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Researchers at the UCL Institute of Child Health have demonstrated for the first time in humans that feeding babies enriched milk led to statistically significant increases in body fat at age 5-8 years.
Over-nutrition in infancy can lead to overweight, and reduced longevity, in adulthood. Studies have shown this in a vast range of creatures from rats to butterflies. There is also human data supporting a link between infant overnutrition and being overweight in later life, but without any systematic randomized controlled double blind trial. With humans, there has been concern that previous studies have not adequately allowed for confounding factors, (such as any genetic tendency for overweight mothers to have overweight babies.)
The new study is published online in the American Journal of Clinical Nutrition. This key finding of the link between overnutrition in infancy and body fat was independent of confounding factors such as maternal BMI. Fat mass in childhood was 22–38% greater in infants randomized to nutrient-enriched versus standard formula.
As increased fat in childhood is a significant risk for obesity in adulthood, the public health implications are profound. The study confirms previous estimates that more than 20% of adult obesity might be caused by overnutrition, or other early excessive weight gain in infancy.
The research led by Professor Atul Singhal, The MRC Childhood Nutrition Research Centre, UCL Institute of Child Health, looked at two different randomized, double blind, controlled trials, in which children small for their gestational age were randomly assigned a nutritionally enhanced formula milk, or a standard formula. At that time it was considered ethically appropriate to give such babies nutritional enhancement in line with the practice at the time, a practice which may now have to be re-evaluated. Indeed, the later study was terminated on ethical grounds because of the strength of the link between early over-nutrition and later obesity. The two studies used different methods of testing body fat which, however, produced similar results. The link between over-nutrition and body fat was stronger in the study where over-nutrition took place over a longer period.
Professor Singhal said “This study robustly demonstrates a link between early nutrition and having more fat in later life in humans – a finding suggested by previous studies and confirmed in many other animals. Our findings are strong, consistent, show a dose-response effect, and are biologically plausible.”
“Immediately, it raises the issue about the best way to feed those children small for gestational age, which should now be evaluated in the light of all current evidence. In public health terms, it supports the case in the general population for breastfeeding – since it is harder to overfeed a breastfed baby. And it will undoubtedly be of interest to formula milk companies wishing to improve their products.”
“Nutrition in Infancy and Long-term Risk of Obesity: Evidence from Two Randomised Controlled Trials” – published online in American Journal of Clinical Nutrition.
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