|Paetau Robinson, Inke|
Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/1998
Publication Date: N/A
Interpretive Summary: Epidemiological studies indicate that ingestion of tomato products is associated with reduced risk of certain cancers in humans. Lycopene and other tomato carotenoids are major constituents of tomatoes and may be responsible for the observed beneficial effect. The objectives of this study were 1) to compare the bioavailability of lycopene from a food source, tomato juice, to that from two lycopene supplements, and 2) to monitor the plasma for lycopene metabolites as an indicator of antioxidant action of lycopene in the human body. The hypotheses were that 1) lycopene bioavailability is better from supplements than from foods, and 2) plasma concentrations of lycopene metabolites and lycopene increase concurrently. Fifteen subjects (33-61 y) completed the study. Lycopene was equally bioavailable from tomato juice and the supplements studied. Plasma concentrations of lycopene and other tomato-related carotenoids were significantly increased by the treatments. It could not be concluded from this study that lycopene acts as an antioxidant in vivo. Considering the potential health benefit of tomato products, the finding that plasma concentrations of tomato-related carotenoids can be increased by ingestion of tomato juice is important. These findings will benefit other nutritionists, dietitians, health professionals, and/or policy makers involved in improving health throughout the world.
Technical Abstract: The bioavailability of lycopene from tomato juice and two dietary supplements, each containing 70 - 75 mg lycopene, was studied in 15 healthy volunteers in a randomized cross-over design. Subjects ingested tomato juice, tomato oleoresin, lycopene beadlets, and a placebo for four weeks each while consuming self-selected diets. Treatment periods were separated by 6-wk washout periods. Plasma lycopene concentrations, assessed at baseline and weekly throughout the treatment periods, were significantly higher during tomato juice, oleoresin, and lycopene beadlet ingestion compared with the placebo. Mean (ñ SEM) plasma lycopene increments at week 4 of the three lycopene-containing treatments were similar, 0.24 ñ 0.07, 0.23 ñ 0.05, and 0.24 ñ0.06 mmol/L, respectively. The various lycopene-containing treatments had no effect on the relative distribution of lycopene among the plasma lipoproteins. Plasma concentrations of phytofluene, phytoene, Beta-carotene, zeta-carotene, and 2,6-cyclolycopene-1,5-diol (a metabolite of lycopene), which were present in small amounts in tomato juice, oleoresin and beadlets, increased significantly upon ingestion of these treatments. A marked increase in plasma concentrations of an unknown compound was observed; it was detected at trace levels in tomato juice, oleoresin, and lycopene beadlets, and had a maximum absorbance at 448 nm and a molecular mass (m/z) of 556. Concentrations of plasma lycopene, and other carotenoids with potential for enhancing human health, can be increased by ingestion of realistic levels of tomato juice.