Original Article
Relationship between the Awareness of Salt Restriction
and the Actual Salt Intaker in Hypertensive Patients
Yuko OHTA, Takuya TgUCHI-HASHI, Michio UENO, Tomoko KAJIOm,
Uran ONAm., Mitsuhiro TOMINAGA, and Kimika ETO
A 24-h home urhe collection was conducted to estimate accurate salt ntake ln hypertensive outpatients.
Using 24-h urinary creatinine excretion as a criterion for success, urhe samples were obtained from 534 hy-
pertensive patients. The urinary salt excretion of hypertensive outpatients ranged widely from 1.5 to
23.4 glday (mean value 9.7t3.9 glday). Urinary salt excretion was higher in males than in females (10.6j=4.0
vs. 9.2+_3.7glday, p<0.01). Based on the questionnaires, the patients were divided into salt-conscious pa-
tients, or those who were careful to reduce their daily salt intake, and non-salt-conscious patients. It was
found that urinary Salt excretion was Iower in the salt-conscious group than in the non-salt-conscious group
(9.4j=3.8 vs. 10.6j=4.0 g/day, p<0.01), but that urinary salt excretion adjusted for body weight was not signif-
icantly different between the two groups (0.16i:0.06 vs. 0.17j:0.07 glkglday). Our results suggest that there
was no obvious reduction in the actual salt intake in salt-conscious patients, suggesting the importance of
rnonitoring salt intake by 24-h home urine collection and informing patients of their actual salt intake as a
means of encouraging the achievement of salt restriction. (Hypertens Res 2004; 27: 243-246)
Key Words: salt restriction, 24-h home urine collection, urinary salt excretion, hypertension, salt intake
Patients.
Introduction

Fig. 1. The distribution of 24-h urinaq salt excretion in
salt-conscious and now-salt-conscious patients.
blood pressure (DBP)290mmHg, or those patients on anti-
hypertensive medication. The patients were asked, by ques-
tionnaire, about aspects of their lifestyle, such as habitual al-
cohol intake, smoking, and exercise, and were also asked
whether they were conscious of salt, calorie and fat restric-
tions. The protocol was explained in detail, and informed
consent was obtained from each patient.
StatisticaI Analysis
values are presented as the meansj=SD. me differences in--:
the variables were compared by one-way ANOVA. A x2 test
was also utilized when appropriate. P values less than 0.05
were considered statistically signiAcant.
+
ReSults
Among the 652 patients enrolled in this study, 534 patients
)
successfully collected 24-h urine samples.
characteristics in male and female patients are shown in
Table l. The patients had a mean age of 58.3i: 1 I.6 (26-90)
years, and a mean BP of l44.0+J2.5/87.4j=7.7mmHg.
There were no differences in age, body mass index (BMI),
BP, or prevalence of patients receiving antihypertensive
drugs between males and females. Body weight and urinary
salt excretion were signiBcantly higher in males than in fe-
males. However, urinary salt excretion adjusted for body
weight was similar between the two groups.
The questionnaire on the awareness of salt restriction was
obtained from 360 patients. As shown in Fig. I, the values of
the 24-h urinary salt excretion were distributed widely, rang-
ing from 1.5 to 23.4g/day. Comparisons of the characteris-
tics between the patients who were careful to reduce their
daily salt intake (salt-conscious group, n=271) and the non-
salt-conscious group (n= 89) are presented in Table 2. There
were no diaerences in BMI and frequency of family history
of hypertension between the two groups. The salt-conscious
group was old6r than the non-salt-conscious group, and there
bias -a- higher 'prevalence of females. This group also showed
a lobe; Bp' 'and' a higher prevalence of being on antihyper-
tensive medication. Urinary salt excretion was signiBcantly
lower in the salt-conscious group than in the non-salt-con-
scious group (9.4i3.8 vs. 10.6j=4.0' g/day, p<0.Ol), but uri-
nary salt excretion adjusted for body weight was not signi&-
cantly different between the groups.

Discussion
/
The present study demonstrated that in hypertensive outpatients, there was no relationship between the awareness of salt restriction and the actual salt intake evaluated by 24-h urinary collection, which has been widely used to estimate dietary salt intake in epidemiological studies (10-13).
In the present study, urinary salt excretion was higher in males than in females, which may be attributable to the greater energy intake in males than females (14).
In fact, males showed a higher body weight, and when urinary salt excretion was adjusted for body weight, urinary salt excretion was comparable between males and females.
1t seems reasonable that BP and urinary salt excretion were signiBcantly lower in the salt-conscious group than in the non-salt-conscious group.
The characteristics of the two groups diaer in sex and age.
Thus, we may speculate that elderly and female individuals could be more aware than others of the importance of lifestyle modiBcations, such as salt restriction.
However, no significant difference was found in urinary Salt excretion adjusted for body weight between the salt-conscious and non-salt-conscious groups.
This observation indicates that awareness of the necessity of salt restriction may not lead to an actual reduction of salt intake.
Salt intake by the Japanese population has traditionally been high, although it has been decreasing in recent years.
The National Nutrition Survey in Japan showed that the salt intake was ll.5g in 2001 (15).

The difficulty in achieving long-term dietary salt restriction might be attributable to the
difficulty in changlng the dietary habits of the Japanese．It
has also been pointed out that although there has been an in−
crease in variety in the Japanese diet，there is now a greater
reliance on dining out，and the consumption of fast foods is
increasing（12，16）．These trends in the dietaγ habits of
Japanese may also make it difficult to reduce salt intake．

　With regard to seasonal variation，urinary salt excretion
tended to decrease in summer（17)．In the present study，24−h
urine collection was performed thoughout the year in both
groups．Thus，it seems unlikely that the seasonal variation of
uninary salt excretion influenced the principal results of this
study．
　Doctors advise all hypertensive patients to reduce their
salt intake，but it is important to evaluate　whether　patients
follow this advice．Some methods have been proposed to im−
prove compliance with dietary salt restriction．One study in−
dicated that group management, in which feedback is provid−
ed to patients on their urinary salt excretion，was more effec−
tive in decreaslng diet salt intake than advice given with−
out this support，or though an intensive educational effort by
doctors and clinics（18）．Another study showed that self−
monitoring of urinary salt excretion　at　home，uslng chloride
titrator strips，could，in conjunction with dietary counseling，
facilitate compliance with a reduced salt intake（19）．Howev−
er，another report indicated that short counseling sessions
with advice on salt restriction were not successful in produc−
ing dietary Changes（5）．Taken together，these results suggest
that repeated monitorlng of urlnary salt excretion，along with
providing feedback to patients，is the most important and
practical way to achieve the reduction of salt intake in indi−
vidual hypertensives．
In conclusion，there was no obvious reduction in actual
salt intake in salt -conscious patientsin the present study，
suggestlng the importance of monitoring salt intake and in−
forming patients of their actual salt intake as a means of　en−
couraging the achievement of salt restriction．
　　　　　　　　　　　　　　　　　　　　●
　　　　　　Acknowledgements
We greatly appreciate the technical assistance we received from
the staff of the Division of Nutrition，National Kyushu Medical
Center．We would also like to thank Ms．T．Shimada for her
technical and secretarial assistance．

　　　　　　　　　　References

l．AlliC，AvanziniF，Bettell iG，et al：Feasibility of a long−
　　term low-sodium diet in mild hypertension．J Hum Hyper・
　　tens 1992；6：281-286．
2．RioAD，Villamil JLR：Metabolic effects of strict salt re−
　　striction in essential hypertensive patients．J Intern Med
　1993；233：409−414．
3．Haddy FJ，Pamnani MB：Role of dietary salt in hyperten−
　　sion．J Am Coll Nutr 1995；14：428−438．
4．Korhonen MH，Jarvinen RMK，Sarkkinen ES Uusitupa
　　MIJ：Effects of a salt−restricted diet on the intake of other

Extensive epidemiological literature has already documented
the correlation between salt intake and blood pressure (BP)
or the prevalence of hypertension (1, 2). Salt restriction is
now a'1so widely promoted as an effective non-pharmacologi-
cal approach to managing mild hypertension, as well as an
important adjunct to pharmacological treatment in moderate
and severe hypertension (3-7). The seventh report of the
Joint National Corrmittee (JNC 7) recorrmends sodium
reduction to a level of no more than 100mmouday in hyper-
tensive patients (8). Thus, it is recommended that physicians
advise patients to reduce their salt intake, but the encacy of
this advice is questionable if patients' actual salt intake is not
monitored. The aim of this study was to investigate urinary
salt excretion and the relationship between the awareness of
salt restriction and the actual salt intake in hypertensive out-
Methods

We undertook 24-h home urine collection at Rrst visit in 652
outpatients between January, 1998 and December, 1999.
Twenty four-hour urine samples were collected using a parti-
tion cup (proportional sampling method (9)), which collects
a 1/50 portion of the 24-h urine. If the 24-h creatinine excre-
tion was within j=30% of the estimated values, the urine col-
lection was considered successful. If the urine collection was _
judged to be unsuccessful, the patients were asked to.try
again. Patients who failed to complete the 24-h urine collec-
tion, in spite of possible repeated collection, were excluded
from further analysis. BP was measured with a sphygmo-
manometer by the doctors while the patients were seated.
Hypertension was considered to be present in patients with
systolic blood pressure (SBP)2140rrmHg and/or diastolic
From the Division of Hypertension and Nephrology, Clinical Research Institute, National Kyushu Medical Center, Fukuoka, Japan.
Address for Reprints: Yuko Ohta, M.D., Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University,
Maidashi 3-1-1 , Higashi-ku, Fukuoka 8 I 2-8582, Japan. E-mail: yukoo@intmed2.ned.kyushu-u.ac.jp
Received September 22, 2003; Accepted in revised form January 9, 2004.