The proposed study is a single-center, placebo-controlled, randomized, 2-arm, 2-sequence, crossover study that characterizes the bioavailability and kinetic profile of potatoes over 6-hour postprandial day (PPD).
A planned sample size of 12 will be enrolled into the study. This study will require one initial screening visit, pre-study visit, and 2 PPDs. This study will take 3-6 weeks per subject to complete.
The trial will initiate with a screening visit, which will last for about 1-1.5 hours where the subjects' height, weight, waist circumference, fasting blood glucose, fasting hs-CRP (high sensitivity C-reactive protein) concentration, blood pressure and heart rate will be measured and a survey related to general eating, health and exercise habits will be completed.
If willing and eligible to participate, a 3-day food record (2 weekdays and 1 weekend) will be given at the screening visit and collected on the following pre-study Visit to assess subject's baseline dietary intake and pattern. Also, subjects will be instructed to follow a relatively low polyphenolic-diet at least 7 days prior to the first PPD and for the duration of the study. Prior to each PPD, a dinner meal will be provided the day before the PPD to control the second meal effect from food and beverage intake of the night before the PPD.
Subjects will arrive at the center in a fasting state for at least 10 hours, well hydrated and rested. Each PPD will require blood draws throughout the visit. After evaluation of subject's health status (via anthropometric, vital sign and blood glucose measurements and in-person interview), a registered nurse will place a catheter in subject's arm for the purpose of multiple blood sample collections and take the initial blood draw at fasting. A standard high carbohydrate and high fat test meal with either 200g white potato or 200g purple potato will be served. Thereafter, timers will be started and blood sample will be collected at 20, 40, 60, 120, 180, 240, 300, and 360 minutes for assessment in plasma bioavailability and kinetic profile of potato polyphenols and changes in inflammation markers and relative metabolic indices. The sequence of receiving the potato treatment at each visit will be randomly assigned based on computer generated sequences: white potato-purple potato or purple potato-white potato.
Premenopausal female subjects will be studied during the follicular phase of their menstrual cycle because food intake tends to be more stable during the follicular phase (days 1-13) than during the luteal phase (days 14-28) when the rise in progesterone levels decrease satiety and often resulting in increased intake. Both PPD visits will be placed at least 3 days apart as well.
