Human Lycopene and Beta-cryptoxanthin Absorption From Citrus Fruit
Condition: Bioavailability of Carotenoids
Study type: Interventional

Summary: 
      The goal of the research study is to measure and compare the absorption of equivalent amounts
      of beta-cryptoxanthin and Iycopene provided in citrus fruit. The investigators want to
      determine whether adults absorb beta-cryptoxanthin to a greater extent than lycopene, when
      both are supplied in comparable citrus fruits.
    

Detailed description: 
      Lycopene and beta-cryptoxanthin are carotenoids found in a small number of foods. Unlike
      lycopene, beta-cryptoxanthin is among the 10% of carotenoids that can form vitamin A.
      Lycopene is primarily found in tomatoes and tomato-based products, but also in pink
      grapefruit and pink guava. Beta-cryptoxanthin is primarily found in tangerines, oranges,
      pumpkin, peaches, and papayas. Tomatoes and tomato products contain very high concentrations
      of lycopene, but beta-cryptoxanthin is present in modest amounts, of about 2 to 3 mg per
      serving, even in its primary food sources. Lycopene is typically the most abundant carotenoid
      in the diet and in the blood. Despite its scarcity in foods, beta-cryptoxanthin is the third
      or fourth most abundant carotenoid in blood.

      This suggests that beta-cryptoxanthin absorption and metabolism may be quite different from
      the absorption and metabolism of lycopene and other carotenoids. Specifically, it suggests
      either that beta-cryptoxanthin itself is absorbed unusually well or that the citrus fruits
      that are the primary food sources of beta-cryptoxanthin in the diet are much more
      bioavailable than the tomato products that are the major source of lycopene. The
      investigators hypothesize that adults absorb a significantly greater amount of
      beta-cryptoxanthin than lycopene even when both carotenoids are supplied in comparable
      amounts in a similar matrix.

      Subjects will be given a list of foods that are good sources of lycopene and
      beta-cryptoxanthin and asked to avoid them. Both carotenoids are found in limited numbers of
      foods, and can be avoided by limiting intakes of tomatoes, red and orange peppers, pumpkin,
      watermelon, pink guava, pink grapefruit, tangerines, oranges, papayas and mangos. The
      investigators will feed citrus fruit to volunteers in a randomized crossover design. On study
      days 14 and 28, subjects will receive either tangerines, or pink grapefruit in a randomized
      fashion so that each subject gets both treatments during the study. Each subject will serve
      as his/her own control, and will be fed both treatments at different times, separated by a
      two-week washout period.

      On days 14 and 28, subjects will arrive at the Western Human Nutrition Research Center at
      approximately 10:30 AM. After a baseline blood draw, subjects will be fed their
      carotenoid-containing fruit with a controlled meal (low carotenoid, 30-35% fat). Subjects
      will be given a controlled, low carotenoid, 30-35% kcal from fat dinner at about 6:30 PM on
      treatment days (days 14 and 28) and a controlled low carotenoid, 30 - 35% kcals from fat
      breakfast at about 8 AM on study days 15 and 29. Investigators will collect 25 mL of blood
      per collection, by venipuncture of an arm vein at the following time points, 0, 3, 5, 7, 9,
      21, and 24hr following the fruit containing meal. Blood will be collected into heparinized
      vacutainer tubes and placed on ice in a covered ice bucket.
    

Intervention name(s): Pink grapefruit first followed by tangerines two weeks later; Tangerines first followed by pink grapefruit two weeks later
Intervention type(s): Other; Other
Intervention description(s): A 504 gram serving of pink grapefruit was fed as a single meal followed by 234 grams tangerines two weeks later; A 234 gram serving of tangerines was fed as a single meal followed by 504 grams pink grapefruit two weeks later
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Investigator)
Primary purpose: Basic Science
Keywords: Carotenoids; absorption; citrus