The purpose of this study is to learn how plants can play a role in gain/loss of sodium in the urine and in the regulation of blood pressure. Dopamine is a chemical mostly present in the brain and kidneys which assists in regulation of the body's salts (sodium and potassium). Fava beans contain a lot of the chemical that increases the production of dopamine by the kidneys. The purpose of these studies is to characterize the diuretic effects of dietary catecholamine sources in healthy individuals. Specific aims are: 1. To determine the effect of dietary dopa sources on plasma and urinary catecholamines. 2. To investigate the capacity of botanical dopaminergic agents (fava beans) to induce natriuresis in a short term study. 3. To provide preliminary data on the effects of dietary dopa on heart rate and blood pressure. In these studies, we will test the null hypothesis (Ho) that urinary sodium excretion will not differ in healthy volunteers after consumption of a fixed-sodium study diet and the study diet plus fava beans.
Fava beans are a broad bean, with potential clinical relevance in Parkinson's patients since they contain high levels of the dopamine precursor, dihydroxyphenylalanine (dopa).In addition to the central nervous system functions of dopamine that are compromised in Parkinson's disease, renal dopamine has vasodilatory and natriuretic activity. Elevated urinary dopamine, however, does not consistently correlate with increased urinary sodium excretion, and there are conflicting opinions over the conditions under which renal dopamine might regulate sodium balance.The goal of our study was to clarify the natriuretic effect of fava beans, obtained from a source that serves patients with Parkinson's disease. Catechol and sodium data were compared in healthy volunteers using a longitudinal design in which all participants consumed a fixed sodium study diet on day 1 and the fixed sodium diet plus fava beans on day 2. Blood was sampled at 1, 2, 4 and 6 hours after breakfast, and three consecutive 4-hr urine samples were collected. Postural tachycardia syndrome (POTS) is the most common form of orthostatic intolerance, affecting an estimated 500,000 Americans, principally young women. POTS refers to an excessive increase in heart rate (\>30 beats per minute) on standing in the absence of orthostatic hypotension. Previous findings by the Robertson/Garland research group suggest that mechanisms involved in orthostatic and absolute volume regulation contribute to POTS pathophysiology. A follow-up study might compare the influences of diet in patients with POTS and healthy volunteers.
Study Type
INTERVENTIONAL
Allocation
NA
Masking
NONE
Enrollment
14
Participants will receive 100g of fresh fava beans for breakfast and lunch on one study day and prior to this study day will be restricted to a fixed sodium low monoamine diet
Fixed sodium low monoamine diet
Vanderbilt University Clinical Research Center
Nashville, Tennessee, United States
Plasma Dopa 1 hr After Breakfast
Subjects consumed the standard fixed sodium diet for at least two days prior to study and on study day one during an inpatient stay in the Vanderbilt Clinical Research Center. On study day two, participants ate 100 g of puréed fava beans and pods with study diet at breakfast (0800hr) and lunch (1200hr). Blood was sampled for catechol assays before and at 1, 2, 4 and 6 hours after breakfast. Plasma dopa 1 hour after breakfast was specified as a primary outcome. Other catechols (dihydroxyphenylglycol, norepinephrine, epinephrine, dopamine, dihydroxyphenylacetic acid) and other time points (2, 3, 4, 6hr after breakfast) are non-primary outcomes.
Time frame: Plasma samples collected 1 hour after breakfast on both study days.
Urinary Dopa
Urinary dopa excreted 4-8 hours after breakfast was specified as a primary outcome. Other catechols (dihydroxyphenylglycol, norepinephrine, epinephrine, dopamine, dihydroxyphenylacetic acid) and other time points (0-4 hr, 8-12 hr after breakfast) are non-primary outcomes.
Time frame: 4-8 hours after breakfast
Urinary Sodium
Urinary sodium excreted 4-8 hours after breakfast was designated as a primary outcome. Other urine samples (0-4 hr, 8-12 hr after breakfast) are considered as non-primary outcomes.
Time frame: 4 to 8 hours after breakfast
Plasma Dopa 2 Hrs After Breakfast
Subjects consumed the standard fixed sodium diet for at least two days prior to study and on study day one during an inpatient stay in the Vanderbilt Clinical Research Center. On study day two, participants ate 100 g of puréed fava beans and pods with study diet at breakfast (0800hr) and lunch (1200hr). Blood was sampled for catechol assays before and at 1, 2, 4 and 6 hours after breakfast. Plasma dopa 1 hour after breakfast was specified as a primary outcome. Other catechols (dihydroxyphenylglycol, norepinephrine, epinephrine, dopamine, dihydroxyphenylacetic acid) and other time points (2, 3, 4, 6hr after breakfast) are non-primary outcomes.
Time frame: Plasma samples collected 2 hours after breakfast on both study days.
Plasma Dopa 4 Hrs After Breakfast
Subjects consumed the standard fixed sodium diet for at least two days prior to study and on study day one during an inpatient stay in the Vanderbilt Clinical Research Center. On study day two, participants ate 100 g of puréed fava beans and pods with study diet at breakfast (0800hr) and lunch (1200hr). Blood was sampled for catechol assays before and at 1, 2, 4 and 6 hours after breakfast. Plasma dopa 1 hour after breakfast was specified as a primary outcome. Other catechols (dihydroxyphenylglycol, norepinephrine, epinephrine, dopamine, dihydroxyphenylacetic acid) and other time points (2, 3, 4, 6hr after breakfast) are non-primary outcomes.
Time frame: Plasma samples collected 4 hours after breakfast on both study days.
Plasma Dopa 6 Hrs After Breakfast
Subjects consumed the standard fixed sodium diet for at least two days prior to study and on study day one during an inpatient stay in the Vanderbilt Clinical Research Center. On study day two, participants ate 100 g of puréed fava beans and pods with study diet at breakfast (0800hr) and lunch (1200hr). Blood was sampled for catechol assays before and at 1, 2, 4 and 6 hours after breakfast. Plasma dopa 1 hour after breakfast was specified as a primary outcome. Other catechols (dihydroxyphenylglycol, norepinephrine, epinephrine, dopamine, dihydroxyphenylacetic acid) and other time points (2, 3, 4, 6hr after breakfast) are non-primary outcomes.
Time frame: Plasma samples collected 6 hours after breakfast on both study days.
Plasma Norepinephrine
Plasma norepinephrine 1 hour after breakfast
Time frame: 1 hour after breakfast on both study days.
Plasma Norepinephrine
Plasma norepinephrine 2 hours after breakfast
Time frame: 2 hours after breakfast on both study days.
Plasma Norepinephrine
Plasma norepinephrine 4 hours after breakfast
Time frame: 4 hours after breakfast on both study days.
Plasma Norepinephrine
Plasma norepinephrine 6 hours after breakfast
Time frame: 6 hours after breakfast on both study days.
Plasma Dopamine
Plasma dopamine 1 hour after breakfast
Time frame: 1 hour after breakfast
Plasma Dopamine
Plasma dopamine 2 hours after breakfast
Time frame: 2 hours after breakfast on both study days.
Plasma Dopamine
Plasma dopamine 4 hours after breakfast
Time frame: 4 hours after breakfast on both study days.
Plasma Dopamine
Plasma dopamine 6 hours after breakfast
Time frame: Plasma samplesPlasma dopamine 6 hours after breakfast on both study days.
Urinary Dopa
Urinary dopa excreted 4-8 hours after breakfast was specified as a primary outcome. Other time points (0-4 hr, 8-12 hr after breakfast) are non-primary outcomes.
Time frame: 0-4 hours after breakfast
Urinary Dopa
Urinary dopa excreted 4-8 hours after breakfast was specified as a primary outcome. Other time points (0-4 hr, 8-12 hr after breakfast) are non-primary outcomes.
Time frame: 8-12 hours after breakfast
Urinary Dopamine
Urinary dopamine excreted 0 to 4 hours after breakfast
Time frame: 0 to 4 hours after breakfast
Urinary Dopamine
Urinary dopamine excreted 4 to 8 hours after breakfast
Time frame: 4 to 8 hours after breakfast
Urinary Dopamine
Urinary dopamine excreted 8 to 12 hours after breakfast
Time frame: 8 to 12 hours after breakfast
Urinary Norepinephrine
Urinary norepinephrine excreted 0-4 hours after breakfast
Time frame: 0 to 4 hours after breakfast
Urinary Norepinephrine
Urinary norepinephrine excreted 4-8 hours after breakfast
Time frame: 4 to 8 hours after breakfast
Urinary Norepinephrine
Urinary norepinephrine excreted 8-12 hours after breakfast
Time frame: 8 to 12 hours after breakfast
Supine Systolic Blood Pressure
Supine systolic blood pressure 6 hours after breakfast
Time frame: Supine-6 hours after breakfast on both study days.
Supine Heart Rate
Supine heart rate 6 hours after breakfast
Time frame: 6 hours after breakfast
Urinary Sodium
Urinary sodium excreted 0-4 hours after breakfast.
Time frame: 0-4 hours after breakfast
Urinary Sodium
urinary sodium 8-12 hours after breakfast
Time frame: 8-12 hours after breakfast
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