274

Asia Pac J Clin Nutr 2010;19 (2):274-282

Short Communication

Sources and intake of resistant starch in the Chinese diet
Liyong Chen MD1, Ruiping Liu MD2, Chengyong Qin MD1, Yan Meng MPH3, Jie Zhang
13
3
MPH , Yun Wang MPH , Guifa Xu MD
1

Nutritional department of Provincial hospital affiliated to Shandong University, Jinan, China
Nutritional department of Xian Children’s Hospital, Xian, China
3
Institute of Nutrition and Food Hygiene of Shandong University, Jinan, China
2

Resistant starch (RS) escapes digestion in the small intestine and may ferment in the large intestine. The purposeof this study was to determine the resistant starch content in typical starchy foods and to estimate the daily resistant starch intake and identify key sources of dietary resistant starch in the Chinese diets. The resistant starchcontents of 121 foods were determined using a method that mimicked gastrointestinal conditions. Tubers andlegumes had high resistant starch contents. Rough food processing retained large amounts of resistant starch. In
general, the content of RS decreased when foods were cooked. Deep fried and roasted foods had higher levels of
resistant starch than braised foods. The average resistant starch intake in the Chinese population was estimated to
be 14.9 g per day based on a dietary survey. The main resistant starch sources in the Chinese diet were cereal
and tuber products. Based on dietary habits, however, the resistant starch intake varies considerably among individuals.

Key Words: content, dietary survey, intake, resistant starch, source

INTRODUCTION
For nutritional purposes, starch in foods may be classified
into three types according to in vitro digestibility: rapidly
digestible starch (RDS), slowly digestible starch (SDS),
and resistant starch (RS).1 RS is defined as “the sum of
starch and the products of starch degradation not absorbed in the small intestine of healthy individuals”.2 In
the gastrointestinal tract, the rapidly and slowly digestible
fractions are digested and absorbed in the small intestine,
generally within 120 min of consumption of foods,
whereas RS is fermented in the colon.1 By the standard
American Association of Cereal Chemists method for
determining dietary fiber (DF), RS is insoluble and possesses physiologic properties similar to those of DF. Nutritional studies have shown that RS improves lipid andcholesterol metabolism, increases fecal bulk, reduces therisk of ulcerative colitis, colorectal cancer, coronary heartdisease, constipation, and Type II diabetes and binds toxins, bile acids, and carcinogens.3-5
The nature of RS in foods is variable and is classified
on the basis of its botanical source and processing. It occurs as physically inaccessible starch (RS1), resistantstarch granules (RS2), retrograded starch (RS3), andchemically modified starch (RS4). The RS1 fraction is
physically inaccessible to digestion as it is entrapped in a
non-digestible matrix, whereas RS2 is native dehydrated
granular starch packed in a compact molecular structurethat limits the accessibility of amylases. The RS1 andRS2 fractions occur in whole cereal grains and root crops,
respectively, and have significant nutritional value evenafter cooking and processing. The content of RS1 andRS2 fractions represent most of the RS in a typical diet.

After the processing of amylose polymers, gelatinization,and recrystallisation, the RS3 fraction is formed. This
fraction is enzyme-resistant; the starches adopt a double
helix structure stabilized by hydrogen bonds, which ischaracterized by a high thermal stability.1,3,6 RS4 isformed by chemical modification of starch.
Legumes, potatoes, banana and cereals are typicalsources of starch and have been shown to contain various
amounts of RS.7,8 Several factors can influence RS quantities, including botanical origin, starch nature (amylose/amylopectin ratio, interaction between starch/nutrients),
food processing (starch gelatinization degree, particle size,
cellular structure, starch granules variation) and the presence of other components (lipids, protein, dietary fiber,
antinutrients, and organic acids).9
Obesity, cardiovascular disease, diabetes, and cancer
have recently become major threats to human health inmany nations at least in part due to changes in eating anddrinking habits. Although the etiology is multi-factorial,
diet has been identified as the most important environmental risk factor for development of these diseases. Thus,
dietary modification, like increases in dietary fiber intake,could be a cost-effective way to reduce prevalence of
these conditions. RS should be taken into account when
the optimum level of daily dietary fiber is determined.

Corresponding Author: Prof Guifa Xu, Institute of Nutrition
and Food Hygiene of Shandong University, Jinan, China.
Tel: 86 0531 88382135; Fax: 86 0531 88382208
Email: yyxu@sdu.edu.cn
Manuscript received 11 March 2008. Initial review completed 28
April 2008. Revision accepted 22 February 2010.

L Chen, R Liu, C Qin, Y Meng, J Zhang, Y Wang and G Xu
Thus, it becomes important to determine the RS content of foods. The true value of RS can be derived only
from that found in the contents of the terminal ileum.
However, to date, only two methods have been utilized
for in vivo measurement of RS in the terminal ileum. One
method requires individuals to be subjected to an ileostomy10-12 and the other requires oral or nasal intubationof the ileum through the gut.13,14 These methods bothhave limitations. In the first approach, the ileostomy subjects analyzed usually have had a history of gastrointestinal disease and their intestinal function might be modified
by the ileostomy. Moreover, the intestinal flora of ileostomy subjects may be quite different from that of healthy
subjects. In the oral or nasal intubation studies, accurate
physiological measurement may be prevented by the existence of a tube in the small intestine where foodstuffs aredigested and absorbed. Clearly, a suitable methodology tomeasure RS needs to be developed so that the RS content
of foods can be estimated.
Some data concerning RS content in common foodproducts is available. The RS intakes in 10 different
European countries have been evaluated from national
consumption statistics.15 According to these calculations,
the RS intake varied from 3.2 g to 5.7 g/day depending on
country. Brighenti et al.16 estimated that the intake of RS
was 8.5 g/day in the Italian diet based on representative
analysis of the main sources of starch intake. Silvester etal.10 showed that RS intakes varied from 0.4 g to 34.8
g/day, depending on dietary starch content and type. In
2008, Murphy et al.17 reported that RS intake was 3g-8
g/day for Americans. A survey by Muir et al. estimatedthat the content of total starch and RS of the low-income
Chinese diet is 392 g/day and 17.6 g/day, respectively.18
Using an analytical method that mimics gastrointestinal conditions in vitro, the RS contents of typical starchy
foods common in the Chinese diet were determined. The
contents of total starch (TS) were also evaluated. In addition, the daily RS intake among the Chinese was estimated based on a dietary survey.
MATERIALS AND METHODS
Sample preparation
Seven kinds of food samples (cereals, tubers, legumes,
starches, vegetables, nuts and seeds, fruits) consumed in a
typical Chinese diet were included in the study. Fortynine raw foods (Table 1) and 72 cooked food products(Table 2) were tested. These samples were obtained fromlocal farm product markets or supermarkets.
The in vitro model mimics gastrointestinal enzyme digestion.19,20 Mechanical agitation was performed withglass pearls (to mimic chewing), the samples were thenblended and two 0.1-0.2 g samples were taken. The samples were weighed (accurately to 0.0001 g) and subjected
to enzymolysis to determine the content of TS and RS.
Foods were prepared according to typical Chinese cooking methods and were analyzed immediately after coolingto room temperature. Samples with more than 10% fat
content were defatted with absolute ether prior to theanalysis.
Total starch analysis.

275

Total starch (TS) content was determined according to themethod of Goñi et al.18 Samples (50 mg) were suspendedin 2 M KOH to disperse starch and shaken at room temperature for 30 min. The samples were incubated (60oC,
45 min) at pH 5.0 in a 1 mL solution of amyloglucosidase(300 U/mL, Sigma 10113) to hydrolyze starch. The freeglucose was determined using the glucose oxidase
method.7 Total starch was calculated as glucose (g) ×
0.9(g/100g). Corn starch was used as reference standard.
All chemicals used were at least of analytical grade.
Resistant starch analysis
The RS content was analyzed using the procedure described by Goñi et al.7 and Åkerberg et al.19 Briefly, thesamples were incubated (40oC, 60 min, pH 2.0) in a 1 mL
solution of pepsin (10 mg/mL, Sigma P-7012) to remove
protein and then 0.1 mL of α-amylase (40 mg/mL, Sigma
A-3176) was added and the sample was incubated at 37oC
for 16 h at pH 5.0 to hydrolyze digestible starch. Next,
the residue was treated with 2 M KOH to solubilize RS
and was then incubated (60oC, 45 min, pH 5.0) with 140
U/mL amyloglucosidase (Sigma 10113) in 80 mL to hydrolyze the solubilized resistant starch. Finally, glucose
was determined as described above.
Dietary survey
Dietary surveys were completed by 6382 men and women
aged 18 to 70 from cities and countryside areas of China.
This study was approved by the Ethics Committee of
Shandong University (China). A food frequency questionnaire was administered to each subject. Information
was obtained on the frequency that certain foods and liquids were consumed (daily, weekly, monthly, yearly, occasionally, or never) and the portion size (small, medium,and large). Portion sizes were estimated using common
household bowls, dishes, spoons, cups, and glasses.
All subjects were asked to complete a dietary record
for 7 consecutive days of food items and liquids consumed. Each subject was issued appropriate dietary intake
recording sheets. At the beginning of the 7-day period,
each subject was given detailed instructions on how toestimate the amount of each food item consumed. The
procedure was then repeated by the subjects in the presence of the investigator to ensure competence. Subjects
were visited on at least four different occasions during the
7 day period. On the eighth day, the subjects were visited
to check the dietary intake recording sheets for completeness and accuracy. At that time, each subject was asked toprovide a complete description of the methods of preparation, cooking, and recipes used for composite dishes.
Estimation of resistant starch intake
Based on the RS values measured and on food consumption data (g/subject/day) calculated from the dietary survey, RS intake was estimated for each individual. In addition, the main sources of RS in foods were also determined.
RESULTS AND DISCUSSION
Total starch and resistant starch in raw foods
In Table 1, the total starch (TS) and resistant starch (RS)are listed for the 49 raw food materials tested. The major-

Resistant starch content in Chinese diets

276

Table 1. Total starch and resistant starch in raw food materials†
Food
Cereals
1. Wheat flour, refined, special grade 1
2. Wheat kernel
3. Glutinous rice
4. Corn
5. Round grained rice
6. Long grained rice, fragrant
7. Foxtail millet, hulled
8. Long grained rice, purple
9. Broomcorn millet, hulled, yellow
10 .Buckwheat, hulled
11. Sorghum
12. Adlay
13. Oat flour
Dried legumes
14. Soybean
15. Kidney bean, red
16. Red bean
17. Black soybean
18. Mung bean
19. Garden pea
20. Common cowpea
21. Kidney bean, purple
22. Soybean stick, dried, skimmed from soybean milk
Tubers
23. Potato (preserved)
24. Potato (fresh)
25. Sweet potato, white flesh
26. Big taro
27. Taro
28. Yam
Starches
29. Corn starch
30. Potato starch
31. Sweet potato starch
32. Cassava starch
Vegetables
33. Water caltrop
34. Water caltrop, dried
35. Water chestnut
36. Lotus root
37. Water bamboo
38. Pumpkin
39. Chinese wax gourd
40. Lily, dried
41. Garlic bulb
42. Silverweed cinquefoil
43. Kidney bean, green, with pod
44. Hyacinth bean, green, with pod
45. Pale green soybean, without seed coat
Fruits
46. Green banana
47. Ripe banana
Nut and seed
48. Cashew nuts
49. Lotus seed, driedTS‡ (g/100 g esculent)RS§(g/100 g TS)

87.0±4.74
77.0±3.32
80.1±3.11
84.6±2.39
84.4±14.4
84.8±1.22
77.9±0.33
80.0±3.76
77.0±2.53
76.0±5.81
86.6±2.89
68.5±1.2385.6±6.03

4.37±0.32
25.6±0.68
20.8±0.76
16.0±0.83
15.9±1.82
10.3±1.1217.6±0.99
19.3±5.81
18.1±1.62
23.6±7.01
43.7±6.83
10.7±1.77
1.82±0.63

30.0±0.84
43.9±8.21
47.7±9.38
19.9±2.83
56.7±2.91
68.2±6.99
44.1±4.11
66.0±3.37
21.8±3.20

11.4±1.36
32.3±4.03
17.3±1.28
26.7±0.39
29.4±2.23
21.3±4.86
28.7±4.54
27.1±4.73
20.4±2.53

19.5±3.16
15.0±0.63
27.3±0.24
18.5±0.84
18.8±0.89
31.1±1.48

12.7±1.91
72.0±5.82
30.1±2.1444.1±4.85
27.5±2.65
27.6±2.43

96.8±1.58
98.9±4.84
92.6±0.90
88.8±4.20

7.83±2.02
79.3±9.06
28.9±11.63
80.8±14.82

29.0±2.65
82.4±1.81
9.01±0.84
13.7±1.71
1.66±0.09
5.63±0.12
2.94±0.30
73.1±3.75
1.36±0.26
58.9±3.23
1.56±0.04
1.60±0.05
27.0±0.10

41.5±9.72
36.8±3.33
8.05±0.78
2.10±0.45
17.7±0.79
37.1±2.42
0.00±0.00
10.5±0.09
0.00±0.00
23.2±3.15
6.93±2.87
6.15±0.35
14.9±1.85

18.7±2.15
16.7±0.61

38.3±3.10
4.85±0.40

49.8±4.72
72.5±2.56

12.9±0.1919.7±2.02†

Values are means ± SD of five replicatesTS, total starch§
RS, resistant starch‡

ity of TS figures are in good agreement with carbohydrate
data from a previous analysis.20
Cereals
In the thirteen cereals (two flour, eleven grain) analyzed,
the RS contents were lower in cereal flour than in grain.

RS contents were 1.82% (on a total starch basis) in oat
flour, and 4.37% in refined wheat flour. However, the RS
levels in cereal grains varied from 10.3% to 42.7%. The
higher RS levels in cereal grain than in flour were probably due to the fact that a part of the starch remained encapsulated in the grain structure. Digestive amylases may

L Chen, R Liu, C Qin, Y Meng, J Zhang, Y Wang and G Xu

277

Table 2. Total starch and resistant starch in cooked food products†
Food product and description
Cereals
1. Wheat bun, leavened, steamed
2. Wheat bun, leavened, baked
3. Wheat noodle
4. Wheat dough stick, deep-fried
5. Wheat pancake, deep-fried
6. Wheat kernel porridge
7. Round grained rice, steamed
8. Long grained rice, fragrant, steamed
9. Glutinous rice lumps, steamed
10 .Round grained rice porridge
11. Corn bun, leavened, steamed
12. Corn flour paste, yellow
13. Corn flake porridge, instant
14. Corn grits porridge, yellow
15. Corn, yellow, fresh, steamed
16. Sticking corn, steamed
17. Foxtail millet porridge
18. Foxtail millet pancake, unleavened
19. Long grained rice porridge, purple
20. Sorghum porridge
21. Broomcorn millet flour paste
22. Buckwheat porridge
Ethnic food, fast food and cakes made mainly with cereals
23. Wheat noodle, instant
24. Bread
25. Biscuit
26. Fried dough twisted, crispy
27. Cake, with egg and baking powder, baked
28. Walnut cookie, with walnuts and vegetable oil, baked
29. Wheat Starch jelly sheet, steamed, cooled
30. Rice noodle
31. Oatmeal flake
Legumes
32. Red bean porridge
33. Red bean paste
34. Soybean, boiled
35. Garden pea, boiled
36. Common cowpea, boiled
37. Mung bean porridge
38. Black soybean, boiled
39. Broad bean, roasted
40. Broad bean, deep fried
Tubers
41. Potato sliced, boiled and cooled
42. Potato sliced, fried
43. Potato chips, deep-fried
44. Potato, steamed, cooled
45. Potato, roasted, cooled
46. Sweet potato, yellow skin, steamed, cooled(preservative)
47. Sweet potato, yellow skin, roasted (preservative)
48. Sweet potato, red skin, steamed (fresh)
49. Sweet potato, yellow skin, steamed(fresh)
50. Sweet potato slice, steamed and dried
51. Big taro, steamed
52. Taro, steamed
53. Yam slice, fried
Starch products
54. Mung bean starch noodle
55. Sweet potato starch noodle, broad, dried
56. Sweet potato starch jelly sheet, dried
57. Potato starch noodle, dried
58. Lotus root starch
Vegetables
59. Lotus root sliced, boiled and cooled
60. Lotus root sliced, fried
61. Silverweed cinquefoil, boiled

Servingsize (g)TS (g/100 g
esculent)‡

RS§(g/100 g
TS)

RS (g/100g
esculent)

20 g
20 g
25 g
30 g
30 g
125 g
50 g
50 g
50 g
125 g
60 g
125 g
125 g
125 g
50 g
50 g
125 g
30 g
125 g
125 g
20 g
125 g

59.7±1.98
79.2±4.70
27.7±1.61
76.8±1.4743.8±2.81
21.3±5.5434.2±3.16
44.3±1.08
40.7±7.23
19.5±2.48
59.2±7.87
17.0±1.07
18.1±0.59
12.0±0.43
36.4±3.22
51.7±6.09
37.1±2.69
95.3±2.36
22.5±0.95
27.3±2.66
14.6±0.36
7.99±0.62

3.71±0.62
2.38±0.47
3.51±0.86
4.28±0.29
6.47±0.42
12.8±0.31
3.60±0.52
4.21±0.71
2.68±0.06
5.93±1.15
10.3±2.74
5.08±2.74
7.45±1.95
7.10±0.71
2.65±0.137.47±0.46
7.39±0.80
5.16±1.87
13.6±4.21
9.83±0.88
2.59±0.138.32±1.43

2.21±0.56
1.89±0.48
0.97±0.25
3.29±0.86
2.83±0.45
2.72±0.12
1.23±0.08
1.87±0.15
1.09±0.06
1.16±0.10
6.08±1.02
0.86±0.08
1.35±0.06
0.85±0.12
0.96±0.07
3.86±0.11
2.74±0.10
4.92±0.14
3.06±0.12
2.68±0.07
0.38±0.04
0.66±0.02

30 g
20 g
20 g
30 g
20 g
20 g
20 g
30 g
20 g

74.0±6.75
80.0±5.89
93.0±2.1572.5±7.44
33.9±3.86
70.5±8.1727.3±2.90
19.5±3.01
75.6±9.49

4.11±0.89
6.03±0.31
6.06±0.66
7.98±0.91
12.0±0.20
11.8±0.26
16.3±1.73
9.87±0.17
4.76±0.50

3.04±0.66
4.82±0.55
5.63±0.49
5.79±0.78
4.05±0.86
8.29±0.96
4.47±0.75
1.92±0.24
3.60±0.68

125 g
20 g
20 g
70 g
20 g
125 g
20 g
60 g
60 g

30.3±5.24
22.8±1.18
10.3±2.31
27.2±1.03
25.0±1.65
11.8±3.69
9.18±2.63
67.6±2.73
58.7±8.19

14.7±0.72
14.3±0.03
12.3±1.10
14.1±3.15
14.9±3.51
11.0±4.13
3.17±0.39
18.7±2.40
13.1±1.99

4.45±0.92
3.26±0.68
1.27±0.04
3.84±0.42
3.72±0.39
1.30±0.06
0.29±0.02
12.7±2.37
7.72±1.24

90 g
90 g
90 g
90 g
90 g
60 g
60 g
60 g
60 g
60 g
60 g
60 g
60 g

17.5±2.13
16.4±2.3154.8±3.71
18.7±3.82
36.5±8.43
25.9±0.51
46.1±9.91
22.0±1.57
11.8±0.33
43.4±2.17
21.8±1.17
22.1±0.92
12.1±0.30

4.37±0.58
5.19±1.08
9.05±0.59
31.0±0.95
52.5±2.97
13.1±2.13
4.59±0.90
5.13±1.03
12.0±2.82
8.95±0.26
9.90±0.43
17.0±1.80
24.8±4.44

0.77±0.09
0.85±0.08
4.96±0.87
5.80±1.28
19.2±1.68
3.39±0.32
2.11±0.24
1.13±0.06
1.41±0.07
3.88±0.26
2.16±0.18
3.76±0.32
3.01±0.26

30 g
30 g
30 g
30 g
20 g

67.2±3.94
96.8±0.59
98.9±4.47
98.2±5.50
98.0±1.43

34.1±7.13
41.0±4.10
31.6±4.60
27.8±1.44
5.34±1.36

23.0±1.35
39.7±2.02
31.3±1.56
27.3±1.32
5.23±0.98

100 g
100 g
200 g

16.3±2.27
17.2±1.58
8.77±1.15

5.87±0.18
1.58±0.19
15.2±5.13

0.95±0.08
0.27±0.03
1.34±0.07

Resistant starch content in Chinese diets

278

Table 2. Total starch and resistant starch in cooked food products† (con.)
Food product and description
62. Water caltrop, unshelled, dried, boiled
63. Water caltrop, steamed
64. Pumpkin, steamed
65. Chinese wax gourd, stewed
66. Yardlong cowpea, boiled and cooled
67. Pale green soybean, without seed coatNuts and seeds
68. Peanut kernel, deep-fried
69. Peanut, in shell, roasted
70. Peanut, boiled
71. Chestnut, in shell, fried with sugar
72. Pistachio, in shell, salted and roasted

Servingsize (g)
200 g
200 g
200 g
200 g
20 g
20 g

TS (g/100 g
esculent)
29.9±3.61
20.2±2.62
6.93±0.23
2.48±0.23
4.76±0.1426.8±2.83

RS (g/100 g
TS)13.7±4.09
12.4±0.96
12.5±0.64
0.00±0.00
0.00±0.00
5.21±0.00

RS (g/100g
esculent)
4.10±0.23
2.50±0.26
0.87±0.09
0.00±0.00
0.00±0.00
1.39±0.22

8g
14 g
8g
35 g
14 g

29.3±4.21
29.3±1.55
29.3±1.10
28.6±0.78
15.6±1.01

15.1±1.52
14.5±1.77
14.7±2.22
17.2±2.93
21.9±3.24

4.41±0.43
4.24±0.34
4.32±0.32
4.91±0.24
3.43±0.38§†

Values are means ± SD of five replicatesTS, total starch§
RS, resistant starch‡

be unable to penetrate or break down the cellulose cell
walls and, therefore, this starch was inaccessible. For RS1,
a starch physically entrapped within the food, the degreeof milling was an important factor.21,22 More extensive
milling should make these starches more accessible andless resistant to digestion.
Legumes
The RS levels of legumes varied from 11.4% to 32.3%.
The presence of intact cell walls contributed to the RS
content of legumes.
Tubers
The highest RS content, among the tuber products tested,
was found in fresh potato (72.0%), which was almost six
times higher than in the preserved sample. This might bedue to starch hydrolysis to mono or oligosaccharides during the period of preservation. Big taro (44.1%) and sweet
potato (30.1%) also had high RS content. Taro and yam
had a similar RS content but taro showed a lower level ofTS (18.8%) than yam (31.1%). Therefore yam provides
significantly more nutritional value than taro.
Starches
As expected, pure potato starch (79.3%) and cassava
starch (80.8%) had high RS concentrations.
Vegetables
Among the vegetables, water caltrop, silverweed cinquefoil, and pale green soybean showed high levels of RS.
BananasThe RS concentration was almost ten times higher in unripe bananas than in ripe ones.
Nuts and seeds
Cashews and dried lotus seed had high RS contents.
Total starch and resistant starch in cooked foods
In Table 2, the TS and RS per 100 gm of cooked food andthe average serving size of that food are listed for the 72
cooked foods products evaluated.

Cereals
Among cereal products, wheat and rice were the mostimportant sources of starch in the Chinese diet. Daily
intakes were estimated at 147 g and 74 g, respectively.
The RS contents in the 31 cooked products included in
the present study varied from 2.38% (total starch basis) to
16.4%. The high RS level in wheat starch jelly sheets wasprobably due to the degradation of the gelatinized amylose after thermal processing. Among the wheat products,
wheat kernel porridge had considerable RS. Cakes, walnut cookies, fried dough twists, pancakes and biscuits had
lesser, but significant, amounts of RS. In contrast, lowconcentrations of RS were found in buns (3.71%) andnoodles (3.51%). This data indicates that baking anddeep-frying catalyze RS formation. Among different porridges, purple long grained rice porridge, sorghum porridge, and buckwheat porridge also contained majoramounts of RS. The contribution of RS from intact cereal
grains to the diet was emphasized in a previous study.19
LegumesLegume products were a main source of starch in the diets of the study subjects. In the present study, except for
black soybean (3.17%) and roasted broad bean (18.7%),
cooked legumes contained 11.0%-14.9% RS. Values in asimilar range were reported for legume products by otherlaboratories using ileostomists.23,24 However, in the present study, the mean RS content of seven cooked legumes
varieties (with the exceptions of black soybean androasted broad bean) was higher (13.5%) than the meanvalue obtained in the previous study (11.7%) by Brighenti
et al.16
TubersTuber products were also an important source of starch inthe subjects’ diets. In our dietary survey, the daily intake
was estimated to be 149 g. Potato and sweet potato accounted for 59 g and 56 g, respectively. The RS content
in boiled potatoes and fried potatoes were similar, 4.37%
and 5.19%, respectively. High RS levels were found in
the deep-fried products, like potato chips (9.05%). Even
higher RS contents were found in steamed and cooled

L Chen, R Liu, C Qin, Y Meng, J Zhang, Y Wang and G Xu
potato (refrigerated for 24 h) and roasted and cooled (in arefrigerator for 24h) potato, 31.0% and 52.5%, respectively, suggesting an influence of the deep-frying androasting process on RS formation. According to Åkerberg
et al,19 refrigeration of boiled potatoes might influence theformation of retrograded starch considerably. Therefore,
when steamed or roasted potatoes were stored at 4oC for
24 h, the RS contents presumably increased considerably.
The nature of the RS formed was probably retrogradedamylopectin, since retrogradation of amylose is favored ataround 100oC.25 In addition, the RS fractions in the fried
yam slices and steamed taro were also considerable.
Starch products
The daily intake of starch products by our subjects wasestimated to be 46.9g. Sweet potato starch noodles(41.0%) and sweet potato starch jelly sheets (31.6%),
both commercially processed starch products, were foundto have higher levels of RS than sweet potato starch(28.9%). Mung bean starch noodles had surprisingly
higher (31.1%) starch content than boiled mung bean
(11.0%). The high RS levels in starch products were
probably due to the retrogradation of the gelatinizedstarch after thermal processing.
Vegetables
Among the vegetables tested, water caltrop and silverweed cinquefoil showed high contents of RS. Boiled andcooled lotus root slices and pale green soybeans also had
considerable RS. The percentage of RS based on total
starch was high in steamed pumpkin, but it was not significant due to the small amount of total starch.
Nuts and seeds
The RS fractions in peanut, chestnut, and pistachio were
high. But pistachio was infrequently consumed by the
Chinese in our study.

279

Comparison of RS in raw food materials and cooked
food products
Figure 1 illustrates changes in RS content due to cooking;in general, RS content was lower after processing. When
starch is heated, starch granules swell and are disrupted.
This process, known as gelatinization, makes the starchmore accessible to digestive enzymes. When heated andgelatinized starch is cooled, retrogradation occurs andsome of the gelatinized starch is converted to a crystalline
form, which is resistant to digestion. Foods, such as bread,cold cooked potatoes, wheat starch jelly sheets, rice noodles, and sweet potato starch noodles, contain retrogradedstarch, which is resistant to digestion.
Cooking conditions are very important in determining
the amounts of RS3 through gelatinization and retrogradation. Chewing also decreases the amount of RS present by
reducing particle size.21
Kutoš et al.26 evaluated common RS amounts in raw
bean samples processed by different methods and verified
that the amount was almost two times higher in raw samples than those that had been soaked and cooked. In contrast, however, when Tovar and Melitoevaluated the effect of thermal processing (conventional and at high pressure) on beans, these authors found values of RS three tofive times greater in the cooked samples than raw.27 The
variation in the results may be due to the use of different
methods of analysis. This emphasizes the need for methodological standardization.
Daily intake of resistant starch in Chinese study subjects
Xu et al.31 estimated the daily RS intake among a Chinese
sample to be 14.9±9.1 g (16.2±8.8 g in male and 14.2±
9.3 g in female, respectively). Obviously, RS intake willvary among individuals based on dietary habits. Table 3
summarizes the RS intakes in different areas of the worldthat have been reported in the literature. The level of RS
intake was higher in Chinese subjects than Europeans

8070
raw food material
60
cooked foodRS(g/100gTS)

50
40
30
20
10

W
he

at
Br fl oea ur
W d flohG e at urlu
ti n gra
ou in
sr
Lo Ro
ic
ng un
e
gr d g C
ai
ne rai n orndri c ed r
Loe,f ic engFr
Br gra ox a gr
oo in tai anm ed l m t
coi
rn ri ce lle t
m ,pu
il l
et rpl e,yBu ellock w
whSo ea t
rg
h
So um
yb
e
Bl Red an
ac
b
e
k
so an
M ybe
un an
g
Co Ga beam rde nm
on n peco aw
pe
Sw Po ate e at
tp o
ot
a
Bi to
g
ta
ro
Ta
ro
Si
lv
e r Lo Yam
we t ued s ro
o
ci
nq t
W
W
a t a ter uefoer
c a c alt il
lt r roop p,dPu ried
m
pk
Ba in
na
na

0

Figure1. RS content comparison in uncooked food materials and cooked food products

Figure 1. Comparison of RS content in raw and cooked food.*Value in cooked food was average content of food after processing in different ways (p<0.01)

Resistant starch content in Chinese diets

280

Table 3. Resistant starch intake in different areas of theworld

Cummings & Englyst (1989)
Englyst et al. (1992)

Intake(g/day)20-30
3Dysseler & Hoffem (1994)

3.2-5.7

Brighenti at al. (1998)
Liljeberg (2002)
Goldring (2004)
Murphy et al. (2008)
Liu et al. (2007)

8.5
3.2
3-10
3-8
14.9

Area

Information source

AfricaEuropeTen European
countries
Italy
SwedenGlobal intake
America
China

Table 4. Average daily intake of macro-nutrients andcholesterol for survey participants
Classification
Energy (kcal)(KJ)
Protein (g)Fat (g)Carbohydrate (g)Dietary Fiber (g)Cholesterol (mg)

Total
2211.59253.2
86.9
80.9
311.9
10.1
467.5

Male
2379.69956.1
97.2
76.1
353.2
10.0
500.9

Female2117.58859.5
81.1
83.5
288.8
10.2
448.8

(3.2g-5.7 g/day)15 and Americans (3g-8g/day)17 but lower
than that in African studies (20g-30 g/day). RS intake iscorrelated with incidence of colorectal cancer, which ishigher in Europe and lower in Africa.32
Table 4 shows the average daily intakes per capita ofmacro nutrients and cholesterol for Chinese subjects inour study. We compared the diets of our subjects withrecommended intake (RNI).23 The percentage of energy
provided by carbohydrates in diets of our subjects was
close to the recommended daily allowances normal
minimum. The percentage of energy provided by fat accounted for 32.9%, exceeding the adequate intake (AI) of
20%-30%.23 Table 5 shows a menu that was typical of thefood eaten by study subjects. The sources of RS in the
Chinese diet in our study are shown in Figure 2. The main
RS sources were cereals; including: wheat, rice, and corn.
Cereals accounted for over half of the RS in the study

Table 5. Typical daily menu for a survey participant
Meal
Breakfast

Lunch

SupperSnacksFood type
Porridge
Pancake
Egg
Milk
NoodleEggplant
Rice
Green Pepper
Egg
Garlic Sprout
Lean Meat
Porphyra
Oil
Flour
Leek
Streaky Pork
Ribbonfish
Cucumber
Oil
BananaWalnut kernelApplesubjects’ diets. Other significant sources were ethnic
foods, fast food and cakes.
CONCLUSION
This study is the first evaluation of the RS content of a
Chinese diet. RS intake has implications for colonic
health and glucose as well as lipid metabolism; and mostdiets do not contain enough of this starch fraction. In thepresent study, we evaluated the RS content of foods typically consumed by our Chinese subjects. The RS content
varied with plant source. In general, tubers and legumes
had more RS than cereals. Among the selected foods,
potato showed the highest amount of RS. Commerciallyprocessed starch products were found to have a higher RS
content than products prepared via methods used in private kitchens. In general, cooking decreased RS content.
Although deep-fried and roasted foods had more RS than

3%
1%
1%
16%

12%

9%

32%

12%

11%

2%
1%

Figure 2. The sources of resistant starch in diets of study subjects

Serving size
50 g
75 g
65 g
240 ml
100 g
100 g
200 g
80 g
50 g
100 g
30 g
5g
30 g
100 g
120 g
70 g
50 g
75 g
20 g
150 g
25 g
200 g

rice products
wheat products
corn products
other cereals
tubersstarch products
legumesethnic,fast foods and cakes
vegetables
banananuts and seeds

L Chen, R Liu, C Qin, Y Meng, J Zhang, Y Wang and G Xu
braised foods, it should be emphasized that deep-friedproducts also had a high fat content. Hence, an increased
intake of such products should not be encouraged. Legumes are a good source of RS. It would be prudent torecommend increased consumption of tubers, legumes
and cereal grain products.
In order to estimate the daily RS intake in the Chinese
population, food consumption data from dietary surveys
of men and women from both city and country areas wereused. A mean RS value was calculated from the analyzed
individual products in each food group. The daily RS
intake was estimated to be 14.9±9.1 g. Obviously, RS
intake varied considerably among individuals. The main
RS sources in the Chinese diet were wheat products, riceproducts, and starch products. Other important sources of
RS were tubers and legume products, followed by corn
products and other cereals, nuts and seeds. The estimateof resistant starch intake provides a valuable reference forresearchers and food and nutrition professionals and willallow for more accurate estimates of total intakes of carbohydrate compounds that escape digestion in the small
intestine.
ACKNOWLEDGMENTS
The authors are grateful to the Province Natural Science Council, Shandong, China and Chinese Society of Nutrition, for thefinancing of this research project (Y2006C32).
AUTHOR DISCLOSURESThe authors have declared no conflict of interest.

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Short Communication

Sources and intake of resistant starch in the Chinese diet
Liyong Chen MD1, Ruiping Liu MD2, Chengyong Qin MD1, Yan Meng MPH3, Jie Zhang
13
3
MPH , Yun Wang MPH , Guifa Xu MD
1

Nutritional department of Provincial hospital affiliated to Shandong University, Jinan, China
Nutritional department of Xian Children’s Hospital, Xian, China
3
Institute of Nutrition and Food Hygiene of Shandong University, Jinan, China
2

中国居民膳食中抗性淀粉摄入量及食物来源
抗性淀粉在小肠中不能被消化，而在大肠中可能被酵解。本研究的目的是测定特
定食物中的抗性淀粉的含量，并估计中国居民每人每日抗性淀粉摄入量，以及提供抗性淀粉的主要食物来源。用体外模拟胃肠道酶解法对 121 种常用食物中的抗性淀粉含量进行测定。根茎类和豆荚类食物中抗性淀粉含量较高。粗加工食物中
保留较多抗性淀粉。食物经过烹调加工后，抗性淀粉含量普遍降低。油炸和烘烤
的食物较蒸煮的食物抗性淀粉含量较高。根據膳食调查來估计，中国居民抗性淀
粉的平均摄入量为每日 14.9 g。中国居民膳食抗性淀粉的主要来源为面制品、米制品和淀粉产品类。居民的抗性淀粉摄入量因为饮食习惯的差异个体差异较大。
关键词：含量、膳食调查、摄入量、抗性淀粉、来源