Older Adults Who Use Vitamin/Mineral Supplements Differ from Nonusers in Nutrient Intake Adequacy and Dietary Attitudes RHONDA S
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RESEARCH Current Research Older Adults Who Use Vitamin/Mineral Supplements Differ from Nonusers in Nutrient Intake Adequacy and Dietary Attitudes RHONDA S. SEBASTIAN, MA; LINDA E. CLEVELAND, MS, RD; JOSEPH D. GOLDMAN, MA; ALANNA J. MOSHFEGH, MS, RD Even so, less than 50% of both users and nonusers met ABSTRACT the EAR for folate, vitamin E, and magnesium from food Objective To measure nutrient intake adequacy of vitamin/ sources alone. Overall, supplements improved the nutri- mineral supplement users and nonusers aged 51 years ent intake of older adults. After accounting for the con- and older, determine the efficacy of supplement practices tribution of supplements, 80% or more of users met the in compensating for dietary deficits, and identify predic- EAR for vitamins A, B-6, B-12, C, and E; folate; iron; and tors of supplement use. zinc, but not magnesium. However, some supplement Design Analyses of two 24-hour recalls, demographic vari- users, particularly men, exceeded Tolerable Upper Intake ables, and attitude questions collected during the Con- Levels for iron and zinc and a small percentage of women tinuing Survey of Food Intakes by Individuals and Diet exceeded the Tolerable Upper Intake Level for vitamin A. and Health Knowledge Survey in 1994 to 1996. Data were Significant sociodemographic factors related to supple- weighted to be representative of older Americans. ment use for older men were age group, metropolitan Subjects Four thousand three hundred eighty-four adults aged 51 years and older (1,777 daily supplement users, area, and educational status. Race, region, smoking sta- 428 infrequent users, and 2,179 nonusers) residing in tus, and vegetarian status were significant factors for households in the United States. women. Attitude about the importance of following a Statistical analyses Usual nutrient intake distributions healthful diet was a consistent predictor of supplement were estimated using the Iowa State University method. use for both men and women. The Estimated Average Requirement (EAR) cutpoint Conclusions A large proportion of older adults do not con- method was applied to determine the proportion of older sume sufficient amounts of many nutrients from foods adults not meeting requirements before and after ac- alone. Supplements compensate to some extent, but only counting for nutrient intake from supplements. Student t an estimated half of this population uses them daily. tests were used to assess differences between users and These widespread inadequacies should be considered nonusers. Logistic regression was used to determine so- when developing recommendations for supplement use ciodemographic and attitudinal predictors of supplement for clients in this age group. Modifying dietary attitudes use. may result in a higher rate of supplement use in this Results For one or more of the sex-age groups studied, a at-risk population. significantly smaller proportion of supplement users than J Am Diet Assoc. 2007;107:1322-1332. nonusers had intakes from food alone below the EAR for vitamins A, B-6, and C; folate; zinc; and magnesium. nalyses of nationwide survey data have shown that a large percentage of older adults do not receive R. S. Sebastian is a nutritionist, J. D. Goldman is a Arecommended amounts of many nutrients from food statistician, and A. J. Moshfegh is research leader, US alone (1-11). Other measures, such as the Healthy Eating Department of Agriculture, Agricultural Research Ser- Index, also indicate that the diets of older adults need vice, Food Surveys Research Group, Beltsville, MD. improvement and may leave them susceptible to nutri- L. E. Cleveland is retired; at the time of the study, she tion-related problems (12,13). This is of particular con- was a supervisory nutritionist, US Department of Agri- cern because conditions prevalent in this population, in- culture, Agricultural Research Service, Food Surveys cluding chronic diseases and absorption problems, can Research Group, Beltsville, MD. compromise nutritional status (14-16). At the same time, Address correspondence to: Rhonda S. Sebastian, MA, a growing proportion of older adults are using vitamin Nutritionist, US Department of Agriculture, Agricul- and mineral supplements, which can substantially in- tural Research Service, Food Surveys Research Group, crease nutrient intake and counter some of these short- 10300 Baltimore Ave, Bldg 005, Room 102, BARC-West, falls (17-19). Little is known about the effectiveness of Beltsville, MD 20705. E-mail: Rhonda.Sebastian@ars. vitamin/mineral supplements in appropriately compen- usda.gov sating for dietary deficits. Published by Elsevier Company on behalf of the With the introduction of the Dietary Reference Intakes American Dietetic Association. (DRIs), new standards are available for the assessment of 0002-8223/07/10708-0002$0.00/0 nutrient intakes. The establishment of Estimated Average doi: 10.1016/j.jada.2007.05.010 Requirements (EARs) makes it possible, for the first time, to 1322 Journal of the AMERICAN DIETETIC ASSOCIATION estimate the prevalence of nutritional inadequacy in popu- collected using two in-person, interviewer-administered lation groups. Additionally, the Tolerable Upper Intake 24-hour recalls conducted 3 to 10 days apart. The Diet Levels (ULs) provide cutpoints for estimating the percent- and Health Knowledge Survey was administered by tele- age of the population of interest that is at potential risk of phone to one adult sample person in the household 3 adverse effects due to overconsumption of a nutrient (20). weeks after the second intake interview. These two components of the DRIs provide new opportuni- Supplement information was collected through a series ties for assessing nutrient intake and evaluating the influ- of questions following the first 24-hour recall. Two hand- ence of supplement use on dietary status. cards were used to query respondents on the types of Although supplement use provides potential benefits in vitamin/mineral supplements taken (ie, multivitamin, increasing nutrient intakes, there are potential draw- multivitamin with iron, combination of vitamin C and backs (21-25). The extensive use of supplements by older iron, and single vitamins and/or minerals); and if indi- adults increases the possibility for overconsumption of cated, what specific types of single vitamins/minerals nutrients. The American Dietetic Association’s position were consumed (eg, vitamin A, vitamin C, calcium, and paper on food fortification and dietary supplements (26) iron). The frequency of consumption (taken daily or less notes that documented cases of toxicity are often caused often) was also obtained, but not the specific quantity. by supplementation. In fact, the ULs were developed The amount of each nutrient in the supplement (the largely in response to the growing use of supplements and formulation) and the brand name were not collected. fortified foods (20). Data from the CSFII sample were used to determine Considering the potential for both positive and nega- nutrient intake adequacy of supplement users and non- tive effects on overall nutrient intake, an important ques- users. Data from the smaller Diet and Health Knowledge tion to ask is what factors influence supplement use. Survey sample were used to identify attitudinal and so- Characteristics associated with taking supplements are ciodemographic predictors of supplement use. A total of well documented. Users generally consume more nutri- 4,384 respondents aged 51 and older provided two com- ent-dense diets and vary significantly from nonusers in plete 24-hour recalls in the CSFII. Supplement users many sociodemographic factors, including age, sex, race, were defined as individuals who took any kind of vitamin education status, and income level (17,27-45). Research is or mineral supplement every day. Almost 10% of the more limited on the effect of more modifiable factors, such sample (nϭ428) was classified as infrequent supplement as attitudes about diet and health, on supplement use. users and excluded from the analysis. These individuals The Diet and Health Knowledge Survey, a component of reported that they took vitamin or mineral supplements the US Department of Agriculture’s Continuing Survey of “every so often.” The remaining sample of 3,956 supple- Food Intakes by Individuals (CSFII), was designed to ment users and nonusers was used in assessments of provide information about people’s attitudes and knowl- nutrient intake adequacy. The infrequent users were edge on topics that could affect their dietary intake (46). then added back to the sample, and information from the Currently, the Diet and Health Knowledge Survey offers 2,571 respondents aged 51 years and older providing the only national survey data that links attitudes about complete responses to the Diet and Health Knowledge diet and health with dietary behavior, including supple- Survey attitude questions were used in the analysis to ment use. identify predictors of supplement use. The purpose of this study was to examine the effects of supplement use on nutrient intake and dietary adequacy for adults aged 51 years and older, and to identify deter- Calculating Nutrient Intake from Foods and Supplements minants of supplement use. Objectives were to compare Foods. Some nutrients required conversion to standard- the nutrient intake adequacy of older adults who con- ized measurement units before comparison of dietary in- sumed vitamin/mineral supplements daily to those who takes to the DRIs could be made. Vitamin A had to be did not, to estimate the contribution