Dietary Protein Sources and Atherogenic Dyslipidemia
| Status: | Active, not recruiting |
|---|---|
| Conditions: | High Cholesterol, Peripheral Vascular Disease, Endocrine |
| Therapuetic Areas: | Cardiology / Vascular Diseases, Endocrinology |
| Healthy: | No |
| Age Range: | 30 - 65 |
| Updated: | 2/16/2017 |
| Start Date: | January 2012 |
| End Date: | June 2017 |
Saturated Fat and Protein Effects on Atherogenic Dyslipidemia
There is growing epidemiological evidence that consumption of red meat is associated with
greater incidence of Cardiovascular Disease (CVD) than either white meat or non-meat foods.
Research from our group has shown that a high saturated fat (SF) diet with a moderate red
meat content selectively increases intermediate density lipoproteins (IDL) and larger low
density lipoproteins (LDLs), which are more weakly associated with CVD risk than smaller
LDLs. In contrast, the investigators have found that with a similar intake of SF, high beef
consumption results in a preferential increase in small and medium LDL particles that are
strongly related to CVD. To date, no studies have directly compared the lipoprotein effects
of red meat with that of other food sources of protein in the context of both high and low
saturated fat intake.
The overall objective of this project is to test the hypothesis that the effects of SF on
lipoprotein markers of CVD risk are influenced by sources of dietary protein. The
investigators hypothesize that adverse effects of SF on plasma levels of LDL-cholesterol
(C), apolipoprotein B (apo B), and atherogenic LDL particles are greater in a diet with a
high content of red meat than in diets in which the major proteins are from white meat
(poultry) or non-meat sources. The investigators propose a clinical trial in which 180
healthy men and women will be randomized to high SF or low SF diet groups, and within each
group, consume diets with equivalent amounts of protein from red meat, white meat, and
non-meat sources for 4 wks each in random order. Specifically, the investigators will test
whether: (1) With high SF, the red meat diet, compared to the other protein sources, will
result in higher levels of LDL-C, apoB, small and medium LDL, and total/high density
lipoprotein (HDL)C; (2) With low SF, dietary protein source will not be related to any of
these measurements; (3) With both the white meat and non-meat protein diets, increased LDL-C
with high vs. low SF will be due primarily to increases in large LDL, whereas with red meat
the additional increase in small and medium LDL will result in greater increases in plasma
apoB and total LDL particle number. Aim 4 will test hypotheses that increases in small and
medium LDL with high SF plus red meat are related to increased activity of hepatic lipase, a
key determinant of small LDL production, and that increases in large LDL induced by high SF
are related to suppression of LDL receptors. The investigators will also assess the effects
of protein source and saturated fat content on markers of insulin resistance, inflammation
and endothelial function.
greater incidence of Cardiovascular Disease (CVD) than either white meat or non-meat foods.
Research from our group has shown that a high saturated fat (SF) diet with a moderate red
meat content selectively increases intermediate density lipoproteins (IDL) and larger low
density lipoproteins (LDLs), which are more weakly associated with CVD risk than smaller
LDLs. In contrast, the investigators have found that with a similar intake of SF, high beef
consumption results in a preferential increase in small and medium LDL particles that are
strongly related to CVD. To date, no studies have directly compared the lipoprotein effects
of red meat with that of other food sources of protein in the context of both high and low
saturated fat intake.
The overall objective of this project is to test the hypothesis that the effects of SF on
lipoprotein markers of CVD risk are influenced by sources of dietary protein. The
investigators hypothesize that adverse effects of SF on plasma levels of LDL-cholesterol
(C), apolipoprotein B (apo B), and atherogenic LDL particles are greater in a diet with a
high content of red meat than in diets in which the major proteins are from white meat
(poultry) or non-meat sources. The investigators propose a clinical trial in which 180
healthy men and women will be randomized to high SF or low SF diet groups, and within each
group, consume diets with equivalent amounts of protein from red meat, white meat, and
non-meat sources for 4 wks each in random order. Specifically, the investigators will test
whether: (1) With high SF, the red meat diet, compared to the other protein sources, will
result in higher levels of LDL-C, apoB, small and medium LDL, and total/high density
lipoprotein (HDL)C; (2) With low SF, dietary protein source will not be related to any of
these measurements; (3) With both the white meat and non-meat protein diets, increased LDL-C
with high vs. low SF will be due primarily to increases in large LDL, whereas with red meat
the additional increase in small and medium LDL will result in greater increases in plasma
apoB and total LDL particle number. Aim 4 will test hypotheses that increases in small and
medium LDL with high SF plus red meat are related to increased activity of hepatic lipase, a
key determinant of small LDL production, and that increases in large LDL induced by high SF
are related to suppression of LDL receptors. The investigators will also assess the effects
of protein source and saturated fat content on markers of insulin resistance, inflammation
and endothelial function.
Clinic Visits:
Participants will visit the clinic a total of 11 times from screen to completion of study.
This will include weekly visits with the nutritionist and 9 visits requiring blood draws (at
screen and on 2 consecutive visits after each dietary period). At each visit, participants
will be weighed, waist and hip circumference will be measured and blood pressure will be
monitored. The total amount of blood collected during the course of the study will be 455
mL.
Screening visit (SV: 1 hour):
Recruiters will initially determine eligibility through review of a screening questionnaire
and a telephone or personal interview. If a potential subject is eligible and interested, an
orientation package will be mailed that will include written information about the study
requirements. Interested individuals passing pre-screening will be scheduled for a screening
blood draw visit to determine final eligibility. At the screening visit (SV), participants
will give informed consent, review their medical history with a registered nurse, and have
their blood pressure, weight, height, and waist and hip circumference measured. Thirty ml of
blood will be drawn for measurement of plasma triglycerides (TG), total-C, LDL-C, HDL-C,
glucose and thyroid stimulating hormone (TSH). Women of childbearing potential will be given
a beta-Human Chorionic Gonadotropin (b-hCG) urine pregnancy test. Participants will be
contacted within 2 weeks to notify them of their eligibility.
Nutritionist Visits (Initial: 1 hr):
Participants will meet weekly with a nutritionist to receive counseling including weight
management and diet review. At these meetings, participants will receive a week's worth of
frozen entrees and study foods, as well as standardized menus with check lists. During the
washout period (weeks 6-8; weeks 12-14), subjects will continue to refrain from alcohol but
will consume their usual home diet for 14 days.
Post-diet Visits Requiring Blood Draws (A visits: 1.5 hr, B visits: 2.5 hr):
Participants will visit the clinic on two separate days following completion of each diet to
provide blood samples. Duplicate sampling reduces biological variability, and hence improves
the power of the study to detect significant diet-induced changes in measurement. On the
penultimate day of each diet (visits 1A, 2A, 3A, 4A) a fasting blood draw (45 mL) will be
taken for plasma measurements (TG, total-C, LDL-C, HDL-C, lipoprotein subfractions, glucose,
insulin, apolipoproteins AI, AII, B, and CIII, and inflammatory markers). On the last day of
each dietary period (visits 1B, 2B, 3B, 4B) participants will provide a second fasting blood
sample (for lipids and lipoproteins as above). Lipoprotein lipase and hepatic lipase
activities will also be measured in plasma (20mL) collected 15 minutes after intravenous
heparin (75 units/kg).
Clinical Procedures:
Clinical measurements: Blood pressure will be measured 3 times in a sitting position and the
last 2 values averaged. Anthropometric measurements include height, weight, waist and hip
circumference, and % body fat by bioimpedance (Tanita scale). Waist circumference is
measured two times at the iliac crest and hip circumference is measured at the widest point
of the hips.
Standard Blood sampling: Using standard blood collection procedures, blood samples will be
collected from participants after a 12-14 hour fast. The blood will be collected into tubes
containing the following preservative solution: 3.0 gms EDTA (dipotassium), 1.7 mg P-Pack,
0.15 gms gentamycin sulfate, 0.15 gms chloramphenicol, 5.96 mls aprotinin (Sigma A-6279),
and 0.30 gms sodium azide all of which are diluted to 20mls with doubly deionized water.
Plasma is separated by immediate centrifugation at 4°C. Lipid and lipoprotein measurements
are performed and aliquots of plasma are frozen for future analyses.
Post-heparin Blood Sampling: A blood sample (20ml) will be drawn 15 minutes after
intravenous administration of a heparin bolus (75 U/kg, see Risk section for justification)
for the analysis of plasma lipase activity. Prior to administration, participants will be
interviewed for family history of clotting disorders or personal contraindications including
use of anticoagulants, history of bleeding or bruising abnormalities or other diseases,
allergies, or recent dental work. Following administration, participants will remain in
clinic for 2 hours under observation. They will also be provided with an information sheet
regarding heparin and the procedure.
Measurement of endothelial function: Endothelial function will be assessed in the fasting
state by finger reactive hyperemia peripheral arterial tonometry (RH-PAT, Endo-Pat2000,
Itamar Medical, Israel) and expressed as RH-PAT index. Participants will rest in a supine
position in a quiet, temperature-controlled room for 30 min. prior to PAT measurements and
will abstain from caffeine for 6 hours and from water for 2 hours prior to the test, per
manufacturer's guidelines.
Participants will visit the clinic a total of 11 times from screen to completion of study.
This will include weekly visits with the nutritionist and 9 visits requiring blood draws (at
screen and on 2 consecutive visits after each dietary period). At each visit, participants
will be weighed, waist and hip circumference will be measured and blood pressure will be
monitored. The total amount of blood collected during the course of the study will be 455
mL.
Screening visit (SV: 1 hour):
Recruiters will initially determine eligibility through review of a screening questionnaire
and a telephone or personal interview. If a potential subject is eligible and interested, an
orientation package will be mailed that will include written information about the study
requirements. Interested individuals passing pre-screening will be scheduled for a screening
blood draw visit to determine final eligibility. At the screening visit (SV), participants
will give informed consent, review their medical history with a registered nurse, and have
their blood pressure, weight, height, and waist and hip circumference measured. Thirty ml of
blood will be drawn for measurement of plasma triglycerides (TG), total-C, LDL-C, HDL-C,
glucose and thyroid stimulating hormone (TSH). Women of childbearing potential will be given
a beta-Human Chorionic Gonadotropin (b-hCG) urine pregnancy test. Participants will be
contacted within 2 weeks to notify them of their eligibility.
Nutritionist Visits (Initial: 1 hr):
Participants will meet weekly with a nutritionist to receive counseling including weight
management and diet review. At these meetings, participants will receive a week's worth of
frozen entrees and study foods, as well as standardized menus with check lists. During the
washout period (weeks 6-8; weeks 12-14), subjects will continue to refrain from alcohol but
will consume their usual home diet for 14 days.
Post-diet Visits Requiring Blood Draws (A visits: 1.5 hr, B visits: 2.5 hr):
Participants will visit the clinic on two separate days following completion of each diet to
provide blood samples. Duplicate sampling reduces biological variability, and hence improves
the power of the study to detect significant diet-induced changes in measurement. On the
penultimate day of each diet (visits 1A, 2A, 3A, 4A) a fasting blood draw (45 mL) will be
taken for plasma measurements (TG, total-C, LDL-C, HDL-C, lipoprotein subfractions, glucose,
insulin, apolipoproteins AI, AII, B, and CIII, and inflammatory markers). On the last day of
each dietary period (visits 1B, 2B, 3B, 4B) participants will provide a second fasting blood
sample (for lipids and lipoproteins as above). Lipoprotein lipase and hepatic lipase
activities will also be measured in plasma (20mL) collected 15 minutes after intravenous
heparin (75 units/kg).
Clinical Procedures:
Clinical measurements: Blood pressure will be measured 3 times in a sitting position and the
last 2 values averaged. Anthropometric measurements include height, weight, waist and hip
circumference, and % body fat by bioimpedance (Tanita scale). Waist circumference is
measured two times at the iliac crest and hip circumference is measured at the widest point
of the hips.
Standard Blood sampling: Using standard blood collection procedures, blood samples will be
collected from participants after a 12-14 hour fast. The blood will be collected into tubes
containing the following preservative solution: 3.0 gms EDTA (dipotassium), 1.7 mg P-Pack,
0.15 gms gentamycin sulfate, 0.15 gms chloramphenicol, 5.96 mls aprotinin (Sigma A-6279),
and 0.30 gms sodium azide all of which are diluted to 20mls with doubly deionized water.
Plasma is separated by immediate centrifugation at 4°C. Lipid and lipoprotein measurements
are performed and aliquots of plasma are frozen for future analyses.
Post-heparin Blood Sampling: A blood sample (20ml) will be drawn 15 minutes after
intravenous administration of a heparin bolus (75 U/kg, see Risk section for justification)
for the analysis of plasma lipase activity. Prior to administration, participants will be
interviewed for family history of clotting disorders or personal contraindications including
use of anticoagulants, history of bleeding or bruising abnormalities or other diseases,
allergies, or recent dental work. Following administration, participants will remain in
clinic for 2 hours under observation. They will also be provided with an information sheet
regarding heparin and the procedure.
Measurement of endothelial function: Endothelial function will be assessed in the fasting
state by finger reactive hyperemia peripheral arterial tonometry (RH-PAT, Endo-Pat2000,
Itamar Medical, Israel) and expressed as RH-PAT index. Participants will rest in a supine
position in a quiet, temperature-controlled room for 30 min. prior to PAT measurements and
will abstain from caffeine for 6 hours and from water for 2 hours prior to the test, per
manufacturer's guidelines.
Inclusion Criteria:
- 30-65 years old
- Non-smoking
- Agrees to abstain from alcohol and dietary supplements during the study
- Willing to consume all study foods as instructed
Exclusion Criteria:
- History of heart disease, cerebrovascular disease, peripheral vascular disease,
bleeding disorder, liver or renal disease, lung disease, diabetes, Human
immunodeficiency virus (HIV), or cancer (other than skin cancer) in the last 5 years
- Body mass index (BMI) > 35 kg/m2 or < 20 kg/m2
- Not weight stable
- Abnormal thyroid stimulating hormone
- Blood pressure > 150/90
- Fasting blood sugar >126 mg/dl
- Fasting triglyceride levels >500 mg/dl
- Total- and LDL cholesterol >95th percentile for age and sex
- Pregnant or breastfeeding
- Taking hormones or drugs known to affect lipid metabolism
We found this trial at
1
site
Berkeley, California 94705
Principal Investigator: Ronald M Krauss, MD
Phone: 510-665-0506
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