Milk acid tests offer dairymen healthy future
By Jessica Buss
MILK could be set for a new image, if levels of a specific fatty acid can be manipulated and research proves its beneficial effect on human health.
Philip Calder, human nutrition researcher at Southampton University, aims to find specific fatty acids which improve human health and how much is needed to realise these benefits.
"People think animal fat, meat, butter and dairy foods are bad for us, but they do contain a fatty acid which might be good for us."
The three-year £798,000 project, in partnership with the University of Reading, will be funded by the Milk Development Council and Biotech-nology and Biological Sciences Research Council.
Dr Calder says that there is evidence from earlier studies that the group of fatty acids described as conjugated linoleic acid (CLA) produces a beneficial effect in rats and mice when given in large doses.
These benefits include a slowing in the growth of tumors, so it seems to have anti-cancer properties. CLA may also have an anti-obesity effect as it stops deposition of fat and it may lower blood lipids, reducing risks of heart disease. "These are the three things that are most likely to lead to death in our society."
A further benefit is that CLA enhances immune function. It is this immune response that Dr Calder will study by measuring fat and cholesterol levels in blood and how white blood cells work in human volunteers.
"The irony is that CLA found in milk is a trans fatty acid. But its trans fatty acids which receive bad press in margarine, so manufacturers have tried to remove them.
"However, there are different sorts of CLA. We dont know which ones are useful, so research will focus on two likely to be beneficial to health."
It is impractical to eat the levels of CLA given to mice and rats in studies, he says, but it is estimated that we eat 0.1-1.5g/day, adds Dr Calder. However, to achieve a similar intake as the rats and mice humans would need to eat 10-50 times the normal intake. Success in the project, therefore, depends on finding the specific CLA isomer which is beneficial at levels which can be consumed by humans.
Initially, two CLA isomers will be given to volunteers, each in a 95% pure form as a pill – similar to a cod liver oil tablet. Doses will add about 1, 2 or 3g a day to volunteers normal diets.
During the studys first 18-months, researchers will look for beneficial effects which can be measured in a short period, he says. Anti-cancer properties are too difficult to assess in such a project.
"If CLA is beneficial to human health it is important to be able to produce a milk high in CLA."
During this same period, therefore, project partners at the University of Reading department of agriculture will undertake dairy cow studies.
CLA production occurs naturally in the rumen. "Cows eat grass which is rich in linoleic acid. In the rumen bacteria start metabolising the fatty acids and some CLA is formed. Some of this CLA is transferred into the mammary gland via the bloodstream. Enzymes in the mammary gland can also make CLA," explains Dr Calder.
Studies at Reading will aim to alter CLA levels produced in milk, possibly through diet or changing the way the rumen works – such as altering the pH level.
In the second 18 months of the project high CLA milk products will be developed and tested on volunteers. This will identify whether there are any differences compared with using a pill form.
While humans could gain the benefits from a CLA pill, Dr Calder points out that a natural source has much to offer. "There is interest in human nutrition, but people are not good at sticking to a healthy diet.
"Milk and dairy products have an advantage as CLA is already in them, so the dairy industry could create enriched products which would be acceptable, and many people like dairy products."
Providing his research proves that milk high in a specific CLA is possible, he believes it will be easy to market.
Any new products would need branding and a marketing effort, he adds. "But to have products you can claim are good for you will be phenomenal for the dairy industry." *
In future a whole range
of milk products could
be marketed with
content to improve
HIGH CLA MILK
• Beneficial to humans?
• Best CLAs to be found.
• Hope to produce naturally.