In feeding babies the mantra has been for decades that "breast is best" and there is indeed a growing body of research producing solid evidence that breast feeding is better for baby and for mother.

Scientific studies have found that a diet of breast milk for babies is correlated with benefits including less diarrhea as well as lower incidence of diabetes or asthma when compared to formula-fed babies.

But precisely how or why this happens remains a mystery and while scientists know the basic ingredients of breast milk, it is not fully understood how exactly they work to provide the best nutrition for infants and protect them against disease.

Science tells us that human breast milk is a complex fluid composed of several key components, including lactose, a sugar that provides energy for the infant, and lipids, which are thought to provide healthy fats to infants.

But scientists are only just beginning to understand the composition and function of many of the components of human breast milk - certain sugars in breast milk could be developed into treatments that help fight necrotizing enterocolitis (NEC), a potentially deadly disease that affects about 10 percent of premature infants. Some types of sugars in breast milk appear to prevent bacterial infections, including those that cause severe diarrhea.

Scientists say a better understanding of the components of human breast milk - especially its lipids and oligosaccharides - and their role in ensuring infant health could lead to improved foods and better ways to treat gastrointestinal diseases, not just for infants but perhaps also for adults.

They also say understanding the chemistry and function of breast milk can also lead to the design of more nutritious infant formulas and cow's milk products.

The researchers say breast milk is a remarkable fluid but it is extremely embarrassing how little we still know about it.

Dr J. Bruce German, a food science professor at the University of California, Davis says the one thing that has evolved with humans, to nourish humans, is breast milk and it is the ideal evolutionary model for what nourishment should be.

An article on the topic is scheduled for the Sept. 29 issue of Chemical & Engineering News, ACS' weekly newsmagazine.