Effects of lipids’ composition and structure in meat and dairy foods on digestibility and low-grade inflammation in cells, animals and humans (LipidInflammaGenes)

Dietary intake of saturated fatty acids (SFA) from dairy and meat products, have for a long time been associated with several negative health effects. Meat and dairy products contribute 62 % of total SFA intake from the average Norwegian diet. The fatty acid composition and location of fatty acids in the TAG-molecules are different in dairy, beef and pork fat, with more C16:0 in the mid, (sn-2) position. The SFAs C12-C16 are thought to elevate the risk factors of CVD. SFA constitutes about 45% of the total fat from beef, about 35% of the fat from pork and about 66% of the fat from dairy products. During digestion, monoacylglycerol and fatty acids are absorbed, and TAGs are resyntehsized. The uptake and metabolic fate of the fatty acid in the sn-2 position have been less investigated than  the uptake of fatty acids.

Pork fat has a higher fraction of C16:0 in the sn-2 position of TAGs than beef fat. Data suggests that the TAG structure in pigs is influenced by a genetic component leaving an option for changing this structure, that needs to be explored.

The structure of dietary TAGs is suggested to influence absorption of both fatty acids and calcium (Ca). As beef fat/dairy fats have more saturated fat in sn-1 position of TAGs than pork fat, these fatty acids are more available for formation of Ca-soaps. Magnesium (Mg) is another mineral shown to increase soap formation. The molecular mechanisms regarding formation of Ca- and Mg-soaps in the gut still needs further exploration.

Chronic, low grade inflammation increases with age and is prevalent in the pre-disease stages that later may lead to heart diseases, diabetes type 2, and obesity etc. This is in contrast to the swift and necessary inflammatory response when acutely attacked (e.g. by bacteria and virus). A chronic elevated level of inflammatory compounds will activate cellular pathways that gradually promotes life-style diseases. Intestinal microbiota has been suggested as another contributor in the regulation of inflammation, obesity and even atherosclerosis. So far, there are few studies scrutinizing the effects of TAGs on microbiota composition, metabolism and possible health consequences thereof.

The consequences of the type of fatty acid in the sn-2 position, the Ca level and Ca and fat absorption, on postprandial chylomicron formation are unclear. There is a need to study effects of TAGs from dairy, beef and pork products in postprandial studies to identify if C16:0 in the sn-2-MAG impacts differently on blood risk markers of inflammation and atherosclerosis, than other saturated fatty acids.

Genetic polymorphisms may also impact the response to lipids. There is limited research on genetics and diet interactions in Norwegian populations. Internationally, sequence modifications in intestinal fatty acid binding protein 2 has been linked to myocardial infarction and diabetes. Changes in a chromosome that affect gene activity and expression are called epigenetic changes. The most recent addition to studying diet responses is based on the principle that iso-epigenetic diets exist; i.e. an ideal diet, should not affect the epigenetics (beyond inevitable aging effects). Diet interventions with SFA including studies of epigenetic changes may therefore provide useful information about the possible magnitude of such changes. Epigenetic changes are highly relevant to correlate to inflammation markers that signal diseases. Such studies using SFA seems lacking in the literature.

Despite the often claimed association between SFA and CVD, our Norwegian Institute of Public Health points to obesity as an emerging risk of CVD and are in particular worried about the morbidity and socio-economical differences among younger adult/ adults (25-44 yrs); i.e the same group that has the highest relative weight gain. The situation in this relative young group is alarming with respect to future medical costs. It is timely to gain knowledge of how food producers can alleviate this trend.

Joint investigations between dairy and meat industry seem warranted as the Norwegian Red Cattle is a dual purpose breed that provides 75% of the beef meat in the market, and provides most of the milk and dairy products produced in Norway. Such comparative studies are completely missing in the literature.
___________

  Participants at the opening Meeting of the project:

Foto

Janne Karin Brodin