Sung Keun Park

Both sodium intake and sleep have an important effect on cardiovascular health. However, few studies have looked at the association between sodium intake and sleep. Therefore, we analysed the association of sodium intake with sleep quality, sleep duration and nocturnal urination. The data for the present study were obtained from the Kangbuk Samsung Health Study . Study participants were 156 696 working‐aged Korean adults (average age 38.0 years ±8.0 in men and 36.0 years ±8.1 in women). They were categorised into five groups by quintile of sodium intake, measured by food frequency questionnaire. Poor sleep quality and short sleep duration were determined by Pittsburgh Sleep Quality Index >5, and sleep duration <7 h, respectively. Nocturnal urination was defined as awakening to urinate more than three times a week. Multivariable adjusted logistic regression analysis was used in calculating the odds ratio (OR) and 95% confidence interval (CI) for poor sleep quality, short sleep duration and nocturnal urination (adjusted OR [95% CI]) across five study groups. In all study participants, increased sodium intake was significantly associated with poor sleep quality (quintile 1: reference, quintile 2: 1.07 [1.04–1.11], quintile 3: 1.12 [1.08–1.16], quintile 4: 1.15 [1.11–1.19] and quintile 5: 1.13 [1.09–1.18]). This pattern of relationship was similarly observed in association of sodium intake with short sleep duration ( p for trend <0.001) and nocturnal urination ( p for trend <0.001). In gender subgroup analysis, increased sodium intake had a significant association with poor sleep quality and short sleep duration in men and with poor sleep quality and nocturnal urination in women. In conclusion, high sodium intake is associated with an increased likelihood of poor sleep quality, short sleep duration and nocturnal urination.

There are reports that nut consumption provides potential benefit for gastric pathologies including stomach cancer and Helicobacter pylori infection. However, there are no studies investigating the effect of nut consumption on gastric intestinal metaplasia (GIM). In a Korean cohort of 53 424 men (average age 38.7 ± 7.0 years) and 33 024 women (average age 38.0 ± 7.0 years), we analysed the risk of GIM according to the frequency of nut consumption (peanuts, pine nuts and almonds only) as the following: rare (<1 serving/month), ≤1 serving/month and <1 serving/week, ≤1 serving/week and <3 serving/week, ≤3 serving/week and <5 serving/week and ≥5 serving/week where one serving is 15 g. Cox proportional hazards model was used to calculate the multivariable‐adjusted hazard ratio (HR) for GIM and their 95% confidence intervals (CI) in each group (adjusted HR [95% CI]). Subgroup analysis was conducted by body mass index (BMI, non‐obesity <25 and obesity ≥25). The models were adjusted for age, regular exercise, BMI, smoking, alcohol intake (g/day), diabetes mellitus, hypertension, dietary fibre intake, sodium intake and total calorie intake. After 5.3 years (median 5.9 years) of follow‐up, GIM was observed in 5073 subjects. In men, compared with rare nuts consumption, greater nuts consumption was associated with a lower risk of GIM (rare consumption: reference, 1/month–1/week: 0.85 [0.79–0.91], 1–3/week: 0.81 [0.72–0.91], 3–5/week: 0.70 [0.57–0.86] and ≥5/week: 0.59 [0.48–0.73]). Subgroup analysis indicated that the inverse relationship between nuts consumption and the risk of GIM is more distinct in men without obesity (rare consumption: reference, 1/month–1/week: 0.83 [0.76–0.91], 1–3/week: 0.78 [0.67–0.91], 3–5/week: 0.68 [0.51–0.89] and ≥5/week: 0.51 [0.37–0.69]). However, this association was not observed in women. In conclusion, increased nuts consumption was associated with a decreased risk of GIM in working aged Korean men.