Occurrence and biochemical characteristics of natural bioactive substancesin bovine milk lipids

Bovine milk lipids (BML) contain a number of bioactive substances with posi tive as well as negative properties, mainly in the class of fatty acids. Be sides trans fatty acids (TFA), conjugated linoleic acids (CLA) are of parti cular interest. Apart from ruminant meat products the main source of CLA in food are BML. Although TFA as well as saturated fatty acids (12:0-16:0) ar e thought to be positively correlated with atherosclerosis and coronary hea rt disease, CLA are considered antiatherogenic. Further, CLA are reported t o reduce adipose fat and to have anticarcinogenic properties. The varying C LA and TFA contents of lipids from milk and dairy products are positively c orrelated with one another. However, TFA are also negatively correlated wit h 12:0-16:0 in BML. Anticarcinogenic effects are also ascribed to butyric a cid as well as to some phospholipids and ether lipids present in BML. Moreo ver, the essential fatty acids 18:2n-6 and 18:3n-3 are found in BML which a re involved in a variety of biochemical processes and thus have numerous fu nctions in human metabolism. Contents of the individual bioactive component s of BML are summarised taking into account also seasonal variations. The t otal content of bioactive substances in BML is approximately 75% but their overall impact on human health considering benefits and drawbacks is diffic ult to assess.