Second Hand Sugars in Breast Milk

New concerns over childhood obesity begin at the infant level, and so even breast milk is not above scrutiny. A new study out of the Keck School of Medicine of USC shows how what once was regarded as the gold standard for infant nutrition can become tainted by certain sugars in a mother's diet.

Nursing babies exposed to high amounts of fructose can produce problems with cognitive development and learning as well as create lifelong risk for obesity, diabetes, fatty liver disease and heart disease. Fructose is found in fruit, but in greater concentrations in soda and some processed foods. Notably, it is not a natural component of breast milk. The sugars that infants do require are all contained within lactose, which should be a newborn's principal source of carbohydrate energy.

"We know very little about why some children eventually become overweight or obese," said Michael Goran, lead author of the USC study. "It's important that we study what may be taking place in the earliest times of their development to determine whether anything could be done just after birth to lower their risks." He noted that previous studies have shown that fructose and artificial sweeteners are particularly damaging during critical periods of growth and development in children.

It does not even take a lot of fructose to throw a baby's metabolism off-kilter. Even minute amounts of fructose may have detrimental effects on infant metabolism. Scientists believe that consumption of fructose could “coach” pre-fat storage cells to become fat cells, thereby raising a child's risk of one day becoming obese. The study indicates that a single microgram of fructose per milliliter of breast milk -- that's 1,000 times lower than the amount of lactose found in breast milk -- is associated with a 5 to 10 percent increase in body weight and body fat for infants at six months of age.

"Early life is a period of rapid development and early nutrition is strongly linked to long-term health outcomes," said Tanya Alderete, co-author of the study. "We know that the decision to breastfeed or bottle feed may have impacts on later health. Results from this work suggest that the composition of breast milk may be another important factor to consider in regard to infant health."

In the USC study, the scientists took a breast milk sample from each mom and scanned it for different types of sugars, then measured each baby's fat mass, muscle mass and bone mass. Each infant's bone, muscle and fat masses were likewise measured, and tracked over a six month period.

"New moms can prevent passing secondhand sugars to their children by eating and drinking less sugars while pregnant or breastfeeding," Goran said. "Caregivers can shield babies and children from harmful effects of sugars by carefully choosing infant formula, baby foods and snacks without added sugars or sweeteners."

The research has been published in Nutrients.