The proposed research will help characterize the impact that simultaneous consumption of anthocyanins and carotenoids has on the bioavailability of the provitamin A carotenoids a-carotene and b-carotene and the non-provitamin A carotenoid lycopene, and on their respective antidiabetic activity in humans. The central hypothesis is that provitamin A carotenoids will be bioavailable from purple-red multicolored carrots in humans, and the co-ingestion of carotenoids and anthocyanins from these carrots will have synergistic impacts on their respective antioxidant and antidiabetic effects. This hypothesis will be assessed through a 53 day randomized crossover time course study that consists of three arms in which healthy males and females ages 18-40 (n = 12) will consume carrot juice prepared from red, purple-red, or purple carrots. During each arm, participants will switch the type of juice they consume and by the end of the third arm, all participants will have ingested juice made from all three carrot varieties. Blood will be collected at multiple time points over 72 hours following consumption.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
TRIPLE
Enrollment
12
Purple-Red carrot juice contains provitamin A carotenoids (beta-carotene, alpha-carotene), the non-provitamin A carotenoid, lycopene, as well as anthocyanins
Red carrot juice contains provitamin A carotenoids (beta-carotene, alpha-carotene), and the non-provitamin A carotenoid, lycopene, but does NOT contain anthocyanins..
Purple carrot juice does NOT contain provitamin A carotenoids (beta-carotene, alpha-carotene), nor the non-provitamin A carotenoid, lycopene, but contains anthocyanins.
UW-Madison Department of Nutritional Sciences
Madison, Wisconsin, United States
Change in serum retinol concentration
Blood draws will take place on the first, second, and fourth test day (days 8, 9, 11 of each arm)
Time frame: Blood will be drawn on the first test day (treatment day) at baseline, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2.5 hours, 4 hours, 6 hours, 9 hours, 24 hours, 72 hours
Change in serum carotenoid concentration
Blood draws will take place on the first, second, and fourth test day (days 8, 9, 11 of each arm)
Time frame: Blood will be drawn on the first test day (treatment day) at baseline, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2.5 hours, 4 hours, 6 hours, 9 hours, 24 hours, 72 hours
Change in serum anthocyanin concentration
Blood draws will take place on the first, second, and fourth test day (days 8, 9, 11 of each arm)
Time frame: Blood will be drawn on the first test day (treatment day) at baseline, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2.5 hours, 4 hours, 6 hours, 9 hours, 24 hours, 72 hours
Change in antioxidant capacity of the carrots and carrot juice measured by enzyme activity assay
Three different antioxidant activity assays will be used including the Oxygen Radical Absorbance Capacity (ORAC), 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS+), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays, all of which will be analyzed by Ultraviolet (UV) spec. Each method analyzes different ways anthocyanins and carotenoids may act as antioxidants, and a combination of the three will more accurately represent the parameters of human biology. Data will be expressed as Trolox equivalent antioxidant capacity (TEAC).
Time frame: up to 1 month
Change in alpha-glucosidase inhibition activities of the carrots and carrot juice measured by enzyme activity assay
Enzyme inhibition will be assessed using specific enzymatic assay kits for alpha-glucosidase and alpha-amylase, analyzed using Enzyme-Linked Immunosorbent Assay (ELISA), and results will be expressed as IC50 (% inhibition).
Time frame: up to 1 month
Change in alpha-amylase inhibition activities of the carrots and carrot juice measured by enzyme activity assay
Enzyme inhibition will be assessed using specific enzymatic assay kits for alpha-glucosidase and alpha-amylase, analyzed using ELISA, and results will be expressed as IC50 (% inhibition).
Time frame: up to 1 month
Change in serum glucose concentration
Blood draws will take place on the first, second, and fourth test day (days 8, 9, 11 of each arm)
Time frame: Blood will be drawn on the first test day (treatment day) at baseline, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2.5 hours, 4 hours, 6 hours, 9 hours, 24 hours, 72 hours
Change in serum insulin concentration
Blood draws will take place on the first, second, and fourth test day (days 8, 9, 11 of each arm)
Time frame: Blood will be drawn on the first test day (treatment day) at baseline, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2.5 hours, 4 hours, 6 hours, 9 hours, 24 hours, 72 hours
Change in serum incretin concentration
Blood draws will take place on the first, second, and fourth test day (days 8, 9, 11 of each arm)
Time frame: Blood will be drawn on the first test day (treatment day) at baseline, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2.5 hours, 4 hours, 6 hours, 9 hours, 24 hours, 72 hours
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