The purpose of this study is to investigate the relative bioavailability and
absorption/kinetic profile of red raspberry polyphenols consumed with a meal and further to
determine the relationship of these findings on meal-associated metabolic- oxidative- and
inflammatory- responses in relatively insulin sensitive and insulin resistant individuals.
The proposed study is a randomized, 3-arm, diet-controlled, cross-over study using a
multi-sampling postprandial paradigm to evaluate the relative bioavailability and
absorption/kinetic profile of red raspberry polyphenols consumed with a typical American
breakfast meal and further to determine the relationship of these findings on meal-associated
metabolic- oxidative- and inflammatory- responses in relatively insulin sensitive and insulin
resistant individuals. A planned sample size of 24 will be recruited into the study. This
study will require one initial screening visit, 1 pre-study visit, and 3 study visits. This
study will take 4-6 weeks per subject to complete.
The trial will initiate with a screening visit, which will last for about 1-1.5 hours and
include measuring subjects' height, weight, waist circumference, fasting blood glucose,
insulin sensitivity, body temperature, blood pressure and heart rate as well as collecting
general eating, health and exercise habits via questionnaire.
If willing and eligible to participate, a 3-day food record (2 weekdays and 1 weekend) will
be given to be completed over the following week to assess subject's baseline dietary intake
patterns. Information will be used to help subjects adopt a relatively low polyphenolic diet
over the course of the study. Prior to each postprandial study visit, a dinner meal will be
provided the day before the study visit to help control for visit to visit variability in due
to differences in meals the night before the study visit.
Subjects will arrive at the center in a fasting state for at least 10 hours, well hydrated
and rested (with normal sleep). Each study visit 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 qualified health professional will place a
catheter in subject's arm for the purpose of multiple blood sample collections and take the
initial blood draw in the fasting state. Each subject will be randomized to receive 1 of 3
meal treatments: Control meal (0 g red raspberry), red raspberry meal 1 [~125 g fresh weight
(1 cup equivalent)] or red raspberry meal 2 [~250 g fresh weight (2 cup equivalent)], based
on randomization sequence on 3 Study Day Visits. At each Study visit, after the first blood
draw (0 h), subjects will be served with the standard breakfast meal (a moderate to high
fat/carbohydrate) along with fruit variable based on the order randomly selected by computer
generated sequence. From this point forward, blood collection will occur at the following
time points: 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 6.5 h, 7 h, 8 h and 24 h to test for
polyphenol metabolites and other metabolic markers. After the 6h blood draw, a standardized
lunch meal (polyphenol free) will be provided to subjects. After the 8 h blood draw, the
catheter will be removed from subjects arm. Subject will be provided with a dinner meal (low
polyphenol) to take home and asked not to consume anything else other than the provided
dinner meal except plain water. Subject will be scheduled to come back the next morning for
the 24 h blood sample collection.
- Fasting blood sugar between 100-125 mg/dL for insulin resistant group and below 100
mg/dL for the reference/control group.
- Insulin resistance defined by the homeostasis model assessment method of insulin
resistance (HOMA-IR) (glucose [in millimoles per liter] × insulin [in microunits per
milliliter]/22.5) values of at least 1 for insulin resistant group and less than 1 for
- Aged between 20 to 60 years old male/female
- Non-smoker or Past smokers: abstinence for less than 2 years
- No clinical evidence of cardiovascular, metabolic, respiratory, renal,
gastrointestinal or hepatic disease
- Not taking any medications or dietary supplements that would interfere with outcomes
of the study.
- Men and women who smoke
- Men and women with known or suspected food intolerance, allergies or hypersensitivity
to the study materials or closely related compound or any their stated ingredients.
- Men and women known to have/diagnosed with diabetes mellitus
- Men and women who have fasting blood glucose concentrations ≥126 mg/dL
- Men and women with documented vascular disease, e.g., heart failure, myocardial
infarction, stroke, angina, related surgeries.
- Men and women with cancer other than non-melanoma skin cancer in previous 5 years.
- interfere with the outcomes of the study; e.g., antioxidant supplements,
anti-inflammation, lipid lowering medication. Subjects may choose to go off dietary
supplements (requires 30 days washout).
- Men and women who have donated blood within 3 months of the screening visit and blood
donors/participants for whom participation in this study will result in having donated
more than 1500 milliliters of blood in the previous 12 months.
- Substance (alcohol or drug) abuse within the last 2 years.
- Excessive coffee and tea consumers (> 4 cups/day)
- Unstable weight: gained or lost weight +/- 5 lbs in previous 3 months
- Women who are known to be pregnant or who are intending to become pregnant over the
course of the study and women who are lactating