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Salt reduction is the most important lifestyle modification, especially in Japanese individuals who still consume a significant amount of salt. The Dietary Reference Intakes for Japanese 2020, issued by the Ministry of Health, Labour and Welfare, propose a salt intake goal of <7.5 g/day for men and <6.5 g/day for women. Regarding the goal of salt reduction in hypertensive patients, the hypertension guideline by the Japanese Society of Hypertension 2019 (JSH2019) proposes a goal of <6 g/day. Although the average salt intake in Japan gradually decreased in the early 2000s, the declining trend has not been seen in recent years, and thus, it seems difficult to achieve these target salt intake levels. To overcome this challenge, the JSH announced the 'JSH Tokyo Declaration' and pledged to create a specific action plan to achieve the target salt intake level of <6 g/day. The six strategies to achieve the target salt intake level are as follows: (1) educating citizens on the harms of excessive salt intake and the importance of reducing salt intake; (2) recommending the assessment of the salt intake of individuals or populations and proposing adequate methods to reduce salt intake; (3) promoting salt reduction for children as a part of dietary education at school; (4) promoting salt reduction in takeout food, prepared dishes, canteens, and school lunches; (5) encouraging companies to develop and promote low-salt foods; and (6) encouraging the government to take measures to promote salt reduction. Through these activities, a society with a low salt intake will be expected in the near future.

The guidelines for the management of hypertension by the Japanese Society of Hypertension (JSH2019) defined blood pressure (BP) levels of 130–139/80–89 mmHg as “elevated blood pressure”. The JSH2019 also revised the target level of BP control to a lower level. Thus, lifestyle modifications are quite important regardless of the use of antihypertensive drugs. Among the lifestyle modifications, salt reduction is most important, especially among East Asian people, who still consume a significant amount of salt. Since the awareness of salt reduction may not necessarily lead to actual salt reduction, the assessment of individual salt intake is essential when members of the medical staff provide practical guidance regarding salt reduction. The evaluation methods of salt intake are classified as the assessment of dietary contents and the measurement of urinary sodium (Na) excretion. Since highly reliable methods, such as the measurement of 24-h urinary Na excretion, are not convenient in practical clinical settings, the combination of the assessment of dietary contents using questionnaires and the estimation of salt intake using spot urine is recommended as a practical evaluation procedure. Repeated assessment of salt intake and practical guidance from dieticians are useful for long-term adherence to salt reduction. The Japanese Society of Hypertension Salt Reduction Committee began to certify flavorful foods as being low in salt content in 2013. More than 200 products have been certified as of April 2019. The utilization of these products is expected to aid in the salt reduction of hypertensive individuals as well as the Japanese general population.

Sodium reduction is an important public health goal. Individual and population approaches are necessary for reducing the sodium content of processed foods and meals. The aim of the present study is to affirm the effect of monosodium l-glutamate (MSG), an umami substance, on the saltiness or palatability of low-salt solutions and to explore the preferred salt concentration in soup. Five hundred and eighty-four healthy participants from nineteen regions in Japan tasted 0.3, 0.6, and 0.9% NaCl solutions with or without 0.3% MSG. Evaluations of saltiness and palatability for each solution were conducted using a visual analog scale in a double-blinded randomized manner. Saltiness gradually increased depending on the concentration of NaCl. The saltiness of the 0.3% NaCl solution with MSG was rated significantly higher than that without MSG. The palatability ratings were higher for the solutions with MSG than for those without MSG for all NaCl concentrations. In particular, the palatability rating of the 0.3% NaCl solution with MSG was twice as high as that without MSG and was significantly higher than that of the other five test solutions. Furthermore, these results were observed to be approximately the same, irrespective of sex, age, region, etc. Salt reduction is believed to result in a loss of palatability. However, our results suggest that umami can compensate for the loss of palatability caused by salt reduction and that the addition of an appropriate amount of an umami substance can facilitate salt reduction from 0.9 to 0.3% without sacrificing palatability.

Epidemiological studies have demonstrated that the urine sodium-to-potassium (Na/K) ratio is more positively associated with high blood pressure and cardiovascular disease risk than either urine sodium or potassium excretion alone. In this consensus statement, we recommend using the average Na/K ratio of casual urines randomly taken in various times on at least four days a week for a reliable individual estimate because of high day-to-day and intraday variability of casual urine Na/K ratio within individuals. Although a continuous positive association exists between the Na/K ratio and high blood pressure or cardiovascular disease risk, for clinical and public health decision making for Japanese, we recommend using an average urine Na/K ratio of 2 as an optimal target value because this aligns with recommendations for both sodium and potassium intake in the Dietary Reference Intakes for Japanese, 2020, considering a typical Japanese dietary pattern. We also suggest that an average urine Na/K ratio of 4 is a feasible target value to achieve a temporary goal of being below the mean values of the urine Na/K ratio across Japanese general populations. These recommendations apply mainly for apparently healthy individuals, but not for patients with specific conditions due to the lack of supporting data. Current evidence for the usefulness of measuring the urine Na/K ratio for the prevention or control of hypertension remains inconclusive and warrants further investigation.

The urine sodium-to-potassium (Na/K) ratio is associated with blood pressure and cardiovascular diseases. A single urine sample is preferable for determining the Na/K ratio in clinical practice. We evaluated whether the Na/K ratio measured using morning casual urine samples predicts the ratio measured using the preceding 24 h urine sample in patients with hypertension. The study included 187 hypertensive patients (mean age 66.1 years, 52.4% female) whose Na and K concentrations were measured both in 24 h (24Na/K) and casual urine the next morning (CNa/K). The Na/K ratios were 3.54 ± 1.5 in 24NaK and 2.63 ± 1.9 in CNa/K. The two estimates showed a significant positive correlation ( r  = 0.49, p  < 0.0001), and (CNa/K-24Na/K)/24Na/K was −23.5 ± 44.4%. In the Bland–Altman plot, the mean difference was −0.91. When CNa/K was divided into three groups, <2 (low), 2–4 (medium), and ≥4 (high), the overall agreement with 24Na/K was 46.0% (86 of 187). The low group had 24.4% agreement and 75.6% underestimation (24Na/K > CNa/K); the medium group had 60.8% agreement, 30.5% underestimation, and 8.7% overestimation (24Na/K < CNa/K); and the high group had 71.8% agreement and 28.2% overestimation. These results indicate that CNa/K and 24Na/K were significantly correlated; however, CNa/K was generally lower than 24Na/K, particularly at Na/K levels < 2. Further efforts should be made to address the validity of using casual urine Na/K ratios in hypertension management practices.

Fixed-dose combinations (FDCs) for blood pressure control can simplify prescribing, improve medication adherence, and be cost-effective. In Japan, real-world data about the class effects of antihypertensive drugs on medication adherence are limited. Using the nationwide database of medical health claims from Diagnosis Procedure Combination hospitals, treatment patterns and adherence were analyzed for 47,891 patients prescribed antihypertensive medication between April 2014 and March 2015. Adherence was assessed by the proportion of days covered (expressed as % PDC). Patients were prescribed a mean of 2.0 ± 1.0 antihypertensive drugs and 2.4 ± 1.7 pills for their index prescription. Mean adherence overall was 91.5% PDC and was inversely correlated with the number of antihypertensive drugs or pills prescribed on the index date. Mean % PDC was significantly higher (all P  < 0.0001) for CCB + ARB versus ARB + thiazide diuretic combinations and for CCB + ARB + β-blocker versus CCB + ARB + thiazide diuretic combinations. Adherence was significantly higher ( P  < 0.0001) for FDC (CCB + ARB) versus corresponding single-drug combinations, but not for other comparisons of FDCs versus single-drug combinations. On the other hand, FDCs were not always used effectively; specifically, FDCs were frequently used concomitantly with a single agent(s) from the same drug class(es) as the FDC. From the results of our study, no clear differences were observed in medication adherence according to the presence or absence of FDC formulations, and there were cases in which FDCs were not being utilized effectively to simplify prescribing.