To develop and test a quantitative, interviewer-administered food frequency questionnaire (FFQ) to ascertain nutrient intakes of individuals in northern India.

A 92-item FFQ was developed based on food use and market surveys of the study area. A validation study was conducted consisting of 24-h diet recalls (24HR) administered on 6 randomly selected days over 1 year. Two FFQs were administered, one each at the beginning and end of the 1-year period. FFQ and 24HR-derived nutrient scores were compared using correlation and regression analyses and by computing differences between nutrient intakes estimated by the two methods.

Rural villages in Bhavnagar District, Gujarat, North India.

60 individuals who agreed to provide all necessary data.

Pearson (parametric) correlation coefficients averaged 0.69 in comparing nutrient scores derived from the 24HR with those from the first FFQ and 0.72 in comparing the second FFQ (P < 0.0001). Spearman correlation coefficients were virtually identical to the Pearson correlations, averaging 0.68 and 0.72, respectively. In regression analyses, most coefficients were close to 1.0 (perfect linear association). Nutrient scores were significantly and consistently higher on both FFQs relative to the 24HR.

This FFQ produces results broadly comparable, and superior in some respects, to those commonly used in the West. Higher than average measures of association indicate its suitability for comparing exposures within this study population in reference to health-related endpoints.

To test the effect of dietary nutrients on oral precancerous lesions in a reverse-smoking (i.e. smoking with the glowing end inside the mouth) population in South India.

Case–control. Cases with precancerous lesions were matched to an equal number of lesion-free controls matched on age (±5 years), sex and village. All subjects used tobacco in some form. Dietary data were obtained using an interviewer-administered food-frequency questionnaire, designed for use in this population. All interviews were conducted blinded to the disease status of the subject. Data were analysed using logistic regression.

Nineteen rural villages in Srikakulam District, Andhra Pradesh.

From a survey of 6007 tobacco users, 485 (79% women) were found to have precancerous, mostly palatal, lesions (cases), and 487 lesion-free subjects were selected as controls.

All eligible subjects consented to participate and nearly all (>99%) had complete data for analyses. Reverse smoking was the most common form of tobacco use among cases (81.9%) and controls (73.5%), and reverse smokers were 5.19 times more likely than chewers to have these lesions (95% confidence interval = 1.35, 19.9). After controlling for relevant covariates, including the type of tobacco use, protective linear effects were observed for zinc (70% reduction across the interquartile range, P<<0.002 ), calcium (34% reduction, P<0.002 ), fibre (30% reduction, P<0.009 ), riboflavin (22% reduction, P<0.03 ) and iron (17% reduction, P<0.05 ).

Several dietary nutrients appear to protect against oral precancerous lesions that are strongly associated with reverse smoking. The results of this study indicate scope for targeting dietary factors in preventing oral cancer, which should be coupled with aggressive anti-tobacco use efforts.

To develop and test a food frequency questionnaire (FFQ) for use in rural areas of Kerala, India.

Based on food use and market surveys of the study area, a quantitative 81-item interviewer-administered FFQ was developed. A validation study was conducted consisting of 24-h diet recalls (24HR) administered on 8 days randomly selected over an entire year and two administrations of the FFQ, one at the beginning of the l-year period and the other at the end. FFQ and 24HR-derived nutrient scores were compared using correlation and regression analyses and by examining differences in the nutrient scores.

Rural villages in Ernakulum district, Kerala, South India.

In each of 30 households, the male head of household and female food preparer were enrolled.

Pearson (parametric) correlation coefficients (rp) averaged about 0.50 in comparing nutrient scores derived from the 24HR with those from the first FFQ and about 0.55 in comparing the second FFQ. On average, Spearman correlation coefficients (rs) were slightly lower than the rp in comparing the scores derived from the first FFQ, but virtually identical for the second FFQ. Regression analyses indicated better agreement in the comparison of the 24HR-derived scores with the first FFQ than the second FFQ. Difference scores, however, tended to be larger in comparing the first FFQ scores with the 24HR.

This FFQ produces results broadly comparable to those used in Europe and North America, indicating its suitability for comparing exposures within a study population in reference to health-related endpoints.