People who eat a lot of dairy foods may be at lower risk of traveller's diarrhoea, according to scientists in the Netherlands, who have shown that calcium inhibits infection with the bacteria Escherichia coli.
E coli is often responsible for the diarrhoea experienced by tourists in less developed regions such as Asia and Africa and also causes serious illness among the populations of developing countries.
Researchers from the Wageningen Centre for Food Sciences and NIZO Research in Ede had previously found dietary calcium to inhibit infection with salmonella in rats. The new study found that both animals and humans recovered faster from infection with E coli when fed a calcium-rich diet, making them less likely to suffer from dehydration.
For the double-blind, placebo-controlled study, published in the August issue of Gastroenterology, 32 healthy men consumed either regular milk products (calcium content of up to 1100 mg/day) or placebo dairy products that only supplied 60 mg of calcium daily for a period of three weeks.
On day 10, subjects were given an E coli strain (E1392/75-2A), able to induce mild but short-lived symptoms. This induced diarrhoea in both groups. Total faecal output doubled and mean relative faecal dry weight dropped from 25 per cent to 20 per cent, reported the researchers. However these symptoms had disappeared in the calcium group on the second infection day, in contrast to the placebo group, which recovered on the third infection day.
The findings supported earlier results seen in rats, wrote the researchers. They suggest that calcium taken in supplements may offer the same protection as that shown in dairy products.