3.1 Descriptive statistics
Descriptive statistics were used to calculate the means and standard deviations of the demographic variables and physical examination indicators (Table 1).
Table 1
Descriptive statistics of participants’ age, body mass index, and physical examination indicators
Variables
|
mean
|
Sd.
|
Number of people in the normal range (percentage)
|
age
|
20.65
|
0.85
|
|
BMI
|
21.47
|
3.23
|
ALB
|
50.93
|
1.90
|
95(100%)
|
GLB
|
23.70
|
3.42
|
83(87.3%)
|
A/G
|
2.19
|
0.31
|
71(74.7%)
|
ALT
|
21.92
|
16.30
|
82(86.3%)
|
AST
|
21.80
|
9.96
|
87(91.6%)
|
AST/ALT
|
1.21
|
0.49
|
40(42.1%)
|
UREA
|
4.97
|
1.19
|
90(94.7%)
|
CREA
|
97.66
|
17.65
|
71(74.7%0
|
UA
|
457.22
|
81.51
|
33(34.7%)
|
NEUT#
|
3.16
|
0.96
|
86(90.5%)
|
LYMPH#
|
2.62
|
0.54
|
95(100%)
|
NEUT%
|
49.39
|
7.82
|
40(42.1%)
|
LYMPH%
|
42.14
|
8.33
|
31(32.6%)
|
RBC
|
5.80
|
0.36
|
26(27.4%)
|
HGB
|
181.07
|
8.87
|
1(1.1%)
|
HCT
|
53.69
|
2.82
|
93(97.9%)
|
MCV
|
92.71
|
3.43
|
93(97.9%)
|
MCH
|
31.27
|
1.21
|
42(44.2%)
|
MCHC
|
337.38
|
6.02
|
95(100%)
|
BMI, body mass index ALB, albumin; GLB, globulin; A/G, albumin/globulin; ALT, alanine aminotransferase; AST, aspartate aminotransferase; AST/ALT, aspartate aminotransferase/ alanine aminotransferase; CREA, creatinine; UA, uric acid; NEUT#, neutrophil count; LYMPH#, lymphocyte count; NEUT%, neutrophil ratio; LYMPH%, lymphocyte ratio; RBC, red blood cell count; HGB, hemoglobin; HCT, hematocrit; MCV, mean corpuscular volume; MCH, mean corpuscular hemoglobin; MCHC, mean corpuscular hemoglobin concentration.
BMI is a person’s weight in kilograms divided by the square of height in meters.
3.2 Reliability and validity of the FFQ
The retest reliability of the FFQ was calculated, and the Pearson’s correlation coefficient was used to calculate the reliability. The reliability ranged between 0.187 and 0.897, with an average value of 0.541. The category with the highest reliability was sweets (reliability coefficient r = 0.897), and the category with the lowest reliability was dry goods (reliability coefficient r = 0.187). The calculated Pearson’s correlation before and after measurement was significant, except for dry goods and dry beans. This finding shows that the FFQ has good reliability and can be used in follow-up studies and analyses within an acceptable range. Details of the reliability results are presented in Table 2.
Table 2
Retest reliability of FFQ
items
|
r
|
p
|
items
|
r
|
p
|
rice
|
0.545
|
0.000
|
bean products
|
0.309
|
0.019
|
wheat
|
0.398
|
0.002
|
vegetables
|
0.451
|
0.000
|
cereal
|
0.536
|
0.000
|
pickled vegetables
|
0.759
|
0.000
|
tuber
|
0.518
|
0.000
|
dried food
|
0.187
|
0.163
|
tsampa
|
0.635
|
0.000
|
fruit
|
0.730
|
0.000
|
fried food
|
0.365
|
0.005
|
carbonated
|
0.607
|
0.000
|
porridge
|
0.650
|
0.000
|
juice
|
0.308
|
0.020
|
livestock meat
|
0.261
|
0.050
|
tea & coffee
|
0.548
|
0.000
|
poultry meat
|
0.622
|
0.000
|
beer
|
0.589
|
0.000
|
processed meat
|
0.777
|
0.000
|
Baijiu
|
0.838
|
0.000
|
aquatic product
|
0.640
|
0.000
|
wine
|
0.744
|
0.000
|
egg
|
0.639
|
0.000
|
chang
|
0.789
|
0.000
|
milk
|
0.387
|
0.003
|
sweet food
|
0.897
|
0.000
|
yogurt
|
0.590
|
0.000
|
nut
|
0.363
|
0.006
|
sweet tea
|
0.701
|
0.000
|
snacks
|
0.445
|
0.001
|
buttered tea
|
0.587
|
0.000
|
oil
|
0.536
|
0.000
|
powdered milk
|
0.269
|
0.043
|
suger
|
0.799
|
0.000
|
tofu
|
0.444
|
0.001
|
salt
|
0.515
|
0.000
|
soybean milk
|
0.308
|
0.020
|
soy sauce
|
0.542
|
0.000
|
bean
|
0.213
|
0.111
|
vinegar
|
0.614
|
0.000
|
To analyze validity, participants who completed the pre- and posttest questionnaires were asked to take pictures and record their intake for 3 consecutive days from October 21 to 23. The collected pictures and dietary records were also converted into data, and Pearson’s correlation was calculated using the post-test FFQ. Some foods not consumed by the participants during the 3-day period, such as tsampa, ghee tea, and alcoholic products, were not found to be correlated with Pearson’s product correlation, which explains the drawbacks of this method. For the remainder, the Pearson’s product correlation ranged from −0.176 to 0.491. The details of the validity results are presented in Table 3. Bland-Altman plots show the valid comparability of dietary intakes estimated from post-test FFQ and 24HDR. Figure 2 shows the Bland-Altman plots for the different food groups. The Figure reveals the consistency of the two food measures across the 12 food groups, with most values within 95% of the LOA.
Table 3
Validity of the FFQ
items
|
r
|
p
|
items
|
r
|
p
|
rice
|
0.160
|
0.237
|
bean products
|
0.041
|
0.763
|
wheat
|
0.079
|
0.561
|
vegetables
|
0.009
|
0.945
|
cereal
|
-0.021
|
0.877
|
pickled vegetables
|
0.027
|
0.843
|
tuber
|
-0.051
|
0.711
|
dried food
|
0.004
|
0.974
|
tsampa
|
.a
|
fruit
|
0.112
|
0.412
|
fried food
|
0.199
|
0.141
|
carbonated
|
0.209
|
0.121
|
porridge
|
0.491
|
0.000
|
juice
|
0.176
|
0.194
|
livestock meat
|
0.026
|
0.846
|
tea & coffee
|
0.029
|
0.833
|
poultry meat
|
-0.139
|
0.308
|
beer
|
.a
|
processed meat
|
-0.044
|
0.748
|
Baujiu
|
0.087
|
0.526
|
aquatic product
|
0.137
|
0.313
|
wine
|
.a
|
egg
|
0.367
|
0.005
|
chang
|
.a
|
milk
|
0.198
|
0.144
|
sweet food
|
0.035
|
0.799
|
yogurt
|
-0.015
|
0.910
|
nut
|
0.049
|
0.722
|
sweet tea
|
0.265
|
0.049
|
snacks
|
0.007
|
0.957
|
buttered tea
|
.a
|
oil
|
.b
|
powdered milk
|
.a
|
suger
|
.b
|
tofu
|
0.069
|
0.614
|
salt
|
.b
|
soybean milk
|
0.169
|
0.212
|
soy sauce
|
.b
|
bean
|
0.025
|
0.855
|
vinegar
|
.b
|
“a”: Indicates no intake within 3 days.
“b”: Not presented due to difficulties in calculating condiments
The average intakes from both the post test of food frequency questionnaire and 3-day 24-hour dietary recall are plotted on the X-axis, and the difference is plotted on the Y-axis. The orange line means the mean of difference. Two green lines mean the limits of agreement (LOA), defined as mean difference ± 1.96 × SD. The black points mean dietary intakes data of participants.
3.3 Gap of actual dietary intakes and recommended intakes
Specific food intake was assessed based on the CDP (2021 version), which is the national standard for Chinese people. One-sample t-test was used to compare the means of specific food intake against the reference values. As the recommended values of condiments were not included in the recommended dietary intake of Chinese residents in 2021, the 2016 version of the Balanced Dietary Pagoda for Chinese Residents was used as a reference standard for comparison. As the units do not coincide, they were initially converted, and comparisons were made only afterward. The intake of livestock and poultry meat was significantly higher than the intake recommended in the 2021 version (t = 6.279, p = 0.000); the staple foods included in the FFQ were rice, wheat, cereals, potatoes, tsampa, and porridge. The intake of staple foods was higher than that in the 2021 version of the recommended value, and the difference between the two was not significant. For the remaining specific foods, the intake was significantly lower than that in the 2021 version of the standard recommendations (p = 0.000). As regards the intake of condiments, salt intake was greater than the maximum value required by the 2016 Chinese Residents’ Balanced Diet Pagoda (m = 4.316, μ = 3.6, t = 1.812, p = 0.073), and the difference between the two was marginally significant. Oil intake was higher than the standard value of the 2016 Chinese Residents’ Balanced Diet Pagoda, but the difference was not significant (t = 0.297, p = 0.767). The results are presented in Table 4.
Table 4
Gap of actual dietary and standard intakes
Category
|
Actual intake(liang/month)
|
Standard intake
(liang/month)
|
t
|
P
|
staple food
|
209.790
|
195
|
1.095
|
0.276
|
livestock and poultry meat
|
93.295
|
34.5
|
6.279
|
0.000
|
vegetables
|
72.968
|
240
|
-24.969
|
0.000
|
egg
|
17.411
|
27
|
-3.914
|
0.000
|
dairy
|
51.768
|
180
|
-20.100
|
0.000
|
aquatic product
|
3.084
|
34.5
|
-76.927
|
0.000
|
fruit
|
30.221
|
165
|
-31.370
|
0.000
|
soybean and nut
|
6.947
|
18
|
-10.999
|
0.000
|
salt
|
4.316
|
<3.6
|
1.812
|
0.073
|
oil
|
17.179
|
16.5
|
0.297
|
0.767
|
1 liang = 50 g
3.4 Dietary patterns of Tibetan migrants
After taking the pretest, the results of the completed questionnaire were subjected to principal component analysis, and six principal components were retained based on the parallel analysis. The total variance explained by all six principal components reached 74.72%. The component matrix was rotated using the variance maximization method, and the principal components were named according to the rotation results. During the process of naming the principal components, the absolute value of the factor loadings ≥ 0.30 was mainly considered. Thus, six principal components were obtained: coarse grain dietary pattern, which included potatoes, cereals, ghee tea, and dried beans; meat dietary pattern, which included livestock meat and poultry meat; beverage dietary pattern, which included tea and coffee, carbonated drinks, and yogurt; dairy dietary pattern, which included milk, pickled vegetables, and yogurt; fruit dietary pattern, which included fruits, nuts, and fruit juices; and unhealthy dietary pattern, which included carbonated drinks, porridge, eggs, and beer. However, the factor loadings of porridge and eggs were negative; therefore, it was classified as an unhealthy dietary pattern. The specific dietary patterns are shown in Figure 3.
3.5 Correlation of dietary patterns with physical examination indicators
Principal component 1 (coarse grain dietary pattern) was positively correlated with NEUT% (r = 0.240, p = 0.019), negatively correlated with LYMPH% (r = −0.225, p = 0.028), significantly positively correlated with MCV (r = 0.202, p = 0.049), and positively correlated with MCH (r = 0.268, p = 0.009). Principal component 2 (meat dietary pattern) showed a significant positive correlation with AST levels (r = 0.202, p = 0.050). Principal component 3 (beverage dietary pattern) was positively correlated with both ALT and UA levels (r = 0.253, p = 0.014). Principal component 5 (fruit dietary pattern) was positively correlated with A/G (r = 0.256, p = 0.012) and negatively correlated with MCHC (r = -0.216, p = 0.036). The results of the correlation analysis are presented in Table 5 and Figure 4.
Table 5
Correlation of dietary pattern with physical examination indicators
Principal components
|
physiological index
|
r
|
p
|
coarse grain dietary pattern
|
NEUT%
|
0.240
|
0.019
|
coarse grain dietary pattern
|
LYMPH%
|
-0.225
|
0.028
|
coarse grain dietary pattern
|
MCV
|
0.202
|
0.049
|
coarse grain dietary pattern
|
MCH
|
0.268
|
0.009
|
meat dietary pattern
|
AST
|
0.202
|
0.050
|
beverage dietary pattern,
|
ALT
|
0.253
|
0.014
|
beverage dietary pattern,
|
UA
|
0.253
|
0.014
|
fruit dietary pattern
|
A/G
|
0.256
|
0.012
|
fruit dietary pattern
|
MCHC
|
0.216
|
0.036
|
NEUT#,neutrophil count;LYMPH%,lymphocyte ratio;
MCV,mean corpuscular volume;MCH,mean corpuscular hemoglobin;
AST, aspartate aminotransferase;ALT,alanine aminotransferase;
UA, uric acid;A/G,albumin/globulin;
MCHC,mean corpuscular hemoglobin concentration.
PCA1, coarse grain dietary pattern; PCA2, meat dietary pattern; PCA3, beverage dietary pattern; PCA4, dairy dietary pattern; PCA5, fruit dietary pattern; PCA6, unhealthy dietary pattern
ALB, albumin; GLB, globulin; A/G, albumin/globulin; ALT, alanine aminotransferase; AST, aspartate aminotransferase; AST/ALT, aspartate aminotransferase/ alanine aminotransferase; CREA, creatinine; UA, uric acid; NEUT#, neutrophil count; LYMPH#, lymphocyte count; NEUT%, neutrophil ratio; LYMPH%, lymphocyte ratio; RBC, red blood cell count; HGB, hemoglobin; HCT, hematocrit; MCV, mean corpuscular volume; MCH, mean corpuscular hemoglobin; MCHC, mean corpuscular hemoglobin concentration.
3.6 Binary logistic regression of dietary patterns with physical examination indicators
The abovementioned correlation analysis illustrates the association of some dietary patterns with physical examination indicators; however, owing to the large standard deviation of the principal component scores, the statistical method of binary logistic regression was more appropriate. Results were obtained using the method described in the Statistical Analysis section. Individuals with high MCHC were likely to consume more coarse-grained foods (OR = 1.077, p = 0.054). The opposite result was observed for urea level, which was negatively correlated with adherence to coarse-grained foods; individuals with high urea level typically consumed less coarse-grained foods (OR = 0.601, p = 0.013). The final independent variable that was retained for high or low adherence to meat dietary pattern that had an impact was CREA, which was positively correlated; individuals with high CREA level consumed more meat (OR = 1.050, p = 0.023). At the mechanistic level, adherence to the meat dietary pattern was associated with lower GFR (OR = 0.960, p = 0.020). Adherence to beverage dietary pattern was positively associated with serum UA levels; individuals with high UA levels may have consumed more drinks (OR = 1.005, p = 0.044). For dairy dietary pattern, the physical examination indicators had no significant effect. For principal component 5, the fruit dietary pattern was associated with two physiological indicators: a positive correlation between AST/ALT ratio (OR = 5.271, p = 0.005) and a positive correlation between RBC level and fruit dietary pattern (OR = 4.805, p = 0.033). Adherence to an unhealthy dietary pattern was positively correlated with LYMPH# (OR = 2.904, p = 0.011). The results of the binary logistic regression analysis are shown in Figure 5.