Validity of a short food frequency questionnaire for estimating nutrient intake in elderly people

Validation of the German version of the Protein Screener 55

BACKGROUND/OBJECTIVES

The Protein Screener 55 + (Pro55 + ) is a brief food questionnaire to screen older community-dwelling adults for low protein intake. The result is the predicted probability of protein intake <1.0 g/kg adjusted body weight (aBW)/d ranging from 0-1. For purposes of cross-cultural validation, we translated the Pro55+ into German and tested its discriminative accuracy in detecting low protein intake of older community-dwelling people in Germany.

SUBJECTS/METHODS

After translation and pilot-testing, the Pro55+ and the reference standard (3-day dietary record) were completed by 144 participants (81.6 ± 3.9 years, 61.8% female). Discriminative properties were tested by receiver operating characteristic curves and by calculating sensitivity and specificity for different cut-offs of predicted probability (>0.3/>0.5/>0.7) using <1.0 or <0.8 g/kg aBW/d to define low protein intake.

RESULTS

Protein intake was <1.0 g/kg aBW/d in 39.6% of the sample and <0.8 g/kg aBW/d in 17.4%. Area under the curve was 62.0% (95%CI 52.6-71.5) and 68.8% (58.1-79.4), respectively. Specificity was 82-90% using probability cut-offs of 0.5 and 0.7 for both protein thresholds. Sensitivity was poor for protein threshold of 1.0 g/kg aBW/d regardless of the used probability cut-offs. For protein threshold of <0.8 g/kg aBW/d, sensitivity was 88.0% (71.8-96.9) using a probability cut-off of 0.09.

CONCLUSION

The overall discriminative accuracy of the German Pro55+ to identify older community-dwelling people with low protein intake was poor. However, applying different probability cut-offs allows increasing specificity and sensitivity for 0.8 g/kg aBW/d to levels justifying the use for certain purposes e.g. excluding individuals with adequate protein intake. Further validation is needed.

Validity and reliability of a food frequency questionnaire for community dwelling older adults in a Mediterranean country: Lebanon

Background

Food frequency questionnaires (FFQ) is an easy and inexpensive tool that can be used to evaluate nutrient and dietary trends of groups and individuals. Few studies in the East Mediterranean region tailored FFQs to describe dietary intakes of older adults. The purpose of the study is therefore to assess the validity and reproducibility of a FFQ, designed for use with older adults living in a Mediterranean Arabic speaking country, Lebanon.

Methods

The FFQ is composed of a list of 90 food items, commonly consumed by adults above 60 years of age. Validity of the FFQ was tested using the mean of two 24-hours dietary recalls (24HDR), and reproducibility, by repeating the questionnaire within a one-month period, along the second dietary recall. Our study included 42 and 76 participants, for the repoducibility and validity analysis respectively. Subjects were randomly selected from 2 of the 8 governorates in the country.

Results

FFQ reproducibility showed a mean relative difference of 1.03% without any significant difference between all paired components of nutrients. Intra class correlation (ICC) showed good and excellent reliability for caloric intake and all macronutrients, moderate to good reliability for all remaining nutrients, except for poly-unsaturated fatty acids, vitamins A, B12 and fibers. Correlation coefficients for all nutrients were fair to strong. Both administrations of the FFQ showed good internal validity. Validation of FFQ showed a mean relative difference between FFQ and mean 24HDR at 19.5%. Agreements between the 2 methods, for classifying individuals in the same or adjacent quartile, for nutrient intake and nutrient adequacy, were 80 and 78.2% respectively. Mean Kappa coefficient was 0.56 and energy-adjusted correlations were within the recommended values for all items except for vitamin A and B12. Adjusting for nutrient-dense food intake improved the agreement for theses 2 vitamins to 0.49 and 0.56, respectively.

Conclusion

The proposed FFQ can be considered a valid tool to help describe nutrient intake of older individuals in an Arabic speaking Mediterranean country. It could serve for possible use in the East Mediterranean region for the evaluation of regular dietary intake of community-dwelling older adults.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12937-022-00788-8.

Relative Validity and Reproducibility of a Semi-Quantitative Food Frequency Questionnaire for Determining Nutrient Intake in Older Adults in New Zealand: The REACH Study

Dietary intake is an important predictor of health and disease outcomes. This cross-sectional study evaluated the relative validity and reproducibility of a semi-quantitative food frequency questionnaire (FFQ) for assessing energy and nutrient intake in older adults. Dietary data were collected 2018–2019 in Auckland, New Zealand from a convenience sample of community-dwelling adults (65–74 years, n = 294, 37% male) using a 109-item self-administered FFQ at baseline (FFQ1) and four weeks later to assess reproducibility. FFQ1 was compared to a four-day food record to determine relative validity. Agreement between dietary assessment tools was assessed for both raw and energy-adjusted nutrient intakes using paired t-tests, correlation coefficients, weighted kappa statistic, Bland–Altman plots, and linear regression analysis. Energy adjustments moderately improved the relative validity and reproducibility for most nutrients. For energy and energy-adjusted nutrient intakes, the mean correlation coefficients were 0.38 (validity) and 0.65 (reproducibility); the mean weighted kappa statistics were 0.27 (validity) and 0.51 (reproducibility). A significant slope of bias was present in 54% (validity) and 25% (reproducibility) of Bland–Altman plots. The Researching Eating, Activity, and Cognitive Health (REACH) FFQ has acceptable relative validity and good reproducibility for ranking nutrient intakes in older New Zealand adults, but is less suitable for assessing absolute nutrient intakes.

Providing Comprehensive Dietary Fatty Acid Profiling from Saturates to Polyunsaturates with the Malaysia Lipid Study-Food Frequency Questionnaire: Validation Using the Triads Approach

To address limited food frequency questionnaire (FFQ) capacity in public health monitoring in Malaysia, we aimed to develop a semi-quantitative FFQ for an adult multiethnic population for comprehensive fatty acid (FA) profiling inclusive of saturated (SFA), monounsaturated (MUFA), polyunsaturated fatty acids (PUFA), PUFA:SFA ratio, trans fatty acids, omega-3 and omega-6 FAs. A 240-food itemed FFQ used diet records (DR) of Malaysia Lipid Study (MLS) participants and fatty acid composition database from laboratory analyzed foods. The developed MLS-FFQ underwent face and content validation before relative validation in a free-living population (n = 114). Validation was facilitated for macronutrient data comparisons between DR and FFQ via Spearman’s correlation coefficient analyses; and for fatty acid composition data by independent pairing of DR, FFQ and plasma triglyceride using the triads method. Moderate correlation between dietary methods was obtained for macronutrients and FAs (r = 0.225–0.457, p < 0.05) except for ω-3 FAs, presenting good agreement with grossly misclassified nutrients <10%. For fatty acid composition data, the magnitude of validity coefficients (z) for SFA, PUFA, PUFA:SFA ratios and ω-6 FAs by all 3 methods were not significantly different (p > 0.05). In conclusion, the MLS-FFQ was shown to be a valid tool to assess population dietary intakes.

Validation of semiquantitative FFQ administered to adults: a systematic review

Objective:

To conduct a systematic review of studies for the validation of semiquantitative FFQ (SFFQ) that assess food intake in adults.

Design:

The authors conducted a systematic search in PubMed for articles published as late as January 2020 in Spanish, English, French and Portuguese. Individual searches (twelve in total) paired three hyphenated and non-hyphenated variations of ‘semiquantitative food frequency questionnaire’ with both ‘validity’ and ‘validation’ using the ‘all fields’ and the ‘title/abstract’ retrieval categories. Independent extraction of articles was performed by four authors using predefined data fields.

Setting:

We searched for original SFFQ validation studies that analysed general diet composition (nutrients with or without food groups or energy analysis) in healthy adults, in any setting, and that also reported correlation coefficients.

Participants:

Healthy adults.

Results:

Sixty articles were included. The preferred comparison standard for validation was food records (n 37). The main correlation coefficients used were Pearson’s (n 41), and validity coefficients varied from −0·45 to 1. Most correlation coefficients were adjusted by energy (twelve studies presented only crude values). The elements mentioned most frequently were energy, macronutrients, cholesterol, SFA, PUFA, fibre, vitamin C, Ca and Fe.

Conclusions:

Although all these SFFQ are reported as validated, coefficients may vary across groups of foods and nutrients. Based on our findings, we suggest researchers to consult our revision before choosing a SFFQ and to review important issues about them, such as their validation, number of items, number of participants, etc. Systematic Review Registration: PROSPERO number CRD42017064716. Available at: http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42017064716.

Association between low dietary zinc and hyperuricaemia in middle-aged and older males in China: a cross-sectional study

OBJECTIVE

To examine the associations between dietary zinc intake and hyperuricaemia.

DESIGN

Cross-sectional study.

SETTING

This study was conducted in a health examination centre of China.

PARTICIPANTS

A total of 5168 middle-aged and older participants (aged 40 years or above) (2697 men and 2471 women) were included.

OUTCOME MEASURES

Dietary zinc intake was assessed using a validated semiquantitative food frequency questionnaire. Hyperuricaemia was defined as uric acid ≥416 µmol/L for males and ≥360 µmol/L for females.

RESULTS

For males, the prevalence of hyperuricaemia was 22.9%. After adjusting for age, body mass index (BMI) and energy intake, the ORs were 0.68 (95% CI 0.45 to 0.92) in the second quintile, 0.63 (95% CI 0.45 to 0.89) in the third quintile, 0.68 (95% CI 0.46 to 1.00) in the fourth quintile and 0.55 (95% CI 0.35 to 0.87) in the fifth quintile comparing the lowest quintile of Zn intake, respectively (p for trend=0.03). In the multivariable adjusted model, the relative odds of hyperuricaemia were significantly decreased by 0.71 times in the second quintile of zinc intake (OR 0.71, 95% CI 0.52 to 0.98), 0.64 times in the third quintile (OR 0.65, 95% CI 0.44 to 0.94) and 0.55 times in the fifth quintile (OR 0.56, 95% CI 0.32 to 0.97) compared with those in the lowest quintile, and p for trend was 0.064. For females, the prevalence of hyperuricaemia was 10.0%, and unadjusted, minimally adjusted as well as multivariable adjusted ORs all suggested no significant association between dietary zinc intake and hyperuricaemia.

CONCLUSIONS

The findings of this cross-sectional study indicated that dietary zinc intake was inversely associated with hyperuricaemia in middle-aged and older males, but not in females. The association was significant after considering the influence of age, BMI and energy intake, and after that, minimum adjustment remained independent of further confounding factors such as vitamin C intake, alcohol drinking status and nutrient supplementation.

Dietary protein and beef consumption predict for markers of muscle mass and nutrition status in older adults

OBJECTIVE

To determine the relationship of beef and protein intake to nutrition status, body composition, strength, and biochemical measures of vitamin and mineral status, inflammation and blood lipids in older adults.

DESIGN

Cross-sectional observational study.

SETTING

State of Ohio, U.S.A.

PARTICIPANTS

142 adults ages 60-88.

MEASUREMENTS

Subjects completed a Diet History Questionnaire, and questionnaires related to nutrition status and activity. Subjects also underwent measurements of body composition and strength, and a subset took part in a blood draw for biochemical measurements.

RESULTS

Beef intake (g/d) was positively correlated to muscle mass measured by mid-arm muscle area (R=0.128, p=0.030). From multiple linear regression analysis, a 1oz/d (~28g/d) increase in beef consumption predicts for a 2.3cm(2) increase in mid-arm muscle area. Beef intake was negatively correlated to total (R=-0.179, p=0.035) and HDL (R=-0.247, p=0.004) cholesterol, and there was no association between beef and LDL-cholesterol, triglycerides, liver enzymes, or inflammatory markers. Protein intake (% of total energy) was positively correlated to nutrition status measured by the Mini Nutrition Assessment (R=0.196, p=0.020), and calf circumference (R=0.190, p=0.024), and these correlations remained when potential confounders were accounted for in multiple linear regression models. Protein intake was also positively correlated with BMI when analyzed with multiple linear regression.

CONCLUSIONS

Beef intake was positively associated with mid-arm muscle area, and protein intake was positively associated with nutrition status, calf circumference, and BMI in older adults. Consuming lean cuts of beef in moderation may be a healthy way in which older adults can increase protein intake, preserve muscle mass and improve nutrition status.

Activity Limitation and Food Intake in Community-Living Seniors

The purpose of this study was to determine the extent to which functional ability was associated with dietary intake in community-living seniors with some activity limitation. In this cross-sectional survey, 145 seniors were recruited from 15 recreation, day programs or seniors' apartment complexes. Dietary intake was assessed with a food frequency questionnaire and evaluated for adequacy with a Diet Score. An Activity Score was derived from 15 questions on basic and instrumental activities of daily living. Demographic, health, psychosocial, functional and behavioural factors that could influence diet intake were measured with standardized, validated scales. Diet Score was significantly and positively associated with income, hearing, education, satisfaction with use of time, number of medications and age. Activity Score, the belief that health affects activity level, shopping behaviour and smoking were negatively and significantly associated with Diet Score. Many factors influence the dietary intake of seniors, including extent of functional limitations. This analysis suggests that the most dependent seniors living in the community consume better diets than those seniors with few limitations; this finding is probably a result of informal and formal support services for these functionally dependent seniors.

Dietary assessment methods for micronutrient intake in elderly people: a systematic review

The European micronutrient recommendations aligned (EURRECA) Network of Excellence seeks to establish clear guidelines for assessing the validity of reported micronutrient intakes among vulnerable population groups. A systematic literature review identified studies validating the methodology used in elderly people for measuring usual dietary micronutrient intake. The quality of each validation study selected was assessed using a EURRECA-developed scoring system. The validation studies were categorised according to whether the reference method applied reflected short-term intake ( < 7 d), long-term intake ( ≥ 7 d) or used biomarkers (BM). A correlation coefficient for each micronutrient was calculated from the mean of the correlation coefficients from each study weighted by the quality of the study. Thirty-three papers were selected, which included the validation of twenty-five different FFQ, six diet histories (DH), one 24-h recall (24HR) and a videotaped dietary assessment method. A total of five publications analysed BM, which were used to validate four FFQ, and one 24HR, presenting very good correlations only for vitamin E. The analysis of weighted correlation coefficients classified by FFQ or DH showed that most of the micronutrients had higher correlations when the DH was used as the dietary method. Comparing only FFQ results showed very good correlations for measuring short-term intakes of riboflavin and thiamin and long-term intakes of P and Mg. When frequency methods are used for assessing micronutrient intake, the inclusion of dietary supplements improves their reliability for most micronutrients.

Diet and cognitive function in later life: a challenge for nutrition epidemiology

BACKGROUND

As the proportion of old and very old people in the population increases, new research on the influence of diet on health and nutritional needs in later life will be needed. Dietary assessment methods that rely on short-term memory or lengthy interviews, such as the 24-h recall and diet history methods, could have some limitations in this age group. There is some support for the use of food frequency questionnaires (FFQs) in older people, although their validity in the older old and in those with more advanced cognitive decline has not been extensively assessed.

SUBJECTS/METHODS

In a study designed to assess the validity of a modified FFQ in men and women over 65 years, 50 men and 47 women completed two FFQs, and 42 men and 41 women completed one FFQ followed by a 4-day weighed diet diary. Digit span forward (a test of short-term memory) and verbal fluency (a test of executive function) tests were used to assess the possible influence of cognitive function on repeatability and validity of the FFQ.

RESULTS

The FFQ was found to have good repeatability for most nutrients and reasonable validity for some but not all nutrients. Cognitive function assessed prior to the dietary assessment showed no relationship with repeatability, but there was some evidence that validity was lower in those with lower executive function.

CONCLUSIONS

Dietary assessment in healthy older people without overt cognitive decline can be achieved, but development and testing of methods of data collection for each target population and nutrient of interest are particularly important in this age group to ensure valid results. The possibility that cognitive decline influences dietary assessment needs to be borne in mind in the interpretation of observational studies of the influence of dietary intake on cognition in later life.

Reliability and Validity of a Brief Questionnaire to Assess Calcium Intake of Middle-School–Aged Children

OBJECTIVE

Evaluate the validity and reliability of a short (10-item) calcium food frequency questionnaire (FFQ) for use with middle-school-aged (11 to 14 years of age) children.

DESIGN

The calcium FFQ was completed twice, with 1 week between administrations. Three 24-hour dietary recalls were collected from each participant after the second administration of the calcium FFQ.

SUBJECTS/SETTING

Students in an ethnically diverse middle school in Minneapolis, MN (n=248).

MAIN OUTCOME MEASURES

Calcium intake estimates from the calcium FFQ and dietary recalls.

STATISTICAL ANALYSES

Correlations between calcium intake estimates from the first and second questionnaire administrations of the calcium FFQ were calculated and paired t tests were conducted to compare mean calcium intake estimates from each questionnaire administration. Mean intake estimates from the calcium FFQ and the dietary recalls were compared. Also, correlations between intake estimates from the calcium FFQ and the recalls were calculated.

RESULTS

Correlation between calcium intake estimates derived from the first and second administration of the calcium FFQ was 0.74. Mean calcium intake estimates from the calcium FFQ and the average of the three dietary recalls were 856 mg/day and 993 mg/day, respectively (P<0.001). The correlation between calcium intake estimates derived from the calcium FFQ and the average of the recalls was 0.43.

CONCLUSIONS

Reliability of the FFQ was found to be good while validity was weaker, with calcium intake from the calcium FFQ moderately associated with estimates from dietary recalls. Where a brief instrument for assessing calcium intake of middle-school-aged children is needed, the calcium FFQ evaluated in this study may be useful.

Reliability and validity of a food-frequency questionnaire for Chinese postmenopausal women

OBJECTIVES

(1). To determine the reliability and validity of a food-frequency questionnaire (FFQ) for use in epidemiological research in postmenopausal women; and (2). to compare the volume estimation (VE) and weight estimation (WE) method of administration of this questionnaire.

DESIGN

An initial list of foods was derived and modified after pre-testing in 22 subjects. Test-retest reliability was assessed in 21 subjects who had repeat administrations of the questionnaire 14 days apart (FFQ1, FFQ2). The validity of the FFQ was assessed by comparing nutrient intakes with those from a 4-day food record.

SETTING

Chengdu, People's Republic of China.

SUBJECTS

Twenty-two postmenopausal women (50-70 years) were recruited from The Second University Hospital, West China University of Medical Sciences, Chengdu and participated in the pre-test. Another 21 women (50-70 years) were randomly selected from the general population of all five districts of Chengdu and participated in the reliability and validity sub-studies.

RESULTS

Energy, protein, carbohydrate, magnesium and sodium intakes in this sample were less than the Recommended Dietary Allowances (RDAs) for 45-70-year-old women in China. Intake of non-cooking fat was higher than the Chinese RDA. Pearson correlation coefficients and intra-class correlation coefficients (ICCs) for reliability of the VE FFQ ranged from 0.51 to 0.85 and from 0.51 to 0.81, respectively; for the WE FFQ, they ranged from 0.22 to 0.86 and from 0.21 to 0.81. Correlation coefficients and ICCs for validity of the WE FFQ ranged from 0.36 to 0.69 and from 0.34 to 0.57, respectively; corresponding values for the VE FFQ were -0.30 to 0.65 and -0.14 to 0.65.

CONCLUSIONS

Both the VE and WE FFQs were reliable and valid except for sodium intake. The VE FFQ provided more valid estimates of nutrient intakes than did the WE FFQ.

Lifestyle factors associated with glycaemic control and body mass index in older adults with diabetes

OBJECTIVE

To investigate the relations between lifestyle factors (diet and exercise), glycated haemoglobin (HbA(1c)) and body mass index (BMI) in older adults with diabetes.

DESIGN AND SETTING

A community hospital-based cross-sectional study of 150 noninstitutionalized, ambulatory adults (>/=65 y) with diabetes, residing within New Zealand's Kapiti region.

SUBJECTS

Patients were recruited from all general practices; two diabetes clinics; local diabetes society and through advertisements in community newspapers. A total of 211 eligible people were identified, but 60 refused to participate and one withdrew. In all, 150 people completed the study (71% participation rate).

METHODS

Nutrient intakes were calculated by a food-frequency questionnaire. Physical activity was assessed by interview using a validated questionnaire. Medical history and demographic data were obtained by interview or self-completed questionnaires; height, weight and HbA(1c) were measured. Multivariate models using bootstrapping and stepwise linear regression were used to select factors associated with HbA(1c) and BMI.

RESULTS

Each five-unit increase in energy from dietary saturated fat and five-unit increase in BMI were associated with 6% (95% confidence interval=2-10%; P=0.004) and 4% (0.3-7%; P=0.031) increases in HbA(1c), respectively. For females with moderate, compared with low overall activity, there was a 14% (7-20%; P=0.000) reduction in BMI while for males the reduction was only 5% (-1-11%; P=0.116). BMI decreased 5% (2-9%; P=0.004) with each 10-y increase in age, while a five-unit increment in energy from dietary sucrose was associated with a 6% (1-11%; P=0.025) increase in BMI.

CONCLUSIONS

Reducing dietary saturated fat and excess body weight may be useful means of improving glycaemic control in older adults with diabetes. Increasing physical activity and reducing energy from dietary sucrose may assist weight control, the former particularly in women.

Dietary conjugated linoleic acid (CLA) intake assessment and possible biomarkers of CLA intake in young women

OBJECTIVE

The habitual intake of the conjugated linoleic acid (CLA) isomer C18:2 c9t11 (rumenic acid, RA) was assessed and compared with plasma biomarkers.

DESIGN

The newly developed food-frequency questionnaire (FFQ) comprised 46 food items and was validated by means of a 7-day estimated record (7-d ER). Additionally, the dietary intake results of the FFQ, 7-d ER, the last day (1-d ER) and the last two days (2-d ER) before blood sampling of the 7-d ER were compared to the content of C18:2 c9t11 in plasma phospholipids (PL) and triglycerides (TG) as possible biomarkers.

SETTING

Metabolic unit of a university institute.

SUBJECTS

Fifty-seven students completed both dietary instruments. From all participants fasting blood samples were taken.

RESULTS

Mean daily intake of rumenic acid was 246 mg day(-1) and 323 mg day(-1) as measured by the FFQ and the 7-d-ER, respectively. The degree of correspondence between both assessment methods was acceptable; this is indicated by a total kappa value of kappa = 0.31 (P < 0.01) and a Pearson correlation coefficient of r = 0.46 (P < 0.01). Rumenic acid content in plasma triglycerides was twice as high as found in phospholipids. The correlation between the intake results gained with the 7-d ER and the plasma PL contents of C18:2 c9t11 was statistically significant; this was also true for the C18:2 c9tl 1 values in plasma TG compared with the intake results of one or two days before blood sampling.

CONCLUSIONS

Regarding RA intake, the FFQ data revealed an acceptable degree of correspondence with the 7-d ER data but failed to show significant correlations to the potential biomarkers. However, with respect to the results of the 7-d ER, the RA content in plasma PL and TG are possible biomarkers of short-term and medium-term intake, respectively.

Selenium and zinc status are suboptimal in a sample of older New Zealand women in a community-based study

The importance of selenium and zinc in the immune functioning of the aged is widely recognized. Seniors in New Zealand are at particularly high risk of low selenium status because of the low selenium soil environment. The zinc status of the New Zealand elderly has never been assessed. In this cross-sectional study, the biochemical selenium, zinc and lipid levels, physical functional capacity and dietary intakes of 103 randomly selected free-living New Zealand women (mean age +/- SD, 75 +/- 3 y) were assessed. Among nonusers of selenium supplements (n = 80), 80% [95% confidence interval (CI): 70; 88%] had plasma selenium levels (0.85 +/- 0.23 micromol/L) below 1.00 micromol/L [ approximately 10% below mean plasma selenium necessary for full expression of glutathione peroxidase (GPx) activity in New Zealand subjects]. Plasma selenium was strongly correlated with GPx: r = 0.56; P < 0.0001. For nonusers of zinc supplements (n = 88), serum zinc concentrations were 12.4 +/- 1.4 micromol/L, with 12% (95% CI: 6; 21%) having levels below the cut-off value (10.7 micromol/L). Estimated mean daily selenium and zinc intakes were 34 +/- 10 microg and 8.7 +/- 2.0 mg, respectively. Subjects in the highest tertile of a functional capacity index had higher biochemical zinc and selenium values than those in the lowest tertile (P < 0.05). The correlation between plasma selenium and GPx indicates that selenium intake in these women is still insufficient for full expression of GPx activity. Lower serum zinc levels also appear to be prevalent. Because a suboptimal trace element status may be more common among those with a poor physical functioning, promotion of the consumption of nutrient dense foods or supplements to improve selenium and zinc status of elderly women in New Zealand may be beneficial.

Calcium intakes among Australian women: Geelong Osteoporosis Study

BACKGROUND

Dietary calcium deficiency may be a risk factor for osteoporosis.

AIMS

To estimate habitual calcium intakes and prevalence of calcium supplementation among free-living Australian women and validate a calcium-specific food-frequency questionnaire.

METHODS

Calcium intakes for 1045 randomly selected women (20-92 years) were estimated by questionnaire which was tested against estimates from four day weighed records kept by 32 randomly selected women.

RESULTS

The mean difference between calcium estimates was not statistically significantly different from zero (mean difference=121 mg; standard deviation of differences=357 mg; p>0.05). There was moderate agreement (weighted kappa=0.4) between methods in ranking subjects into tertiles of calcium intake. Mean dietary calcium intakes were 615 mg/day for 20-54 years, 646 mg/day for 55-92 years and 782 mg/day for lactating women. Seventy-six per cent of women aged 20-54 years, 87% of older and 82% of lactating women had intakes below the recommended dietary intake (RDI). There was no association detected between calcium intake and age. Dairy foods provided 79.0% of dietary calcium intake. Calcium supplements were used by 6.6% and multivitamins by a further 4.3% of women. Supplementation was independent of dietary calcium intake and more likely used by postmenopausal women.

CONCLUSIONS

Our results suggest that 76% of women consume less than the RDI even when supplemental calcium is included. Furthermore, 14% have less than the minimal requirement of 300 mg/day and would, therefore, be in negative calcium balance and at risk of bone loss. Despite advertising campaigns promoting better nutrition and increased awareness of osteoporosis, many women are failing to achieve an adequate calcium intake.

Validity and reproducibility of a self-administered food frequency questionnaire in older people

This study assesses the validity and reproducibility of a 145-item self-administered food frequency questionnaire (FFQ) in a representative older population aged 63 to 80. Semi-quantitative FFQs were completed by 89% of 3,654 residents attending a community-based eye study in Sydney, Australia. The FFQ's validity was assessed against three, four-day weighed food records (WFRs) completed four months apart by 79 people. A further 152 subjects completed a repeat FFQ about a year after the baseline FFQ, of whom 131 completed a second repeat FFQ about six weeks later. Both short and long-term reproducibility of the FFQ were assessed using data from these subjects. Comparison of the FFQ with the average of the three, four-day weighed food records resulted in energy-adjusted Spearman correlations above 0.5 for most of the nutrients. The proportion of subjects correctly classified to within one quintile category for each nutrient intake ranged from 57% for zinc to 82% for vitamin C. with most nutrients correctly classified within one quintile for about 70% of subjects. Quadratic weighted kappas were reasonable, between 0.3 and 0.5 for most nutrients. The FFQ was highly reproducible in the short term, with correlations for most nutrients about 0.70 to 0.80 and acceptably reproducible in the longer term, with correlations mostly 0.60 to 0.70. The results verify that it is possible to use relatively simple, but comprehensive, self-administered FFQs to study nutrient exposures in large-scale epidemiological studies of the elderly and to expect reasonably high FFQ response rates.

Validity of observed differences in dietary surveys by two self-administered questionnaires over a 5-year period: Concordance with self-reported change

Differences observed by comparing the responses to two surveys taken 5 years apart were compared with self-reported changes in dietary habits in the second survey to examine the construct validity of dietary change. That is, when an observed difference about a certain food was consistent with a self-reported change, these two methods seemed to show a high validity regarding dietary change. Both surveys used the same self-administered food intake frequency questionnaire, and subjective changes in food intake were evaluated at the second survey (self-reported change). Eight hundred fifty-five males and one thousand females aged 30-69 years were analyzed. Since results by both methods showed a higher frequency of increased intake of green-yellow vegetables in general, pale- colored vegetables in general, carrots, and squash, these results were thought to be of high validity. However, cabbage, lettuce, and seaweeds showed inconsistent results regarding higher frequencies of intake. Changes among quintiles of lower frequency seemed to show lower validity because the results obtained by the two methods were often inconsistent for dairy foods and some other foods. Thus, self-reported changes may reflect respondents' attitudes toward foods, not their actual behavior.