Standing Up to POTS
Written by Jane Crosby
Edited by Miriam Bermejo
September 27th, 2023
Edited by Miriam Bermejo
September 27th, 2023
Research
Isn’t eating too much salt bad for you? For most, the recommended sodium intake is around 2,300mg/day, but for the 1,000,000+ [1] Americans living with Postural Orthostatic Tachycardia Syndrome (POTS), a high sodium diet can improve symptoms and increase quality of life. POTS is a type of dysautonomia, or autonomic nervous system dysfunction, that causes tachycardia, migraine, dizziness, shaking and sweating, nausea, digestive issues, and fatigue, among other things, all of which are worsened by standing. A high sodium diet is a recommended treatment for POTS but proof that it definitively works is not available. This gap led researchers at the Vanderbilt Autonomic Dysfunction center to investigate the efficacy of a high sodium diet.
They hypothesized that a high sodium diet (HS) in POTS patients would decrease standing heart rate and orthostatic change in heart rate, increase plasma volume, and decrease standing norepinephrine volume compared with a low sodium diet (LS), where HS was 30x the sodium intake of LS. [2] 14 female POTS patients were included, between 23-49 years of age, one Hispanic and all White, all from the Vanderbilt Autonomic Dysfunction Center. 13 female controls from the Vanderbilt community were included. They were between 23-43 years of age, and were either Hispanic, White, Asian and Black. None of the participants had other health conditions that could affect autonomic function and both phases were conducted during the same part of the menstrual cycle to minimize the effects of hormone fluctuations on study results. Participants followed a LS or HS diet for 6 days, came in for assessment on day 7, and then approximately a month later switched to the opposite diet for another 6 days. Day 7 assessments included supine and vertical blood pressure and heart rate measurements along with blood draws for PRA, catecholamines, and aldosterone. They also assessed participant’s symptoms upon standing, determined plasma volume, drew samples to check hormones & electrolytes in the supine position, and did a 24hr urine test for potassium, sodium, and creatinine. [2]
Plasma and urinary electrolytes were found to be consistent with the LS and HS diets, and there was a measured decrease in orthostatic heart rate change and upright heart rate on the HS diet, but not change in blood pressure in any position on either diet. Upright plasma epinephrine was not lowered by the HS diet, but standing norepinephrine was. PRA and aldosterone decreased overall on the HS diet. There was no significant difference in individual reported symptoms, but overall they trended downwards on the HS diet. Plasma Volume was significantly lower than normal for patient demographics on an LS diet, and increased on HS. Patient compliance with the study diets was satisfactory. The study concluded that the HS diet significantly improved HR, plasma volume, and plasma norepinephrine, but it failed to alleviate symptoms and participants still met clinical criteria for POTS diagnosis. [2] This shows us that while a high sodium diet can be helpful, it is not the end all be all for POTS. More research is needed to come up with better treatments to supplement the high sodium diet and address all facets of dysautonomia, especially those not intertwined with blood volume.
References
Safavi-Naeini P, Razavi M. Postural Orthostatic Tachycardia Syndrome. Tex Heart Inst J. 2020;47(1):57-59. Published 2020 Feb 1. doi:10.14503/THIJ-19-7060
Garland EM, Gamboa A, Nwazue VC, et al. Effect of High Dietary Sodium Intake in Patients With Postural Tachycardia Syndrome. J Am Coll Cardiol. 2021;77(17):2174-2184. doi:10.1016/j.jacc.2021.03.005
Image Source: “Free photo sea salt coming out of salt shaker” by 8photo licensed under Freepik License