Vitamin D remains one of my favorite nutrients. It has a Cinderella story arc, ignored for decades and suddenly rocketing to fame thanks to the persistence of a handful of dedicated researchers. There’s more news today, including a new study from Iran of all places (this is the second time I’ve seen nutrition research from Iran in the past month).
The details: the subjects were 77 women who were either obese or overweight. They were divided into 2 groups: vitamin D supplemented or placebo. The study lasted 12 weeks. The women who were taking vitamin D had increased HDL levels, which is good for heart health. They also experienced some increase in LDL cholesterol. That might seem like a bad thing, but the researchers looked closer at this and found that other blood lipid factors were changed in a way that made the LDL less harmful. Conclusion: vitamin D improved markers for heart disease risk. However, since the study was short, there was no way to conclude that the vitamin D actually prevented any heart attacks. A study that evaluated actual health outcomes would take years and require far more subjects.
In other D news, pediatricians from the Johns Hopkins Children’s Center are advising all children be screened for suspected vitamin D deficiency.
- those with vitamin D-poor diets
- breast-fed infants because breast milk contains minimal vitamin D
- obese children
- those with darker skin because darker skin synthesizes less vitamin D from sun exposure than lighter skin
- those with certain medical conditions, including cystic fibrosis, type 1 and type 2 diabetes and certain gastrointestinal disorders, such as inflammatory bowel disease, which can interfere with food absorption
Children who fit any of those categories should be tested. The doctors note that deficiency may affect as many as 1 in 10 children, with 60% of children at suboptimal levels. The more risk factors, the more important a blood test would be. An obese* child with darker pigmented skin and poor vitamin D intake from milk would be especially likely to be deficient. While breast fed babies are routinely put on vitamin D supplements, research shows that when the mother has adequate blood levels, her breast milk vitamin D levels increase.
*vitamin D is fat soluble, and can end up sequestered in fat cells, making it unavailable for important metabolic functions. This is also true for adults.