Women's breast milk is rich in a chemical that combats infant infections making it far better than cow or formula milk, according to new research.

It has more than 200 times as much glycerol monolaurate (GML) as cow's whereas infant formula has none.

The compound also boosts 'good bacteria' - and could be a beneficial additive to dairy products, say scientists.

The discovery published in Scientific Reports sheds fresh light on why 'breast is best'. Babies nursed naturally have fewer respiratory illnesses and bouts of diarrhoea.

The UK has one of the lowest breastfeeding rates in the world. One in three babies receive any breast milk at six months, compared with more than six in ten in Sweden.

First author Professor Patrick Schlievert, a microbiologist at the University of Iowa, said: "While antibiotics can fight bacterial infections in infants, they kill the beneficial bacteria along with the pathogenic ones.

"GML is much more selective, fighting only the pathogenic bacteria while allowing beneficial species to thrive.

"We think GML holds great promise as a potential additive to cows' milk and infant formula that could promote the health of babies around the world."

It is already used in cosmetics and as a food additive. It can also be taken as a dietary supplement. What is more, it is cheap to manufacture.

Senior author Prof Donald Leung, a paediatrician at the National Jewish Health hospital, Denver, Colorado, said: "Our findings demonstrate high levels of GML are unique to human breast milk and strongly inhibit growth of pathogenic bacteria."

After showing it contains much more than cows', experiments revealed the chemical inhibited the growth of Staphylococcus aureus, Bacillus subtilis and Clostridium perfringens.

The bacterium can cause serious infections and food poisoning. Neither cows' nor formula milk had any effect.

Meanwhile, the human breast milk did not block Enterococcus faecilis, part of the flora of gastrointestinal tracts of healthy humans.

Infants suckled on mother's milk are known to have plenty of good bacteria that improve immunity.

When the researchers removed the GML, the human breast milk lost its antimicrobial activity. But the cows' milk became antimicrobial - after it was added.

The researchers also showed GML inhibits inflammation in epithelial cells, which line the gut and other mucosal surfaces. This can lead to bacterial and viral infections.

Encouraged by the results from samples of human, cow and infant milk, they have now applied for a patent for the use of GML as an additive to cows' milk and infant formula.

Breastfed babies are less likely to develop diabetes or become obese later in life. The UK has one of the lowest breastfeeding rates in the world.

A recent report found just over a third (34 per cent) of babies are receiving any breast milk at six months, compared with 62.5 per cent in Sweden.

The Royal College of Midwives advises mothers to exclusively breastfeed their newborn for the first six months, in line with guidance from the World Health Organisation.

But is says some mothers find it difficult to start or continue breastfeeding, and the decision is a woman's individual right.