Is it possible that lack of a key nutrient could actually put a child at risk for obesity? Vitamin D is important for healthy growth and development particularly of bones throughout childhood. But could a deficiency of this important nutrient affect more than just the skeleton? A study published in the American Journal of Clinical Nutrition examines the relationship between vitamin D deficiency and risk of childhood obesity. Obesity in childhood is a risk factor for adult obesity, heart disease and diabetes.
This study followed 479 school children in Bogota, Colombia, aged 5 to 12 years for about two-and-a-half years on average. They took fasting blood samples and a variety of physical measurements. At baseline, 10 percent of the children were considered vitamin D deficient by prevailing clinical standards, and another 46 percent were considered vitamin D insufficient.
The researchers found that vitamin D deficiency and insufficiency was associated with a 0.1 point yearly increase in BMI and a substantial 0.8 cm yearly increase in waist circumference compared to vitamin D sufficiency. While these numbers may seem modest, bear in mind that they are annual figures, meaning that the effects add up over the course of childhood and can translate into significant overall body fatness. The researchers also saw slower increases in height among girls, but not boys, who were vitamin D deficient. These findings were independent of whether the children were considered thin, normal weight or overweight at the beginning of the study.
The key caveat of these findings is the old chicken and egg argument: Were heavier kids more likely to have lower blood levels of vitamin D as the study progressed due to the tendency of this fat-soluble vitamin to be stored in body fat rather than circulating around in the bloodstream? Or did the vitamin D deficiency actually cause the increase in body fat? Only more research studies with different designs will be able to clear up this question for sure.
Previous studies suggest that vitamin D may influence fat mass accumulation through its influence on calcium regulation within the cells. Since calcium has been shown to influence the breakdown of fat cells and storage of fat within these cells, it is thought that vitamin D might influence Body Mass Index (BMI) and metabolism via this mechanism. Other research suggests vitamin D status in kids can affect risk of conditions as variable as asthma attacks to the seasonal flu.
Here in the U.S., the American Academy of Pediatrics recommends a daily intake of 400 IU of vitamin D for infants, children and teens. Since this important nutrient is not widely available in the food supply, many experts suggest using dietary supplements to meet vitamin D needs. Nonetheless, some food sources of vitamin D include:
- Fortified yogurt (6 oz.) – 80 IU
- Fortified ready-to-eat cereals (1 cup) – 40 IU
- Egg yolk — 25 IU
- Fortified orange juice (1 cup) — 100 IU