At least 40 percent of American infants and toddlers are not getting enough vitamin D, according to a report in Archives of Pediatrics and Adolescent Medicine.
Twelve percent of the youngest children in the US are already deficient in vitamin D, and another 28 percent are at risk for vitamin D deficiency, according to the study.
Because human breast milk lacks sufficient vitamin D, the number of babies in the research sample being breast-fed were important to the findings.
"These data underscore the fact that breast-fed infants should be supplemented with vitamin D," says study author Dr. Catherine Gordon at Children's Hospital in Boston.
She adds that mothers who are breastfeeding often need vitamin D supplements as well.
Breastfeeding is a known risk factor for low vitamin D levels in infants, which is why many pediatricians routinely recommend vitamin D supplementation for breast-fed infants.
Other factors that may contribute to low levels of vitamin D include not drinking enough vitamin D-fortified milk (for toddlers), staying out of the sun, or using sunscreen.
Vitamin D, also known as the sunshine vitamin, is produced naturally when the body reacts to sunlight.
However, the use of sunscreen and advice to stay out of the sun - which is important for preventing skin cancer - may also be reducing levels of vitamin D in people.
Few foods naturally contain vitamin D, which is essential for strong bones because it helps the body absorb calcium.
In addition to helping maintain bone health, Dr. Gordon says that vitamin D also appears to play a role in maintaining the immune system.
Persons with low levels of vitamin D may be more susceptible to autoimmune diseases, such as type 1 diabetes and multiple sclerosis, and to certain cancers.
Previously, Dr. Gordon studied vitamin D levels in adolescents and found very high levels - about 42 percent - of vitamin D deficiency in teens. That finding made her interested in assessing levels in younger children.
The current study included 380 children between eight and 24 months old. About 80 percent were from urban areas, and the majority of the youngsters were African American or Hispanic, according to the study. However, the study made no association between skin pigmentation and vitamin D levels.
For this study, the researchers defined severe vitamin D deficiency as blood levels of less than 8 nanograms per milliliter (ng/mL), vitamin D deficiency as less than 20 ng/mL and suboptimal as less than 30 ng/mL.
Dr. Gordon says there is some debate within the medical community about what truly signifies vitamin D deficiency, but that they felt current evidence supports the levels they used, and less than 20 ng/mL is the level her hospital uses as a cut-off point.
In an accompanying editorial, Dr. James Taylor, at the University of Washington, says that although he believes the study was well done, Dr. Gordon and her colleagues used a "higher cut-off" than what has been used by other researchers.
But, he adds, because Dr. Gordon's team found X-ray evidence of low bone density in children who fell into their category of low levels of vitamin D, "it might be that this might be an indication of long-term problems.
“If this is the case, then [Dr.] Gordon and colleagues might have picked the right definition,” says Dr. Taylor. “However, it might be that for many of the children with osteopenia [low bone density], the changes are transient and not indicative of disease. Time and more research will tell."
The key findings from the study say that breastfeeding without vitamin D supplementation is a risk factor for vitamin D deficiency, and that a higher body- mass index was associated with a risk of vitamin D deficiency.
There was no association between the seasons - an indication of possible sun exposure - and vitamin D deficiency.
There was no association between skin pigmentation and vitamin D deficiency. Consumption of vitamin D-fortified milk confers protection against deficiency.
Dr. Gordon says it is very difficult to consume too much vitamin D, so she recommends vitamin D supplements for breastfeeding infants and lactating mothers. She also recommends a multivitamin containing vitamin D for older children.
Dr. Taylor is not as convinced about the need for routine supplementation, however.
"I think that more research is needed before routine vitamin D supplementation is recommended for all children," he says.
Always consult your physician for more information.
There are many reasons why breast milk is the best milk, including the following:
Research has found that breastfed babies perform better on different kinds of intelligence tests as they grow older. They also develop better eye function. This is due mostly to certain types of fat (fatty acid chains) in human milk, which are not available in artificial formulas.
The sugar (carbohydrate) and protein in breast milk are also designed to be used easily and more completely by the human baby. Breast milk is the perfect first food to help your baby achieve every aspect of ideal growth and development.
The American Academy of Pediatrics recommends that babies who are exclusively breastfed receive additional vitamin D.
Your baby's physician can recommend the proper type and amount of vitamin D supplement for your baby.
Antibodies in human milk directly protect against infection. Other anti-infective factors create an environment that is friendly to "good" bacteria, referred to as "normal flora," and unfriendly to "bad" bacteria, viruses, or parasites.
Human milk also appears to have properties that help a baby's own immune system work best. If your baby does become ill when breastfeeding and receiving your milk, the infection is likely to be less severe.
A nutritious, yet easily digested first food is important for a baby's immature digestive tract. Your baby uses less energy, yet breaks your milk down more completely into its basic ingredients, so the nutrients, anti-infective factors, and all the other ingredients in your milk are more available to fuel your baby's body functions and to promote your baby's growth and development.
The high bio-availability of nutrients in human milk means your baby gets more benefits from the nutrients it contains - even for nutrients that appear in lower levels in breast milk when compared to artificial formulas (because your baby's body can absorb and use them most effectively).
Suitability is also thought to be one reason that breastfed babies are less likely to develop allergic-related skin conditions and asthma.
The digestibility, bio-availability, and suitability of your milk means that your baby's body is able to work less yet receive more nourishment.
Always consult your physician for more information.
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