Could formula milk halt obesity?

Modified baby formula milk may reduce obesity in later life. Sanjay Tanday investigates

What is the story?
Adding leptin, a hormone shown to control hunger, to formula milk could prevent children from growing up obese, according to media reports.

A quarter of women and a fifth of men in the UK are now so overweight that their health is at serious risk, according to data compiled by the European Union statistical office.

British women are the most obese in Europe, with 23 per cent classified as clinically obese. British men fare little better. In all, 22.3 per cent are obese, second only to men in Malta.

But UK researchers have suggested that their studies of leptin could help to confront the nation’s weight crisis and prevent related illnesses such as type-2 diabetes.

They found that giving leptin to pregnant rats could protect their offspring from becoming obese.

Experts have criticised the concept of adding leptin to formula milk as unethical and for encouraging women to switch from breastfeeding to bottle-feeding, said the papers.

What is the research?
The reports are based on a UK study that assessed whether giving leptin to normally-nourished rats could affect the weight of their offspring.

For the study, pregnant rats were fed a daily diet containing 2mg/kg of leptin from the end of the second trimester of pregnancy and throughout lactation.

A control group of pregnant rats were fed a normal diet that did not contain leptin.

At 21 days of age, the offspring were assessed for body composition and energy expenditure.

Leptin was found to reduce both birth weight, by 0.6g, and body length, by 0.28cm, in the leptin rat pups compared with the placebo pups.

The leptin and control rat pups were then weaned on to either a normal or a high-fat diet.

Throughout the study all of the rats were given unlimited access to food and water.

The rat pups from leptin-fed mothers did not gain weight on either the normal or the high-fat diets. But those in the control group did increase in weight when fed a high-fat diet.

Leptin had a greater effect on the male rat pups. In males, those given leptin had 2.6 per cent less body fat than those in the control group. But in females, those given leptin had just 0.1 per cent less body fat than control females.

Additionally, energy expenditure was found to be 15 per cent higher in the offspring of leptin-treated mothers compared with the control offspring.

What do researchers say?
Lead researcher Professor Mike Cawthorne, director of metabolic research at the University of Buckingham, said the study had shown that treatment with leptin early in life could programme offspring to become resistant to developing obesity. This could reduce the risk of them developing comorbidities in later life.

Leptin is already present in human breast milk but not yet in formula feeds, said Professor Cawthorne.

‘The work is at an early stage, but nevertheless raises the future possibility that supplemental leptin given to infants by mouth, possibly by adding it to formula feeds, may lead to a reduction in adult obesity.’

Providing leptin early on could programme the body’s energy balance so that offspring of leptin-treated mothers burn more energy, said Professor Cawthorne.

‘The leptin infants are permanently inefficient in terms of using energy,’ he explained.

But adding leptin to formula would not replace the need for a healthy diet containing fruit and vegetables and taking regular exercise, added Professor Cawthorne.

What do the experts say?
Jonathan Seckl, professor of molecular medicine at the Queen’s Medical Research Institute at the University of Edinburgh, said: ‘We need to know whether leptin acts pre- or postnatally, understand how it works, and dissect the possible side-effects before this becomes a potential approach for humans.’

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