Dietary-induced changes in the fatty acid composition of human cheek cell phospholipids: correlation with changes in the dietary polyunsaturated/saturated fat ratio.

Healthy normotensive volunteers aged 20 to 59 yr were randomly allocated either to a control group or to one of two experimental groups. The control group ate a low P/S ratio diet for 12 wk while the first experimental group ate a high P/S ratio diet for 6 wk followed by a low P/S ratio diet for the next 6 wk. The second experimental group ate a low P/S ratio diet in the first 6 wk followed by a high P/S ratio diet for the next 6 wk. Dietary P/S ratio, plasma linoleic acid (18:2), and cheek cell phospholipid 18:2 levels were compared in each dietary group at the end of the 1st and 2nd 6 wk. On change from a low to a high P/S ratio diet, there was a 36% increase in the proportion of 18:2 in the cheek cell phospholipids in comparison with the proportion existing before the change. This was associated with an increase in the proportion of 18:2 in the plasma lipids of this group. No reduction in the proportion of 18:2 in the cheek cell phospholipids was apparent in the control group or the group which changed from a high to a low P/S ratio diet, although in the latter group there was a reduction in the proportion of 18:2 in the plasma lipids. As the phospholipid fatty acid composition of human cheek cells reflects dietary lipid status under certain conditions, this observation may be useful in dietary and nutritional studies, particularly as human cheek cells can be obtained in a noninvasive manner.