High-sensitivity HPLC with coulometric array detection enabled us to quantify the intestinal absorption of carotenoids ingested from a single vegetable salad. Essentially no absorption of carotenoids was observed when salads with fat-free salad dressing were consumed. A substantially greater absorption of carotenoids was observed when salads were consumed with full-fat than with reduced-fat salad dressing.

This thesis is organized into three chapters including a literature review, a manuscript to be submitted to the American Journal of Clinical Nutrition, and general conclusions. The literature review covers the provitamin A and non-provitamin A actions of carotenoids, the role of carotenoids in chronic disease, carotenoid absorption and bioavailability, and the use of electrochemical detection in carotenoid analysis. The manuscript describes a study carried out using electrochemical detection to quantify low concentrations of carotenoids in the chylomicron fraction of subjects who ingested a single test meal of fresh vegetables with a varying amount of dietary fat and to determine the amount of fat needed to optimize carotenoid absorption. The general conclusions chapter summarizes the findings of this study. Literature Review compared with fat-free dressing, the area under the curve (AUC) increased 20.9 nmol/L (P = 0.010), 97.5 nmol/L (P = 0.012), and 3.6 nmol/L (P = 0.016), and with regular fat as compared with reduced-fat dressing, the AUC increased 2.5-fold (P = 0.025), 2.0-fold (P = 0.033), and 4.0-fold (P = 0.031), for all trans-a-carotene, all trans-f3-carotene, and all translycopene, respectively. Conclusions: The use ofHPLC-ECD is a sensitive and efficient approach to measure the postprandial carotenoid response in chylomicrons. Carotenoid absorption was negligible when a vegetable salad was consumed with fat-free salad dressing; carotenoid absorption was higher with regular than with reduced-fat salad dressing.