Milk and dairy products are cornerstones of a healthy diet. However, if those products are consumed unpasteurized, they can present a serious health hazard because of possible contamination with pathogenic bacteria. An average of 5.2 outbreaks per year linked to raw milk have occurred in the United States between 1993 and 2006 - more than double the rate in the previous 19 years, according to co-authors Jeffrey T. LeJeune and Paivi J. Rajala-Schultz of the College of Veterinary Medicine in Columbus, Ohio.

Contamination can occur at the time of collection, processing, distribution, or storage of milk, the authors write. Many pathogens can be found in the dairy farm environment, which can contaminate the teat skin of dairy cows and consequently the milk at the time when cows are milked. For example, Salmonella and E. coli have been reported in pooled milk collected from farms., Outbreaks of salmonellosis, campylobacteriosis, and E. coli related to raw milk consumption have been reported since 2005.

Although the sale of raw milk was illegal in 26 states as of 2006, the authors note that those who are opposed to pasteurization have found ways to circumvent the law and obtain raw milk. For example, participants in "cow-share" programs pay for the upkeep of the cow and receive raw milk in exchange, rather than buying raw milk outright.

Raw milk advocates claim that unpasteurized milk cures or prevents disease, but no scientific evidence supports this notion. Testing raw milk, which has been suggested as an alternative to pasteurization, cannot ensure a product that is 100 percent safe and free of pathogens. Pasteurization remains the best way to reduce the unavoidable risk of contamination, according to the authors.

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They say their results raise the question of whether early introduction of peanut during infancy, rather than avoidance, will prevent the development of peanut allergies and that with food allergies, there might be a benefit from early exposure.

A proposed clinical trial by researchers in the UK is currently recruiting 480 children ages 4 months to 10 months who will be randomly assigned to consume or avoid peanuts but these results are not expected for about five years.

While there is at present some hope in oral immunotherapy, where gradually increasing an allergic person's exposure to offending foods, might help ward off allergies, that therapy is still to be proven.

The American Academy of Allergy, Asthma and Immunology now recommends that vegetables, rice, meat, and fruit should be added to a child's diet between 6 months and one year so that problem foods can be easily identified.

The Academy says thereafter a child should try milk, wheat, corn, citrus fruit, and soy and at age 2, eggs and at 3, fish and peanuts.

Experts say children with parents who have allergies should be regarded as high risk but breastfeeding for the baby's first four to six months of life offers some protection.

The British study is published in November issue of The Journal of Allergy and Clinical Immunology.