Milk produced by transgenic goats is seen to shore up protective intestinal bacteria against illness, thanks to the antibacterial action of an enzyme found in human breast milk; if the findings hold true for humans it could help prevent death from diarrheal illness in the developing world.
In a new study to be published in the August issue of Transgenic Research (reference unavailable at time of publication), researchers from UC Davis report positive results in milk from goats bred to carry the gene for human lysozyme on the intestinal health of young goats and pigs.
They hope that their findings, said to "underscore the potential for using biotechnology to improve the healthfulness of the milk of dairy animals by introducing the beneficial properties of human milk into dairy animals," could one day be used to protect children against diarrheal illness.
The goats whose milk was used in the study were bred eight years ago using gene-transfer technology, as part of a long-standing effort by researchers to find a way of enriching cow's or goat's milk with beneficial compounds found in human breast milk.
Lysozyme is understood to be one of the most beneficial components contributing to the well-being of breast-fed infants, thanks to its inhibitory effect on growth of bacteria that cause intestinal infections by destroying the bacterial cell wall, combined with encouraging the growth of beneficial bacteria.
However natural goats milk contains only 0.06 per cent the amount of lysozyme as human milk, meaning that children who, for whatever reason, receive goats milk instead of human milk, may be missing out on an important booster in early life.
"This goat's milk represents one of the first transgenic food products that has the potential to really benefit human health," said co-leader of the study Professor Jim Murray.
Although cow's milk is the most commonly consumed milk in the West, on a worldwide basis goat's milk is believed to be drunk by more. Since more than 2 million children a year die of diarrheal illness, it is hoped that this breakthrough could offer protection to some of the goat milk-drinkers among them.
Murray and co-researcher Elizabeth Maga suggest that the transgenic procedure could be used to produce powdered milk enriched with lysozyme - and even whole goat herds for developing nations.
Even though human studies have not yet been conducted, their optimism is based on results in pigs, which are often used as a research model by virtue of having a digestive system similar to humans'. Kid goats were also used, so that the effects of the milk could also be observed on ruminants with multi-chamber stomachs.
The pigs fed milk from the transgenic goats were seen to have lower levels of coliform bacteria in the small intestine - including few E coli, some strains of which can cause serious illness - when compared to a control group of pigs fed normal goats milk.
The goats fed the transgenic goat milk, however, displayed higher levels of coliform bacteria and similar levels of E Coli compared to the control goats.
"Although the effects were different in the goats than in the pigs, the study demonstrates clearly that the consumption of pasteurized goat's milk containing human lysozyme can impact the bacterial makeup of the digestive tract in two distinct models," said Maga.
The researchers are recommending larger, more in-depth studies to examine other possible benefits, and also project that the technology could prove even more beneficial if applied to cow's milk, since cows produce a greater volume of milk.