Vitamin Information Center

Exclusive breastfeeding can increase a child’s risk of developing rickets because breast milk alone does not provide adequate levels of vitamin D, a critical ingredient that helps to absorb calcium and build strong bones, the New York Times reports. Rickets develops when a child’s vitamin D levels are too low and is characterized by the curving of a child’s legs and the softening of other bones. Some children are asymptomatic.

Darker-skinned children have a greater risk of vitamin D deficiency than other children because they do not absorb vitamin D as easily through the skin. Sunlight enables the skin to synthesize vitamin D.

Cases of nutritional rickets among infants and young children in the U.S. have been “accumulating over the last decade or so,” and children with the condition are more likely to be black or dark-skinned and have been breastfed exclusively for an extended period of time without vitamin supplementation, according to the Times. Some experts say that an increase in infants being exclusively breastfed, more children drinking soda or juice and less milk, and children spending less time in the sun could contribute to rickets re-emerging as a public health problem, the Times reports.

According to the Times, while physicians have known for years that exclusive breastfeeding is associated with vitamin D deficiency in infants and rickets, many are “reluctant to say anything that might discourage breastfeeding.” The American Academy of Pediatrics in 2003 recommended that infants who are exclusively breastfed receive vitamin D drops daily.

According to one study on rickets and vitamin D that included mostly black and Hispanic infants and toddlers, 40% of the participants had low levels of vitamin D, 12% were vitamin D deficient, 13 children showed evidence of bone loss and three children had signs of rickets. The study, published in the June issue Archives of Pediatrics & Adolescent Medicine, also found that breastfeeding without vitamin supplementation was a significant risk factor for rickets.

Study author Catherine Gordon, director of Children’s Hospital Boston’s bone health program, said, “I completely support breastfeeding, and I think breast milk is the perfect food, and the healthiest way to nourish an infant. However, we’re finding so many mothers are vitamin D deficient themselves that the milk is therefore deficient, so many babies can’t keep their levels up.” She added, “They may start their lives vitamin D deficient, and then all they’re getting is vitamin D deficient breast milk” (Rabin, New York Times, 8/26).

Infants who get vitamin D supplements have a lower risk of getting type 1 diabetes, a small study suggests.

The study was not a clinical trial. Researchers Christos S. Zipitis, MBChB, of NHS Foundation Trust, and Anthony K. Akobeng, MBChB, combined data from five studies that looked for differences between kids who got type 1 diabetes and kids who did not.

The combined data suggest that giving infants vitamin D supplements cuts their risk of type 1 diabetes by 29%.

It’s not clear how vitamin D might fight diabetes. However, Zipitis and Akobeng note that insulin-making beta cells in the pancreas are sensitive to vitamin D.

Moreover, the body makes vitamin D in response to sunlight on the skin. The researchers note that infants in wintry Finland are 400 times more likely than a child in sunny Venezuela to have childhood diabetes.

The researchers note that randomized clinical trials will be needed to determine whether vitamin D truly helps prevent diabetes.

Pediatricians already recommend vitamin D supplements for children to prevent rickets. The American Academy of Pediatrics recommends that all infants, including those who are exclusively breastfed, have a minimum intake of 200 IU of vitamin D per day during the first two months of life. After that, daily intake of 200 IU of vitamin D per day is recommended throughout childhood and adolescence.

Zipitis and Akobeng report their findings in the online edition of Archives of Diseases in Childhood.

BEIRUT, Lebanon, May 27 — High weekly doses of vitamin D₃ for a year raise serum 25-hydroxyvitamin D levels safely in adolescents, a randomized study showed. Hypovitaminosis D is prevalent in youth worldwide, but recommended doses of 200 IU/day are insufficient to raise levels of serum 25-hydroxyvitamin D levels to optimum. At the same time, the safety of vitamin D at doses exceeding 200 IU/day has been unknown for adolescents.

Seeking to ascertain the optimal serum vitamin D level for them, Ghada El-Hajj Fuleihan, M.D., M.P.H., of American University of Beirut, and colleagues found that vitamin D₃ at a dose 10 times the recommended intake was well tolerated by those ages 10 to 17.

The vitamin D levels achieved with the highest dose by the end of the yearlong study were within the optimal range for adults — over 30 ng/mL — but the low dose, which matched recommendations of the Institute of Medicine and American Academy of Pediatrics, failed to meet the goal.

In 115 children ages 10 to 17, mean serum 25-hydroxyvitamin D levels increased significantly from 15 ± 7 to 36 ± 22 ng/mL after one year of weekly treatment with 14,000 IU of vitamin D₃ (P<0.0001), Dr. El-Hajj Fuleihan and colleagues reported online in the Journal of Clinical Endocrinology & Metabolism. The study will be published in the July print issue.

Both the Institute of Medicine and the pediatrics academy recommend a weekly intake of 1,400 IU, which, in the current study, was associated with a smaller increase in mean serum 25-hydroxyvitamin D levels in 114 children after one year (15 ± 8 to 19 ± 7 ng/mL, P<0.0001).

None of the participants developed vitamin D intoxication, the researchers said.

The findings are “particularly relevant in view of the increasingly recognized musculoskeletal benefits of vitamin D not only in the adult but also in the pediatric age group, and the pleiotropic effects of vitamin D on multiple physiologic and pathologic processes,” they said.

“The high prevalence of hypovitaminosis D worldwide across all age groups, the fact that many diseases of adulthood are rooted in the pediatric age group, and the safety data available to-date render it quite compelling to modify the current recommendations regarding adequate vitamin D intake not only for adults but also for children,” they concluded.

The safety of vitamin D doses as high as 10,000 IU per day had been established in adults, the researchers said, but pediatric data were lacking.

To explore the issue, Dr. Fuleihan and colleagues undertook a 16-week pilot study that randomized 26 children ages 10 to 17 (mean age 13.7) to a weekly vitamin D₃ dose of 14,000 IU (17) or placebo (nine) for eight weeks followed by eight weeks without treatment.

Mean serum 25-hydroxyvitamin D levels increased significantly in the treatment group from 44 ± 11 ng/mL at baseline to 54 ± 19 ng/mL at eight weeks (P=0.033) but dropped back down within two weeks of stopping therapy. There was a steady decrease in the levels with placebo (P<0.01) through 16 weeks.

After establishing the safety of the high dose, the researchers randomized 340 children (mean age 13.1, 51% male) to weekly vitamin D₃ doses of 1,400 IU (114) or 14,000 IU (115) or placebo (111) for one year.

Among girls, mean serum 25-hydroxyvitamin D levels increased significantly from baseline with placebo (P=0.041), the low dose of vitamin D₃ (P=0.011), and the high dose (P<0.0001). The level in the high-dose group was significantly higher than those in the other two groups (P<0.0001) at one year.

Among boys, serum vitamin D levels increased with both doses of vitamin D₃ (P=0.0034 with the low dose and P<0.0001 with the high dose). As with girls, the level in the high-dose group was significantly higher than those in the other two groups (P<0.001) at one year.

Mean serum calcium and 1,25-hydroxyvitamin D levels did not change significantly from baseline in any group in either the pilot or long-term study.

One major adverse event — glomerulonephritis — occurred in the low-dose group, and the participant dropped out at seven months.

The researchers previously reported that participants in the high-dose group had “substantial increments in lean mass, bone area, and bone mass.” This confirmed that the serum vitamin D levels achieved in the study were beneficial, as well as safe, they said.

They acknowledged some limitations, including the lack of data on urinary calcium excretion and the fact that they did not screen the children with ultrasonography for kidney stones which represented a potential significant adverse affect. They pointed out that urinary calcium would have been an earlier safety marker, as it likely increases to maintain serum calcium normal with increased calcium absorption associated with increased vitamin D intake.

Also, they said that the results might not apply to different age groups or to children with different calcium and vitamin D intake.

Finally, the mean serum 25-hydroxyvitamin D levels in the study might not be reproducible because of inter-assay variations between kits, they said.

The study was supported by an educational grant from the Nestle Foundation and a grant from Merck KGaA, which provided some of the vitamin D₃ used in the study.

Primary source: Journal of Clinical Endocrinology & Metabolism
Source reference:
Maalouf J, et al “Short term and long term safety of weekly high dose vitamin D₃ supplementation in school children” J Clin Endocrinol Metab 2008; DOI: 10.1210/jc.2007-2530.