Original Article
The Vitamin D Content of Fortified Milk and Infant Formula
N Engl J Med 1992; 326:1178-1181April 30, 1992
- Abstract
- Abstract
Background.
The fortification of milk and infant formula with vitamin D has had an important role in eliminating rickets in children and osteomalacia in adults. A recent outbreak of vitamin D intoxication caused by drinking milk fortified with excess vitamin D has led to questions about the level of vitamin D in milk from other producers.
Methods.
We used high-performance liquid chromatography to measure vitamin D in samples of 13 brands of milk with various fat contents and 5 brands of infant formula purchased at random from local supermarkets in five Eastern states.
Results.
Only 12 (29 percent) of the 42 samples of the 13 brands of milk and none of the 10 samples of the 5 brands of infant formula contained 80 to 120 percent of the amount of vitamin D stated on the label. Twenty-six of the 42 milk samples (62 percent) contained less than 80 percent of the amount claimed on the label. No vitamin D was detected in 3 of the 14 samples of skim milk tested (lower limit of assay, 4.7 IU per quart [5.0 IU per liter]). One milk sample labeled as containing vitamin D2 (ergocalciferol) contained vitamin D3 (cholecalciferol).
Seven of the 10 samples of infant formula contained more than 200 percent of the amount stated on the label; the sample with the highest concentration contained 419 percent of the stated amount. None of the samples of infant formula contained less than the amount stated.
Conclusions.
Milk and infant-formula preparations rarely contain the amount of vitamin D stated on the label and may be either underfortified or overfortified. Since both underfortification and overfortification are hazardous, better monitoring of the fortification process is needed. (N Engl J Med 1992;326:1178–81.)
Media in This Article
Figure 1
Reverse-Phase High-Performance Liquid Chromatograms of Samples Containing Known Amounts of Vitamin D2 and Vitamin D3 (Upper Panel) and a Lipid Extract of Milk Containing Vitamin D3 (Lower Panel).Table 1
Type of Vitamin D and Vitamin D Concentration in Milk Samples.*Article Activity
- Article
RICKETS plagued the children who lived in the industrial cities of North America and Europe from the 17th through the 19th century. At the beginning of this century, over 85 percent of the children living in these areas had rickets.1 Although cod-liver oil had been used by some physicians to cure this crippling disease, it was not until the early 1900s that Huldschinsky showed that exposure to ultraviolet radiation could cure rickets2 and Hess and Unger demonstrated that exposure to sunlight could cure the disease.3 These observations provided the crucial link between exposure to sunlight and normal skeletal development. In 1924, Steenbock and Black4 and Hess and Weinstock5 independently found that ultraviolet irradiation of human and animal food substances such as corn oil, egg yolk, milk, and rat chow could impart antirachitic activity to them.
These seminal observations were the impetus for the addition of provitamin D2 (ergosterol) to milk, followed by ultraviolet irradiation. Once a simple method of producing vitamin D was developed, vitamin D was added directly to milk. The fortification of milk in Europe and North America resulted in the eradication of rickets as a major health problem in children. In the 1940s and 1950s, however, there were several sporadic outbreaks of vitamin D intoxication in Europe that led to the prohibition of the fortification of foods with vitamin D and a resurgence of rickets in Europe.6 , 7
In 1957, the American Medical Association's Council on Foods and Nutrition8 reaffirmed the importance of vitamin D—fortified milk as the chief means of preventing rickets in children. The council recommended that milk contain 400 IU (10 μg) per quart and that the vitamin D content be measured at least twice yearly by an independent laboratory. The recent report of high concentrations of vitamin D — more than 500 times the amount stated on the label — in milk from a dairy in Massachusetts9 prompted us to determine the vitamin D concentration of randomly selected samples of vitamin D—fortified milk and infant formula.
Methods
We purchased 42 containers of milk and 10 cans of infant formula from supermarkets in five Eastern states. They included 14 samples of whole milk, 10 samples of milk with a fat content of 2 percent, 4 samples of milk with a fat content of 1 percent, and 14 samples of skim milk from 13 milk processors and 10 samples of different types of infant formula from 5 manufacturers. All the samples were purchased before the expiration date and analyzed within 24 hours after purchase. The concentration of vitamin D was determined in 10 ml of each milk sample according to modifications of the procedures of Hollis10 and Chen et al.11
Tritiated vitamin D3 (cholecaliferol) (10,000 cpm; specific activity, 10 to 20 Ci per millimole; Amersham, Arlington Heights, Ill.) in 100 μl of ethanol was added to each 10-ml sample. The samples were equilibrated at room temperature, after which 40 ml of ethyl acetate was added. The samples were shaken and centrifuged, and the organic (upper) phase was removed. The aqueous (lower) phase was extracted twice with 40 ml of ethyl acetate. The organic phases were combined, dried under nitrogen, redissolved in 6 ml of methanol, placed at —80°C for 10 minutes, and then centrifuged. The precipitate was reextracted with methanol and again centrifuged. The supernatants were combined, dried under nitrogen, and redissolved in methylene chloride. Five milliliters of 0.2 N disodium phosphate (at pH 10.5) was added, and the mixture was centrifuged. The organic (lower) phase was removed, and the aqueous phase was reextracted with methylene chloride. The methylene chloride fractions were dried and dissolved in 2 ml of 50 percent methanol in water.
The sample was applied to a C-18 cartridge (Analytichem International, Harbor City, Calif.). The column was eluted with distilled water, 70 percent methanol in distilled water, and then acetonitrile, after which the vitamin D was eluted with methanol. The methanol fraction was dried under nitrogen and redissolved in 1 percent isopropyl alcohol in n-hexane, after which it was fractionated by normal-phase high-performance liquid chromatography with use of an Econosphere silica column (5-μm particle size, 250 by 4.6 mm; Alltech Associates, Deerfield, Ill.) at 1.1 ml per minute. The fractions containing vitamin D2 (ergocalciferol) and vitamin D3 were collected, dried under nitrogen, and dissolved in 25 percent methanol in acetonitrile. The vitamin D2 and vitamin D3 were separated by high-performance liquid chromatography on a reverse-phase Vydac C-18 column (250 by 4.6 mm; 5-μm particle size; Rainin Instruments, Woburn, Mass.).
The concentrations of vitamin D2 and vitamin D3 were determined by comparison of the areas under the peaks for each vitamin with the areas of peaks obtained by high-performance liquid chromatography of samples containing known amounts of vitamin D2 or vitamin D3 (Fig. 1Figure 1
Reverse-Phase High-Performance Liquid Chromatograms of Samples Containing Known Amounts of Vitamin D2 and Vitamin D3 (Upper Panel) and a Lipid Extract of Milk Containing Vitamin D3 (Lower Panel).). The amount of radioactivity recovered was determined in order to measure the overall recovery for both vitamin D2 and vitamin D3, and the results were corrected for this recovery. The recovery for vitamin D2 and vitamin D3 from the reverse-phase column was the same; the typical amount recovered was 50 to 70 percent, and the intraassay and interassay coefficients of variation for the vitamin D assay were 8 percent and 10 percent, respectively.To determine the concentration of vitamin D in infant formula, 5 ml of liquid formula or 0.5 g of powdered formula was saponified and extracted as described previously12; we then followed the two-step Chromatographic procedure, as described for the milk samples.
Results
Figure 1 shows a representative reverse-phase high-performance liquid Chromatographic profile of standard vitamin D2 and vitamin D3 and a lipid extract of milk. There was clear separation of vitamin D2 and vitamin D3 from ultraviolet-absorbing lipid contaminants. To be certain that the vitamin D3 in the milk was stable during storage, we measured, in triplicate, the concentration of vitamin D3 in samples of whole and skim milk on the day of purchase and after storage in a refrigerator (at 4°C) for seven days (until the expiration date). The mean (±SD) vitamin D3 concentrations were similar on both occasions (whole milk, 193±13 vs. 185±5 IU per quart [205± 14 vs. 196±5 IU per liter]; skim milk, 356±33 vs. 333±6 IU per quart [377±35 vs. 353±6 IU per liter]).
The results of the measurements of vitamin D in the milk and infant-formula samples are shown in Tables 1Table 1
Type of Vitamin D and Vitamin D Concentration in Milk Samples.* and 2Table 2
Vitamin D Concentrations in Infant Formula.*. Although each quart of milk was labeled as containing 400 IU (10 μg) of either vitamin D2 or vitamin D3, there was wide variation in the amount of vitamin D measured in the milk samples. For example, the brand A whole milk and milk with 2 percent fat purchased on July 19, 1991, contained 276 IU and 11 IU of vitamin D3 per quart (293 and 12 IU per liter), respectively. The same brand of skim milk purchased at the same time contained no detectable vitamin D3 (lower limit of assay, 4.7 IU per quart [5.0 IU per liter]), but skim-milk samples purchased on August 30, 1991, contained as much vitamin D3 as whole milk or more. Brand B milk with 1 percent fat that was fortified with Lactobacillus acidophilus (Lactaid) or with calcium (Calcimilk) contained 496 IU and 515 IU of vitamin D2 per quart (526 and 546 IU per liter), respectively, whereas brand B skim milk purchased at the same time contained only 155 IU per quart (164 IU per liter), or 39 percent of the amount stated on the label. Brand B skim milk purchased on June 18, 1991, had even less vitamin D2 (87 IU per quart [92 IU per liter]). In brand C milk, not only the content but also the type of vitamin D varied with the date of purchase; one brand J milk sample labeled as containing vitamin D2 contained vitamin D3.Only 12 (29 percent) of the 42 milk samples from the 13 milk processors that we analyzed contained 80 to 120 percent of the amount stated on the label. Twenty-six (62 percent) of the milk samples contained less than 80 percent and 4 (10 percent) contained more than 120 percent of the amount stated on the label.
The vitamin D concentrations of the 10 samples of five brands of infant formula contained from 715 to 1608 IU of vitamin D per quart (756 to 1700 IU per liter) (Table 2). Seven of the 10 samples (70 percent) contained more than 200 percent of the amount stated on the label. That with the highest concentration was the iron-fortified brand Q, which contained 419 percent of the amount of vitamin D stated.
Discussion
In the United States, the chief food that is fortified with vitamin D is milk. Indeed, the fortification of milk and infant formula with vitamin D during the past 60 years has eradicated rickets as a major health problem in the United States. Until the development of sophisticated Chromatographic assays for vitamin D, vitamin D activity in milk was measured by bioassay.13 The Food and Drug Administration Standard of Identity for Milk states that if vitamin D is added, the milk should contain 400 IU per quart and the fortification process should follow standard manufacturing practices. The federal government has given the states the responsibility for monitoring the vitamin D content of milk.
In 1988, a survey of the vitamin D concentrations of fortified milk by the FDA14 revealed that only 26 percent of 669 samples obtained in Oregon, Rhode Island, and Ohio contained 80 to 120 percent of the amount of vitamin D stated on the label. In general, the vitamin D concentration tended to be lower in samples with lower fat content. The FDA speculated that this might result from the method of adding vitamin D, in which the fat is removed from whole milk after the addition of vitamin D, which is soluble in fat. The report urged that this problem be corrected; otherwise, the FDA would institute regulatory programs to ensure compliance. Our results clearly demonstrate that this warning has not been heeded, since only 29 percent of the 42 milk samples we analyzed contained 80 to 120 percent of the amount of vitamin D stated on the labels. Ten percent of the milk samples and all the samples of infant formula contained excessive amounts of vitamin D, but some of the samples of skim milk contained no detectable vitamin D.
The lack of a national program to monitor the vitamin D content of milk has serious and costly consequences. Because the Massachusetts Department of Public Health did not monitor the vitamin D content of the state's milk supply twice a year, as required by law, the fortification of milk with very large amounts of vitamin D in one dairy was not recognized. Nearly 12,000 households were, therefore, at risk of excessive vitamin D intake, and several cases of vitamin D intoxication were recently identified.9
Conversely, the lack of vitamin D in milk can eventually have devastating consequences in both children and elderly persons, who depend on this food source for their vitamin D requirement. If children are not exposed to sunlight, they are at risk for rickets. Elderly people not only have decreased capacity to produce vitamin D in their skin,15 but they are also more likely to have little exposure to sunlight. Therefore, they depend on multivitamins and milk as their principal sources of vitamin D. Several studies in the United States have suggested that 30 to 40 percent of patients with hip fractures are deficient in vitamin D.16 17 18 Thus, elderly people who drink milk that contains no vitamin D or is underfortified with vitamin D are likely to be more prone to have vitamin D deficiency and, therefore, to have an increased risk of hip fracture. This possibility is supported by the recent observation that healthy postmenopausal women with daily vitamin D intakes of only 100 IU can reduce wintertime bone loss by increasing their vitamin D intake.19
Particularly when considered along with the findings of Jacobus et al.,9 the results of this study demonstrate the need for greatly increased testing of all food products containing vitamin D. Although in the past such testing had to be done with cumbersome bioassays, the availability of relatively simple and much more precise Chromatographic methods, such as that used in our study, makes frequent testing much easier. There is no longer any excuse for the failure to monitor vitamin D fortification regularly.
Supported in part by grants (AG-04390 and AR-36963) from the National Institutes of Health.
We are indebted to Dr. Ellen Seely and Dr. Claire Jacobus for their helpful suggestions and to Mr. Jay Bua, Mr. Frank Holick, Ms. Elizabeth Martin, and Ms. Catherine St. Clair for obtaining the milk samples.
Source Information
From the Vitamin D, Skin, and Bone Research Laboratory, Boston University School of Medicine and Boston City Hospital, 80 E. Concord St., M-1013, Boston, MA 02118, where reprint requests should be addressed to Dr. Holick.
- References
References
1
Holick MF. Vitamin D and the skin: photobiology, physiology and therapeutic efficacy for psoriasis. In: Heersche NM, ed. Bone and mineral research. Vol. 7. Amsterdam: Elsevier, 1990:313–66.
2
Huldschinsky
CrossRef | Web of Science3
Hess
Web of Science4
Steenbock
Web of Science5
Hess
Web of Science6
Jeans
CrossRef | Web of Science7
Sheldon
CrossRef8
Statements and decisions of the Council on Foods and Nutrition of the American Medical Association. Chicago: American Medical Association, 1957:35–8.
9
Jacobus
Full Text | Web of Science | Medline10
Hollis
CrossRef | Web of Science | Medline11
Chen
CrossRef | Web of Science | Medline12
Reynolds
CrossRef | Web of Science | Medline13
Holick
Web of Science | Medline14
Tanner
Medline15
Holick
CrossRef | Web of Science | Medline16
Sokoloff
CrossRef | Web of Science | Medline17
Doppelt 18
Kavookjian 19
Dawson-Hughes
Web of Science | Medline
- Citing Articles (60)
Citing Articles
1
P Urbain, F Singler, G Ihorst, H-K Biesalski, H Bertz. (2011) Bioavailability of vitamin D2 from UV-B-irradiated button mushrooms in healthy adults deficient in serum 25-hydroxyvitamin D: a randomized controlled trial. European Journal of Clinical Nutrition 65:8, 965-971
CrossRef2
K.Y. Patterson, K.M. Phillips, R.L. Horst, W.C. Byrdwell, J. Exler, L.E. Lemar, J.M. Holden. (2010) Vitamin D content and variability in fluid milks from a US Department of Agriculture nationwide sampling to update values in the National Nutrient Database for Standard Reference. Journal of Dairy Science 93:11, 5082-5090
CrossRef3
Lisa Liang, Caroline Chantry, Dennis M. Styne, Charles B. Stephensen. (2010) Prevalence and risk factors for vitamin D deficiency among healthy infants and young children in Sacramento, California. European Journal of Pediatrics 169:11, 1337-1344
CrossRef4
A.L. Hanson, L.E. Metzger. (2010) Evaluation of increased vitamin D fortification in high-temperature, short-time–processed 2% milk, UHT-processed 2% fat chocolate milk, and low-fat strawberry yogurt. Journal of Dairy Science 93:2, 801-807
CrossRef5
Jennifer L. Kelly, Jonathan W. Friedberg, Laura M. Calvi, Edwin van Wijngaarden, Susan G. Fisher. (2009) Vitamin D and Non-Hodgkin Lymphoma Risk in Adults: A Review. Cancer Investigation 27:9, 942-951
CrossRef6
Francis B Mimouni, Raanan Shamir. (2009) Vitamin D requirements in the first year of life. Current Opinion in Clinical Nutrition and Metabolic Care 12:3, 287-292
CrossRef7
Michael F. Holick. (2009) Vitamin D and Health: Evolution, Biologic Functions, and Recommended Dietary Intakes for Vitamin D. Clinical Reviews in Bone and Mineral Metabolism 7:1, 2-19
CrossRef8
Amy D. DiVasta, Kristen K. Veen, Catherine M. Gordon. (2009) Vitamin D Deficiency in Children and Its Health Consequences. Clinical Reviews in Bone and Mineral Metabolism 7:1, 52-62
CrossRef9
Ann Prentice. (2008) Vitamin D deficiency: a global perspective. Nutrition Reviews 66, S153-S164
CrossRef10
Jordan L. Geller, John S. Adams. (2008) Vitamin D therapy. Current Osteoporosis Reports 6:1, 5-11
CrossRef11
ALLEN W. ROOT, FRANK B. DIAMOND. 2008. Disorders of Mineral Homeostasis in the Newborn, Infant, Child, and Adolescent. , 686-769.
CrossRef12
2007. Vitamin D. , 83-117.
CrossRef13
Elizabeth R. Bertone-Johnson. (2007) Prospective Studies of Dietary Vitamin D and Breast Cancer: More Questions Raised than Answered. Nutrition Reviews 65:10, 459-466
CrossRef14
Claudia Plaisted Fernandez, Kelly Adams. 2007. Vegetarian Diets in Health Promotion and Disease Prevention. , 389-413.
CrossRef15
Syed Arif Kazmi, Reinhold Vieth, Dérick Rousseau. (2007) Vitamin D3 fortification and quantification in processed dairy products. International Dairy Journal 17:7, 753-759
CrossRef16
Heike A. Bischoff-Ferrari. (2007) The 25-hydroxyvitamin D threshold for better health. The Journal of Steroid Biochemistry and Molecular Biology 103:3-5, 614-619
CrossRef17
Helen M. Pappa, Richard J. Grand, Catherine M. Gordon. (2006) Report on the Vitamin D Status of Adult and Pediatric Patients with Inflammatory Bowel Disease and its Significance for Bone Health and Disease. Inflammatory Bowel Diseases 12:12, 1162-1174
CrossRef18
R. RIZZOLI, J. A. EISMAN, J. NORQUIST, Ö. LJUNGGREN, G. KRISHNARAJAH, S-K LIM, J. CHANDLER. (2006) Risk factors for vitamin D inadequacy among women with osteoporosis: an international epidemiological study. International Journal of Clinical Practice 60:8, 1013-1019
CrossRef19
M. F. Holick. (2006) High Prevalence of Vitamin D Inadequacy and Implications for Health. Mayo Clinic Proceedings 81:3, 353-373
CrossRef20
2006. Vitamin D analogues. , 3669-3677.
CrossRef21
C. F. Garland. (2005) The Role of Vitamin D in Cancer Prevention. American Journal of Public Health 96:2, 252-261
CrossRef22
Heike A Bischoff-Ferrari. (2005) Extra-skeletal effects of vitamin D. Current Opinion in Endocrinology & Diabetes 12:6, 464-470
CrossRef23
Charles F. Hildebolt. (2005) Effect of Vitamin D and Calcium on Periodontitis. Journal of Periodontology 76:9, 1576-1587
CrossRef24
R. J. Mellanby, A. P. Mee, J. L. Berry, M. E. Herrtage. (2005) Hypercalcaemia in two dogs caused by excessive dietary supplementation of vitamin D. Journal of Small Animal Practice 46:7, 334-338
CrossRef25
Joellen Welsh. 2005. Vitamin D-Regulated Pathways. .
CrossRef26
Jean-Yves Reginster. (2005) The high prevalence of inadequate serum vitamin D levels and implications for bone health. Current Medical Research and Opinion 21:4, 579-585
CrossRef27
Leif Mosekilde. (2005) Vitamin D and the elderly. Clinical Endocrinology 62:3, 265-281
CrossRef28
M.A. Lloyd, J. Zou, H. Farnsworth, L.V. Ogden, O.A. Pike. (2004) Quality at Time of Purchase of Dried Milk Products Commercially Packaged in Reduced Oxygen Atmosphere. Journal of Dairy Science 87:8, 2337-2343
CrossRef29
Catherine M Gordon, Laura K Bachrach, Thomas O Carpenter, Gerard Karsenty, Frank Rauch. (2004) Bone health in children and adolescents. Current Problems in Pediatric and Adolescent Health Care 34:6, 226-242
CrossRef30
Carolyn Moore, Mary M. Murphy, Debra R. Keast, Michael F. Holick. (2004) Vitamin D intake in the United States. Journal of the American Dietetic Association 104:6, 980-983
CrossRef31
Laurie Hickey, Catherine M Gordon. (2004) Vitamin D deficiency: new perspectives on an old disease. Current Opinion in Endocrinology & Diabetes 11:1, 18-25
CrossRef32
Lorraine A. Fitzpatrick. (2004) Pathophysiology of bone loss in patients receiving anticonvulsant therapy. Epilepsy & Behavior 5, 3-15
CrossRef33
L. Ovesen. 2004. Vitamin D fortification and bone health. , 139-173.
CrossRef34
D. Sudhaker Rao, Suhad Alqurashi. (2003) Management of vitamin D depletion in postmenopausal women. Current Osteoporosis Reports 1:3, 110-115
CrossRef35
Rick L. Smith. (2003) Calcium and Vitamin D Supplementation in Nursing Home Residents. Journal of the American Medical Directors Association 4:2, S24-S31
CrossRef36
Michael F. Holick. (2002) Vitamin D: the underappreciated D-lightful hormone that is important for skeletal and cellular health. Current Opinion in Endocrinology & Diabetes 9:1, 87-98
CrossRef37
J. A. Paixão, T. L. M. Stamford. (2002) LACTEAL MATRICES. A SINGLE GUIDE FOR EXTRACTION AND QUANTIFICATION OF FAT-SOLUBLE VITAMINS. Journal of Liquid Chromatography & Related Technologies 25:2, 217-239
CrossRef38
S.C. Murphy, L.J. Whited, L.C. Rosenberry, B.H. Hammond, D.K. Bandler, K.J. Boor. (2001) Fluid Milk Vitamin Fortification Compliance in New York State. Journal of Dairy Science 84:12, 2813-2820
CrossRef39
Rick L. Smith. (2001) Calcium and Vitamin D Supplementation in Nursing Home Residents. Journal of the American Medical Directors Association 2:6, 289-296
CrossRef40
Claudia Plaisted, Kelly Adams. 2001. Vegetarian Diets in Health Promotion and Disease Prevention. .
CrossRef41
Sarah L. Morgan. (2001) Calcium and Vitamin D in Osteoporosis. Rheumatic Disease Clinics of North America 27:1, 101-130
CrossRef42
Melissa K. Thomas, Marie B. Demay. (2000) VITAMIN D DEFICIENCY AND DISORDERS OF VITAMIN D METABOLISM. Endocrinology & Metabolism Clinics of North America 29:3, 611-627
CrossRef43
H. Faulkner, A. Hussein, M. Foran, L. Szijarto. (2000) A Survey of Vitamin A and D Contents of Fortified Fluid Milk in Ontario. Journal of Dairy Science 83:6, 1210-1216
CrossRef44
C Banville, J.C Vuillemard, C Lacroix. (2000) Comparison of different methods for fortifying Cheddar cheese with vitamin D. International Dairy Journal 10:5-6, 375-382
CrossRef45
D. Sudhaker Rao. (1999) Perspective on Assessment of Vitamin D Nutrition. Journal of Clinical Densitometry 2:4, 457-464
CrossRef46
M Wjst, S Dold. (1999) Genes, factor X, and allergens: what causes allergic diseases?. Allergy 54:7, 757-759
CrossRef47
Robert M. Russell, Helen Rasmussen, Fada. (1999) The Impact of Nutritional Needs of Older Adults on Recommended Food Intakes. Nutrition in Clinical Care 2:3, 164-176
CrossRef48
J. Jean, C. Turcotte, R.E. Simard, I. Fliss. (1999) Production and characterization of polyclonal antibodies against cholecalciferol (vitamin D3). Journal of Immunological Methods 223:2, 155-163
CrossRef49
1998. Vitamin D. .
CrossRef50
Thomas, Melissa K., Lloyd-Jones, Donald M., Thadhani, Ravi I., Shaw, Albert C., Deraska, Donald J., Kitch, Barrett T., Vamvakas, Eleftherios C., Dick, Ian M., Prince, Richard L., Finkelstein, Joel S., . (1998) Hypovitaminosis D in Medical Inpatients. New England Journal of Medicine 338:12, 777-783
Full Text51
SOROKU NISHIYAMA. (1997) Hypercalcemia in children: An overview. Pediatrics International 39:4, 479-484
CrossRef52
Hilary J. Powers. (1997) Vitamin requirements for term infants: considerations for infant formulae. Nutrition Research Reviews 10:01, 1
CrossRef53
H. Indyk, V. Littlejohn, D.C. Woollard. (1996) Stability of vitamin D3 during spray-drying of milk. Food Chemistry 57:2, 283-286
CrossRef54
Tammy Hicks, A.P. Hansen, J.E. Rushing. (1996) Procedures Used by North Carolina Dairies for Vitamins A and D Fortification of Milk. Journal of Dairy Science 79:2, 329-333
CrossRef55
M. Joseph Scobey, Wendy J. Holmgren, Rajasingam S. Jeyendran. (1994) Effect of preincubation of human spermatozoa in milk on penetration of zona-free hamster oocytes: Comparison to TEST yolk. Journal of Assisted Reproduction and Genetics 11:3, 162-164
CrossRef56
A. Kurmann, H. Indyk. (1994) The endogenous vitamin D content of bovine milk: influence of season. Food Chemistry 50:1, 75-81
CrossRef57
Chen, Tai C., Shao, Qing, , Heath, Hunter III, , Holick, Michael F., . (1993) An Update on the Vitamin D Content of Fortified Milk from the United States and Canada. New England Journal of Medicine 329:20, 1507-1507
Full Text58
(1992) Vitamin D Content of Infant Formula. New England Journal of Medicine 327:12, 894-895
Full Text59
Haddad, John G., . (1992) Vitamin D — Solar Rays, the Milky Way, or Both?. New England Journal of Medicine 326:18, 1213-1215
Full Text60
Jacobus, Claire H., Holick, Michael F., Shao, Qing, Chen, Tai C., Holm, Ingrid A., Kolodny, Jonathan M., Fuleihan, Ghada El-Hajj, Seely, Ellen W., . (1992) Hypervitaminosis D Associated with Drinking Milk. New England Journal of Medicine 326:18, 1173-1177
Full Text
- Letters
