A case against vitamin D
In a large review of studies, researchers have found almost no evidence that taking vitamin D supplements has any effect in preventing osteoporosis in middle-age adults.
The analysis, published online in The Lancet, included 23 randomized trials that measured the effect of vitamin D on bone density at four sites — spine, neck, hip and forearm — and included more than 4,000 generally healthy participants whose average age was 59.
The studies used dosages that varied from 500 units a day to 800 or more, given on varying schedules. In some studies, the subjects were given calcium as well.
Neither the pooled data nor any single study showed a significant increase in bone density across all four sites, and the overall number of positive results was no better than would be expected by chance.
The large number of participants and the wide range of regimens give the review's conclusions considerable strength.
The authors write that the widely believed idea that vitamin D promotes bone mineralization is probably incorrect.
"We're not talking about people who are really vitamin D-deficient," said the lead author, Dr. Ian R. Reid, a professor of medicine at the University of Auckland in New Zealand. "But for healthy people focused on osteoporosis prevention, vitamin D does not make a positive contribution."
The spanking backlash
Spare the rod and spoil the child? A new study suggests that the opposite may be true: Spanking could increase the risk of bad behavior.
Using a nationally representative sample, researchers interviewed 1,933 parents when their children were 3 years old and again at 5, asking whether and how often they were spanked. More than half of the mothers and a third of the fathers had spanked their children, with the frequency declining slightly by age 5.
Then the scientists tested the children at age 9, using more than 50 questions to assess aggression and rule-breaking. They also tested vocabulary. The report was published Monday in Pediatrics.
After controlling for numerous variables — a child's age and birth weight, aggression and vocabulary skills at younger ages, family income and race, among many others — the researchers found that maternal spanking at age 5 was significantly associated with greater aggression and rule-breaking and lower scores on the vocabulary test at age 9.
"Spanking does make the kid stop," said the lead author, Michael J. MacKenzie, an associate professor at the Columbia School of Social Work. "It gives the immediate feedback that it's working. But the goal is to have kids regulate themselves over time. And in that, spanking fails."