Milk fat biomarkers

Few studies have studied the association between the milk fat biomarkers and disease risk. The following section gives a comprehensive overview of studies conducted so far. 

Thus, the two case-controls studies from Scandinavian countries have reported beneficial associations between milk fat biomarkers and heart disease, while the study from the United States reported a positive association. The differences in results may well reflect the type of foods and the context in which the dairy food was consumed. In the United States, cheese and milk are commonly found in takeaway meals such as cheeseburgers and shakes, and often consumed with less healthy foods such as fries. 

Likewise in the single study involving type 2 diabetes, Krachler et al. (2008) measured 15 0 and 17 0 in erythrocyte membrane fatty acids and investigated their relation to the development of type 2 diabetes mellitus. The study included 159 individuals with type 2 diabetes mellitus and 291 sex- and age-matched controls. Higher proportions of 15 0 and 17 0 were associated with a lower risk of diabetes. After adjustment for BMI, HbAlc, alcohol intake, smoking, and physical activity, the association between the milk fat biomarkers and diabetes remained (Krachler et al., 2008). 

Thus, studies involving milk fat biomarkers produced results that were similar to those using dietary intake measures. As the forms of error were different, the results provide some confidence in conclusions that can be drawn from the observed relationships. 

Two saturated fatty acids, pentadecanoic acid (15 0) and heptadeca-noic acid (17 0), in adipose tissue (Baylin et al., 2002) and serum lipids (Smedman et al., 1999 Sun et al., 2007a Wolk et al., 1998) have been proposed and validated as biomarkers of dietary ruminant fat intake, that is, mainly from milk fat and to lesser extent from ruminant meat. The human body is unable to synthesize fatty acids with an uneven number of carbon atoms, whereas ruminal microbes of cows have this ability (Wu and Palmquist, 1991). To measure the content of 15 0 and/or 17 0 in plasma lipids or adipose tissue is consequently a way to estimate the milk fat intake. It is known that the proportion of 15 0 and 17 0... 

Milk Fat Inhibits Growth and Modulates CLA-Responsive Biomarkers in MCF-7 and SW480 Human Cancer Cell Lines, 90 877—885 (2003). 

The primary biomarkers of exposure to mirex include mirex concentrations in blood (Byrd et al. 1982 Kavlock et al. 1980 Smrek et al. 1977 Wiener et al. 1976), fat (Burse et al. 1989 Kutz et al. 1974), feces (Byrd et al. 1982 Chambers et al. 1982 Gibson et al. 1972 Ivie et al. 1974b), or milk (Dorough and Ivie 1974 Kavlock et al. 1980 Mes et al. 1978 Smrek et al. 1977). Since mirex is not metabolized, it is the only biomarker to be measured in these biological media. Since mirex is retained in the body for long periods of time and only slowly excreted, its measurement is useful as a biomarker of acute, intermediate, or chronic exposures to both low and high levels. 

Exposure. The biomarkers of exposure to mirex and chlordecone are well established and specific to each compound. The known biomarkers of exposure to mirex are mirex concentrations in blood, fat, feces, and milk (Burse et al. 1989 Byrd et al. 1982 Chambers et al. 1982 Dorough and Ivie 1974 Gibson etal. 1972 Ivieetal. 1974b Kavlocketal. 1980 Kutzetal. 1974 Smrek etal. 1977 ... 

Exposure. Because DEHP is rapidly metabolized and excreted, it is difficult to monitor anything but recent human exposures through the body fluids. MEHP and several oxidized MEHP metabolites can be measured in blood and urine and are biomarkers of exposure, and DEHP has been detected in human milk. Since DEHP is a lipophilic substance, it has the potential to deposit in adipose tissues. More chronic exposures can be detected with a fat biopsy, but there are no validated approaches for assessment of chronic exposure by fat biopsy analysis. Additional studies of methods for monitoring DEHP exposure would be of value. 

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