By Kathy Sena
BEING ACTIVE AS A YOUNGSTER PAYS DIVIDENDS LATER
Living an active lifestyle at age 5 helps kids stay lean as they age -even if they don't remain as active later in childhood, a new University of Iowa study shows.
"We call this effect 'banking' because the kids benefit later on, similar to having a savings account at a bank. The protective effect is independent of what happens in between," says lead author Kathleen Janz, professor of health and sport studies in the UI College of Liberal Arts and Sciences. "The implication is that even 5-year-olds should be encouraged to be as active as possible because it pays off as they grow older."
The UI team tested the body fat and activity level of 333 kids at ages 5, 8 and 11 using a special scanner that accurately measures bone, fat and muscle tissue, and an accelerometer that measures movement every minute. The kids wore the accelerometers to record their activity level for up to five days, providing much more reliable data than relying on kids or parents to track minutes of exercise.
The study, published in the American Journal of Preventive Medicine, indicates that kids who are active at age 5 end up with less fat at age 8 and 11, even when controlling for their accumulated level of activity.
The average 5-year-old in the study got 30 minutes of moderate-to- vigorous exercise per day. For every 10 minutes on top of that, kids had one-third of a pound less fat tissue at ages 8 and 11.
Janz says further investigation is needed to learn what happens to the active kids' bodies that keeps them in better shape down the road. It may be possible that the active 5-year-olds didn't develop as many fat cells, improved their insulin response or that something happened metabolically that provided some protection even as they became less active.
The study also indicates that boys are more likely to experience the sustained benefit from being active as preschoolers, possibly because they are more active at age 5 than girls, highlighting a need to especially encourage young girls to exercise.
The U.S. Centers for Disease Control and Prevention recommend that kids get at least 60 minutes of age-appropriate physical activity every day - "and an activity like coloring madly won't cut it," Janz says.
The challenge is that it can be difficult to measure minutes of activity, since kids exert themselves in short bursts, like sprinting after a ball, rather than in continuous activities, like jogging. So what can parents do?
"Avoid long periods - more than 60 minutes - of sedentary activity, insist that schools provide morning and afternoon recesses and whenever possible get kids outside," says Janz. Kids who meet the CDC activity recommendations tend to be kids who spend a fair amount of time outdoors enjoying unstructured play," she adds. "In the end, it doesn't take that much extra physical activity to see a measurable outcome. Even 10 extra minutes a day makes a difference in protecting against excessive fat gains."
DIABETES GENE TIED TO LOWER BIRTH WEIGHT
Pediatric researchers have found that a gene previously shown to be involved in the development of type 2 diabetes also predisposes babies to having a lower birth weight. This may shed light on how prenatal events may set the stage for developing diabetes in later childhood or adulthood, according to the results of a new study.
Researchers from The Children's Hospital of Philadelphia and the University of Pennsylvania School of Medicine published their study in the online version of the medical journal Diabetes.
"It's a bit unusual to find a gene linked to both prenatal events and to a disease that occurs later in life," says study leader Struan F. A. Grant, Ph.D., a researcher at The Children's Hospital of Philadelphia. "This gene variant carries a double whammy, in raising the risk of both lower birth weight and the development of type 2 diabetes in later life."
Type 2 diabetes occurs either when the pancreas produces too little insulin or when the body cannot efficiently use the insulin that is produced. Formerly called adult-onset diabetes and still most common in adults, type 2 diabetes has been increasing sharply among children.
Grant and his fellow researchers investigated 20 gene locations previously reported to be associated with type 2 diabetes. Drawing on data from some 5,700 children in an ongoing study of childhood obesity at Children's Hospital, the researchers compared birth weights with the occurrence of the 20 gene variants.
They found that one of the gene variants, called CDKAL1, had a strong association with lower birth weight - a finding that supports the so-called "fetal-insulin hypothesis." Previous studies by European diabetes researchers had suggested that this gene variant was implicated in both lower birth weight and type 2 diabetes, and the current study, using a large sample size, reinforced that association.
The researchers believe that under this hypothesis, a slight underproduction of insulin (an important fetal growth factor) during the prenatal period may cause a baby to be born smaller. Low birth weight is already known to increase the risk of disease later in life, and the fetal-insulin hypothesis proposes that the same gene that causes lower birth weight also increases the risk of developing type 2 diabetes.
Grant says further research may investigate how the gene functions and may also study whether it may influence the risk of developing other diseases in later life.
MILLIONS OF U.S. KIDS ARE LOW IN VITAMIN D
Seven out of 10 U.S. children have low levels of vitamin D, raising their risk of bone and heart disease, according to a study of more than 6,000 children by researchers at Albert Einstein College of Medicine at Yeshiva University in New York City. The findings suggest that vitamin D deficiency could place millions of children at risk for high blood pressure and other risk factors for heart disease. The study was published in the online version of the medical journal Pediatrics.
Vitamin D deficiency was thought to be relatively rare in the U.S. However, recent studies have documented this growing problem in adults. With cases of rickets (a bone disease in infants caused by low vitamin D levels) on the rise, it became clear that many children were also not getting enough of this essential vitamin, which is needed for healthy bone growth and other biological processes.
"Several small studies had found a high prevalence of vitamin D deficiency in specific populations of children, but no one had examined this issue nationwide," says study leader Michal L. Melamed, M.D., assistant professor of medicine at Einstein.
The researchers looked at data on more than 6,000 children and young adults ages 1 to 21, collected by the National Health and Nutrition Examination Survey from 2001 to 2004. Low vitamin D levels were especially common in children who were older, female, African-American, Mexican-American, obese, who drank milk less than once a week or who spent more than four hours a day inside watching TV, playing videogames or using computers.
The widespread use of sunscreens, which block UV-B rays, has only compounded the problem, says Melamed. The body uses UV-B sunlight to convert a form of cholesterol in the skin into vitamin D. "It would good for parents to turn off the TV and send their kids outside," says Melamed. "And unless they burn easily, don't put sunscreen on them until they've been out in the sun for 10 minutes, so they get the good stuff but not sun damage."
Melamed says children should consume more foods rich in vitamin D, such as milk and fish. "But it's very hard to get enough vitamin D from dietary sources alone," she says. Supplements are especially important for infants who are breast-fed, say the researchers. Breast milk contains relatively little vitamin D, while formula is fortified with the vitamin.
Vitamin D supplementation can help. In the study, children who took vitamin D supplements (400 IU/day) were less likely to be deficient in the vitamin. However, only four percent of the study population actually used supplements. The American Academy of Pediatrics, which recently updated its vitamin D guidelines, now recommends that infants, children and teens take 400 IU per day in supplement form.
- Kathy Sena is a freelance journalist specializing in health and parenting issues and is the mother of a 13-year-old son. Visit her blog here on our site.