1000
Asia Pacific J Clin Nutr (1996) 5(4): 229-234
Asia Pacific J Clin Nutr (1996) 5(4): 229-234
A dietary survey of the Chinese
population in urban and rural areas of Tianjin
HG Tian PhD, Y Nan, G Hu, QN Dong, XL
Yang MD
Tianjin Municipal Institute of Food
Safety Control and Inspection, Tianjin, China
Plenary lecture presented at an
APCNS Satellite Meeting of the Asian Congress of Nutrition on "Nutrition,
Body Composition and Ethnicity" in Tianjin, China on 5th October
1995.
Objectives:
A survey was carried out to assess the food pattern and of nutrient
intakes of 15-64 year old Chinese in Tianjin.
Design:
The survey was randomised and the diet assessed by weighing household
food items and by individual food records over 3 consecutive days.
Setting:
The survey was carried out in Tianjin; the third largest city in
China (population about 8 million).
Subjects:
A random stratified multi-level cluster sampling technique was used.
Of the 5233 eligible subjects, 207 dropped out, and the response
rate was 96%.
Results:
Distinct differences in dietary patterns and nutrient intakes were
found between subjects living in urban and rural areas. The diet
of urban people was richer in fat and high quality protein compared
with that of rural people. Energy intake from fat was about 31%
in the urban diet and about 21% in the rural diet. Low intakes of
vitamin A, riboflavin, calcium and zinc were found in both areas,
with the situation being worse in the rural areas. Sodium intake
was found to be high in both areas. Cholesterol intake was much
higher among urban people.
Conclusion:
The present survey revealed that the intake of some nutrients was
lower than recommended and that total sodium intake was very high
in Tianjin. An integrated nutrition intervention program would appear
necessary for such a population.
Key words: Dietary survey, food
and nutrient intakes, Tianjin, China, rural, urban
Introduction
The availability of various foods has increased with
rapid economic development in China in recent years. However, the
incidences of cardiovascular disease, cerebrovascular disease and
certain cancers have also risen significantly1,2. In Tianjin,
the third largest city in China, non-communicable diseases have been
identified as a major health problem since the 1980s. In 1985, essential
hypertension was diagnosed in 11% of Tianjin’s urban residents
aged 15 or above. Mortality from cerebro-vascular, cardiovascular
diseases and cancer combined accounted for 73% of total deaths in
Tianjin in 19893.
The first national community-based interventi 1000
on project aimed at reducing the risk factors for non-communicable
diseases was started in Tianjin in 1984. The prevention and control
of hypertension was the first priority of this project. Because diet
has been identified as an important factor relating to the changes
seen in disease patterns4,5, research which focuses on
diets in Tianjin’s population has been given emphasis.
Based on a nationwide nutrition survey in China in
1982 and some subsequent smaller local nutrition surveys it can be
said that diets have improved with increasing living standards in
China6-8. Because most of the previous nutrition surveys
in China have been carried out on a household basis, information about
the food consumption and nutrient intakes of individuals is, however,
lacking. In this report, we present individual food and nutrient intakes
from a dietary survey carried out in Tianjin in 1992.
Subjects and methods
The dietary survey was carried out in the autumn of
1992. It covered the whole population of Tianjin. A sample representative
of the Tianjin civilian (non-institutionalised) population was obtained
through a random stratified multi-level cluster sampling9.
Urban and rural areas were sampled separately using the same procedure.
First, 8 districts (urban) and 6 counties (rural) were selected randomly.
Then, 17 urban streets and 10 rural communities were selected from
each district and county sampled. From these samples, 2 resident sections
in each street and 2 villages in each community were chosen for the
survey. The total number of households was selected from the household
register was 1510. Every resident in a sampled household became a
subject in the survey. Of the 1510 households selected, 181 (12%)
refused to take part in the survey. These households were replaced
with other randomly selected households using the same sampling method.
Of the 5233 eligible persons, 207 subjects only, were unable to participate
in the survey because they were not available during the survey period.
The response rate of the individual persons was 96%. Altogether 3682
(73%) of 5026 persons in the households were between 15 to 64 years
of age, and are the focus of these analyses (1804 men and 1878 women).
Basic characteristics of these subjects are presented in Table 1.
The methods used for assessing the diet were food
weighing plus three-day food records. The collection of data was carried
out by trained health care workers. Standardised scales which weighed
up to 5 kg (±0.01 kg) were used for most foods. Weighing scales, which
measured up to 0.5 kg (± 0.001 kg) were used for weighing salt, monosodium
glutamate, and sodium carbonate. The survey started after supper on
the first day by measuring and recording all foods in each household
including raw materials, processed foods and home prepared foods of
the survey. Then for three consecutive days food records were collected
on individual food intake data. The health workers visited each household
after supper on the second day of the survey. They recorded new foods
bought during the day and the number of household members and visitors
present at each meal. On a 24-hour recall basis, individual food intake
was estimated using the bowls and plates in the household and food
consumed away from home was collected by individuals. Food waste was
estimated when weighing was not possible. The same visit was repeated
for 3 days. All household foods were again weighed and recorded on
the forth day of the survey after the three day food records had been
collected.
The data were checked and coded by trained quality control groups and
keyed into computers located in the surveyed districts and counties.
The completed data were sent to the Tianjin Food Safety Control and
Inspection Institute, for rechecking. Food consumption data were analysed
using the 1991 Food Composition Tables and SPSS computer program in
Kuopio University, Finland (Preventive Medicine Academy of China).
All the mean values for men and women in urban and rural areas have
been adjusted for age. Tests of significance were conducted using
analyses of covariance.
Results
In both sexes, there were distinct differences in
the mean consumption of most foodstuffs between urban and rural areas
for both sexes (Table 2). The consumption of cereal and root products
was higher among rural people and the intake of animal foods, vegetables,
and fruits was higher among urban people. Pork was the major source
of meat products in both areas. Very low intakes of sugar and alcoholic
drinks were seen in both areas. Even though there were differences
in the consumption of milk and bean products, the consumption level
was low in both areas.
The differences in food consumption patterns between
both areas have brought about differences in the intakes of most nutrients
(Table 3). The nutrients listed in Table 3 refer to ones where there
are recommended dietary allowances in China. In addition, intakes
of sodium, potassium, magnesium and cholesterol are presented. No
significant differences were found in intakes of energy, vitamin C
or iron between the two areas. Low intakes of vitamin A, calcium,
riboflavin and zinc were found in both areas, with rural people having
lower intakes than urban people. A high intake of sodium was found
in both areas. The intake of sodium (expressed as NaCl) was 14-16
g in the urban areas and 15-17 g in the rural areas. The intake of
potassium was low, especially for women. A high sodium to potassium
ratio was observed in both areas ranging from 3.1-3.6. The intake
of cholesterol was much higher from the urban diet than the rural
diet (454 mg per day for urban men and only 182mg for rural men) and
the figures were similar for women.
Table 1. Mean of age, weight,
height (± standard deviations) and other baseline characteristics
of the subjects.
| Items |
Men
(1804)
|
Women
(1878)
|
| Age (years) |
38.4±14.0
|
38.8±13.6
|
| Weight (kg) |
67.0±11.8
1000 |
58.7±10.6
|
| Height (m) |
1.70±0.06
|
1.59±0.06
|
| BMI (kg/m2) |
23.1±3.7
|
23.3±4.1
|
| Occupation |
|
|
| Blue-collar workers |
570
|
388
|
| White-collar workers |
464
|
349
|
| Retired and housewives |
161
|
622
|
| Farmers |
368
|
246
|
| Students |
128
|
114
|
| Service workers |
79
|
122
|
| Unemployed |
21
|
28
1000 |
| Education |
|
|
| 0-6 years |
551
|
775
|
| 7-12 years |
1061
|
991
|
| l3 or above |
180
|
97
|
| Area |
|
|
| Urban area |
1133
|
1184
|
| Rural area |
671
|
694
|
|
Table 3. Age-adjusted mean
daily intakes of energy and some nutrients among 15-64 year old
population in Tianjin by sex and area (± standard deviations)
| |
1000 Men
|
Women
|
| |
Urban
(n=1133)
|
Rural
(n=671)
|
SOD
|
Urban
(n=1184)
|
Rural
(694)
|
SOD
|
| Energy (Kcal)
|
2679±712
|
2649±711
|
ns
|
2143±536
|
2124±568
|
ns
|
| Protein (g) |
87±26
|
79±22
|
***
|
71±21
|
63±18
|
***
|
| Fat (g) |
92±41
|
62±39
|
***
|
76±32
|
49±31
|
***
|
1000
| Carbohydrate (g) |
369±97
|
437±125
|
***
|
294±75
|
356±101
|
***
|
| Vit A (ret eq,
m g) |
674±978
|
372±958
|
***
|
593±768
|
290±540
|
***
|
| Thiamin (mg) |
1.1±0.4
|
1.5±0.5
|
***
|
0.9±0.3
|
1.2±0.4
|
***
|
| Riboflavin (mg)
|
1.0±0.5
|
0.8±0.3
|
***
|
0.9±0.4
|
07±03
|
***
|
| Niacin (mg) |
< 1000 p align="center">18±7
|
17±6
|
***
|
15±6
|
13±5
|
***
|
| Vit C (mg) |
95±84
|
100±78
|
ns
|
92±76
|
87±62
|
ns
|
| Iron (mg) |
28±22
|
26±10
|
ns
|
23±19
|
21±8
|
ns
|
| Sodium (mg) |
6523± 2522
|
6926± 2503
|
***
|
5710± 2222
|
6090± 2256
|
***
|
| Potassium (mg) |
2110±739
|
2028±823
|
*
|
1806±636
|
1646±636
|
***
|
| Sodium/ potassium
ratio |
3.1±1.1
|
3.4±1.2
|
*
|
3.2±1.4
|
3.6±1.4
|
**
|
| Calcium (mg) |
498±288
|
400±273
|
***
|
427±237
|
320±203
|
***
|
| Magnesium (mg) |
360±131
|
411±137
|
***
|
301±105
|
334±108
|
***
|
| Phosphorus (mg) |
1203±357
|
1280±362
|
***
|
989±299
|
1033±288
|
***
|
| Zinc (mg) |
14±5
|
13±4
|
***
|
11±4
|
10±3
|
***
|
| Selenium (m g) |
73±30
|
49±22
|
***
|
60±24
|
39±17
|
***
|
| Cholesterol (mg) |
454±311
|
182±239
|
***
|
402±260
|
152±214
|
***
|
Analyses of covariance, * p< 0.05, ** p<
0.01, *** p< 0.001.
"ret eq" refers to retinol equivalents
|
| The urban/rural differences in food
patterns were also seen in the percentage distributions of energy
intake from fat, protein and carbohydrate (Table 4). The percentage
of total energy from fat was about 21% in the rural diet and about
31% in the urban diet.
The role of different food groups as sources
of energy and energy-providing nutrients is presented in Table
5. Plant foods provided 66% of fat intake in the urban diet,
and 63% in the rural 1000 diet. The major sources of cholesterol
were eggs, and meat in both areas. Animal fat used in cooking
was another source of cholesterol but only in rural areas (14%)
|
Table 4. Age-adjusted percentage
distribution of energy intake from protein, fat and carbohydrate
(± standard deviations)
| E % |
Men
|
Women
|
| |
Urban
|
Rural
|
SOD
|
Urban
|
Rural
|
SOD
|
| |
(n=1133)
|
(n=671)
|
|
(N=1184)
|
(694)
|
|
| Protein |
13.2±2.6
|
12.2±2.3
|
***
|
13.3±2.6
|
12.0±2.0
|
***
|
| Fat |
30.8±8.8
|
20.8±10.1
|
***< 1000 /font>
|
31.6±8.2
|
20.6±10.4
|
***
|
| Carb |
56.0±8.5
|
67.0±9.9
|
***
|
55.1±8.0
|
67.4±10.0
|
***
|
Analyses of covariance, *** p< 0.001.
|
Table 2. Age-adjusted mean daily intakes of
foods in grams (± standard deviations) among the 15-64 year old population
in Tianjin by sex and area.
| |
Men
|
Women
|
| |
Urban
|
Rural
|
SOD
|
Urban
|
Rural
|
SOD
|
| |
(n=1133)
|
(n=671)
|
|
(N=1184)
|
(694)
|
|
| Cereal Products |
429±122
|
543±163
|
***
|
332±92
|
440±131
|
***
|
| Wheat products |
261±130
|
385±166
|
***
|
190±97
|
299±128
|
***
|
| Rice |
159±101
|
118±102
|
***
|
132±76
|
105±86
|
***
|
| Corn flour |
9±26
|
40±63
|
***
|
10±25
|
36±57
|
***
|
| Legumes |
11±21
|
6±24
|
***
|
9±18
|
4±14
|
***
|
| Vegetables |
360±190
|
322±196
|
***
|
330±167
|
280±162
|
***
|
| Potatoes and roots |
34±53
|
75±120
|
***
|
38±61
|
63±97
|
***
|
| Fruits |
78±136
|
23±66
|
*** 1000
|
90±152
|
29±98
|
***
|
| Meat products |
118±90
|
42±71
|
***
|
91±67
|
28±48
|
***
|
| Pork |
79±66
|
32±48
|
***
|
62±50
|
23±35
|
***
|
| Beef |
24±56
|
4±28
|
***
|
18±40
|
2±13
|
***
|
| Chicken |
11±34
|
4±26
|
***
|
8±26
|
2±16
|
***
|
| Organs |
4±17
|
2±16
|
*
|
3±16
|
1±11
|
**
|
| Milk |
39±89
|
6±43
|
***
|
43±91
|
5±32
|
***
|
| Eggs |
54±46
|
22±39
|
***
|
51±42
|
19±36
|
***
|
| Fish |
58±72
|
40±74
|
***
|
57±67
|
36±68
|
***
|
| Oil |
35±27
|
32±28
|
*
|
30±25
|
27±22
|
ns
|
| Nuts |
6±22
|
4±18
|
*
|
4±18
|
3±20
|
ns
|
| Sugar |
3±8
|
1±3
|
***
|
3±8
|
1±5
|
***
|
| Alcoholic drinks, ml
|
7±23
|
8±31
|
ns
|
-
|
-
|
|
Analyses of covariance, * p< 0.05, ** p< 0.01,
*** p< 0.001 SOD: Significance of difference
Table 5. Percentage supply of energy and energy-providing
nutrients by different food groups and area
| |
Urban area
|
Rural area
|
| |
Energy
|
Protein
|
Fat
|
Carb
|
Chol
|
Energy
|
Protein
|
Fat
|
Carb
|
Chol
|
| |
%
|
%
|
%
|
%
|
%
|
%
|
%
|
%
|
%
|
%
|
| Cereal Products |
59
|
48
|
21
|
87
|
0
|
75
|
72
|
26
|
92
|
0
|
| Legumes |
2
|
5
|
2
|
1
|
0
|
1
|
3
|
1
|
0
|
0
|
| Vegetables and roots |
5
|
8
|
1
|
6
|
0
|
5
|
8
|
2
|
6
|
0
|
| Fruits |
1
|
0
|
0
|
2
|
0
|
0
|
0
|
0
|
1
|
0
|
| Animal fat used in cooking |
0
|
0
|
0
|
0
|
0
|
3
|
0
|
13
|
0
|
14
|
| Plant oil |
13
|
0
|
39
|
0
|
0
|
8
|
0
|
40
|
0
|
0
|
| Meat |
12
|
19
|
28
|
1
|
28
|
4
|
6
|
13
|
0
|
24
|
| Fish |
2
|
8
|
1
|
0
|
13
|
1
|
5
|
2
|
0
|
22
|
| Milk and eggs |
4
|
9
|
8
|
1
|
59
|
1
|
3
|
3
|
0
|
40
|
| Beverages and sugar |
1
|
0
|
0
|
1
|
0
|
1
|
0
|
0
|
0 1000
|
0
|
| Condiments |
1
|
3
|
0
|
1
|
0
|
1
|
3
|
0
|
1
|
0
|
Carb: Carbohydrate; Chol: Cholesterol
Discussion
The present survey indicates differences in dietary
patterns and nutrient intakes between individuals living in the urban
and rural areas of Tianjin. The diet of urban people was richer in
fat and high quality protein compared with that of rural people. The
percentage of total energy from fat was 31% in men and 32% in women
in the urban areas and 21% in the rural areas. It has been suggested
by WHO that the percentage of total energy from fat should be 15-30%10,
and the Chinese recommendation is 20-25%11. The 1992 Tianjin
results show similar urban-rural differences to previous dietary surveys
nationwide in 1982, and to Tianjin in 1986. This implies that an improvement
in living standards increased the intake of protein and fatty foods.
Similar dietary and related lifestyle changes elsewhere have been
argued to increase the prevalence of chronic disease12.
Animal foods and bean products contributed 41% of
protein in the urban diet and only 17% in the rural diet. An increase
in the intake of bean products should improve protein quality in the
rural diet and reduce the animal fat intake in the urban diet.
Some studies have suggested that some components of
dairy products, probably calcium, exert a protective effect against
hypertension13-15. The Chinese RDA for calcium intake is
800 mg The Tianjin study revealed that the intake of calcium was 62%
of the RDA for men and 53% of the RDA for women in urban areas. In
the rural areas, the intake of calcium was 50% of the RDA for men
and only 40% of the RDA for women. Vitamin A intake was also found
to be lower than the Chinese RDA (800m g) in both areas. The intake of vitamin A was 84% of the RDA for men
and 74% of the RDA for women in the urban people. In the rural areas,
the intake of vitamin A was 46% of the RDA for men and 36% of the
RDA for women. The results suggest that advice to increase the consumption
of foods rich in calcium and vitamin A, such as milk products and
some vegetables would be of value. The development of fortified foods
could also contribute to the dietary intake of calcium and vitamin
A.
Relationships of dietary sodium and potassium to blood
pressure have been reported in many studies. Several studies have
shown a negative correlation between potassium and blood pressure
and a positive correlation between sodium and blood pressure16-18.
High sodium in 1000 takes were found in this survey compared to those
generally reported by others19-21. In the INTERSALT study,
246mmol/24 h sodium excretion (equivalent to 14.2 g NaCl) was found
in Tianjin subjects aged 20-59, the highest figure recorded in the
whole study22,23. The results of the two studies are very
similar since urinary sodium excretion is about 90-95% of intake24.
The dietary sodium to potassium ratio in the population was much higher
than the recommended level25. It was also reported in the
INTERSALT study that the Tianjin had the highest sodium to potassium
ratio (7.6) of all INTERSALT centres23. More studies are
needed in relation to sources of dietary sodium and the effect of
the sodium and potassium intake profile on blood pressure level inTianjin.
The association between dietary magnesium with blood
pressure has been studied in recent years26,27. The intake
of magnesium in a Chinese population is reported in this survey for
the first time. Higher intakes of magnesium were found in rural people
than urban in both sexes. Urban women had the lowest intake of magnesium
which was 10% below the RDA25.
WHO has recommended an intake level not greater than
300 mg cholesterol per day based on evidence that serum cholesterol
levels may respond to dietary cholesterol especially with excessive
saturated fat10. The intake of cholesterol was more than
400 mg per day in the urban residents. The most important source of
cholesterol intake was eggs. More information on the intakes of cholesterol
and associated fat in relation to health outcomes is needed for nutrition
intervention programs.
The 1992 Tianjin dietary survey indicates that nutrition
intervention programs are warranted so that people may modify their
dietary patterns to prevent nutrient deficiencies and to reduce dietary
risk factors related to chronic diseases. A change in the food behaviour
of a population calls for related changes in the food environment.
Support through food and nutrition planning, food policy and marketing
approaches is required. Change also needs to involve agriculture,
the food industry, the public health sector and other related sectors.
An integrated approach will encourage more effective nutrition intervention.
Although further studies are necessary to clarify
the role of dietary sodium, potassium, calcium and magnesium in the
aetiology of hypertension among Chinese, the present Tianjin study
suggests that there are possible public health benefits from increasing
the intakes of calcium, vitamin A and potassium and decreasing the
intake of sodium in the population. Reference to the concomitant food
intake patterns and factors contributing to them and attention to
these, is likely to be a preferred approach to addressing these putative
nutrient-health issues.
Sponsorship: Public Health Bureau of Tianjin,
China; Kuopio University, Finland
A dietary survey of the Chinese
population in urban and rural areas of Tianjin
HG Tian, Y Nan, G Hu,
QN Dong, XL Yang M
Asia Pacific Journal
of Clinical Nutrition (1996) Volume 5, Number 4: 230-232
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