Children who have junk food diets are at greater risk of allergies as well as obesity, according to a new study.

Scientists compared youngsters from a rural African village who had diets rich in fiber with another group living in Italy, and found a dramatic difference.

The African children had less obesity-linked bacteria and a greater abundance of fatty acids which protect against inflammation, which is associated with causing asthma, eczema and other allergic reactions.

The diet of the children living in the African village in Burkina Faso was similar to that of people living in the modern Western world thousands of years ago.

It consisted mainly of cereals, beans, nuts and vegetables.

But the Italian children ate higher quantities of meat, fat and sugar.

Only those who were still breast-feeding had bacteria resembling the African children's - indicating diet may have a greater importance than other factors such as ethnicity, sanitation, geography or climate, say the researchers.

The trillions of microbes that inhabit the human gut are considered an essential 'organ' that helps to digest food, protect against disease-causing bugs and limit inflammation.

One of the researchers said children in industrialized countries who eat low-fiber, high-sugar 'Western' diets may reduce microbial richness - potentially contributing to a rise in allergic and inflammatory diseases in the last half-century.

He said: "... a rise in new diseases such as allergic, autoimmune disorders, and inflammatory bowel disease (IBD) both in adults and in children has been observed, and it is hypothesized that improvements in hygiene together with decreased microbial exposure in childhood are considered responsible for this increase.

"The gastrointestinal microflora plays a crucial role in the pathogenesis of IBD and recent studies demonstrate obesity is associated with imbalance in the normal gut microbiota."

Growing research is finding that one of the keys to good health can be found in the bacteria that live in the digestive tract. These probiotics or "good" bacteria not only help to promote digestive health, but also stimulate a healthy immune system by helping the body to absorb nutrients.

A typical Western diet that is high in meat, sugar and highly refined, processed foods is usually devoid of these good bacteria and does not provide a suitable environment for these bacteria to flourish. This can cause imbalances in the gut which promote inflammation, leading to allergies, obesity, etc. For a healthy gut prone to less inlfammation, eat more natural, raw, or unrefined foods and probiotics. Probiotics are found in 'live' foods like yoghurt, some cheeses, pickles and raw sauerkraut (fermented cabbage).

Research Paper Details:

De Filippo C, Cavalieri D, Di Paola M, et al. Impact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and rural Africa. PNAS published ahead of print August 2, 2010.