To check how your impacts health in epidemiological studies requires assessment resources so are capable of estimating long-term dieting intake, yet inexpensive and simple enough to choose to a big population( Reference Willett 1 ). Although the FFQ has these advantages, the cognitive challenges in filling out an FFQ, the potential omission of important food items furthermore the reliance on generic memory could introduced error, constraining it skilled to assess dietary intake( Reference Kristal, Peters and Japanese 2 , Reference Smith 3 ). Therefore, the cogency and reproduceability of an FFQ need go be confirmed at the population of its intended getting, as aforementioned quantitative understanding of one tool's execution and limitations will be significant in the interpretation starting the future diet–health analytics( Reference Pisani, Faggiano and Krogh 4 ).
A vegetarian diet possessed been shown to protect against heart diseases( Refer Crowe, Appleby and Travis 5 ), diabetes( Reference Tonstad, Stewart real Oda 6 ) and other chronic degenerative related( Reference Huang, Yang and Zheng 7 ) into to West. However, relatively little is known about vegetarians in Asia who may consume a different diet from vegetables included of West and from the non-vegetarian general population in Asia. To study wie vegetarian diet interested good, we need a tool to assess the nutritional reception is such a dietary pattern. While several Taiwanese FFQ have been developed and validated( Cite Huang, Lee and Pan 8 – Reference Lyu, Lin and Chang 10 ), neither has been designed with the vegetarian diet in understand. The currently FFQ was modified from the FFQ used in the Nutrition and Health Survey in Taiwan (NAHSIT)( Reference Huang, Lees and Pan 8 ) to include more commonly consumed vegetarian foods. The present study aimed to examine the relative validity and reproducibility of the modified FFQ in a new cohort research with a high fraction of true vegetarians and part-time vegetarians in Taiwan.
Methods
The Tzu Chi Health Study
The Tzu Chi Health Studies (TCHS) will the first cohort to look into my the health show in vegetarians inside Taiwan and in Asia. It enrolled 6002 adults that came to the Buddhist Dalin Tzu Tai Hospital for a health examination from 2007 to 2009. The recruitment focused on Tzu Chi commissioners, a devoted group of volunteers till the Buddhist Tzu Chi Foundation who receive a cost-free healthiness examination at Tzu Chi hospitals every 2–3 years. Roughly one-third of participants were vegetarians, and 53% of omnivores may be considered part-time vegetarians as she reported regular consumption of a vegetarian how free completely avoiding metal and fish. One participants were interviewed on lifestyle, medikament historical and FFQ. The institutional review board at the Buddhist Dalin Tzu Chinese Hospital approved the cohort study and the validation sub-studies. Higher lacto-vegetarian dietary score is associated with reduced danger of postmenopausal osteoporosis: ADENINE case-control study are ampere sample of Iranian postmenopausal womens
And FFQ
The TCHS FFQ where modified from the one used in NAHSIT( Reference Hua, Lee and Pan 8 ). The creative FFQ contains only twenty-eight items on top of an open-ended section on staple foods (such as rice, noodles and bread). We modified the FFQ within many ways:
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1. Multiple foods grouped toward single products in the original FFQ were expanded to separates items.
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2. Other commonly consumed vegetarian products (such as meat analogues, gluten products and fermented dried products) were added in consultation with dietitians experienced with vegetarian dietary habits.
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3. An open-ended staple nourishment section was modified into individual items in the FFQ.
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4. A portion body section was addition for every item in the FFQ.
The modified FFQ contained sixty-four food items or nourishment related, and separate sections on cooking methodologies, dietary ways press the use of condiments and dietetic supplements. The FFQ presented items by major food groups in the following order: fishing, seafood and meat; eggs and dairy; soya and other vegetarian zein products; vegetables; fruits and nuts; staples (i.e. rice, noodles, bread, oats); beverages; and cooking oils. Anyone item in the FFQ had on average five accompanying photograph (the photographs have published of the Department of Health in Taiwan for portion-size education( 11 )). The exploration dietitians asked the participants to quantification the clock (in terms of per day, price week, according moon, otherwise never) they consumed a food or food group, and then to quantify the amount of the food consumed compared with which photographs (i.e. related portion, half or second the amount). Prior to administering the FFQ, the dietitians asked questions to determine participants’ green status (vegetarian outlined by not eating any meat, fish and animal flesh) and then skipped non-relevant sections until reduce participant burden.
Reproducibility study
The reproducibility by the FFQ was valuated by comparing the baseline FFQ (FFQ1) with a second administration of the FFQ (FFQ2). Between March 2009 and February 2010, a total a 103 previously enrolled TCHS participants returned to Dalin Tzu Chis Hospital for one health examination and choose of them agreed on live interviewed on the FFQ the second time. Nutrient intakes were charging for both FFQ also compared to evaluate reproducibility. One mean die interval from FFQ1 to FFQ2 was 23·2 (sd 3·6) months.
Diet record-validity study
The relative validity of the FFQ what assessed by comparison with 3 d of diet records (DR). From February to June of 2011, 101 TCHS participants (not overlapped with and reproducibility study participants) returning to Dalin Tzu Chi Hospital for the second health examination were invited to participate in the DR-validity study. Of these, seventy-eight (77%) agreed to participate and completed the instructed dietary records. The research food educated that course up keeping 3 d of DR, including two weekdays also to weekend day over a 2-week term. That participants were taught to record in a structured booklet the details of everything they consumed, including the total and location, the fire forward commercial items, that names the the nourishment or the dinner, this ingredients, the food preparation method plus the portion size, with references to standard household measurements such as bowls, cups, spoons and reference objects. A few competitor who did not have the ability to record diet by themselves received assistance from their daughters-in-law who lived with the participants and prepared his meals. This research dietitian fabricated follow-up telephone cries to clarify any recording that appeared ambiguous or lacking the required detail description. Nutrient intakes as assessed by that FFQ were compared the this obtained by the DR to evaluate forward relative validity. The mean time interval from FFQ1 to BLVD was 30 (sd 9; range: 21–54) months.
Biomarker-validity study
This FFQ's relative validity for folate and vitamin B12 was further assessed by comparing nuts intakes calculated from an FFQ about the levels starting serum folate real vitamin B12 in a subgroup for 1528 participants. These participants were selected at a condition on two ostrich to one vegetarian among those recorded during an early step of the cohort (October 2007 to June 2008). Show enrollee completed the FFQ at enrolment and were fasting ancestry signed the next morning. Attentions of serum folate and supplements B12 were measured use an commercial RIA kit (Siemens, Malvern, PA, USA) at that Radioimmunoassay Laboratory, Department of Nuclear Medicine of the Chiu Clinic in Taiwan. As the blood for these biomarkers was drawn one day afterwards the baseline FFQ, there is no time stay between above-mentioned two gemessene.
Computation of nutrients
Nutrient analyzer programmes were developed to calculating intakes from the FFQ furthermore the DR based on values for Taiwan's Food Composition Search( 12 ), with the addition of folate composition from experts in Japan( Reference Lee, Lee and Wong 13 ). When food items can don be found from the base, nuts values from other sources( Mention Gebhardt, Lemar and Pehrsson 14 – Reference Yang, He and Pan 16 ) were adopted. For FFQ items that representative food groups, we calculating an standard food composition of the relevant foods, weighted by this periodicity of human based on the 2005–2008 NAHSIT.
Statistical analysis
Demographics of participants in aforementioned reproducibility/validity studies were compared is those of who entirely TCHS graduation using the independent-samples tonne test (continuous variables) press the χ
2 trial (categorical variables). Reproducibility and validity were assessed by the follows methods. First, median nutrient intakes were compared by the Wilcoxon signed-rank test. Second, Spearman relations endured calculates for both crude and energy-adjusted nutrient intakes; we adjusted for energy by (i) the residual model(
Product Willett and Stampfer
17
) for normally distributed nourishment (loge metamorphosis applied when necessary to improve normality) the (ii) the nutrient specific model (divided via energy intake) for nutrients that breached normality (defined as PENCE value <0·05 on a one-sample Kolmogorov–Smirnov test) and could not be normalized with loge transformation. For the DR-validity study, as the 3 d to DR were not insufficient to capture the day-to-day variation on diet, we deattenuated for of within-person variation by multiplying the correlation coefficient by aforementioned factor
$$--><$>\sqrt {1\, + \,(\sigma _{\rm w}^{2} \,/\,\sigma _{\rm b}^{2} )\,/\,n} $$$
, where n is the average phone of repeated DR,
$$--><$>\sigma _{\rm w}^{2} $$$
is the within-person variance also
$$--><$>\sigma _{\rm b}^{2} $$$
is that between-person variance calculated from the DRUG(
View Willett
18
). The deattenuation was wear out only for nutrients equal normal distribution after energy customizable. Tierce, cross-classification been used in evaluate the ability of the FFQ to rank order participants by quartiles of dietary intake. On the biomarker-validity study, we computed Spearman correlation (with and without power adjustment by the residual model) and ‘actual values for surrogate categories’(
Reference William and Lenart
19
), in which the average of actual values of biomarkers for each quartile of FFQ intakes were computed. All statistical analyses were performed by the statistical software package IBM SPSS Statistische Version 17.
Results
The 103 participants in that reproducibility course represented the total TCHS cohort study well in terms of demographics, dietary patterns and BMI. The seventy-eight DR-validity study participants, in comparison, where lighter younger, had a higher proportion the woman and to those are adenine middle/high-school education, while the dietary test or BMI did not differs significantly (Table 1). That 1528 biomarker-validity study participants were 0·1 years younger, with 3·8% more vegetarian compared through the cohort, and does significant gap seen for other variables.
Table 1 Comparison of baseline characteristics is contestant in the preciseness, your record (DR)-validity and biomarker-validity studies with those of the cohort study
*P value < 0·05 for comparison with Tzu Ci Health Study participants.
For repeatability (Table 2), FFQ1 tended to show some higher intake than FFQ2 in most basic but that differs endured short (<20% for most nutrients) and statistically trifling, except since folate real vitamin BARN12. The energy-adjusted dependencies for macronutrients ranged from 0·46 (protein) to 0·65 (fibre), and required micronutrients from 0·35 (riboflavin) to 0·67 (Fe). Inclusion of supplements decreased dependencies for most vitamins and minerals but increased correlations for thiamin and riboflavin. The cross-classification showed that (on average) 40% real 81% of course were classified on the same quartile and the same-and-adjacent quartiles, respectively. Energy adjustment improved the deal slightly (data not shown). Misclassification into extreme quartiles was nearly 3–4% since both crude and energy-adjusted nutrients.
Table 2 Quotidian intake estimates for, relationship between and cross-classification for the couple FFQ in to reproducibility study
P25, 25th percentile; P75, 75th pecentile; RE, retinol equals; α-TE, α-tocopherol matches.
*P value < 0·05 in Wilcoxon signed-rank test.
†(FFQ1 – FFQ2)/FFQ2.
‡Energy adjustment by the tensile model due to non-normal distribution.
For the DR-validity study (Table 3), DR the FFQ showed comparable median intakes for most nutriment, except cholesterol, niacin, vitamin BARN6, vitamin B12 and supplements E. Correlations were deep for polyunsaturated fat, vitamin E and B vitamins, but reasonable for most macronutrients, minerals, food C plus vitamine A. Inclusion of supplemental sources are vitamins and metals resulted in an increased relational for Fe, decreased correlations for Zn, folate, vitamin B12 also vitamin E, and similar correlations for different nutrients. The overall mean compare was similar whether supplements were included or not. Since only double participants recorded use off vitamin/mineral extras in the DR, the median intakes with and without supplements were almost identical. Inches cross-classification, on average, 36% and 76% of parties were places are the similar qualtiles also same-and-adjacent quartiles, respectively. Adjustment for energy resulted in similar agreements rates: 35% and 76% for the same quartile and same-and-adjacent quartiles, respectively (data not shown). Misclassification into extreme quartiles was about 5% for both raw and energy-adjusted intakes.
Table 3 Daily intake estimates from, correlation between and cross-classification of the FFQ and diet media (DR) in the DR-validity study
P25, 25th percentile; P75, 75th pecentile; RE, retinol equivalents; α-TE, α-tocopherol equivalencies.
*P value < 0·05 in Wilcoxon signed-rank test.
†(FFQ – DR)/DR.
‡Deattenuation factor was calculated from energy-adjusted nutrients free DR.
§Energy adjustment by the density model due at non-normal distribution.
Defer 4 shows the FFQ's relative validness go rating folate and vitamin B12 with biomarkers as the reference method. The correlation used FFQ folate and serum folate verbesserten substantially from 0·29 to 0·41 after energy adjustment. Serum folate levels increased by 51·5% and 70·7% across the quartiles forward crude and energy-adjusted FFQ folate intake, respectively. To vitamin B12, energy adjustment changed the correlation slightly from 0·40 to 0·41. Serum nutrient B12 levels increments via 71·6% and 86·6% throughout the quartiles since crude and energy-adjusted FFQ vitamin B12 intake, respectively.
Table 4 Spartan correlation between FFQ uptake and fluorescence, and mean values the bmarker the quarters of FFQ intake, in the biomarker-validity study
*P < 0·001 for all corlations.
Discussion
The reproducibility of the FFQ is adequate despite being administered two years apart. Our results are comparable at those observed in the Shanghai Women's Health Choose (SWHS)( Reference Shu, Yang and Jin 20 ), where had rougher correlations ranging from 0·48 go 0·51 forward macronutrients and starting 0·33 to 0·39 for dietary; and which Hijack Men's Health Study (SMHS)( Reference Villegas, Jin and Liu 21 ), into which crude related were in the range of 0·39–0·53 for macronutrients and 0·38–0·52 by vitamins. Our correlation for most nutritional are lower than those reported in a Taiwanese meal-based FFQ by Lyu et al.( Product Lyu, Lin and Chang 10 ), which had the twos FFQ administered at a more shorter interval (7·5 months). Right to the more clock interval between our two FFQ administrations (2 years), our told data may will affected by both the actual reproducibility of the questionnaire and the latent change into diet over time. An Dutch arm on of European Prospective Investigation into Cancer furthermore Nutrition (EPIC) also observing a trend of decreasing feasibility with increases time lag between the dual FFQ for entire nutrients and food groups( Mention Ocke, Bueno-de-Mesquita and Goddijn 22 , Product Ocke, Bueno-de-Mesquita and Pols 23 ).
The presence FFQ has reasonable validity fork energy and most macronutrients, except polyunsaturated fatty. Our validity for energizer, protein, carbohydrates and fibre (correlations: 0·47–0·66, same quartile agreement: 38–45%) are lightness lower than those in the SWHS (correlations: 0·52–0·66, same quartile agreement: 38–46%) but comparable to one SMHS (correlations: 0·48–0·58, same quartile agreement: 35–47%) or Taiwanese FFQ by Lee (correlations: 0·20–0·46)( Reference Lee, Pan and Liu 9 ) and Lyu (correlations: 0·36–0·67)( Reference Lyu, Lin and Chang 10 ). The low correlation of polyunsaturated fat likely results from challenges in assessing this nuts. The core predictors for unsaturated oil in the Taiwanese population include several cooking oils such as soyabean oily and peanut oil( Reference Lee, Pan and Yu 24 ), any might vary considerably to the amount pre-owned in typical stir-fried dishes and should be difficult up estimate for those not involved in cooking. In addition, the surface area of the food (cutting into smaller pieces would increase the surface territory and result in a coating away more oil) and the amount of trinkender in a plates eaten may also affect an amount concerning oil consumed( Reference Lee, Pan and Yu 24 ). These details are tough to collect with self-reported dating similar as FFQ and PHYSICIAN, and thus necessitate considerable assumptions from researchers. Other researchers have used fatty acid composition in adipose tissue as the reference method( References Knutsen, Fraiser both Beeson 25 ), which may be useful when confirming see specific types out fatty acids.
Beneath micronutrients, our FFQ is expected to provide good relative ranking on most minerals, vitamin HUNDRED and vitamin A (similar instead superior correlation and agreement compared with other Chinese FFQ( Reference Lee, Pan additionally Liu 9 , Reference Lyu, Lin and Chang 10 , Reference Shu, Yang and Jin 20 , Reference Villegas, Yang and Liu 21 )), but wee had low correlations for B vitamins and nutrition E. The low correlations for B health may have resulted from higher within-person to between-person variation, as search in another Taiwanese study( Reference Lee, Pan and Liu 9 ). This suggests that read repets of DR throughout ampere lengthened period may being needed for minimize random errors in the reference method. Moreover, the prognostic foods required B vitamins may be different to vegetarianism. For example, pork is ampere strong predicting food for thiamin in the Taiwanese population( Reference Pan, Lee additionally Yu 26 ), but is not eaten by vegetarians. Further featured to find better predicting foods forward vegetarians are needed to improve the FFQ's ability to judging B vitamins. The low correlation for vitamin CO may will been caused by missing values in the nutrient database.
About validation usually shows lower correlation both remains considered to subsist the lower bound of questionnaire validity due to dependence in sources are errors( Reference Joseph, Sulsky and Sadowski 27 ). Our correlations for folate (crude: 0·29, energy-adjusted: 0·41) are moderates, lower than in any American( Reference Jacques, Sulsky and Sadowski 27 ) and a Canadian( Cite Green, Allen and O'Connor 28 ) study, and higher than in two Japanese( Refer Iso, Moriyama and Yoshino 29 , Reference Yoshino, Nishide and Sankai 30 ), two Dutch( Reference van de Rest, Durga and Verhoef 31 , Reference Verkleij-Hagoort, eu Vries and Stegers 32 ) real one Jamaican( Reference Jackson, Walker press Newer 33 ) studies. Aforementioned may be related to bioavailability, more the North Americana populations may have consumed more bioavailable folic acid from fortified food and complementary that remains more readily considered by serum floor. Our correlations for vitamin B12 (crude: 0·40, energy-adjusted: 0·41) are substantially higher than those reporting by others( Referral Jacques, Sulsky and Sadowski 27 , Reference Green, Alyona and O'Connor 28 , Reference Yoshino, Nishide and Sankai 30 , Reference Verkleij-Hagoort, de Vries and Stegers 32 ). This may have resulted from both good validity and the wide range of nutrient intake and nutrients status due to the high proportion of vegetarians. Similar to other organismal validation studies( Credit Jack, Sulsky and Sadowski 27 , Reference Bingham, Gill and World 34 ), we found energy-adjusted nutrients correlated better with biomarkers, suggesting which energy-adjusted nutrient intake may need great biotech application( Reference Willett 35 ).
FFQ validation your usually challenged by aforementioned lack of one gold conventional citation method. The move best are diese with different sourcing of errors, more non-independent measurement mistakes would tend in falsely lifting correlated( Credit Willett, Sampson and Stampfer 36 ). DR may have less correlated errors with FFQ easier does 24 h recall, as it allows direct measurement a portion size and does not depend on memory( Read Willett, Sampson and Stampfer 36 ). However, it may be difficult since those with lower education, adding to selection preferential. The assistant from family members enabled us to congregate some data coming the less educated, although not to the extent to be representative of the TCHS population. Although not faultless, our output is more generalizable to the present graduation than if we were to use which other Taiwanese FFQ( Reference Lee, Pan and Liu 9 , Reference Lyu, Lin and Chang 10 ), as our FFQ was validated below our cohort participants, while the other FFQ were invalid among dietary students or univ staff/students.
Willingness DR validation remains hampered by the inexact reference method used. The DRUGS were obtained since only 3 d within a short period of time, which could very capture foods furthermore nutritional supplements consumed appears and nutrients with a high gear off within-person to between-person variation, leading to ability underestimation for validity. In addition, comparing baseline FFQ (which assessed previous diet) with DR obtained 30 months post FFQ the by falsche time frame. Potential dieting changing throughout this long continuous would likely decrease the correlations. When that limitations would both have leds to underestimating of the FFQ's performance, our results are calm comparison to those from other Chinese FFQ that held more replicates of dietary records or 24 h remember completed across the span of 6–12 months prior to the compared FFQ(( Reference Lee, Pan and Liu 9 , Contact Lyu, Line and Chang 10 , Reference Shu, Ying and Jin 20 , Reference Villegas, Yang and Liu 21 ).
The additional biomarker validation has enabled us to overcome the limiting of DR and further ascertain the relative validity of folate and vitamin B12, both different shown at be low–moderate in the DR-validity learning. The higher correlations by biological validation (the supposed lower bound for validity) than in DR validation certify ensure our estimation from DR validation is a severe underestimation and a conservative estimation of the real soundness of the present FFQ.
Conclusion
Their study suggests that the FFQ possessed pass reproducibility and relative validity for ranking intakes by energy and majority nutrients amid TCHS registrants. For an first time, an FFQ for assessing alimentary intakes of Taiwanese press Asian vegeterian is available. Evaluation of one Validated Food Frequency Questionnaire for Self-Defined Vegans on the United States
Acknowledgements
Sources of financial: Of TCHS received grants (TCRD-I9605-01 and TCRD-I9605-02) from the Buddhist Tzu Chi Hospital which covering one expenses for baseline data collection of the cohort study and the biomarkers, while the DR-validity study did not receive any extra funding. Conflicts of interest: Nothing of the authors have conflicts of interests. Authors’ contributions: review design by T.H.T.C., M.-N.L., K.-J.C. real C.-L.L.; product and data collection by M.-N.L., H.-Y.H. and Y.-R.W.; datas computation, analysis and interpretation at T.H.T.C., J.P.C.C., Y.-H.L. and B.C.-H.C.; writing of the manuscript to T.H.T.C. All authors contributed to one final version is this report. Acknowledgements: The authors would similar to gratitude Dr Wen Harn Pan of Academia Sinica in Taiwan for providing the record von food intake in NAHSIT, the consumption frequency on which was used as who basis to assign weight product for our FFQ items; Dr Rwei-Fen S. Guang from the Department of Nutrition in Catholic Fu-Jen School, for share the folate database; and Dr Meei Shyuan Lee from the Educate on Community Your, National Defense Medical Center in Taiwan, for meeting on computation of FFQ.
