New study finds link between kids’ BMI and food prices
The study - The Effect of Food and Beverage Prices on Children’s Weights, “supports the idea that food prices have small, but statistically significant effects on children’s BMI” conclude the authors.
“Lower prices for soda, starchy vegetables, and sweet snacks have likely led to increases in children’s BMI. The reverse is true for some healthier foods such as low-fat milk and dark green vegetables… The effect of subsidizing healthy food may be just as large as raising prices of less healthy foods.”
Price elasticity and food/drink
Conducted by Minh Wendt and Jessica Todd for USDA’s economic research service, the study contributes to a growing body of research exploring price elasticity (the extent to which changes in price impact consumption) for foods and drinks, and follows calls for soda taxes to combat obesity.
The authors looked at how prices of carbonated sweetened beverages, fruit drinks, 100 percent juices, low-fat milk, whole and 2% milk, starchy veg (corn, potatoes), dark green veg (spinach and broccoli), and sweet snacks affected BMI among a cohort of US children as they age from 5 to 14 years old.
They did this by linking average retail food prices (from the Quarterly Food-at-Home Price Database) with data on kids’ body mass index (BMI) from the Early Childhood Longitudinal Study, Kindergarten Class of 1998-99.
What do the figures mean?
Their analysis suggests that “a 10-percent price decrease for low-fat milk in the previous quarter is associated with a decrease in BMI of 0.35 percent and a 10-percent drop in the price of dark green vegetables in the previous quarter is associated with a reduction in BMI of 0.28 percent.”
However, a drop in the price of sweet snacks in the previous quarter was “associated with an increase in BMI of 0.27 percent”.
To put the figures into context, the 0.35-percent increase in BMI is equivalent to about 13 percent of annual average BMI growth for a boy of eight with a BMI of 18.5.
Changes in price have much bigger impact on poorer households
Their study also revealed that children in lower income households were much more responsive to changes in prices than kids from wealthier backgrounds.
“Soda prices have a greater effect on children in households with income below 200 percent of the Federal poverty line, as compared with children in households with higher income.”
Are carbonated drinks too cheap?
Consumption of carbonated sweetened beverages (CSBs) and fruit drinks has increased among US children and adolescents, while consumption of milk has declined in the past 25 years, note the authors.
“The price index for carbonated drinks has been below both the consumer price index (CPI) and the indexes for all non-alcoholic beverages and whole milk over the last 25 years or so.
“That is, the real prices for carbonated drinks are actually declining over time. In contrast, the price index for all fruits and vegetables, particularly fresh, is increasing faster than the CPI.
“Mean intake of CSBs more than doubled, from 5 fluid ounces per day in 1977-78 to 12 fluid ounces in 1994-98.
Per capita daily caloric contribution from CSBs and 100 percent fruit juices increased from 242 kcal per day in 1988-94 to 270 kcal per day in 1999- 2004.”
Childhood obesity
According to the Centers of Disease Control and Prevention (CDC), around a fifth of children are now overweight or obese compared with just over 6 percent in the 1970s.
