This is a research study to determine if an extract made from grape seeds might help
control blood pressure. Previous research studies have found that taking this extract as
a daily supplement at 300 mg per day in a capsule or a beverage may lower blood pressure
in individuals with elevated blood pressure levels. The commercial name of this
supplement is called MegaNatural BP®. The principal investigators of this study were part
of the original research studies on GSE (both MegaNatural BP GSE and MegaNatural Gold
GSE). They are now interested to determine if a lower amount of the grape seed extract
might be effective in lowering people's blood pressure when its elevated. There is also
some earlier information suggesting the GSE may influence how well insulin works in
people's body. This may be helpful for individuals with metabolic conditions like the
early stages of pre-diabetes.
The study will last for six weeks. All participants will visit the Clinical Nutrition
Research Center (CNRC) seven times over the course of the study. These visits include a
screening visit, two ambulatory blood pressure device fitting visits, and four study day
visits throughout the six weeks. Blood will be collected to assess insulin activity
measures during subject visits to the CNRC. The flexibility of subject's blood vessels
will be measured using an ultrasound technique. Flexibility of vessels is important for
blood pressure regulation and GSE has been known to help them become more flexible.
SCREENING VISIT
A subject's eligibility for the study is based on the list (inclusion and exclusion
criteria). Clinical Research Coordinators will determine if the subject qualifies for the
study at the Screening Visit by the following measurements:
General measurements: height, weight, body composition and body temperature
Fasting blood glucose from a finger prick
Blood pressure
Pregnancy test, for women under the age of 60 During the visit, the subject will be
asked to complete a questionnaire or answer questions related to their health,
dietary habits, and physical activity history. Based on the results of the blood
sugar, questionnaires, measurements and evaluation of their health, the subject may
meet the criteria and be invited to participate in the study.
PRE-STUDY / PRE-INTERVENTION VISIT (which may be performed at the same or different day
as screening visit) The Pre-Study visit lasts ~30-45 minutes and the subject will meet
with one of the investigators who will provide detailed instructions on procedures of the
study (Blood pressure devices) and "how to prepare for each of the study days." The
subject will be trained on all study procedures including, but not limited to foods to
avoid during the study, medications/supplements to avoid, food diary recording, and
GI-tract diary recording, fasting overnight. The participants study dates will be
scheduled, and they will be provided a study booklet, including the study calendar and
all instructions covered at the Pre-Study Visit.
Medications/Supplements: If the subject is taking any medications or supplements that do
not interfere with the study or have been OK'd by study staff, they will take those as
instructed by their doctor and will record in the diary. Clinical Research Coordinators
will train the subject on what foods or supplements are OK and NOT OK during the study at
the Pre-Study Visit.
Self-Characteristics and Dietary Surveys: During this visit, participants will be asked
to complete online surveys that cover usual gastrointestinal (GI) symptoms and a 24-hour
food recall.
Ambulatory Blood Pressure Device Fitting and Baseline BP measurement (Day 0) At the
pre-study visit or another scheduled day at the participants convenience, the subject
will be fitted with an ambulatory blood pressure device (ABPD) for collection of blood
pressure for 24 h during their wake and sleep time. This is the most accurate assessment
of their true blood pressure. They will begin wearing the device once fitted until
returning the next day, which they will need to return to the clinic. As part of the 24 h
device wearing, investigators will ask that the subject keeps a sleep, wake, exercise,
eating diary. This helps the clinic understand the subject's data and when the blood
pressure increases and decreases.
The subject will be given a frozen dinner to consume before they start fasting. This meal
will be the same meal that is consumed before Visit 5.
STUDY DAY VISITS
Study Visit 1 / Day 1 Procedures
Staff collects study materials from participant
Blood pressure monitor. Confirm data
Diary and provide 24 h recall ASA24h
Confirmation the subject is ready to go for their study day by interview/discussion
with study staff
Fasted overnight for 10-12 hours
Had a usual night of sleep
Avoided alcohol and vigorous physical activity 24 hours before study day After
confirming the subject is ready for their study day, staff will proceed to
measure their weight, check their vital signs (blood pressure, heart rate and
temperature) as well as measure their fasting blood glucose from a finger
prick, ultrasound for FMD, body composition and collect a blood sample.
Ultrasound for Flow mediated dilation (FMD): FMD is a procedure to test the flexibility
of brachial vessels. The researcher will use an ultrasound machine to visualize the
artery in the subject's arm. The sonographer, who will visual the arm artery and conduct
the procedure, will add sensors to the subject's body to track their heart rate and
inflate a blood pressure cuff for 5 minutes on their arm before releasing to see and
measure by ultrasound how flexible the arteries are. This will take about 30 minutes. The
procedure will take place again 120 min after breakfast.
Blood collection: The subject will see the Licensed Health Care Provider (LHCP) for blood
sample collection. The subject has the choice of an intravenous catheter or multiple
butterfly sticks. There will be eight blood draws total. Once the fasting blood draw is
collected, investigators will provide the subject with a capsule and then 5 min later a
breakfast in the form of a nutritionally complete liquid drink (Ensure). Blood samples
will be collected over the next 3 hours via a multi-sampling protocol. The subject will
then be provided capsules for daily intake over two weeks until the next visit.
Other procedures. Every effort will be made to ensure the subjects safety while
participating in this study.
Anthropometrics: Researchers will measure the subject's height as well as weight and body
composition. Researchers will repeat the weight measurements as shown in the table. The
subject will be asked to wear light comfortable clothing when coming to the screening and
study related visits.
Vital signs: Researchers will check the subjects blood pressure, heart rate and body
temperature using standard clinic devices.
Demographic questionnaire, health and medication questionnaire: Subjects will be asked to
provide personal information, such as name, date of birth, race, etc. They will also be
asked to answer questions about demographics, health, medical history, and the
medications they take.
Study Visits 2 and 3 Procedures- Pick Up Visit Visit 2 (two weeks after Visit 1) and
Visit 3 (two weeks after Visit 2) will involve a weight check, blood draw for compliance
and supplement refill and reconciliation.
Study Visit 4- ABPD Fitting Procedure One day before Visit 5, the subject will be
expected to come into the CNRC to be fitted with an ABPD. The subject will wear the ABPD
day and night and fill out the 24 hour log until returning to the clinic for the final
visit 5 the next day.
The subject will be given a frozen dinner to consume before they start fasting. This meal
is the same as PreStudy or before Visit 1.
Study Visit 5 Procedures Visit 5 (two weeks after Visit 3) is the final study day visit.
This visit will take place the day after Visit 4. This visit will be exactly the same as
Visit 1, except the LMTT will include a capsule of the dietary regimens (placebo or
MN-BP) that are randomly assigned to participants. After all study procedures are
completed, the participant will be given a take-home snack and compensation will be
issued.