Dietary Supplement Use Was Very High among Older Adults in the United States in 2011–2014

Abstract

Background: Dietary supplements (DSs) have the potential to be both beneficial and harmful to health, especially in adults aged ≥60 y, and therefore it is important to monitor the patterns of their use.

Objective: This study evaluated DS use by adults aged ≥60 y to characterize the use of DSs, determine the motivations for use, and examine the associations between the use of DSs and selected demographic, lifestyle, and health characteristics.

Methods: Data from 3469 older adults aged ≥60 y from the 2011–2014 NHANES were analyzed. DSs used in the past 30 d were ascertained via an interviewer-administered questionnaire in participants’ homes. The prevalence of overall DS use and specific types of DSs were estimated. The number of DSs reported and the frequency, duration, and motivation(s) for use were assessed. Logistic regression models were constructed to examine the association between DS use and selected characteristics.

Results: Seventy percent of older adults in the United States reported using ≥1 DS in the past 30 d; 54% of users took 1 or 2 products, and 29% reported taking ≥4 products. The most frequently reported products were multivitamin or mineral (MVM) (39%), vitamin D only (26%), and omega-3 fatty acids (22%). Women used DSs almost twice as often as men [adjusted OR (aOR), 1.8; 95% CI: 1.5, 2.3). Those not reporting prescription medications were less likely to take a DS than those reporting ≥3 prescription medications (aOR, 0.4; 95% CI: 0.3, 0.6). The most frequently reported motivation for DS use was to improve overall health (41%).

Conclusions: Use of DSs among older adults continues to be high in the United States, with 29% of users regularly taking ≥4 DSs, and there is a high concurrent usage of them with prescription medications.

Introduction

By 2030, persons aged ≥65 y are expected to account for 20% of the US population (1). Aging is often accompanied by increased nutritional risk that can cause or exacerbate health conditions. Undernutrition in older adults can be due to reduced energy and food intake, biological changes in the digestive system, medical and psychological conditions, polypharmacy, and social issues such as poverty and the inability to shop and prepare meals (2). In the United States, dietary supplement (DS) use is widespread, with over half of adults reporting use, and the highest use reported in older adults (3–5). DSs can provide nutrients that may be lacking or inadequate in the diet and can help older adults meet recommended intake targets. DSs may be needed to meet nutrient requirements, particularly for nutrients that are not ubiquitous in the food supply, such as vitamin D (6, 7). However, the additional nutrients provided by DSs can also potentially lead to intakes exceeding the Tolerable Upper Intake Level (UL), especially for nutrients that are fortified in the US food supply (6–8). Moreover, some botanical and herbal DSs cause adverse reactions with prescription and over-the-counter drugs (9). The high concurrent use of prescription medications and DSs in older adults may increase the risk of drug-nutrient and other drug-supplement interactions (10–12). Thus, DSs have the potential to be both beneficial and harmful to health, and it is important to monitor usage patterns in this rapidly growing segment of the US population aged ≥60 y. The purpose of this study was to characterize the use of DSs among older adults with the use of the nationally representative data from the NHANES and relate their use to selected demographic, behavioral and health characteristics in that population.

Methods

Survey description.

NHANES is a nationally representative sample of the US civilian, noninstitutionalized population conducted by the National Center for Health Statistics (NCHS). NHANES uses a complex, stratified, multistage probability cluster sampling design. Certain population groups are oversampled to increase the precision of estimates for these subgroups, including non-Hispanic blacks, Hispanics, and non-Hispanic Asians. Non-Hispanic whites and those classified as “other” were oversampled on specific subdomains for low-income and for older adults ≥80 y of age. Information on the NHANES sample design can be found elsewhere (13). Survey participants were asked to complete an in-person home interview and a health examination conducted in a mobile examination center. The NCHS Ethics Review Board approved the survey protocol and materials, and all adult participants provided written informed consent.

This analysis was completed with the use of combined data from NHANES 2011–2012 and NHANES 2013–2014. The NCHS recommends that analysts combine ≥4 years of data to improve the reliability and stability of statistical estimates (14). The unweighted response rate for interviewed and examined older adults aged ≥60 y was 56.9% in 2011–2012 and 57.8% in 2013–2014 (15, 16). The NHANES 2011–2014 examined a sample of 19,151 participants of all ages, and for the present study, those aged <60 y (n = 15,679) and those with unknown or missing DS information (n = 3) were excluded. The final analytic sample was n = 3469.

Covariates.

Demographic, lifestyle, and health history information was collected during the interviewer-administered questionnaire in the participants’ homes. Measured height and weight were used to calculate BMI (in kg/m²), and classifications were used as follows: obese (≥30.0), overweight (25.0–29.9), normal weight (18.5–24.9), and underweight (<18.5) (17). Demographic data included sex, age, race and Hispanic origin, educational attainment, and income. Age groups were defined as 60–69, 70–79, and ≥80 y. Self-reported race and Hispanic origin groups are defined in the 2011–2014 NHANES as non-Hispanic white, non-Hispanic black, Hispanic, non-Hispanic Asian, and “other” (“other” includes multiracial). Following the NCHS recommendations, the “other” group is represented in the estimates for the total sample, but is not presented separately as a group. Educational level was categorized as completion of less than high school (HS), HS diploma or general equivalency diploma, or past HS. Income was defined with the use of the family income-to-poverty level ratio (FIPR), which is a measure of socioeconomic status that represents the ratio of household income to the US poverty guidelines after adjustments for inflation and family size. The FIPR was calculated by dividing family income by the Department of Health and Human Services poverty guidelines specific for family size and geographical location (18). Three FIPR categories were constructed as follows: <130%, 130–349%, and ≥350%. These cutoffs are consistent with eligibility for major food assistance programs that use <130% of the poverty line as the criterion.

Behavioral or lifestyle characteristics included self-reported current usual physical activity, health status, cigarette smoking, and alcohol consumption. Self-reported physical activity for a typical week was assessed with the use of a physical activity questionnaire based on the Global Physical Activity Questionnaire developed by the WHO. Physical activity was classified as none, moderate (<300 min of moderate or vigorous activity/wk), or vigorous (≥300 min of moderate or vigorous activity/wk). Alcohol use was assessed with the use of 3 questions that ascertained use in the last 12 mo, frequency, and number of drinks. A drink was defined at the time of the interview as a 354-mL glass of beer, a 148-mL glass of wine, or 44 mL of liquor. The mean daily drink number was calculated as the number of days a participant reported drinking in the past 12 mo multiplied by the usual number of drinks that were consumed and then divided by the total number of days. The mean daily number of drinks were categorized as none, <1 (but >0), 1 to <2, or ≥2 drinks/d (19). Smoking status was defined as those who responded yes to smoking ≥100 cigarettes during their lifetime and those who reported that they currently smoked every day or nearly every day. Smoking status was categorized as never, former, or current.

Health status and health history characteristics included current health status, insurance status at the time of the household interview, health care visits in the past 12 mo, and number of prescription medications taken in the past 30 d. Self-reported current health status was classified as excellent or very good and good versus fair or poor. The number of health care visits in the past 12 mo was categorized as 0–1 times, 2–3 times, and ≥4 times. Health insurance coverage at the time of the survey was categorized as private (including persons covered by public and private plans), public, and uninsured (20). The number of prescription medications was calculated with the use of the question “In the past 30 d, have you used or taken medication for which a prescription is needed?” Respondents who answered affirmatively were asked to show the interviewer all medication labels, and an interviewer recorded the exact product name from the medication container label. If the container was unavailable, the participant verbally reported this information. For this analysis, the number of prescription medications reported by participants were summed and categorized as 0, 1–2, and ≥3 different prescription medications taken in the past 30 d.

DS data.

Detailed information on the use of all types of prescription and nonprescription DS products was collected during the household interview. Participants were asked to recall all vitamins, minerals, herbs, botanicals, and other types of DSs that were used during the past 30 d. Interviewers asked the participant to show them product containers if they were available; containers were seen for 86% of the reported DSs for older adults ≥60 y of age. Information about product name, frequency and duration of use, dosage, and the motivation(s) for use were recorded for each DS reported during the interview. Collection procedures have been described in detail elsewhere (5, 21, 22). DS categories were then constructed based on nutrient content, product names, and descriptive characteristics commonly used in marketing (Supplemental Table 5). Subcategories were constructed to allow for more specific analyses of products most commonly reported by older adults. The specific types of products were chosen for presentation due to their high frequency of use and their importance to older adult nutritional status (23). Motivations for use were based on a categorical question in which participants were shown a hand card with the categories, could select >1 motivation, and could provide motivations not listed on the hand card. More information on how these data were collected and prepared for data files are available in the NHANES DS documentation for NHANES cycles 2011–2012 (21) and 2013–2014 (22). Motivations reported by >2% of users are presented. The less frequently reported motivations are not presented, but they included reasons such as for weight loss, for antioxidants, to maintain blood sugar (diabetes), for respiratory health, for allergies, to improve digestion, for relaxation (decrease stress), for the nervous system, for liver health (detoxification), for thyroid health (goiter), to build muscle, and stimulated by word of mouth. The “other” category represents a small number of motivations that could not be added to the predefined categories or motivations that were reported by a small number of participants and not analyzed.

Statistical analysis.

All statistical analyses were performed with the use of SAS software (version 9.4; SAS Institute, Inc.) and SAS-callable SUDAAN (version 11.0; Research Triangle Institute) to account for the complex survey design. The examination weights were used for all analyses to account for oversampling and survey nonresponse and are poststratified to US Census Bureau population estimates. SEs for prevalence estimates were approximated by Taylor series linearization. Prevalence estimates are provided for types of DSs, number, frequency, duration, and motivation(s). Geometric means were estimated for number of DSs taken to account for the skewed distribution. Statistical testing of differences between groups were assessed with the use of two-sided Student’s t tests. The Bonferroni method was used to adjust for multiple comparisons. To test for linear trends, the null hypothesis of a nonlinear trend was examined with the use of orthogonal polynomials, with statistical significance set at P < 0.05. Values presented have a relative SE ≤30% unless otherwise noted.

Multivariable logistic regression was used to assess the association between DS use and demographic, behavioral, and health characteristics. Adjusted ORs (aORs) and 95% CIs for the probability of DS use were calculated for each predictor to explain the strength of the association after controlling for sex, age group, race and Hispanic origin, educational attainment, physical activity, health status, smoking status, alcohol consumption, and number of prescription medications reported in the past 30 d. To test for trends, the median was assigned for each category in which the variable was originally continuous and then treating the variable as continuous. For variables that were originally nominal or ordinal, integer scores were assigned and then treated as continuous. Logistic regression was based on a smaller sample size of the participants with complete data on all covariates (n = 3227).

Results

Seventy percent of older US adults reported using ≥1 DS, with significantly higher use reported among women (76%) than men (62%) (Table 1). For both sexes, those in the older age groups reported higher use than those in the youngest age group (60–69 y). The most commonly reported DSs for both men and women included multivitamin or mineral (MVM) supplements (39%), vitamin D supplements (26%), omega-3 FA supplements (22%), and B-complex and B vitamins (16%) (Tables 1 and 2). Calcium and vitamin D (13%), vitamin C (11%), calcium-only (9%), and botanical or herbal (9%) supplement use was also reported by many older adults. The prevalence of MVM, B-complex and B vitamins, calcium and/or vitamin D, vitamin E, iron, and magnesium supplement use was significantly higher in women than men (Table 1). In contrast, the prevalence of selected nonvitamin or nonmineral DS use did not differ by sex or age group (Table 2).

TABLE 1.

Prevalence of DS use in the past 30 d among older US adults aged ≥60 y by sex and age group, NHANES, United States, 2011–2014¹

				Calcium and vitamin D			B vitamins/B complex
	n	Any DS	MVM	Calcium only	Vitamin D only	Calcium and vitamin D	Total2	B-123	B complex3	Folic acid3	Vitamin C	Vitamin E	Iron	Magnesium	Potassium
Total	3469	69.7 ± 1.4	39.4 ± 1.3	9.1 ± 0.7	26.1 ± 1.5	13.2 ± 0.8	16.3 ± 0.8	8.2 ± 0.6	4.9 ± 0.6	2.7 ± 0.4	10.5 ± 0.6	5.0 ± 0.6	3.7 ± 0.4	4.2 ± 0.4	1.7 ± 0.3
Men	1684	62.4 ± 1.9	36.5 ± 1.6	4.8 ± 0.8	20.5 ± 1.7	5.9 ± 0.8	13.3 ± 0.9	6.8 ± 0.8	3.5 ± 0.7	2.1 ± 0.4	9.0 ± 1.0	3.4 ± 0.8	3.0 ± 0.5	2.5 ± 0.5	1.9 ± 0.5
Age, y
60–69	883	57.1 ± 2.9b	33.5 ± 2.7	2.9 ± 0.9b	16.1 ± 2.4b	5.2 ± 1.3	10.6 ± 1.5a	4.6 ± 1.0a	3.8 ± 1.2	0.9 ± 0.4a	8.8 ± 1.5	2.8 ± 0.9	2.4 ± 0.9a	1.8 ± 0.74	1.6 ± 0.64
70–79	496	70.1 ± 2.0a	42.4 ± 2.6	5.6 ± 1.5a,b	28.0 ± 3.0a	6.5 ± 1.5	14.4 ± 2.0a	8.4 ± 1.5a,b	3.0 ± 1.0	3.2 ± 1.1a,b	10.1 ± 1.8	5.0 ± 1.2	2.4 ± 0.8a	3.1 ± 1.14	—
≥80	305	67.7 ± 2.6a	36.3 ± 2.2	11.0 ± 2.3a	22.4 ± 3.0a,b	7.9 ± 1.6	21.5 ± 2.2b	12.2 ± 2.0b	3.7 ± 1.2	4.9 ± 1.2b	7.1 ± 1.9	—	6.9 ± 1.4b	3.6 ± 0.8	2.8 ± 1.04
Women	1785	75.6 ± 1.42	41.8 ± 1.6*	12.6 ± 0.9*	30.7 ± 1.9*	19.1 ± 1.3*	18.8 ± 1.2*	9.4 ± 0.9*	6.0 ± 0.8*	3.1 ± 0.6	11.8 ± 1.0	6.3 ± 0.7*	4.3 ± 0.6*	5.5 ± 0.6*	1.6 ± 0.4
Age, y
60–69	901	72.9 ± 2.2b,*	40.1 ± 2.5*	11.5 ± 1.8*	30.3 ± 2.7*	18.1 ± 1.8*	20.8 ± 2.2*	9.9 ± 1.4*	7.2 ± 1.3*	1.7 ± 0.6b	12.4 ± 1.4	5.4 ± 0.9	3.1 ± 0.8b	5.2 ± 0.8*	1.3 ± 0.54
70–79	531	76.4 ± 1.8a,b,*	40.1 ± 2.1	12.2 ± 1.5*	32.0 ± 2.9	20.7 ± 1.9*	15.8 ± 1.5	7.7 ± 1.3	4.8 ± 1.2	4.6 ± 1.2a	11.1 ± 1.5	7.0 ± 1.5	4.5 ± 0.7a,b,*	7.3 ± 1.1*	1.8 ± 0.64
≥80	353	81.5 ± 1.9a,*	48.8 ± 3.6*	15.9 ± 1.7*	30.0 ± 3.5*	19.5 ± 2.3*	18.3 ± 1.8	10.6 ± 1.5	5.0 ± 1.3	4.3 ± 1.2a,b	11.3 ± 1.8	7.4 ± 1.2	7.3 ± 1.4a	3.8 ± 1.24	1.9 ± 0.74

¹Refer to Supplemental Table 5 for supplement classification. Values are percentages ± SEs. For each sex, labeled percentages in a column without a common superscript letter differ; P < 0.0167 (Bonferroni corrected). *Different from men in the same age group, P < 0.05. DS, dietary supplement; MVM, multivitamin/mineral; —, relative SE >40% (data not shown).

²Includes B complex, thiamin, riboflavin, niacin, vitamin B-6, vitamin B-12, folic acid, and pantothenic acid.

³Vitamin B-12, vitamin B complex, and folic acid are also included in the all vitamin B and B complex prevalence estimates.

⁴The relative SE is >30% but ≤40% and may be statistically unreliable. The NHANES guidelines recommend a relative SE ≤30% (14).

TABLE 2.

Prevalence of nonvitamin/nonmineral dietary supplement use in the past 30 d among older US adults aged ≥60 y by sex and age group, NHANES, United States, 2011–2014¹

	n	ω-3 FAs	Botanical/herbal	Glucosamine/chondroitin	Coenzyme Q-10	Probiotics	Fiber
Total	3469	21.6 ± 1.3	9.0 ± 0.9	7.9 ± 1.0	4.1 ± 0.5	3.0 ± 0.6	1.3 ± 0.3
Men	1684	20.4 ± 1.7	9.4 ± 1.0	7.7 ± 1.3	3.7 ± 0.8	2.3 ± 0.82	1.5 ± 0.4
Age, y
60–69	883	20.7 ± 2.5	8.8 ± 1.9	7.6 ± 1.9	3.4 ± 1.32	3.1 ± 1.12	—
70–79	496	22.4 ± 2.4	11.7 ± 1.6	8.9 ± 1.7	4.9 ± 1.1	—	3.5 ± 1.2
≥80	305	15.4 ± 2.3	6.7 ± 1.3	5.4 ± 1.6	—	—	—
Women	1785	22.6 ± 1.6	8.8 ± 1.1	8.2 ± 0.9	4.5 ± 0.6	3.5 ± 0.7	1.4 ± 0.4
Age, y
60–69	901	24.9 ± 2.8	9.0 ± 1.6	8.4 ± 1.2	3.9 ± 0.9	4.2 ± 1.2	1.6 ± 0.62
70–79	531	21.0 ± 1.8	9.3 ± 1.8	8.6 ± 1.9	6.3 ± 1.4	2.5 ± 0.7	1.4 ± 0.7
≥80	353	19.3 ± 2.8	7.2 ± 1.4	6.9 ± 1.5	3.3 ± 1.22	3.3 ± 1.12	—

¹Refer to Supplemental Table 5 for supplement classification. Values are percentages ± SEs. —, relative SE >40% (data not shown).

²The relative SE is >30% but ≤40% and may be statistically unreliable. The NHANES guidelines recommend a relative SE ≤30% (14).

Thirty-one percent of DS users reported taking only 1 supplement in the past 30 d, 23% took 2, 17% took 3, and 29% took ≥4 (Supplemental Table 2). More women took >1 DS than men (P < 0.05), and women used more DSs (mean number of DSs was 2.47 compared with 2.16; P < 0.05) than men. The mean number of supplements taken did not differ by age group. Users tended to report taking DSs regularly, with ≥79% of older adults reporting daily use of the most commonly reported products (Supplemental Table 3). The number of months of use differed among types of DS products. Notable supplements taken for ≥10 years included vitamin C products (63%), MVM products (48%), vitamin B-12 products (25%), ω-3 FA products (23%), and botanical products (22%).

Analysis of the characteristics of DS users revealed consistent patterns for DS use. The use of any type of DS was significantly higher for those in the older age groups (70–79 and ≥80 y) than those in the youngest age group (60–69 y) (Supplemental Table 1). The prevalence of use of any DS, MVM, calcium and/or vitamin D products, ω-3 FA products, vitamin C, and glucosamine or chondroitin products was significantly higher in non-Hispanic white users than non-Hispanic black and Hispanics users, but not Asian users, who tended to report using DSs at a frequency similar to that of non-Hispanic white users. For most of the DS product types, prevalence was highest for those who had higher educational attainment, higher income, private insurance, ≥2 health care visits in the past 12 mo, were nonsmokers, reported at least some physical activity, and who reported excellent or very good health status and were taking ≥1 prescription medication in the past 30 d. In contrast, DS use in general did not significantly differ by weight status or whether a person lived alone. Multivariate adjusted analysis (Table 3) confirmed many of the descriptive findings with regard to patterns of use by sex, race and Hispanic origin, and types of products used by sex, and they also revealed some novel findings. Those who reported excellent or very good health status were more likely than those who reported fair or poor health status to take MVM products (aOR; 1.6; 95% CI: 1.1, 2.2), ω-3 FA products (aOR: 1.7; 95% CI: 1.3, 2.3), vitamin C products (aOR: 2.1; 95% CI: 1.3, 3.2), and glucosamine or chondroitin products (aOR: 2.2; 95% CI: 1.1, 4.4). Interestingly, those reporting 0 prescription medications were less likely than those reporting ≥3 prescription medications to report using ≥1 DS (aOR: 0.4; 95% CI: 0.3, 0.6), MVM product (aOR: 0.5; 95% CI: 0.4, 0.8), and calcium and/or vitamin D product (aOR: 0.6; 95% CI: 0.4, 0.9).

TABLE 3.

Multivariate analysis of demographic, lifestyle, and health history characteristics associated with DS use by older US adults aged ≥60 y (n = 3227), NHANES, United States, 2011–2014¹

Characteristic	n	Any DS (n = 2093)	MVM (n = 1095)	Calciumand/or vitamin D2(n = 1140)	ω-3 FAs (n = 606)	VitaminB/B-complex3(n = 477)	Vitamin C (n = 294)	Botanical/herbal (n = 253)	Vitamin B-124(n = 264)	Glucosamine/chondroitin (n = 205)
Sex
Men	1559	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)
Women	1668	1.8 (1.5, 2.3)	1.3 (1.1, 1.6)	3.0 (2.4, 3.8)	1.2 (0.9, 1.5)	1.5 (1.2, 1.8)	1.3 (0.9, 1.9)	0.9 (0.7, 1.2)	1.4 (0.9, 2.0)	1.0 (0.8, 1.4)
Age group
60–69 y	1686	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)
70–79 y	957	1.4 (1.1, 1.7)	1.1 (0.9, 1.4)	1.4 (1, 1.8)	0.9 (0.7, 1.2)	0.9 (0.7, 1.3)	0.9 (0.7, 1.4)	1.3 (0.9, 1.9)	1.1 (0.7, 1.7)	1.2 (0.7, 1.9)
≥80 y	584	1.6 (1.3, 2.1)	1.3 (0.9, 1.8)	1.3 (1.0, 1.8)	0.7 (0.5, 1.2)	1.1 (0.8, 1.6)	0.9 (0.6, 1.3)	0.9 (0.6, 1.2)	1.5 (1.0, 2.3)	0.9 (0.6, 1.3)
P-trend		<0.01	0.15	0.06	0.19	0.56	0.52	0.43	0.04	0.55
Race and Hispanic origin5
Non-Hispanic white	1490	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)
Non-Hispanic black	777	0.7 (0.6, 0.9)	0.6 (0.5, 0.8)	0.7 (0.5, 0.8)	0.6 (0.4, 0.8)	0.7 (0.5, 1.0)	0.8 (0.5, 1.3)	0.7 (0.5, 1.0)	1.1 (0.7, 1.7)	0.2 (0.1, 0.5)
Hispanic	615	0.5 (0.4, 0.7)	0.5 (0.3, 0.6)	0.5 (0.4, 0.7)	0.6 (0.4, 1.0)	0.7 (0.4, 1.0)	0.7 (0.4, 1.2)	0.9 (0.6, 1.5)	0.8 (0.5, 1.5)	0.8 (0.4, 1.4)
Non-Hispanic Asian	293	0.8 (0.6, 1.1)	0.7 (0.5, 1.0)	1.0 (0.7, 1.4)	0.8 (0.6, 1.2)	0.6 (0.4, 1.1)	0.9 (0.5, 1.6)	0.8 (0.4, 1.4)	1.1 (0.6, 2.2)	1.1 (0.6, 2.0)
Education attainment
Less than high school	912	0.7 (0.5, 0.9)	0.9 (0.7, 1.2)	0.7 (0.5, 0.9)	0.8 (0.5, 1.3)	0.7 (0.5, 0.9)	0.8 (0.5, 1.2)	0.5 (0.3, 0.9)	0.6 (0.4, 0.9)	1.0 (0.6, 1.8)
High school diploma/GED	744	0.7 (0.5, 0.9)	0.7 (0.6, 0.9)	0.7 (0.5, 0.9)	0.9 (0.7, 1.2)	0.9 (0.6, 1.3)	0.9 (0.6, 1.3)	0.6 (0.4, 1.1)	0.8 (0.6, 1.1)	0.8 (0.4, 1.5)
More than high school	1571	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)
P-trend		<0.01	0.41	<0.01	0.28	<0.01	0.33	0.02	0.01	0.99
Physical activity
Vigorous	467	1.5 (1.0, 2.2)	1.4 (1.0, 2.1)	1.3 (1.0, 1.8)	1.4 (1.1, 1.9)	1.4 (0.9, 2.0)	1.0 (0.7, 1.5)	1.3 (0.8, 2.2)	1.3 (0.8, 1.9)	1.1 (0.6, 1.9)
Moderate	823	2.0 (1.5, 2.7)	1.3 (1.0, 1.7)	1.9 (1.4, 2.5)	1.7 (1.3, 2.3)	1.4 (1.0, 2.0)	1.4 (0.9, 2.1)	1.6 (1.2, 2.1)	1.2 (0.8, 1.8)	1.1 (0.7, 1.7)
None	1937	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)
P-trend		0.07	0.06	0.05	<0.01	0.10	0.86	0.26	0.25	0.71
Self-reported health status
Excellent or very good	1036	1.4 (1.0, 1.9)	1.6 (1.1, 2.2)	1.1 (0.8, 1.6)	1.7 (1.3, 2.3)	0.8 (0.5, 1.3)	2.1 (1.3, 3.2)	1.2 (0.7, 1.9)	0.7 (0.4, 1.1)	2.2 (1.1, 4.4)
Good	1209	1.1 (0.9, 1.6)	1.2 (0.9, 1.7)	1.0 (0.8, 1.4)	1.7 (1.1, 2.6)	0.9 (0.6, 1.4)	2.2 (1.4, 3.6)	1.3 (0.7, 2.3)	0.8 (0.5, 1.3)	1.4 (0.7, 2.9)
Fair or poor	982	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)
P-trend		0.08	<0.01	0.80	<0.01	0.39	<0.01	0.51	0.12	0.02
Smoking status
Never	1614	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)
Former	1202	0.8 (0.7, 1.1)	1.0 (0.8, 1.2)	1.1 (0.8, 1.4)	1.0 (0.8, 1.3)	1.1 (0.8, 1.5)	0.9 (0.6, 1.4)	1.1 (0.8, 1.5)	1.1 (0.7, 1.6)	1.0 (0.7, 1.4)
Current	411	0.7 (0.5, 1.0)	0.7 (0.4, 1.0)	0.8 (0.5, 1.3)	0.6 (0.4, 1.0)	0.9 (0.5, 1.9)	0.4 (0.2, 1.0)	0.7 (0.3, 1.3)	0.8 (0.4, 1.5)	0.8 (0.3, 1.8)
P-trend		0.04	0.05	0.46	0.06	0.82	0.06	0.23	0.44	0.58
Alcohol consumption, drinks/d
0	1720	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)
<1 (not 0)	1220	1.1 (0.9, 1.4)	1.2 (0.9, 1.5)	1.1 (0.9, 1.4)	0.9 (0.7, 1.2)	0.9 (0.6, 1.2)	0.8 (0.5, 1.2)	0.8 (0.5, 1.2)	1.0 (0.7, 1.5)	1.0 (0.7, 1.5)
1 to <2	187	0.9 (0.6, 1.3)	1.3 (0.8, 2.1)	0.8 (0.4, 1.4)	0.6 (0.3, 1.2)	0.5 (0.3, 1.0)	0.6 (0.3, 1.5)	0.6 (0.2, 1.7)	0.6 (0.3, 1.1)	1.0 (0.6, 1.8)
≥2	100	0.6 (0.4, 1.0)	1.1 (0.6, 2.1)	0.5 (0.2, 1.5)	1.1 (0.5, 2.3)	0.8 (0.4, 1.5)	0.5 (0.2, 1.6)	0.9 (0.3, 2.5)	1.0 (0.3, 3.4)	0.7 (0.2, 2.3)
P-trend		0.09	0.85	0.23	0.82	0.41	0.25	0.84	0.97	0.56
Prescription medication (past 30 d), n
0	454	0.4 (0.3, 0.6)	0.5 (0.4, 0.8)	0.6 (0.4, 0.9)	0.6 (0.4, 1.0)	0.6 (0.4, 1.0)	0.9 (0.6, 1.5)	1.3 (0.8, 2.2)	0.9 (0.5, 1.8)	1.7 (0.9, 3.1)
1–2	767	0.8 (0.6, 1.1)	0.8 (0.6, 1.0)	1.0 (0.8, 1.2)	0.9 (0.7, 1.2)	0.8 (0.5, 1.1)	0.8 (0.5, 1.3)	1.2 (0.8, 1.7)	1.1 (0.6, 1.9)	1.3 (0.8, 1.9)
≥3	2006	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)	1 (ref)
P-trend		<0.01	<0.01	<0.01	0.04	0.06	0.76	0.26	0.77	0.08

¹Refer to Supplemental Table 5 for supplement classification. These represent the top vitamin or mineral products and the top nonvitamin or nonmineral products. Values are adjusted ORs (95% CIs). All ORs were adjusted for all other characteristics included in the table. The model was adjusted for sex, age group, education, physical activity, health status, smoking, alcohol and number of prescription medications. DS, dietary supplement; GED, general equivalency diploma; MVM, multivitamin/mineral; ref, reference.

²Includes calcium-only supplements, calcium and vitamin D supplements, and vitamin D–only supplements.

³Includes B complex, thiamin, riboflavin, niacin, vitamin B-6, vitamin B-12, folic acid, and pantothenic acid.

⁴Vitamin B-12 is also included in the all vitamin B/B-complex estimates.

⁵Data for race and Hispanic origin category for “other” not shown (n = 52), but are included in the total.

The most frequently reported motivations for use of DSs were as follows: to improve overall health (41%), for bone health (37%), to maintain health (36%), to supplement the diet (22%), and for heart health and cholesterol (22%) (Table 4). Compared with men, women reported a higher frequency of taking ≥1 DS for bone health (47% compared with 22%), for eye health (11% compared with 6%), and for muscle-related issues (5% compared with 2%). The use of DSs to improve overall health and for bone health were the 2 most popular motivations across all race and Hispanic-origin groups. The use of DSs to prevent colds, boost the immune system, for healthy skin, hair, and nails, and to maintain healthy blood decreased with age, whereas the use of DSs for eye health increased with age. Most DSs were not used under the recommendation of a health care practitioner (e.g., physician, nurse, or dietitian), but over half of calcium and vitamin D products, vitamin D–only products, iron products, and fiber products reported were taken at the recommendation of a health care professional (Supplemental Table 4).

TABLE 4.

Prevalence of reported reasons for use of DSs among older adult DS users aged ≥60 y by sex, race and Hispanic origin, and age, NHANES, United States, 2011–2014¹

Motivation for DS use	Total (n = 2221)	Men (n = 941)	Women (n = 1280)	Non-Hispanic white (n = 1130)	Non-Hispanic black (n = 493)	Non-Hispanic Asian (n = 215)	Hispanic (n = 348)	Aged 60–69 y (n = 1036)	Aged 70–79 y (n = 700)	Aged ≥80 y (n = 485)	P-trend
To improve my overall health	41.2 ± 1.4	42.7 ± 2.4	40.2 ± 1.5	43.4 ± 1.8a	34.9 ± 2.2b	32.0 ± 3.8a,b	28.9 ± 2.7b	42.2 ± 2.1	39.5 ± 2.5	41.4 ± 2.5	0.55
For bone health, to build strong bones, osteoporosis	36.8 ± 1.7	21.5 ± 2.2	47.2 ± 2.4*	36.7 ± 2.1	31.7 ± 1.7	39.9 ± 3.4	35.6 ± 2.4	35.8 ± 2.2	38.3 ± 2.4	37.2 ± 2.4	0.51
To maintain health (to stay healthy)	36.0 ± 1.6	38.9 ± 2.5	34.1 ± 1.7	36.8 ± 2.1	31.1 ± 2.5	31.6 ± 3.2	30.8 ± 4.1	37.7 ± 2.6	33.4 ± 2.3	36.0 ± 2.4	0.37
To supplement my diet (because I don’t get enough from food)	22.0 ± 1.6	20.0 ± 2.1	23.3 ± 1.6	22.5 ± 1.8	21.1 ± 2.7	21.0 ± 2.6	17.6 ± 1.3	24.9 ± 2.4	18.3 ± 2.1	20.5 ± 3.1	0.10
For heart health, cholesterol	22.0 ± 1.6	22.9 ± 2.4	21.4 ± 1.6	22.9 ± 1.9	15.7 ± 2.4	16.2 ± 3.3	20.0 ± 2.4	24.1 ± 2.3	21.9 ± 2.2	16.5 ± 2.9	0.08
For healthy joints, arthritis	15.9 ± 1.5	13.6 ± 2.3	17.4 ± 1.5	17.0 ± 1.9a	9.4 ± 1.6b	18.9 ± 3.4a,b	10.6 ± 2.0a,b	17.1 ± 2.6	15.8 ± 1.8	12.7 ± 1.8	0.21
To get more energy	15.3 ± 1.5	13.6 ± 1.8	16.5 ± 1.7	14.4 ± 1.9b	24.0 ± 2.1a	9.2 ± 2.9b,2	20.0 ± 2.5a,b	17.0 ± 2.0	14.4 ± 1.6	12.6 ± 2.6	0.10
To prevent colds, boost immune system	13.8 ± 1.1	14.6 ± 1.7	13.2 ± 1.3	13.5 ± 1.4	17.1 ± 2.4	9.9 ± 2.1	13.9 ± 2.2	16.8 ± 1.8	11.8 ± 1.1	9.0 ± 1.9	<0.01
To prevent health problems	13.2 ± 1.5	11.7 ± 1.6	14.3 ± 1.8	13.8 ± 1.9a	11.9 ± 1.5a,b	9.8 ± 1.9a,b	7.0 ± 1.5b	14.4 ± 1.9	12.5 ± 2.0	11.2 ± 1.8	0.13
For eye health	9.0 ± 0.7	5.9 ± 0.9	11.1 ± 1.0*	10.0 ± 0.7a	3.5 ± 0.7b	10.3 ± 2.7a,b	—	5.5 ± 1.0	9.9 ± 1.3	16.6 ± 2.2	<0.01
Healthy skin, hair, and nails	6.2 ± 0.8	3.9 ± 0.8	7.7 ± 1.3	6.1 ± 0.9	6.2 ± 1.1	7.7 ± 2.1	7.8 ± 1.9	7.8 ± 1.1	5.3 ± 0.9	3.1 ± 0.8	<0.01
For anemia, such as low iron	5.7 ± 0.8	4.7 ± 1.1	6.5 ± 0.9	5.6 ± 1.0	7.8 ± 1.1	4.9 ± 1.3	4.8 ± 1.1	5.7 ± 1.4	5.2 ± 0.9	7.0 ± 1.4	0.71
For good bowel/colon health	5.3 ± 0.7	4.3 ± 0.9	6.0 ± 0.9	5.8 ± 0.8	4.4 ± 0.9	—	3.1 ± 1.12	5.3 ± 1.1	6.0 ± 1.3	4.1 ± 1.0	0.68
To improve digestion	5.2 ± 0.7	3.9 ± 1.0	6.0 ± 0.9	5.3 ± 0.8	5.2 ± 1.2	3.2 ± 1.12	4.0 ± 1.32	5.8 ± 1.3	4.3 ± 1.0	4.9 ± 1.2	0.52
To maintain healthy blood sugar concentration, diabetes	4.7 ± 0.6	6.0 ± 1.1	3.9 ± 0.7	4.5 ± 0.7	6.5 ± 1.4	5.7 ± 1.7	3.6 ± 1.12	6.4 ± 1.2	3.5 ± 0.8	2.4 ± 0.7	0.02
For muscle-related issues, muscle cramps3	4.0 ± 0.5	2.1 ± 0.5	5.3 ± 0.9*	4.2 ± 0.7	2.0 ± 0.6	—	—	4.4 ± 0.9	4.8 ± 1.1	—
Other4	4.0 ± 0.6	4.0 ± 0.9	4.0 ± 0.9	3.8 ± 0.7	4.8 ± 1.1	3.6 ± 1.32	3.1 ± 1.12	3.6 ± 0.9	4.5 ± 1.0	4.0 ± 1.32	0.64
Low concentrations in blood	3.7 ± 0.6	3.4 ± 0.9	3.9 ± 0.7	4.0 ± 0.7	3.7 ± 0.7	—	—	3.5 ± 0.9	5.0 ± 1.3	2.2 ± 0.72	0.84
For kidney and bladder health	3.7 ± 0.6	2.8 ± 0.6	4.3 ± 0.9	3.8 ± 0.8	4.5 ± 0.8	—	2.0 ± 0.82	2.9 ± 0.8	4.7 ± 1.52	4.0 ± 1.0	0.25
For mental health	3.5 ± 0.7	2.8 ± 1.0	4.0 ± 0.8	3.4 ± 0.9	2.5 ± 0.7	—	5.2 ± 1.5	4.3 ± 1.42	2.2 ± 0.6	3.7 ± 1.0	0.49
For relaxation, to decrease stress, to improve sleep	3.4 ± 0.6	1.6 ± 0.62	4.6 ± 0.8*	3.7 ± 0.7	2.1 ± 0.72	—	—	4.7 ± 0.9	2.2 ± 0.82	—
For prostate health5		6.8 ± 1.2		2.8 ± 0.6	2.8 ± 0.8	—	2.1 ± 0.81	2.5 ± 0.7	3.2 ± 0.6	2.4 ± 0.6	0.78

¹Table includes motivations reported by >2% of overall DS users. Values are percentages ± SEs. Labeled percentages in a row without a common superscript letter differ, P < 0.0083 (Bonferroni corrected). *Different from men, P < 0.05. DS, dietary supplement; —, relative SE >40% (data not shown).

²The relative SE is >30% but ≤40% and may be statistically unreliable. The NHANES guidelines recommend a relative SE ≤30% (14).

³For the NHANES 2011–2012 survey, the hand card also listed “muscle building.”

⁴“Other” includes motivations reported by participants that were not predefined answer categories and could not be added to a predefined answer category.

⁵Men only.

Discussion

These nationally representative data indicate that the majority of older adults are using DSs, primarily micronutrient DSs. Similar to previous reports, we found that women are more likely to take most DSs than men (24–29). There were also differences in DS use by race and Hispanic origin, with the highest DS use found in non-Hispanic white adults and non-Hispanic Asian adults. DS use was also higher for those with higher educational attainment and higher income. Lower income groups of older Americans, such as non-Hispanic black and Hispanic subgroups, may be food insecure, vulnerable to undernutrition, and may not be meeting expert recommendations for certain nutrients of concern (30). For such vulnerable subgroups, micronutrient DSs may help to meet dietary recommendations. Yet these are the very groups who were least likely to use micronutrient-containing DSs.

We found, as have others, that there is high concurrent use of DSs and prescription medications (10, 11, 26, 31, 32). The 73% of older adults who were taking ≥3 prescription medications were more likely to report taking a DS than those that reported taking 0 prescription medications. Furthermore, 8% of older adults who reported taking ≥3 prescription medications were also taking ≥1 botanical DS product. Most DSs are not prescribed by health care practitioners, and DS use is not routinely discussed during health care visits (33). Therefore, it is unlikely that anticipatory guidance about DS use with prescription medications is routinely being provided to patients, particularly for those with polypharmacy both for prescription drugs and botanical DSs. Herb-drug interactions could enhance or negate the other’s effects or could modulate the activity of enzymes and drug transporters (34).

The DRI reports recognize that DSs may be necessary to help older adults supplement their diets and fill nutrient gaps to increase the likelihood of achieving recommended intakes, specifically for vitamins D and B-12 and for calcium. However, we found that older adults were using DSs primarily not for this purpose of supplementing the diet, but rather for other health-related reasons. For example, the most common reason for taking MVM was to improve health, the second and third reasons were for bone health and to maintain health, respectively, and the fourth reason was to supplement the respondent’s diet (Supplemental Table 4). MVM products currently on the market, depending on their formulation, may provide nutrients in amounts that help older adults to meet dietary recommendations, which is the intended use of the products (35). For example, Bailey et al. (7) found that supplementation with folic acid, vitamin C, vitamin B-6, vitamin A, and vitamin E reduced the prevalence of dietary inadequacy significantly in older adults aged ≥71 y. Most of these vitamins were present in MVM formulations in amounts at or above the RDA levels and were consumed by a high percentage of older adults. In that study, ∼40% of older adults were taking ≥1 MVM product, and 5% were taking a B-complex multivitamin. However, calcium and potassium amounts in MVM products were shown to be low in a nationally representative study on MVM products and therefore may not provide nutrients in amounts that improve intake (36). Other over-the-counter products, such as calcium and calcium–vitamin D combinations and prescription potassium supplements, may instead provide the amounts necessary to meet recommendations when dietary measures do not suffice. Although MVMs and other DSs containing micronutrients may fill dietary gaps for some nutrients, they may increase the risk of exceeding the UL for nutrients that are present in highly fortified US foods. Bailey et al. (7) found that the prevalence of older adults aged ≥71 y taking DSs who met or exceeded the UL was ∼7% for folic acid, 3% for vitamin A, and 4% for vitamin B-6. In addition, 19% of men and 8% of women aged ≥71 y taking DSs met or exceeded the UL for iron, with <0.5% meeting or exceeding the UL from diet alone (8). The formulations of MVMs, particularly for older adults, need review and rationalization if they are to fill common nutrient gaps in dietary intakes while avoiding nutrient excess.

The evidence that any DS prevents chronic diseases, such as cardiovascular disease (CVD) or cancers, remains weak although it is an area that deserves continued research. Nevertheless, nearly 40% of US adults aged ≥60 y in our study used MVM to maintain and improve their health, despite inconclusive evidence that they prevented chronic disease. After systematic evidence reviews of the literatures, the US Preventive Services Task Force (USPSTF) concluded that evidence was insufficient that vitamin and mineral supplements were useful for preventing cardiovascular disease (CVD) or cancer (37). However, in 2013 when the review was done, only 2 randomized clinical trials (The Supplementation en Vitamines et Mineraux Antioxydants and Physicians' Health Study II) were available that assessed CVD and cancer outcomes. Although there was no significant reduction in risk from most types of fatal and nonfatal CVD, there was a small but significant reduction in total cancer incidence among men, particularly those with a history of cancer. Limited data were available for women and cancer or CVD. The majority of observational studies have not shown an association between MVM use and CVD incidence or mortality, with the exception of the Nurse’s Health Study, in which the risk of coronary heart disease was reduced by 24% for women who took multivitamins [reviewed in Angelo et al. (38)]. MVM use and cancer incidence or mortality have been mixed, however, most of the research to date that used data from cohort studies have not found an association (38).

Compared with our study, DS use among older adults in the United States has increased slightly from 63.3% (SE: 1.7%) in NHANES 1999–2000 to 69.7% (SE: 1.4%) in NHANES 2011–2014 (38). The use of vitamin B-12 products and iron products has increased, the use of vitamin C and E products decreased, and MVM, B-complex, calcium-only, and folic acid use has been consistent compared with estimates from NHANES 1999–2000 (39). Additionally, Kantor et al. (3) found a significant increase in the use of vitamin D products among older adults aged ≥65 y from NHANES 1999–2000 to NHANES 2011–2012. These changes may reflect recommendations put forth in more recent years for certain nutrients and could also reflect reporting of research findings on DSs. However, this is speculative, because NHANES data cannot be used to answer questions such as the changing of behaviors over time. These findings underscore the need for continuous monitoring of DS use in the population.

This study has several strengths, including the national representativeness of NHANES DS data. Also, although polypharmacy for prescription drugs and DS use have been reported in other studies of older adults, the characterization of the type of DS with verification of the product containers to confirm their identity and the details on the amounts consumed were lacking (10, 26). In NHANES, a high percentage of product containers were seen by interviewers, allowing for accurate transcription of product names compared with self-report, which then provided more information for accurate product label acquisition from manufacturers and more precise estimation of DS exposures.

The limitations of our study include the fact that total dietary intakes of nutrients from DSs and other foods and beverages were not estimated, and therefore the proportion of the population not reaching the Estimated Average Requirement or >UL could not be provided. Future work should address this and provide more recent estimates for older adults. Another limitation is the relatively low response rate for older adults, which was 56.9% in 2011–2012 and 57.8% in 2013–2014. Finally, although DS containers were seen for 87% of reported products, interviewer error or omissions in recording information cannot be ruled out.

In conclusion, the prevalence of DS use, often of several products, was high among older adults in the United States. Almost one-third of the older adults reported using ≥4 types of DSs in the past 30 d. These products were generally taken regularly and for many years. Most of the products used contained micronutrients. Some DSs (such as calcium, vitamin D, and vitamin B-12) may fill gaps in older adults’ food intakes that may be inadequate. Others, however, may contain high amounts of micronutrients like folic acid or vitamin A that are also fortified in the food supply, which may increase risks of intakes that exceed the UL. The risk of adverse reactions due to interactions is increased when these and other DSs containing high amounts of certain botanicals or other nonvitamin or nonmineral supplements are used concurrently with many prescription medications. Health care professionals should be aware of DS use in their patients and should monitor their use for safety and possible nutrient–drug interactions.