Hormonal changes following a low-salt diet in patients with Ménière's disease

Objective: A low-salt diet has been the main treatment modality for Ménière's disease (MD) since the 1930s, although the mechanisms behind this therapy have not yet been elucidated. Salt reduction is associated with a physiological increase in plasma aldosterone concentration. Several experimental reports have suggested that aldosterone may increase endolymph absorption in the inner ear, particularly in the endolymphatic sac. Therefore, aldosterone elevations due to a low-salt diet may increase endolymph absorption in the endolymphatic sac. In this study, urinary sodium excretion, plasma aldosterone, and other hormones were measured during low-salt diet therapy in patients with MD.

Methods: We included 13 patients with unilateral definite MD diagnosed at the Kagawa University Hospital. A national registered dietitian provided nutritional guidance initially for 14 enrolled patients with MD and prescribed them a low-salt diet (2g Na/day). Twenty-four hour urine was sampled at baseline, at 2, 4, 6, and 8 weeks, and at 6, 12, 18, and 24 months after initiating the low-salt diet. Urine osmotic pressure, and Na, K, and Cl levels were measured, and 24-h urinary Na, K, and Cl excretion was estimated. Aldosterone, cortisol, hormones (including anti-diuretic hormone), Na, K, and Cl in the blood were measured, alongside plasma osmotic pressure. A total of 13 patients followed the low salt diet therapy for more than 2 years, while one patient dropped out.

Results: Group 1 (n=7) included patients with a mean urinary sodium excretion amount lower than 3g/day and Group 2 (n=6) included those with more than 3g/day. Vertiginous states of all Group 1 patients comprised complete control (Class A, 100%), while Group 2 patients included Class A (four patients, 66%), Class C (one patient, 17%), and Class D (one patients, 17%). Plasma aldosterone concentrations significantly increased during the 2-year low-salt diet; concentrations in Group 1 tended to be higher than that in Group 2. Hearing improvements after 2 years in Group 1 were significantly better than that in Group 2. The plasma concentration of the hormones except aldosterone was not significantly changed during 2-year low-salt diet.

Conclusion: A low-salt diet was an effective treatment for patients with Ménière's disease. This treatment will have a greater effect, when sodium intake is reduced to less than 3g/day. A low-salt diet may induce an increase in the plasma aldosterone concentration that can activate ion transport and absorbing endolymph in the endolymphatic sac.