Table 1.
Recent sodium balance studiesa
| First author (reference) | N | Sex | Age (y) | Race, country | T (°C) | RH (%) | Physical exercise (min/d) | D (d) | Na intake [g/d (mmol/d)] | 24-h urinary Na excretion [g (mmol)] | Excretion/ intake (%)b | Na retentionc [g/d (mmol/d)] |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rakova (122) | 4 | M | 33–40 | ND, Russia | 18–25 | 30–85 | 30–60 | 29d | 4.81 (209)e | 4.27 (186) | 89 | 0.5 (23.4) |
| Rakova (122) | 4 | M | 33–40 | ND, Russia | 18–25 | 30–85 | 30–60 | 29d | 3.61 (157) | 3.30 (144) | 91 | 0.3 (13.4) |
| Rakova (122) | 4 | M | 33–40 | ND, Russia | 18–25 | 30–85 | 30–60 | 29d | 2.40 (107) | 2.56 (111) | 107 | −0.1 (−4.4) |
| Rakova (122) | 6 | M | 27–38 | ND, Russia | 18–25 | 30–85 | 30–60 | 29f | 4.43 (193) | 4.19 (182) | 95 | 0.2 (10.6) |
| Rakova (122) | 6 | M | 27–38 | ND, Russia | 18–25 | 30–85 | 30–60 | 29f | 3.27 (142) | 2.92 (127) | 89 | 0.4 (15.5) |
| Rakova (122) | 6 | M | 27–38 | ND, Russia | 18–25 | 30–85 | 30–60 | 29f | 2.17 (96) | 1.89 (82) | 87 | 0.3 (12.3) |
| Rakova (122) | 6 | M | 27–38 | ND, Russia | 18–25 | 30–85 | 30–60 | 29f | 4.35 (189) | 4.02 (175) | 92 | 0.3 (13.9) |
| Heer (58) | 9 | M | 26g | ND, German | 24 | 55 | 0h | 6i | 0.7 mmol NaCl/kg/dj | 1.47(64) | ND | −0.4 (−17) |
| Heer (58) | 9 | M | 26 | ND, German | 24 | 55 | 0 | 6i | 2.8 mmol NaCl/kg/d | 3.82 (166) | ND | 0.7 (32) |
| Heer (58) | 9 | M | 26 | ND, German | 24 | 55 | 0 | 10i | 7.7 mmol NaCl/kg/d | 11.98 (521) | ND | 0.6 (24) |
| Heer (58) | 9 | M | 26 | ND, German | 24 | 55 | 0 | 6i | 0.7 mmol NaCl/kg/d | 1.66 (72) | ND | −0.6 (−26) |
| Kodama (80) | 109 | B | 18–28 | ND, Japan | 22–29 | 40–65 | Varied, up to 120 | 5–12 | 2.21–6.87 (51–158) | NDk | ND | ND |
| Palacios (116) | 19 | F | 11–15 | Black, US | ND | ND | ND | 21 | 1.31 (43) | 0.8 (35) | 61 | 0.4 (17) |
| Palacios (116) | 19 | F | 11–15 | Black, US | ND | ND | ND | 21 | 3.95 (174) | 2.5 (109) | 63 | 1.0 (43) |
| Palacios (116) | 12 | F | 11–15 | White, US | ND | ND | ND | 21 | 1.31 (43) | 0.9 (39) | 96 | 0.2 (9) |
| Palacios (116) | 10l | F | 11–15 | White, US | ND | ND | ND | 21 | 3.95 (174) | 3.3 (143) | 84 | 0.3 (13) |
| Heer (57) | 8 | M | 25g | ND, German | 24 | 60 | 0h | 7 | 0.46 (20)m | ND | ND | NDn |
| Heer (57) | 8 | M | 25 | ND, German | 24 | 60 | 0 | 7 | 1.84 (80) | ND | ND | ND |
| Heer (57) | 8 | M | 25 | ND, German | 24 | 60 | 0 | 7 | 3.68 (160) | ND | ND | ND |
| Heer (57) | 8 | M | 25 | ND, German | 24 | 60 | 0 | 7 | 5.06 (220) | ND | ND | ND |
Abbreviations: B, both male and female; D, duration of balance study; F, female; M, male; N, number of participants; Na, sodium; ND, no data or not determined; RH, relative humidity; T, temperature.
(Average sodium urinary excretion divided by average sodium intake) × 100.
In Rakova et al. (122), Na retention is defined as daily Na intake - daily 24-h urine Na excretion, over 29 days. Estimates do not account for sweat or fecal loss of sodium. In the second study, sweat loss was estimated as 12.7 mmol/d. In Palacios et al. (115), Na retention was based on Na intake - (24-h urine Na excretion + Na in feces + Na in sweat) over 20 days (with sweat collected over the last two weeks of each balance period).
Participants consumed diets with sequentially lower daily average amounts of salt (12 g, 9 g, 6 g) over a period of 105 days, with salt maintained at the given level for at least 29 days. Other nutrients were held constant. Microgravity was not simulated (122).
Information based on average daily Na content of individualized meal plans (122).
Participants consumed diets with sequentially lower daily average amounts of salt (12 g, 9 g, 6 g) and then the average amount of salt was increased 12 g over a period of 205 days, with salt maintained at the given level for at least 29 days (122).
The same participants were sequentially fed diets with the amount of sodium based on body weight for the number of days specified (58).
Authors did not report the average sodium intake for each group but indicated the average body weight of participants was 71.5 kg (116).
In this analysis of 11 previously published balance studies, numeric information on urinary sodium excretion and retention is not available; this information is presented in figures only (80).
Participants were randomly assigned to controlled diets in a crossover design. Two participants did not complete this study arm (57).
In this study, 32 participants were randomly assigned to one of four diets. Here we converted meq NaCl/d to mmol Na/d by multiplying NaCl times 0.4 (57).
Na retention data are provided in figures. Retention levels on the first day of each study period are provided in the text as well as storage from the first to last day of the study period: Participants who consumed 400 mmol NaCl/d stored 338 mmol Na, and those who consumed 550 mmol NaCl/d stored 202 mmol Na from the first to the last day of the study period.