Pentadecanoic acid in serum as a marker for intake of milk fat: relations between intake of milk fat and metabolic risk factors

Abstract

Background:The fatty acid composition of the diet is known to be partially reflected by the fatty acid composition of serum lipids. Objective: We examined whether pentadecanoic acid (15:0) in serum lipids can be used as a marker for intake of milk fat, the major dietary source of 15:0. We also investigated the relations between intake of milk fat and cardiovascular disease risk factors. Design: Sixty-two 70-y-old men completed 7-d dietary records. The intake of milk products was studied in relation to the proportions of 15:0 in serum cholesterol esters and phospholipids, as well as to the clinical characteristics of these men, by using Spearman's rank correlation. Results: The proportions of 15:0 in serum cholesterol esters were positively related to butter intake (r = 0.36, P = 0.004) and to the total amount of fat from milk products (r = 0.46, P < 0.0001); 15:0 in phospholipids was related to the amount of fat from milk and cream (r = 0.34, P = 0.008) and to the total amount of fat from milk products (r = 0.34, P = 0.008). Inverse associations were found between intake of milk products and body mass index, waist circumference, LDL-HDL ratio, HDL triacylglycerols, and fasting plasma glucose, whereas relations to HDL cholesterol and apolipoprotein A-I tended to be positive. Conclusions:The results suggest that 15:0 in serum can be used as a marker for intake of milk fat. The explanation for the inverse associations between the intake of milk products and certain cardiovascular risk factors is not known. 1999;69:22-9. Am J Clin Nutr

Evaluation of relative intake of fatty acids according to the Northern Sweden FFQ with fatty acid levels in erythrocyte membranes as biomarkers

“…Significant correlations, especially for 15 : 0, are reported between intake and levels in adipose tissue and serum (22,23) . 14 : 0 is also abundant in dairy products and some studies confer 14 : 0 in adipose tissue, serum Table 3 Comparison of relative values of fatty acids in erythrocytes (ERY) and fatty acid intakes (g/100 g fat) measured by the FFQ and ten repeated 24 h dietary recalls (24-HDR) in eighty-eight men and ninety-two women from Vä sterbotten County, northern Sweden Erythrocyte membrane fatty acids (% of total fatty acids) Mean intake (g/100 g fat) Spearman correlation coefficient and erythrocytes a role as a biomarker for milk fat (22,24) , but the association may be biased by some endogenous production. Our FFQ measured intakes of 14 : 0, 15 : 0 and 17 : 0 correlated well with 24-HDR-recorded intakes and also correlated positively and statistically significantly (except for 14 : 0 in women) with erythrocyte levels.…”

“…This suggests 18 : 2n-6 and 18 : 3n-3 as suitable biomarkers, but transformation to longer fatty acids in the same fatty acid series (26) , or possible demand for targeted FFQ design, may weaken the associations. Previous studies on intake and content in biological tissues are also contradictory; only studies using targeted FFQ instruments have displayed significant correlations between intake and tissue contents (1,2,23,27) , while studies failing to find such associations employed FFQ designed to measure overall intakes (24,25,28) . Thus 18 : 2n-6 and 18 : 3n-3 levels in biological tissues, such as adipose tissue, erythrocyte membranes or plasma phospholipids, may reflect intake of these fatty acids, but a very carefully designed recording instrument seems to be a prerequisite to estimate intake sufficiently well.…”

Evaluation of the odd fatty acids 15:0 and 17:0 in serum and adipose tissue as markers of intake of milk and dairy fat

“…In the previously reported studies on odd saturated fatty acids in serum, the authors analysed fatty acid pattern in cholesterol esters and phospholipids separately (Wolk et al, 1998(Wolk et al, , 2001Smedman et al, 1999). In spite of analytical differences, the association observed in our present study between the proportion of 15:0 in total serum lipids and adipose tissue, was in the same range as was observed by Smedman et al (1999) and Wolk et al (1998Wolk et al ( , 2001, indicating that 15:0 in serum total lipids may be an equally suitable marker for the intake of dairy fat as the 15:0 content of cholesterol esters and phospholipids. In a previous study, it was observed that very-long-chain n-3 fatty acids in adipose tissue and total serum lipids reflected the dietary intake of very-long-chain n-3 fatty acids to the same degree (Andersen et al, 1999).…”

“…Recent studies have suggested that the proportion of 15:0 and 17:0 acid in human adipose tissue (Wolk et al, 1998(Wolk et al, , 2001Baylin et al, 2002) and even in muscle (Andersson et al, 2002) may reflect dairy fat consumption. In addition, two studies have indicated a positive association between the intake of dairy fat and the content of 15:0 in cholesterol esters and phospholipids (Smedman et al, 1999;Wolk et al, 2001). Thus, these odd numbered fatty acids might function as biomarkers for intake of dairy products.…”

“…Owing to errors associated with traditional dietary assessment methods, use of biomarkers may represent an important contribution to the field. The fatty acids pentadecanoic (15:0) and heptadecanoic (17:0) are synthesized by the intestinal bacterial flora of ruminants and these fatty acids cannot be metabolized efficiently by humans (Smedman et al, 1999). Recent studies have suggested that the proportion of 15:0 and 17:0 acid in human adipose tissue (Wolk et al, 1998(Wolk et al, , 2001Baylin et al, 2002) and even in muscle (Andersson et al, 2002) may reflect dairy fat consumption.…”