The relationship between linoleic acid level in serum, adipose tissue and myocardium in humans.

A cross-sectional study of 80 consecutive cases at necropsy was undertaken to determine the relationship between linoleic acid in the serum, adipose tissue and myocardium of humans. The sample consisted of 55 males and 25 females aged 7 to 92 years who had died from cardiac and non-cardiac causes in the Southern Region of Tasmania, Australia. Fatty acids were extracted from samples of serum, adipose tissue and myocardium and separated using capillary gas liquid chromatography. Means and standard deviations were calculated for each of the main fatty acids in the three tissues studied. In serum and adipose tissue, there were significantly higher levels of linoleic acid (p<0.001 and p<0.001 in serum and adipose tissue, respectively) and total n-6 fatty acids (p< 0.002 and p< 0.001 in serum and adipose tissue, respectively) and significantly lower levels of oleic acid in females than in males (p< 0.001 and p<0.05 in serum and adipose tissue, respectively). In serum and adipose tissue, the ratio of total n-6 to total n-3 fatty acids was significantly higher in females than males (p<0.02 and p<0.001 in serum and adipose tissue, respectively). In myocardium, there were significantly higher levels of oleic acid (p<0.05) and linoleic acid (p<0.001) and significantly lower levels of arachidonic acid (p<0.001) and docosapentaenoic acid (p<0.02) in females than males. Total n-3 fatty acids in myocardium were significantly lower in females (p<0.001) resulting in a significantly higher ratio of total n-6 to total n-3 fatty acids in females (p<0.001). Highly significant Pearson correlations were found between levels of linoleic acid in adipose tissue and myocardium (p<0.0001), between adipose tissue and serum (p<0.001 ) and between serum and myocardium (p<0.001). The proportion of total polyunsaturated fatty acids (PUFA) in the myocardium was inversely related to the proportion of monounsaturated fatty acids (p<0.001) and inversely related to the proportion of saturated fatty acids (p<0.001). There was a significant positive correlation between the ratio of linoleic acid to linolenic acid in all three tissues. This study showed that there was a very strong relationship between the level of linoleic acid in adipose tissue and myocardial tissue, which suggests that dietary linoleic acid influences the level of myocar 1000 dial linoleic acid. These findings support the hypothesis that dietary linoleic acid has a direct influence on myocardial membrane linoleic acid levels.