Carotenoid Bioavailability Higher In Salads With Full-fat Dressings 35768

Carotenoid Bioavailability Higher In Salads With Full-fat Dressings

AMES, Iowa--The level of carotenoids in plasma cylomicrons afteringesting fresh vegetable salads is higher when using a full-fat dressing,according to a study published in the August issue of the American Journal ofNutrition (80, 2:396-403, 2004) (www.ajcn.org).

The small study, led by researchers from Iowa State University, involvedseven subjects each consuming three salads containing equivalent amounts ofspinach, romaine lettuce, cherry tomatoes and carrots with salad dressingscontaining 0, 6 or 28 g of canola oil.

The salads were consumed in random order and separated by washout periods oftwo weeks. Blood samples were collected hourly for 12 hours after consumption.Chylomicrons were isolated by ultracentrifugation, and carotenoid absorption wasanalyzed by HPLC with coulometric array detection.

After ingestion of the salads with fat-free salad dressing, the appearance ofalpha-carotene, beta-carotene and lycopene in chylomicrons was negligible,showing essentially no absorption of carotenoids. After ingestion of the saladswith reduced-fat salad dressing, the appearance of carotenoids in plasmachylomicrons increased relative to that after ingestion of the salads withfat-free salad dressing. Similarly, the level of carotenoids in plasmachylomicrons was higher after the ingestion of salads with full-fat than withreduced-fat salad dressing. The researchers concluded essentially no absorptionof carotenoids was observed when salads with fat-free salad dressing wereconsumed, and a substantially greater absorption of carotenoids was observedwhen salads were consumed with full-fat than with reduced-fat or fat-free saladdressings.