium and to determine the extent of utilization by a comparison of the soaps found in the feces of rats fed thereon with the soap consumed with the food. The rats used were of Wistar stock, 35 days old, and weighing about 60 gm. each at the beginning of the test and capable of storing 30 to 40 mg. of calcium per rat per day. A preliminary period for adjustment to the diet was followed by a metabolism test of 17 to 20 days. For collection of urine and feces the rats were housed individually in galvanized wire cages over 12 inch glass funnels, provided with large Witt plates which retained the feces. The urine was collected in toluene-thymol preservative, containing dilute hydrochloric acid to prevent the precipitation of calcium salts. The feces were removed daily and the funnels rinsed down with water. Scattering of food was prevented by the use of a feeding cup devised from a 150 cc. beaker provided with a metal cover in whose center a hole 1 inch in diameter was punched. In order to feed, the rat was compelled to enter its head and shoulders into the cup.

The calcium-low basal ration consisted of special low calcium casein 18 gm., modified calcium-free Osborne and Mendel (17) salt mixture 4 gm., powdered sucrose 35 gm., starch 35 to 40 gm. To this mixture the calcium soap was added in the desired amount to make a total of 100 gm. 0.2 gm. of dried brewers’ yeast and 2 drops of cod liver oil were given each rat daily as vitamin supplements.

The casein was decalcified by extraction with 0.01 N hydrochlo- ric acid at 0’. Under these conditions there was no objectionable swelling. The calcium soaps were prepared according to Harri- son’s (11) method from palmitic, stearic, oleic, and butyric acids obtained from the Eastman Kodak Company. iMixed soaps from

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from

Utilization of Calcium Soaps

the fatty acids of lard were prepared by the usual methods. Some difficulty was experienced from oxidative rancidity production in the preparation of calcium oleate. This was largely avoided by drying and keeping the product in a vacuum desiccator.

Calcium in urine, feces, and foods was determined by McCrud- den’s (15) method in ashed material. The Roese-Gottlieb method as described by Holt, Courtney, and Fales (12) was used for determining soap, free fatty acids, neutral fat, and total fat in feces.

Relative Absorption of Calcium-When the level of calcium intake was relatively high, between 37 and 60 mg. a day per rat, absorp- tion of calcium varied greatly among the different calcium com- pounds tested. Assuming that the calcium of the feces represents unabsorbed calcium, calcium utilization was as follows: lactate 68.5 per cent, butyrate 52.5 per cent, oleate 68.4 per cent, mixed soaps from lard 46.7 per cent, palmitate 39.4 per cent, and stearate 30.9 per cent. On comparing the soaps of the feces with the soap in the food, and assuming that, in feces, calcium soaps only are present, the following soap utilization values are found: oleate 90.4 per cent, mixed soaps 72 per cent, palmitate 38 per cent, and stearate 25 per cent. The higher utilization of calcium lactate as compared with butyrate probably depends upon the shift toward alkalinity produced by butyrate in the intestinal contents. It was noticed that the feces from butyrate-fed rats effervesced strongly when moistened with dilute hydrochloric acid. Most of the calcium in such feces was combined as carbonate, as shown by titration against acid with methyl orange indicator.

The relative absorption of calcium oleate, palmitate, and stea- rate is probably in the order of their solubilities in bile. The utili- zation of oleate is high, as was expected; but the utilization of stearate, while relatively low, is higher than was anticipated. When the soaps were fed at a lower level, enough to supply 13.6 to 21.4 mg. of calcium per rat per day, utilization of calcium was in the same order as that obtained at the higher level, but the per- centage absorption was higher, 81 per cent of the oleate, 65 per cent of the palmitate, and 49 per cent of the stearate calcium having disappeared from the intestine. The utilization of the several soaps was oleate 91 per cent, palmitate 65 per cent, and stearate 45 per cent. In terms of mg., calcium absorption per rat per day varied from 17 mg. on the stearate ration to 40 mg. on the lactate

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from

0. F. Boyd, C. L. Gum, and J. F. Lyman 33

ration. Records of the calcium intake and losses of calcium are given in Table I.

Absorption of Fatty Acid Radical-If the calcium soaps are absorbed as undissociated molecules and no calcium is reexcreted into the bowel, there should be perfect agreement between the loss from the intestine of the fatty acid radical and that of the calcium atom. On the whole our results indicate that the soaps are absorbed without dissociation. Assuming that everything

TABLE I

Average Utilizations of Calcium in Calcium Soaps

8 per cent palmitate.. g “ ‘I ‘I

+lO per cent lard. . 4 per cent palmitate . g ‘I “ oleate.. . . . . 4 “ “ “ . . . 8 “ “ stearate. . . . 4 “ “ “ . . . 8 “ “ butyrate . 4 “ ‘I ‘I . . 3 “ ‘I lactate.. . . . 8 “ “ mixed soaps. 8 “ “ “ “

+lO per cent lard. . .

8

7m. gm.

8.32.3

3 8.73.1 3 1 0.52.9 6 7.11.3 4 8.92.4 3 9.52.6 4 9.92.5 4 8.72.3 3 1 0.02.4 7 9.82.4 6 8.52.3

6 -

7.72.X

mg. mg. mg. WJ. Per mg. cent

53.632.5 1.433.919.736.f

47.120.6 1.221.825.353.< 32.511.3 1.012.320.263.: 37.311.9 2.814.722.660.: 19.8 3.7 1.0 4.715.175.: 56.339.1 1.740.815.527.: 28.314.4 0.915.313.046.: .03.558.312.470.732.831.$ 60.028.5 2.130.629.449.f 58.218.3 2.420.737.564.: 54.929.3 2.631.923.043.:

44.622.1 2.724.819.844.f

Ca. absorbed

mg. g--

21.139.4

16.556.1 31.265.3 25.468.4 16.181.2 17.230.9 13.949.0 45.243.8 51.552.5 j9.968.5 25.6 46.7

12.550.3

All rats were given 0.2 gm. of yeast daily and 2 drops of cod liver oil. The average age of rats at beginning was 35 days; average weight 65 gm.

determined as soap in the feces is unabsorbed calcium soap from the feed and that no absorbed calcium is excreted via the bowel, the percentage utilization values shown in Table II are obtained.

In calculating the absorbability of the calcium of the soaps an uncertainty is introduced because of the presence in the diets of calcium other than that of the particular soap used. In some cases this other calcium amounted to as little as 3 per cent of the total, while in other cases it was as much as 22 per cent. This

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from

34 Utilization of Calcium Soaps

variability was due mainly to variations in calcium content of different lots of yeast and casein. In the experiments with the calcium soaps prepared from the fatty acids of lard, the calcium in the ration other than that combined as soap was relatively high, 17 to 22 per cent of the total; and in these experiments we had the poorest agreement between utilization of calcium and utilization of soap. Table III shows the fat-fatty acid analyses of the feces and the average utilization of the fatty acids of calcium soaps.

Storage of Calcium-Storage of calcium varied from 12.9 to 37.4 mg. of calcium per rat per day. In general, storage paral- leled absorption since there was relatively little excretion of

TABLE II

Utilization of Calcium soap.3 versus Utilization of Calcium

Kind of soap ( >a soap intake ortp utilisaticn

8 per cent palmitate. . . . . . . . . . . . . 8 ‘I “ ‘I + 10 per cent

lard........................... 4 per cent palmitate. . . . . . . . . . . . . 8 “ I‘ oleate . . . . . . . . . . . . . . . . . 4 I‘ ‘I “ . . . . . . . . . . . . . . . . . . 8 “ “ stearate. . . . . . . . . . . . . . . 4 “ ‘( “ . . . . . . . . . . . . . . . . 8 ‘I “ mixed soaps.. . . . . . . . . . . 8 ” ” “ “ + 10 per

cent lard......................

WY.

47.0 per cent 38.3

45.6 57.7 29.7 65.1 35.0 90.4 19.0 91.1 48.0 25.0 26.4 45.1 43.1 72.1

36.6 67.2

-

1 1

-

Ca utilization

per cent

39.4

56.1 65.3 68.4 81.2 30.9 49.0 46.7

50.3

calcium by way of the kidney except in one case in which calcium butyrate was fed at a high level.

E$ect of Dietary Fat upon Utilization of Calcium Soaps--From a fat-free diet calcium palmitate was absorbed to the extent of 38.3 per cent. A similar diet containing lard to the extent of 10 per cent with a corresponding decrease in carbohydrate led to considerably greater calcium palmitate utilization; viz., 57.7 per cent. In this experiment the effect of dietary fat upon calcium soap absorption was distinctly favorable. However, when we added lard to the fat-free diet whose calcium was supplied by the calcium soaps prepared from the mixed fatty acids of lard, there

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from

0. F. Boyd, C. L. Crum, and J. F. Lyman 35

was no marked effect on the utilization of the soap. We regard this experiment with the soaps from mixed fatty acids as less satisfactory than that with calcium palmitate because of the presence in the mixed calcium soap diet of considerable amounts of calcium in other forms than soap.

TAFLE III

Average Utilization of Soap and Patty Acids in Calcium Soaps

Kind of soap

8 per cent palmitate. . . 8 “ “ ‘I

+ 10 per cent lard.. . .

4 per cent palmitate. . . 8 Ld 61 oleate . . . . . 4 ‘I “ “ . . 8 “ “ stearate . . 4 “ “ “ . . . 8 “ “ mixed soaps.. 8 “ “ “ “

+ 10 per cent lard.

Calcium

-l-l- m!J. mg. Per

cent

8.028.838.:

k5.6 19.2 57.: ?9.710.465.1 55.0 3.490.1 19.0 1.791.1 48.035.825.( Z6.414.545.1 43.112.872.1

)6.6112.1167.:

Y- Fatty acid

-___-

WT. ng. mg. mg.

598 368 25 393

-

?

L i

w. Per cent

205 34.:

578244.926 270 378132.024 156 490 47.410 57.4 265 24.0 4 28.E 673 502 41 543 370203 28 231 548153 10 163

308 53.: 222 58.’ 432 88.: 247 89.! 130 19.: 13937.‘ 38570.:

466 154 11.6 166 300 64.:

_-

2

3 7 1 5 3 : 4 3

2 -

ml. 13

16.8 19 12.6 6.1

23.0 15 12

10 -

E$ect of Dietary Fat upon Absorption of Calcium Administered As Salts Soluble in Water

The experimental method was, in general, the same as that already described in the first part of this paper. Food, fecal, and urinary calcium were determined as measurements of calcium absorption and storage. In this part of the work phosphorus determinations and pH measurements of the intestinal contents were made also.

The basal diet consisted of hydrochloric acid-extracted casein, containing about 0.014 per cent calcium as oxide, 18 per cent; modified Osborne-Mendel salt mixture, calcium-free, 3 per cent; starch 40 per cent; powdered sucrose 36 to 37.5 per cent; calcium lactate 3 per cent or calcium chlorjde, anhydrous, 1.5 per cent.

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from

36 Utilization of Calcium Soaps

Each rat was given 0.2 gm. of dried brewers’ yeast moistened with 2 drops of cod liver oil daily. The fat-containing diet was modified from the above by decreasing the starch to 35 per cent, the sucrose to 31 or 32.5, and adding 10 per cent of lard.

After preliminary adjustment to the fat-free diet, urine and feces were collected for 10 days. The diet was then changed to one containing fat, and collections continued 10 days longer, when the rats were killed and the acidity of the intestinal contents deter- mined by means of the quinhydrone electrode. In making the pH determinations, dilution water was kept down to a volume about equal to that of the intestinal material used in the test. The Pemberton-Neuman method was used for phosphorus estimations in both urine and feces.

TABLE IV

Average Food Consumption, Gains in Weight, and Weight of Feces

Ration

Calactate ...................... ,I “ + fat. ............... “ chloride ...................... ‘I “ + fat. ..............

T

No. of rats i

Y

-

AWZ- AVW we

nitial age

final veight weigh1

on.

68 97 82

103

om.

97 115 103 122

-

; P’

--

-

AVCC age

gain er da!

om.

3.1 1.8 2.1 1.9

AVW- age

AXW-

weight >f feces, f%

10 daya per day --

om. 0%.

2.03 11.8 2.13 8.6 2.22 7.4 2.11 8.3

Results--Food consumption and gains in weight are given in Table IV. Gains were fairly good, ranging from about 2 to about 3 gm. per day. The animals appeared to be in good condition at all times.

E$ect of Dietary Fat upon Utilization of Calcium Chloride--When calcium chloride supplied nearly all the calcium present in a fat-free diet, the calcium lost in the feces was 34 per cent of the intake, while 66 per cent was absorbed. After lard, to the extent of 10 per cent, was added to the ration, the loss of calcium in the feces fell to 22 per cent of the intake. After the addition of fat to the diet the loss of calcium in the urine was decreased nearly one-half. The amount of calcium stored per rat per day increased from 20.8 mg. of calcium on the fat-free diet to 29.3 mg. on the fat-containing diet. The addition of fat to a fat-free ration whose

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from

0. F. Boyd, C. L. Crum, and J. F. Lyman 37

calcium was supplied by calcium lactate showed a slight beneficial effect upon the absorption of calcium, but owing to a smaller food intake on the fat-containing diet, the storage of calcium was slightly lower after adding fat than it had been before. Table V gives the average daily data for calcium utilizations for each group of rats.

Efect of Dietary Fat upon Soap Excretion When All the Calcium of the Diet Exists As Soluble Salt-Table VI shows the amounts

TABLE V

Effect of Fat upon Utilization of Calcium

No. 01 rata

Ca lactate. .............. <I “ + fat. ....... “ chloride. ............. ‘I “ + fat. ......

-

Aver- / Aver- 1 1

wl. ml.

410 104 366 84 352 120 393 87

per cem w7.

75.0 12.5 77.0 5.7 66.0 24.3 78.0 13.4

~ Cain urine

Total 2a ex- xeted

Total Ca.

stored per rat

ml. mg.

116.5 293.5 89.7 276.3

144.3 207.7 100.4 292.6

TABLE VI

Effect of Fat upon Carbonate and Soap Excretion

Ration

Calactate ................ ‘l “ + fat. ........ “ chloride ............... I‘ ‘I + fat. .......

No. of rats

mg. 479 416 461 513

m7. ml. WT.

135 122 145 121 74 102 191 162 116 159 99 52

mg. mil.

61 71 51 92 51 131 41 86

of soaps, fatty acids, fat, and carbonate in the feces. The data in Table VI were obtained on only two of the four rats reported in Table V, hence the calcium intakes in the two tables are unlike. It is seen that on the fat-free diet the losses of carbonates and soaps in the feces are much greater than they are on a similar diet when fat is present. The effect of fat in reducing the fecal losses of carbonates and soaps is greater on calcium chloride than it is on calcium lactate. -4s we shall bring out later, this is in line

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from

38 Utilization of Calcium Soaps

with the effect of fat upon increased intestinal acidity. That the rat is capable of digesting all the fat in a food mixture containing at least 10 per cent of fat is indicated by the fact that the losses of fecal free fatty acids and neutral fat are no greater on the fatty diet than upon the fat-free ration. Whatever soaps are produced in the digestive tract under the conditions of this experiment must be well absorbed, since actually less soap is excreted in the feces upon the fat-containing as compared with the fat-free diet. The amount of soaps resulting from both diets, however, was not large.

E.ffect of Dietary Fat upon Utilization of Phosphorus-Table VII shows that the addition of fat to a fat-free ration whose calcium is in the form of a soluble salt resulted in less loss of phosphorus in

T.4BLE VII

Effect of Fat upon Utilization of Phosphorus

Ration No. of rat8

Calactate ................ 2 “ “ + fat. ........ 2 “ chloride ............... 2 ‘I ‘I + fat ......... 2

P in urine

~- --

m7. w7. per cent n&g. mg. ml.

587 67 89 81 148 439 639 38 94 108 146 493 475 72 85 154 226 249 530 22 96 158 180 350

Total P P ex- stored

meted per rat

the feces. This was more marked in the case of the calcium chloride ration, the fecal loss decreasing from 15 per cent of the intake on the fat-free ration to only 4 per cent when fat was present. This beneficial effect is undoubtedly due, partly at least, to the greater acidity of the intestinal contents on the fat- containing diet. The loss of phosphorus in the urine on the cal- cium chloride ration, both with and without fat, was high and not markedly changed by dietary fat. This large loss of phosphate in the urine is associated with the acidosis caused by calcium chloride.

Effect of Fat upon Acidity of Contents of Stomach and Intestines- Table VIII shows that the addition of fat to the calcium lactate, fat-free diet had but slight effect upon the pH of the contents of the stomach and intestines. In general there seemed to be a

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from

0. F. Boyd, C. L. Crum, and J. F. Lyman 39

slight shift toward alkalinity. The total effect of these shifts upon calcium and phosphorus absorption was not very pronounced. The effect of fat upon the reactions produced by the calcium chlo- ride diet was a marked shift toward the acid except in the stomach where there was little change. Without fat in the diet calcium chloride produced a neutral or alkaline reaction in the lower half of the small intestine, in the cecum, and in the feces. In the upper half of the small intestine the shift was decidedly toward a more acid reaction as a result of the fat addition to the diet. These shifts in acidity as a result of adding fat to the diet seem to give

TABLE VIII

Eflect of Fat upon Acidity of Digestive Tract

Ration

Ca lactate. ........... I‘ “ + fat ...... “ chloride ........... ‘I I‘ + fat .....

Ca lactate. ........... ‘I “ + fat ...... “ chloride. .......... “ ‘I + fat .....

Small intestine, pH

No. Stomach, pH

of Upper half Lower half rats

Range AVX- Range AVW- age am

Range AVW- we

-~__ -~-

4 1.96-3.02 2.256.40-6.61 6.466.3fS6.70 6.48 4 2.0@-4.08 2.576.31-6.50 6.406.666.82 6.74 4 2.26-4.65 3.896.14-6.98 6.446.73-7.25 6.98 4 3.42-4.87 4.265.466.07 5.815.97-6.74 6.49

- Chum, pH Feces, pH

-

4 6.00-6.74 6.446.58-6.98 6.76 4 6.74-6.88 6.826.83-7.15 6.94 4 7.50-7.94 7.667.61-7.91 7.71 4 6.51-6.99 6.706.58-7.16 6.82

a good and sufficient explanation of the beneficial effects of fatty food upon the absorption of calcium and phosphorus when the diet contains all of its calcium as calcium chloride.

SUMMARY

Calcium soaps, in a fat-free diet, were fed to young white rats capable of storing from 30 to 40 mg. of calcium daily. On a cal- cium intake of 37 to 56 mg. per rat per day the following utilization values for the various soaps were found: calcium stearate 25 per cent, calcium palmitate 38 per cent, calcium oleate 90 per cent,

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from

40 Utilization of Calcium Soaps

mixed calcium soaps from the fatty acids of lard 72 per cent. On a calcium intake of 20 to 32.5 mg. of calcium daily the utiliza- tion values were calcium stearate 45 per cent, calcium palmitate 65 per cent, and calcium oleate 91 per cent.

The addition of fat to a diet nearly all of whose calcium was supplied by calcium chloride (1) markedly increased the acidity of the contents of the small intestine, the contents of the cecum, and of the feces of rats fed thereon; (2) increased the absorption of calcium; (3) increased the absorption of phosphorus; (4) decreased the loss of carbonates in the feces; and (5) decreased the loss of soaps in the feces.

The effect of fat upon the acidity of the digestive tract and upon the absorption of calcium and phosphorus when the diet con- tained calcium lactate as the sole source of calcium was relatively slight.

The presence in the diet of moderate amounts of fat may have a beneficial influence on the absorption of calcium and phosphorus by maintainjng a favorable acidity of the intestinal contents. The calcium soaps of palmitic and oleic acids that form in the intestine under such conditions are well ut.ilized.

BIBLIOGRAPHY

1. Adler, E., Arch. Verdauungskr., 40,174 (1927). 2. Atchley, D. W., Loeb, R. F., and Benedict, E. M., J. Am. Med. Assn.,

80, 1643 (1923). 3. Bahrdt, H., Jahrb. Kinderheilk., 71,249 (1910). 4. Birk, W., J&-b. Kinderheilk., 66, 69 (1907). 5. Bosworth, A. W., Bowditch, H. I., and Giblin, L. A., Am. J. Dis. Child.,

16, 397 (1918); 16, 265 (1918). 6. Boyd, 0. F., and Lyman, J. F., Proc. Sot. Exp. Biol. and Med., 27, 871

(1929-30). 7. Cronheim, W., and Miiller, E., Biochem. Z., 9,76 (1908). 8. Gamble, J. L., Ross, G. S., and Tisdall, F. F., Am. J. Dis. Child., 26,

455 (1923). 9. Givens, M., J. Biol. Chem., 31, 435,441 (1917).

10. Haldane, J. B. S., Hill, R., and Luck, J. M., J. Physiol., 67, 301 (1922-23).

11. Harrison, G. A., Biochem. J., 18, 1222 (1924). 12. Holt, L. E., Courtney, A. M., and Fales, H. L., Am. J. Dis. Child., 17,

38 (1919). 13. Holt, L. E., Courtney, A. M., and Fales, H. L., Am. J. Dis. Child., 17,

241 (1919); 18, 107 (1919); 19, 97 (1920).

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from

0. F. Boyd, C. L. Crum, and J. F. Lyman 41

14. Holt, L. E., and Fales, H. L., Am. J. Dis. Child., 23, 471 (1922). 15. McCrudden, F. H., J. Biol. Chem., 10, 187 (1911-12). 16. Oelsner, A., and Klinke, K., Juhrb. Kinderheilk., 122,58 (1928). 17. Osborne, T. B., and Mendel, L. B., J. Biol. Chem., 37, 572 (1919). 18. Rothberg, O., Jahrb. Kinderheilk., 66, 69 (1907). 19. Telfer, S. V., Biochem. J., 16, 347 (1921). 20. Telfer, S. V., Quart. J. Med., 17,245 (1923-24). 21. Telfer, S. V., Quart. J. Med., 20, 1 (1926-27). 22. Telfer, S. V., Glasgow Med. J., 33, 265 (1930). 23. Verzitr, F., and Khthy, A., Biochem. Z., 206, 369 (1929). 24. Zucker, T. F., and Barnett, M., Proc. Sot. Exp. BioZ. and Med., 20, 375

(1922-23).

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from

LymanOscar F. Boyd, Carlos L. Crum and J. F.

UTILIZATION IN THE WHITE RATDIETARY FAT TO CALCIUM

SOAPS AND THE RELATION OF THE ABSORPTION OF CALCIUM

1932, 95:29-41.J. Biol. Chem. 

  http://www.jbc.org/content/95/1/29.citation

Access the most updated version of this article at

 Alerts:

  When a correction for this article is posted• 

When this article is cited• 

alerts to choose from all of JBC's e-mailClick here

  #ref-list-1

http://www.jbc.org/content/95/1/29.citation.full.htmlaccessed free atThis article cites 0 references, 0 of which can be

by guest on August 29, 2019

http://ww

w.jbc.org/

Dow

nloaded from