BACKGROUND & AIMS: Circulating carotenoid levels decrease progressively in patients receiving long-term enteral tube feeding with carotenoid-free formulas. Low dietary intake and low blood levels of carotenoids are associated with a higher risk of morbidity and mortality from chronic diseases. The aim of this study was to examine the effects of a low dose carotenoid mixture (3-mg/1500kcal) for 3 months on serum carotenoid levels and oxidative stress in patients receiving long-term enteral nutrition as the sole source of nutrition. METHODS: This randomized, double blind, controlled study compared patients receiving enteral nutrition with carotenoids (N=26) and without carotenoids (control group; N=25). RESULTS: Patients on long-term enteral nutrition had low baseline serum carotenoid levels. Three months of enteral feeding enriched with carotenoids significantly (P<0.01) increased serum carotenoid levels compared with the control group. Oxidative stress as measured by NF-kappaB levels was decreased at 3 months compared with the control group (P<0.05). No significant changes in MDA levels were observed during the study period in either group. CONCLUSIONS: This study demonstrated that enteral nutrition containing small amounts of carotenoids (3-mg/1500kcal) in patients requiring long-term enteral feeding normalizes serum carotenoid levels to the lower end of the range found in age-matched controls. The NF-kappaB data indicate a reduction in oxidative stress in these patients. Therefore, the use of formulas containing a mixture of carotenoids should be recommended for long-term enteral nutrition.