Renal Salt Handling in Postural Tachycardia Syndrome Following Dietary Dopa Administration
Condition: Healthy Participants
MeSH terms: Postural Orthostatic Tachycardia Syndrome; Tachycardia
Study type: Interventional
Phase: Early Phase 1

Summary: 
      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.
    

Detailed description: 
      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.
    

Intervention name(s): Fava beans; Fixed Sodium Diet
Intervention type(s): Dietary Supplement; Other
Intervention description(s): 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
Intervention model: Single Group Assignment
Masking: None (Open Label)
Keywords: Healthy Volunteers; Fava bean consumption; L-Dopa content in Fava Beans; Sodium; Potassium; Electrolyte Balance; Natriuresis