Food and dietary supplement databases for What We Eat in America-NHANES

Relative strengths and potential approaches for improvement of food and dietary supplement databases used for tabulating intakes from the dietary component of the What We Eat in America-National Health and Nutrition Examination Survey (NHANES) are discussed. The U.S. Department of Agriculture's Nutrient Data Laboratory develops and maintains the Nutrient Databank System (NDBS) and many nutrient-specific and population-specific databases. NDBS contains data for approximately 8,000 foods and approximately 115 components; tables for compounds of special interest are also available. Nutrient databases need constant revision because of a constantly changing food supply. The completeness of analytical data varies from nutrient to nutrient. The National Center for Health Statistics developed and maintains a database of dietary supplements based on label information. To date, no verification of ingredients has been undertaken. The development of a dietary supplement database containing analytical values would require extensive resources but would be valuable. Databases for vitamin and mineral supplements are compatible with food databases. Databases for botanicals and other supplements include nonnutrient constituents that may not be documented in food composition databases. Gaps in food and dietary supplement composition data exist because of limited resources, changing availability of foods and products and the advent of new compounds of health interest. More data are needed on nutrients and other bioactive constituents in foods and dietary supplements. Analytical methods do not exist for all ingredients or active constituents in foods and dietary supplements. Research needs for further development of meaningful food and dietary supplement databases are similar.     

Estimation of usual intakes: What We Eat in America-NHANES

Usual intakes of nutrients are reliable indicators for making associations between diet and health or disease risks. Estimates of consumption of specific foods and food groups are also important for evaluating the progress in meeting key objectives in such national public health initiatives as Healthy People 2010. Reliable and valid estimates of intakes of particular foods, food ingredients, dietary supplements and other bioactive substances are also needed for dietary assessment and regulatory purposes. The ability to generate useful estimates of these constituents often requires much larger sample sizes than are needed for estimating nutrient intakes. Statistical methods recommended by the National Academy of Sciences are described that provide estimates of distributions of usual nutrient intakes and permit dietary assessment and planning at the population level. Statistical and modeling approaches for estimating intakes of foods, dietary supplements and other bioactive substances are also summarized. Based on the deliberations of discussion groups consisting of members of key stakeholder groups involved in the planning, implementation and utilization of national survey data, a high priority was placed on the need for more research to determine the best approaches for applying these methods to dietary data in the integrated What We Eat in America-National Health and Nutrition Examination Survey (NHANES).     

Future directions for the integrated CSFII-NHANES: What We Eat in America-NHANES

The history of the integration of the dietary data collection from the National Health and Nutrition Examination Survey (NHANES) and the Continuing Survey of Food Intakes by Individuals (CSFII) is reviewed. The purposes and process of the workshop are presented. The three key topics of the workshop are summarized. The key roles of cosponsors and participants are acknowledged.     

Nutrition,Food and Diet in Health and Longevity: We Eat What We Are

Nutrition generally refers to the macro- and micro-nutrients essential for survival, but we do not simply eat nutrition. Instead, we eat animal- and plant-based foods without always being conscious of its nutritional value. Furthermore, various cultural factors influence and shape our taste, preferences, taboos and practices towards preparing and consuming food as a meal and diet. Biogerontological understanding of ageing has identified food as one of the three foundational pillars of health and survival. Here we address the issues of nutrition, food and diet by analyzing the biological importance of macro- and micro-nutrients including hormetins, discussing the health claims for various types of food, and by reviewing the general principles of healthy dietary patterns, including meal timing, caloric restriction, and intermittent fasting. We also present our views about the need for refining our approaches and strategies for future research on nutrition, food and diet by incorporating the molecular, physiological, cultural and personal aspects of this crucial pillar of health, healthy ageing and longevity.     

Collection of food intake data: an evaluation of methods

Using USDA's recently completed methodological survey designed to evaluate longitudinal measures of food intake, the authors assessed nine methods for measuring dietary status. Methods evaluated included various combinations of prospective and retrospective recording of daily intake; personal, telephone, and mail- and telephone-assisted reporting; semistructured and open-ended recording documents; and number and spacing of days for recording intakes. Results from tabular and regression analyses indicated that the most effective and least costly methods for assessing mean intakes for groups of individuals were those using telephone and/or personal contact and collecting 24-hour recalls for several selected nonconsecutive days during the survey period. More specifically, it was concluded that the method including an initial personal interview for 24-hour recall followed by three telephone interviews for 24-hour recalls over a 1-year period and the method including four telephone interviews for 24-hour recalls for a 1-year period provided food energy intake data comparable with the data collected with other methods and with less effort or cost. Additional analyses were recommended to determine the numbers of days required to obtain estimates of usual intake for individuals and for diet components other than food energy.     

Micronutrients: dietary intake v. supplement use

Whilst clinical deficiency of micronutrients is uncommon in the developed world, a suboptimal intake of certain micronutrients has been linked with an increased risk of chronic diseases such as CVD and cancer. Attention has therefore focused on increasing micronutrient status in order to theoretically reduce chronic disease risk. Increasing micronutrient status can involve a number of approaches: increasing dietary intake of micronutrient-rich foods; food fortification; use of supplements. Observational cohort studies have demonstrated an association between high intakes of micronutrients such as vitamin E, vitamin C, folic acid and beta-carotene, and lower risk of CHD, stroke and cancer at various sites. However, randomised intervention trials of micronutrient supplements have, to date, largely failed to show an improvement in clinical end points. The discordance between data from cohort studies and the results so far available from clinical trials remains to be explained. One reason may be that the complex mixture of micronutrients found, for example, in a diet high in fruit and vegetables may be more effective than large doses of a small number of micronutrients, and therefore that intervention studies that use single micronutrient supplements are unlikely to produce a lowering of disease risk. Studies concentrating on whole foods (e.g. fruit and vegetables) or diet pattern (e.g. Mediterranean diet pattern) may be more effective in demonstrating an effect on clinical end points. The present review will consider the clinical trial evidence for a beneficial effect of micronutrient supplements on health, and review the alternative approaches to the study of dietary intake of micronutrients.     

Collection of food intake data: a reappraisal of criteria for judging the methods

The relationship between diet and the development of chronic disease still remains a controversial area. One major difficulty is to obtain a valid estimate of habitual pattern and level of food consumption for each individual. There is, in fact, a voluminous and largely negative literature on the validity of dietary assessment methods. In the present paper the utility of the most frequently used dietary assessment method in epidemiological studies is discussed in terms of precision and accuracy.     

Dietary supplement and food intake in women of childbearing age

The relationship between dietary adequacy and supplement use was examined in 3,227 nonpregnant women aged 15 to 41 years from the first National Health and Nutrition Examination Survey. Twenty-five percent of the women used dietary supplements regularly; 67% of them consumed some form of multivitamin. Supplement users had a higher income and education, were more often white, had a leaner body composition, and were more likely to reside in the western United States than nonusers. Caloric intake of users and non-users was similar. However, independent of the supplements, the diets of supplement users contained significantly more dietary protein, phosphorus, iron, potassium, thiamin, and niacin than the diets of non-users. A considerable portion of both users and non-users had dietary intakes of less than 50% of the Recommended Dietary Allowances for calcium, iron, vitamin A, and vitamin C; however, a significantly greater proportion of supplement non-users had low intakes of iron and vitamin C. Supplement users generally consumed a more nutrient-dense diet and may be the individuals who least need supplements.     

Patterns of nutrient intake among dietary supplement users: attitudinal and behavioral correlates

A national telephone interview survey of an age-stratified random sample of 2,991 adults, aged 16 and over, provided detailed information from 1,142 vitamin and mineral supplement users about their nutrient intake patterns from dietary supplements. Dietary supplement users were divided into four groups (Light, Moderate, Heavy, and Very Heavy) on the basis of the type and amount of nutrient intake from supplements. The Light, Moderate, Heavy, and Very Heavy nutrient intake groups accounted for 42%, 16%, 28%, and 14%, respectively, of the total users. Young supplement users (aged 16 to 25) tended to be in the Light user group. Older adults (aged 41 to 64) and residents of the western United States tended to be in the Heavy and Very Heavy user groups. Users in the Light and Moderate nutrient intake groups generally used only one broad-spectrum vitamin and mineral product. Users in the Heavy and Very Heavy groups were typically taking two or more specialized vitamin and mineral products at a time as part of a personalized supplement regimen. Heavy and Very Heavy nutrient intakes were associated with more frequent visits to health food stores, greater nutrition activity, and less physician involvement. Light and Moderate nutrient intakes were more likely to be associated with a defensive interest in avoiding nutritional deficiencies. The implications of generally different motivations for dietary supplement use are discussed in the context of public information strategies.     

Vitamin-mineral supplement use: association with dietary intake and iron status of adults

Although vitamin-mineral supplement use is increasing in the United States, few researchers have examined whether supplement users have better nutritional status than do nonusers. Data from 10,515 persons examined in the second National Health and Nutrition Examination Survey (NHANES II) were used to compare mean dietary intakes of several nutrients and food groups, hemoglobin, mean corpuscular volume, transferrin saturation, erythrocyte protoporphyrin, and serum ferritin between regular supplement users and nonusers aged 16 to 74 years. Prevalences of impaired iron status also were compared between user groups. Users consumed more vitamin C and ate fruits and vegetables more frequently than did nonusers in all age/sex groups. No significant differences in mean iron status indicators were observed except in the 65 to 74 year age/sex groups: transferrin saturation among men and mean corpuscular volume, erythrocyte protoporphyrin, and serum ferritin among women. In each case, users had higher values than nonusers in this age group. Prevalences of impaired iron status did not differ between users and nonusers in any age/sex group. In general, iron status was not associated with supplement use.     

Estimated folate intakes: data updated to reflect food fortification, increased bioavailability, and dietary supplement use.

BACKGROUND: There is a critical need to estimate dietary folate intakes for nutrition monitoring and food safety evaluations, but available intake data are seriously limited by several factors. OBJECTIVE: Our objective was to update 2 national food consumption surveys to reflect folate intakes as a result of the recently initiated food fortification program and to correct folate intakes for the apparently higher bioavailability of synthetic folic acid (SFA; ie, folate added to foods or from dietary supplements) than of naturally occurring folate so as to express intakes as dietary folate equivalents. DESIGN: It was not possible to chemically analyze foods, so adjustments were made to food-composition data by using information about food ingredients and characteristics. Total folate intakes were estimated for several sex and age groups by using the modified data coupled with dietary supplement use. RESULTS: Within the limitations of the data, our findings suggested that 67-95% of the population met or surpassed the new estimated average requirement, depending on the sex and age group and survey. Nonetheless, some subgroups had estimated intakes below these standards. Estimated SFA intakes suggested that approximately 15-25% of children aged 1-8 y, depending on the survey, had intakes above the newly established tolerable upper intake level. We estimated that 68-87% of females of childbearing age had SFA intakes below the recommended intake of 400 microgram/d, depending on the age group and survey. CONCLUSION: There is a need to explore ways to improve folate intakes in targeted subgroups, including females of childbearing age, while not putting other population groups at risk of excessive intakes.     

Demographics,lifestyles, health characteristics,and dietary intake among dietary supplement users in Japan

BACKGROUND: The associations between supplement use and certain demographics, lifestyles, health characteristics, and dietary intakes have not been studied in a large population in non-Western societies. The objective of our study was to investigate the association between supplement use and demographics, lifestyles, health characteristics, and dietary intake in a population-based cohort study in Japan. METHODS: Subjects were the 78 531 participants (45-74 years) who completed a self-administered questionnaire in 1995 or 1998 in a 5-year follow-up survey by the Japan Public Health Center-based prospective Study on cancer and cardiovascular disease. The questionnaire included enquiries about supplement use, occupation, height, weight, smoking, alcohol, physical activity, dietary behaviours, working hours, subjective stress, as well as intakes for 138 foods. RESULTS: The supplement users were likely to have formerly smoked or never smoked. Female supplement users were likely to consume alcohol moderately. The prevalence of users was higher in the elderly, the self-employed, those with lower body mass index, greater physical activity, lower frequency of eating prepared food, higher frequency of eating out, and higher stress level in both sexes after mutual adjustment. Mean intakes of energy and nutrients were lower for users than for non-users. CONCLUSION: The demographics, lifestyles, health characteristics, and dietary intakes may need to be adjusted when evaluating the effect of dietary supplements on disease because they can become potential confounding factors.     

Serum lithium as a compliance marker for food and supplement intake

BACKGROUND: Analyzing 24-h urine for lithium after consumption of lithium-tagged foods or supplements provides a validated compliance marker but is laborious. OBJECTIVE: Most studies involve blood sampling; therefore, we tested whether serum lithium concentration could be used as a compliance marker. DESIGN: We used serum lithium as a compliance marker in a dietary trial and an evaluation study. RESULTS: In the dietary trial, 78 volunteers consumed 500 mL yogurt tagged with lithium (250 micromol/d) for 6 wk. Serum lithium increased from 0.9+/-0.3 to 6.6+/-1.5 micromol/L, which was close to the predicted concentration, indicating that the subjects were highly compliant. However, the interindividual variability in serum lithium concentration was large. To test whether this variability resulted from compliance differences or natural variability, we performed an evaluation study: 12 subjects took a lithium supplement (250 micromol/d) for 13 d under supervision. Serum lithium increased from 0.14+/-0.03 to 3.9+/-0.8 micromol/L (range: 2.6-5.4 micromol/L); thus, there was wide interindividual variation in serum lithium despite 100% compliance. However, within-subject variability was small, with a CV of 7% for serum lithium measured on 4 different days. We checked whether taking half the dose on each of 2 d (125 micromol lithium/d) would significantly lower serum lithium. Indeed, serum lithium dropped in all subjects, by a mean of 1.0 micromol/L on the first day (P<0.0001) and by another 0.3 micromol/L on the second day (P = 0.0004). Thus, changes in serum lithium concentration of > or =1.0 micromol/L suggest altered compliance. CONCLUSION: Serum lithium concentrations after intake of lithium-tagged foods or supplements can be used to assess compliance in dietary trials.     

Relationships between vitamin and mineral supplement use, dietary intake, and dietary adequacy among adolescents

OBJECTIVE: To examine patterns of supplement use among US adolescents and the relationship between supplement use and dietary intake and adequacy. DESIGN: Adolescents self-reported 2 days of food intake using the 24-hour recall method and supplement use during a personal interview conducted as part of the 1994 Continuing Survey of Food Intakes of Individuals (CSFII). SUBJECTS: A national sample of 423 adolescents included in the 1994 CSFII survey. STATISTICAL ANALYSIS: chi 2 analysis was used to determine which demographic factors were significantly related to patterns of supplement use. Weighted percentages of adolescents by category of supplement use for selected vitamins and minerals (calcium; iron; zinc; folic acid; and vitamins A, B-6, C, and E) are presented. Relationships between dietary intake of macronutrients and vitamins and minerals among adolescents and supplement use were determined using a least-squares model of general linear regression. RESULTS: Approximately one-third of adolescents reported using supplements, with 15.6% of youth using them on a daily basis. The majority of supplement users reported taking multivitamins (N = 95; 65.5%) whereas only one-third of supplement users reported taking individual vitamins or minerals. Supplement use was found to vary by gender, household size, and US region of residence. Adolescents who reported using supplements had higher mean dietary intakes of most micronutrients and lower intakes of total and saturated fat than those who did not use supplements. More than one-third of adolescents had dietary intakes of vitamins A and E, calcium, and zinc that were < 75% of the US Recommended Dietary Allowance. APPLICATIONS/CONCLUSIONS: The majority of US adolescents do not use vitamin or mineral supplements. Interestingly, adolescents who do use supplements, even on an infrequent basis, consume diets that are more nutrient-dense than those who do not use supplements. Dietary intakes of several micronutrients were inadequate among all adolescents in this study, regardless of supplement use status. There is a need to develop and implement programs aimed at improving the dietary intakes of US adolescents.     

Modest changes in dietary intake across the menstrual cycle: implications for food intake research

Food intake varies across the menstrual cycle in mammals, energy intake usually being greater in the premenstrual phase compared with the postmenstrual phase. Premenstrual increments in energy intake and a preferential selection of carbohydrate have been suggested to be greater in women with premenstrual syndrome (PMS), who may be more sensitive to cyclical hormonal or neurotransmitter fluctuations. This has direct implications for research within populations of women, especially where the primary outcome is diet or a change in energy balance. We aimed to determine whether: the premenstrual intake of energy and macronutrients differed from the postmenstrual intake; the change in intake across the menstrual cycle differed in women with PMS compared with controls; and the change in intake was related to the severity of premenstrual symptoms. We collected 3 d dietary intake data during the postmenstrual and premenstrual phases of the menstrual cycle in thirty-one women with PMS and twenty-seven control women. The consumption of energy and macronutrient intake were similar between the phases of the cycle in women with PMS. Conversely, intakes were usually greater premenstrually in control women, although not all differences were statistically significant. Exceptions were with non-milk extrinsic sugars and alcohol, which were both consumed in greater amounts in the premenstrual phase in women with PMS. Significant correlations were observed between the severity of symptoms and the change in the consumption of these nutrients. These data suggest that a consideration of the menstrual cycle phase and PMS in diet may not be warranted, especially in cross-sectional analysis, although it may need to be taken into account when examining change in intake during dietary interventions.     

Demographic and lifestyle characteristics of functional food consumers and dietary supplement users

Functional foods and/or supplements may be used in the context of a healthy lifestyle or as a means to compensate for an unhealthy lifestyle. Adverse long-term and/or cumulative effects of functional food or supplement intake are of public health concern; it is therefore important to identify functional food and supplement users. The present study compared Dutch functional food and supplement consumers with non-consumers with regard to demographic and lifestyle factors. The consumption of the most common functional foods and supplements in 2000 was studied (yoghurt with extra lactic acid bacteria, cholesterol-lowering margarine, lemonade and sweets with extra vitamins and minerals, milk and margarine with extra Ca, Ca tablets, multivitamin and mineral supplements, and Echinacea supplements). Data were obtained from self-administered questionnaires filled in by a consumer panel, aged 19-91 years (response rate 76 %, n 1183), representative of the Dutch population. The number of daily consumers of functional foods or supplements appeared to be relatively low (daily use of multivitamin and mineral supplements, 20 %; all other products, 3-9 %). Explanatory variables depended on the type of product; but gender, age, education, and vegetable intake were significant factors in the logistic regression model. Consumption of cholesterol-lowering margarines was more likely to be reported by individuals with a poorer subjective health (odds ratio 2.62 (95 % CI 1.15, 6.05)) and by smokers (odds ratio 2.93 (95 % CI 1.34, 6.40)). In conclusion, determinants of functional food or supplement use depended on the type of product, so generalisation of consumer characteristics over different foods is not legitimate. In addition to research on lifestyle factors, surveys about consumers' attitudes, norms and knowledge regarding functional foods in relation to actual dietary patterns and health risk profiles are necessary.     

Using food frequency questionnaire in past dietary intake assessment

This paper aims to discuss which one is the best estimator of past diet: a retrospective report or a recent diet recall. The analysis included 13 articles published between 1984-1997 and selected from a MEDLINE search and from other reviews on this subject. The selection criterion was the use of a food frequency questionnaire (FFQ) in a validation study of retrospective report of dietary intake in remote past. Literature review shows that even taking into account misclassification, retrospective report of diet usually yields to a more reliable estimate of past diet pattern than current report. Past diet recall was strongly influenced by current intake and by diet patterns change. Analyzed investigations indicate that agreement between original and retrospective report was higher either for foods eaten rarely or frequently and lower for foods moderately consumed. This review allows considering the FFQ as a valuable instrument when studying the role of diet on the etiology of chronic diseases.