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Consumption of dietary health supplements among hospitalized patients at an acute tertiary Hospital
PharmaNutrition 2 (2014) 135–140
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PharmaNutrition journal homepage: www.elsevier.com/locate/phanu
Consumption of dietary health supplements among hospitalized patients at an acute tertiary Hospital Pay Wen Yong *, Lee Boo Tan, Yet Hua Loh Department of Dietetics, Singapore General Hospital, Singapore
A R T I C L E I N F O
PubChem classification: Fatty acids Omega-3 (PubChem CID: 56842239) Calcium carbonate (PubChem CID: 10112) Calcium citrate (PubChem CID: 54670067) Glucosamine (PubChem CID: 441477) Ascorbic acid (PubChem CID: 54670067) Keywords: Dietary health supplements Socio-demographic Lifestyle Dietary Dietary supplements-drug interactions Patient-healthcare professionals communication
A B S T R A C T
Dietary health supplements (DHS)-drug interaction risk may be greater in patients requiring numerous medications; yet little is known about DHS use in hospitalized patients. This study aims to characterize patients who use DHS, to evaluate the association between DHS use and socio-demographic, lifestyle and dietary habits; and to investigate whether users report DHS use to healthcare professionals (HCPs). Patients admitted to the medical wards, with age 21 years, medically stable, cognitively intact and conversant in English, Mandarin or Malay language were interviewed by a dietitian. Of the 100 patients surveyed, up to 42% were DHS users. They tend to be non-smokers (98%) (p = 0.02) with higher daily fruit intake of at least two servings (31%) (p = 0.02), daily milk intake of at least one cup (21%) (p = 0.03) and whole grain bread intake of at least once a day (31%) (p < 0.05) when compared with non-users. DHS were mostly used for general well being, disease prevention and treatment. However, more than half of the users did not inform HCPs about DHS use as they were not asked by HCPs. Our findings have important implication by raising concern for DHS–drug interaction given the low disclosure rate of DHS use and poor inquiring by HCPs. ã 2014 Elsevier B.V. All rights reserved.
1. Introduction Dietary health supplement (DHS)1 is the second most commonly used complementary and alternative medicine (CAM) in the general population [1,2]. It is defined as ‘a product that is used to supplement a diet, with benefits beyond those of normal nutrients, and/or to support or maintain the healthy functions of human body’ [3]. DHS contain one or more, or a combination of the following ingredients: a vitamin, a mineral, an amino acid, herbs or botanicals. The DHS use among adults In United States has increased from over 40% for the period 1988–1994 to over one-half for 2003–2006 period [4]. In Singapore, self-reported intakes from the 2004 National Nutrition Survey indicated that 34.3% of Singaporeans consume DHS. The most commonly consumed DHS were vitamin C, calcium, multi-vitamin and mineral supplements, botanical and animal products [5]. Despite the high rate of DHS use, many studies have found relatively low patient disclosure rate to their healthcare
* Corresponding author at: Block. 8 Level 1, Dietetics Department, Singapore General Hospital, Outram Road Singapore 169608, Singapore. Tel.: +65 63265293; fax: +65 63213594. E-mail addresses: [email protected], [email protected] (P.W. Yong), [email protected] (L.B. Tan), [email protected] (Y.H. Loh). 1 DHS: dietary health supplements. http://dx.doi.org/10.1016/j.phanu.2014.07.002 2213-4344/ ã 2014 Elsevier B.V. All rights reserved.
professionals (HCPs)2 [6–10]. This highlights the fact that patients may not be aware of the potential DHS-drug interaction [11]. In a 2005 position paper on fortification and nutritional supplement by the American Dietetic Association (ADA) now known as the Academy of Nutrition and Dietetics, it was stated that there is a greater risk of toxicity, drug or nutrient interaction and adverse reactions of concentrated nutrients in DHS compared with the nutrients in whole foods [12]. The risk may even be greater in patients with multiple medical conditions requiring numerous medications since about one in four prescription medication users also took a DHS [11]. Although several population studies have shown that DHS users generally have healthier lifestyle behaviours, better health status [13] and tend to consume more nutrient dense diets, i.e. low in energy and high in micronutrients [14–17], relatively little, however, is known about the socio-demographic, lifestyle, dietary characteristics and pattern of DHS consumption among hospitalized patients. A study by Goldstein et al. reported that DHS consumption is associated with higher income and non-smoking status [8], while a recent local study by Chow et al. reported that the independent predictors of traditional Chinese medicine (TCM) and DHS use were Chinese ethnicity, tertiary education and age less than 65 years [18].
2
HCPs: healthcare professionals.
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Therefore, in order to understand the spectrum of DHS use among hospitalized patients, this study aims to: (i) profile the characteristics of patients who use DHS, (ii) evaluate the association between DHS use and socio-demographic, lifestyle and dietary habits and (iii) investigate whether DHS users report the use of DHS to HCPs, their perceptions and pattern of DHS use. 2. Methods 2.1. Participants A cross-sectional survey was conducted in the medical speciality wards of a large tertiary hospital. The study population consisted of patients newly admitted to medical wards for the period November 2011 to January 2012. Convenience sampling was used. Eligibility criteria for study participants included: age 21 years and above, medically stable, cognitively intact, conversant in English, Mandarin or Malay language; or with primary caregiver present to answer the questions. After obtaining informed consent, patients were interviewed by a single dietitian using a standardized 40-item questionnaire. Concurrently, patients’ medical records were reviewed for medical diagnoses. This study was approved by the SingHealth Centralised Institutional Review Board. 2.2. Questionnaires The study adopted the definition of DHS by Health Sciences Authority [3]. Since no validated questionnaire was available, the questionnaire was initially developed based on literature review. It was tested on a group of individuals whereby feedback was gathered and the questions were adapted to ensure the appropriateness in our multiethnic patient population. It was available in the English language. There were five sections in the questionnaire: (i) Socio-demographic characteristics (age, gender, ethnic group,
educational level and monthly household income). (ii) Lifestyle behaviours (exercise, alcohol consumption and
smoking status). (iii) Dietary behaviours for the past 12 months: consumption frequency of milk, wholegrain bread, brown rice or other cooked whole grains, fruit and vegetables) adapted from Diet History Questionnaire version II from the National Institutes of Health, USA [19]. (iv) Report of DHS use to HCPs, perceptions about and pattern of DHS use. (v) Type of DHS consumed for at least 4 weeks in the past 12 months. Seven categories of common DHS were included, namely multi-nutrient supplements, single nutrient, mineral/ mineral combinations/trace elements, herbals or botanicals, amino acid, fibre supplements, food constituents and others (e.g. fish oil, glucosamine, probiotics, etc).
2.3. Statistical methods Descriptive analysis (e.g. mean, percentage) was used to determine the characteristics of study participants while Chisquare test was used to assess the association between DHS and patient’s socio-demographic, lifestyle and dietary behaviours. Student’s independent t-test (two-tailed) was used to analyse between-group differences (DHS users/non-DHS users). A p-value of <0.05 is considered statistically significant. Statistical analyses were carried out using SPSS version 17.0 (SPSS, Chicago).
3. Results 3.1. Socio-demographic and lifestyle characteristics A total of 100 patients were recruited into this study and the characteristics of the patients are shown in Table 1. In general, 42% of study population (n = 42) reported using DHS. Percentage of female patients who consumed DHS was 54.8%, slightly higher than the percentage of male patients (45.2%). Ethnic distribution of DHS users was 73.8% Chinese, 16.7% Malay and 9.5% Indian. This distribution was not significantly different from non-DHS users. Majority of the DHS users (64.3%) attained higher education, i.e. secondary level and above. There was a statistically significant difference in smoking status between DHS users and non-users. In the DHS users group, only 2.4% were smokers compared to 17.2% in the non-DHS users group (p = 0.02). For the other lifestyle characteristics, there were no significant differences between the two groups. While a larger proportion of DHS users did not smoke as much as one cigarette a day for as long as a year (97.6%) and did not drink alcohol over the past 12 months (90.5%), more than half (57.1%) also reported not doing any weekly exercise for more than 15 min during their free time. 3.2. Dietary habits and DHS use Dietary habits of patients in this study, particularly consumption of selected food items, were analysed. As shown in Table 2, DHS users were more likely than non-DHS users to report consumption of two to three servings of fruit per day (p = 0.02), at least one cup of milk per day (p = 0.03) and at least once a day of whole grain bread (p < 0.05).
Table 1 Socio-demographic and lifestyle characteristics of the study population. Characteristics (N = 100)
Age, years
DHS users (n = 42)
Non-DHS users (n = 58)
mean SD
mean SD
57.9 12.3 n (%)
55.8 15.8 n (%)
Gender Men 19 (45.2) Women 23 (54.8) Ethnic group Chinese 31 (73.8) Malay 7 (16.7) Indian 4 (9.5) Others 0 (0) Education Nil 3 (7.1) Primary school 12 (28.6) Secondary school 18 (42.9) Tertiary 9 (21.4) Monthly household income Refuse to disclose 22 (52.4) <$4000 11 (26.2) $4000–7999 6 (14.3) $8000 and above 3 (7.1) Exercise Yes 18 (42.9) No 24 (57.1) Alcohol consumption Yes 4 (9.5) No 38 (90.5) Smoking status* Yes 1 (2.4) No 41 (97.6) *
p = 0.02.
25 (43.1) 33 (56.9) 44 (75.9) 8 (13.8) 5 (8.6) 1 (1.7) 6 (10.3) 20 (34.5) 20 (34.5) 12 (20.7) 25 (43.1) 20 (34.5) 10 (17.2) 3 (5.2) 15 (25.9) 43 (74.1) 8 (13.8) 50 (86.2) 10 (17.2) 48 (82.8)
P.W. Yong et al. / PharmaNutrition 2 (2014) 135–140 Table 2 DHS use and consumption of selected food groups. Food group
DHS users (n = 42) n (%)
Non-DHS users (n = 58) n (%)
Fruit (all kinds, fresh, canned and frozen) 2–3 servings/day 13 (31.0) 7 (12.1) 29 (69.0) 51 (87.9) <2–3 servings/day Vegetables (all kinds, raw, cooked, canned and frozen) 2–3 servings/day 20 (47.6) 24 (41.4) <2–3 servings/day 22 (52.4) 34 (58.6) Milk At least 1 cup/day 9 (21.4) 4 (6.9) 33 (78.6) 54 (93.1) <1 cup/day Whole grain bread (whole wheat, rye and oatmeal) At least once a day 13 (31.0) 9 (15.5)
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(15.1%). In comparison, only 7.5% of patients cited the doctor or pharmacist as their source of information on DHS. p-value
3.4. Report of DHS use to HCPs Out of 42% (n = 42) of DHS users, 52% (n = 22) did not inform HCPs of their DHS use. The top two reasons for not informing were that ‘they were not asked by HCPs’ (36.4%) and ‘not important to report DHS use’ (31.8%) (Fig. 1).
p = 0.02
p = 0.54
4. Discussion p = 0.03
p < 0.05
p = 0.87
3.3. DHS consumption Up to 42% of patients (n = 42) surveyed were DHS users, and of these, half were taking more than one type of DHS at the same time. The types and number of DHS consumed by participants for at least 4 weeks over the previous 12 months are listed in Table 3. The top four commonly used DHS were fish oil/v – 3(35.7%), calcium (33.3%), glucosamine (16.7%) and vitamin C (16.7%). Most of the patients took DHS for general well-being reason (64.3%) as well as for disease prevention and treatment purpose (21.4%). In contrast, the two major reasons given by non-users were ‘worried about safety or side effects of DHS’ (32.8%) and ‘I am eating well’ (24.1%). Majority of the DHS users (73.8%) perceived that taking DHS made them feel better while 23.8% felt that there was no difference and only one DHS user indicated worsening effect with DHS use. Friend/relative and family members (children and/or spouse) (56.6%) were the most common source of information on DHS followed by health food retailer or salesperson
To the best of our knowledge, the present study is the first investigation into DHS use and its relationship with demographics, lifestyle and dietary characteristics among hospitalized patients. We found that more than 40% of the total 100 patients admitted to the medical wards took DHS for at least 4 weeks during the past year. Our results most closely match that of a previous finding among multi-ethnic hospitalized medical patients in Asia [9]. In that study, 42% reported using herbs within the past year. However, when compared with other Western studies, those reports showed higher rates of 60–80% of DHS use in patients admitted to the general internal medicine or geriatric services [7] and the internal medicine resident teaching clinics [20] respectively. This could be explained by the difference in sample characteristics, observed time period and possibly sampling bias as more than 10% of patients refused to participate in those studies for unknown reasons [7,20]. As far as the predictors of DHS use are concerned, studies among general population have identified a familiar pattern of DHS users: female, middle-aged or older, better educated and with higher income [8,13,16,21,22]. Such finding was similarly reported in most published studies among pre-surgical patients [23–26]. In the study carried out in medical wards in Israel, there was also a significant association between DHS use with female, higher education and higher income level [8]. In comparison, our study found that the women and study participants with higher education level were more likely to take DHS although this finding
Table 3 DHS consumed over previous 12 months. Type of DHS
DHS users (n = 42) n (%)
Number of DHS taken (n = 84) n (%)
Multivitamin and/or multimineral supplement Antioxidant vitamins B vitamin complex Single vitamin Vitamin C Vitamin A Vitamin E Single minerals Calcium Herbals/botanicals Traditional Chinese medicine Lingzhi Ginseng Other TCM Evening primrose oil Aloe vera Garlic Black seed oil Other herbalsa Food constituents and others Fish oil/omega-3 Glucosamine Othersb Amino acid Fibre
4 (9.5) 2 (4.8) 2 (4.8)
4 (4.8) 2 (2.4) 2 (2.4)
7 (16.7) 2 (4.8) 1 (2.4)
7 (8.3) 2 (2.4) 1 (1.2)
14 (33.3)
14 (16.7)
5 2 5 2 2 2 2 4
5 2 5 2 2 2 2 4
a b
(11.9) (4.8) (11.9) (4.8) (4.8) (4.8) (4.8) (9.5)
15 (35.7) 7 (16.7) 6 (14.3) 0 (0) 0 (0)
Other herbals: milk thistle, mushroom extract, Nopal cactus, traditional Malay medicine. Other food constituents: immune system enhance product, acidophilus, cod liver oil, enzyme product, plant sterol, royal jelly.
(6.0) (2.4) (6.0) (2.4) (2.4) (2.4) (2.4) (4.8)
15 (17.9) 7 (8.3) 6 (7.1) 0 (0) 0 (0)
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Fig. 1. Reasons given for not reporting DHS use to HCPs.
was not statistically significant. This can be due to their greater access to healthcare information [25] but this does not necessarily mean that they are able to correctly classify efficacy and safety of DHS [27]. We were, however, unable to compare the difference in income level between DHS users and non-users as almost half of the participants (47%) did not want to disclose their monthly household income. As for lifestyle characteristics, most cohort studies found that DHS users were more physically active and less likely to smoke regularly or drink alcohol [13–16]. Our findings were comparable with the study by Goldstein et al. [8]. We found that DHS consumption was significantly higher among non-smokers than smokers, possibly due to their higher health awareness although this cannot be verified within the scope of this analysis. There was, however, no statistically significant difference in the alcohol consumption and physical activity levels between DHS users and non-users. These differences could be explained by the differing criteria for classification of ‘alcohol user’ and ‘being physically active’. In general, DHS users are often observed to differ from nonusers by consuming more nutrient dense diets, i.e. higher in micronutrients as indicated by higher intake of fruit, vegetables and dairy products [16,21,28]. Our study is the first study that looked into the relationship between dietary characteristics and DHS use in patient population. We found that DHS users had significantly higher intake of fruit, milk and wholegrain bread, suggesting that they tend to make a healthier choice when compared with non-DHS users. However, there was no statistically significant difference in the consumption of cooked whole grains and vegetable between DHS users and non-users. The reasons could be due to different dietary assessment method used [29] and the variation in grouping of food. For example, in our study, both fruit and vegetables were examined separately whereas in the study by Robson et al., they were grouped together [30]. Our results suggest that most patients used DHS for general well-being which is consistent with societal trends toward increased autonomy for one’s health [31,32]. Nevertheless, we observed that some of the reasons for DHS use appeared to be related to disease prevention and treatment, which suggested that DHS are being taken with the same intent as for drugs [33]. When patients perceive DHS are safe and have added benefits, they are more likely to take them [34]. This study expands on previously reported disclosure rates of CAM/DHS to HCPs in Singapore [6,18]. Our findings are consistent with studies in other countries which reported low patient disclosure rates of DHS use to HCPs as well as poorly documented
inquiring by HCPs. While a Malaysian study found that less than 10% of herbal therapy users disclosed use to their physician [9], the study from Israel also reported that the medical team was unaware of DHS consumption in 77% of the cases. In cases whereby the medical team was aware of DHS use, it was due to patients volunteering the information themselves [8]. Similarly, Young et al. found that 74% of patients did not inform their physician about their DHS use and only 20% of patients’ charts had documented inquiring about DHS use [7]. Similar to those of other investigators [8,31,35], the main reason for non-disclosure was that ‘the doctor never asked’ and patients believed ‘it was not important for the doctor to know’ as the second most popular response. This lack of communication is an area of concern because we found that the main reason of non-disclosure was due to the lack of inquiry by HCPs who may then overlook the potential adverse drug–DHS interactions. In a survey of veteran outpatients taking prescription medications, 45% of DHS users had the potential for a drug–DHS interaction [36]. This is further exacerbated by patient’s belief that DHS are safe as they are ‘natural’ [37–39]. For instance, DHS users consumed more than two-fold the Recommended Dietary Allowance (RDA) for vitamin A and 17-fold for vitamin C on a daily basis without realizing the potential toxicity of mega supplements [40]. Numerous adverse effects and interactions attributed to DHS were based on case reports or high quality clinical trials. For example, cases of bleeding were reported with combined use of warfarin and fish oil [41], known to have anticoagulant effects. A prospective 5-year National Institutes of Health (NIH)-AARP Diet and Health Study showed an increased risk of prostate cancer with increased multivitamin use [42], while a recent 10-year prospective EPIC-Heidelberg cohort study demonstrated a statistically significant increased myocardial infarction risk among users of calcium supplements [43]. Our study has a number of limitations including the limited sample size and potential for recall bias. Estimates of frequency may be imprecise as convenience sampling instead of randomized sampling was used. Generalizability is limited by the fact that the patients enrolled were all hospitalized in the medical wards. Results may be different in other subgroups of patients such as surgical patients and possibly children. There is the possibility of self-selection bias in this study since information could not be obtained from non-respondents. However, the number of nonrespondents was only 5%. We also acknowledged that there is a wide range of DHS but we tried to include DHS more likely to have been consumed in our population.
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Nonetheless, the strength of this study is that all the patients enrolled were interviewed by a single dietitian with a standardized questionnaire which probably reduced the chance of variability and there was no language barrier during the interview. The definition of DHS was explicit while ratio of female to male patients was proportionate. The ethnic distribution was also representative of the local population. In conclusion, DHS users in our study were more physically active, less likely to smoke regularly or drink alcohol and had significantly higher intake of fruit, milk and wholegrain bread when compared to non-users. However, in view of the low disclosure rate of DHS, HCPs should be obliged to ask their patients, especially those with multiple co-morbidities on prescription medications about their DHS use. More studies are needed to determine if there is any relationship between DHS use and the disorders for which patients are admitted, and the potential adverse consequences from DHS–drug interactions. Conflicts of interest None disclosed. Layperson’s summary The use of dietary health supplement has increased considerably over the last decade in the general population. This phenomenon is even more worrisome in hospitalized patients due to their multiple co-morbidities and the potential interaction with medications. In our study, we found that up to 42% of our 100 patients surveyed were dietary health supplements users. They took more than one type of dietary health supplements at the same time and the most commonly consumed were fish oil, calcium, glucosamine and vitamin C. The reason of using dietary health supplements was mainly for general well being but some patients reported using it for disease prevention and treatment. More than half of the patients felt better after using dietary health supplements. Dietary health supplement users tend to have healthier lifestyle behaviours. They were less likely to smoke regularly and had significantly higher intake of fruit, milk and wholegrain bread when compared to non-users. However, we found that more than half of the patients did not disclose their use of dietary health supplements to the healthcare professionals. The main reason was that they were never asked and believed it was also not important to do so. This study highlights the level of dietary supplementation in patients admitted to the medical wards in an acute tertiary hospital. It is important for healthcare professionals to ask their patients about the use of dietary health supplements due to the potential adverse consequences from dietary health supplements–drug interactions. The authors wish to thank all study participants for their time and enthusiasm.
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PharmaNutrition journal homepage: www.elsevier.com/locate/phanu
Consumption of dietary health supplements among hospitalized patients at an acute tertiary Hospital Pay Wen Yong *, Lee Boo Tan, Yet Hua Loh Department of Dietetics, Singapore General Hospital, Singapore
A R T I C L E I N F O
PubChem classification: Fatty acids Omega-3 (PubChem CID: 56842239) Calcium carbonate (PubChem CID: 10112) Calcium citrate (PubChem CID: 54670067) Glucosamine (PubChem CID: 441477) Ascorbic acid (PubChem CID: 54670067) Keywords: Dietary health supplements Socio-demographic Lifestyle Dietary Dietary supplements-drug interactions Patient-healthcare professionals communication
A B S T R A C T
Dietary health supplements (DHS)-drug interaction risk may be greater in patients requiring numerous medications; yet little is known about DHS use in hospitalized patients. This study aims to characterize patients who use DHS, to evaluate the association between DHS use and socio-demographic, lifestyle and dietary habits; and to investigate whether users report DHS use to healthcare professionals (HCPs). Patients admitted to the medical wards, with age 21 years, medically stable, cognitively intact and conversant in English, Mandarin or Malay language were interviewed by a dietitian. Of the 100 patients surveyed, up to 42% were DHS users. They tend to be non-smokers (98%) (p = 0.02) with higher daily fruit intake of at least two servings (31%) (p = 0.02), daily milk intake of at least one cup (21%) (p = 0.03) and whole grain bread intake of at least once a day (31%) (p < 0.05) when compared with non-users. DHS were mostly used for general well being, disease prevention and treatment. However, more than half of the users did not inform HCPs about DHS use as they were not asked by HCPs. Our findings have important implication by raising concern for DHS–drug interaction given the low disclosure rate of DHS use and poor inquiring by HCPs. ã 2014 Elsevier B.V. All rights reserved.
1. Introduction Dietary health supplement (DHS)1 is the second most commonly used complementary and alternative medicine (CAM) in the general population [1,2]. It is defined as ‘a product that is used to supplement a diet, with benefits beyond those of normal nutrients, and/or to support or maintain the healthy functions of human body’ [3]. DHS contain one or more, or a combination of the following ingredients: a vitamin, a mineral, an amino acid, herbs or botanicals. The DHS use among adults In United States has increased from over 40% for the period 1988–1994 to over one-half for 2003–2006 period [4]. In Singapore, self-reported intakes from the 2004 National Nutrition Survey indicated that 34.3% of Singaporeans consume DHS. The most commonly consumed DHS were vitamin C, calcium, multi-vitamin and mineral supplements, botanical and animal products [5]. Despite the high rate of DHS use, many studies have found relatively low patient disclosure rate to their healthcare
* Corresponding author at: Block. 8 Level 1, Dietetics Department, Singapore General Hospital, Outram Road Singapore 169608, Singapore. Tel.: +65 63265293; fax: +65 63213594. E-mail addresses: [email protected], [email protected] (P.W. Yong), [email protected] (L.B. Tan), [email protected] (Y.H. Loh). 1 DHS: dietary health supplements. http://dx.doi.org/10.1016/j.phanu.2014.07.002 2213-4344/ ã 2014 Elsevier B.V. All rights reserved.
professionals (HCPs)2 [6–10]. This highlights the fact that patients may not be aware of the potential DHS-drug interaction [11]. In a 2005 position paper on fortification and nutritional supplement by the American Dietetic Association (ADA) now known as the Academy of Nutrition and Dietetics, it was stated that there is a greater risk of toxicity, drug or nutrient interaction and adverse reactions of concentrated nutrients in DHS compared with the nutrients in whole foods [12]. The risk may even be greater in patients with multiple medical conditions requiring numerous medications since about one in four prescription medication users also took a DHS [11]. Although several population studies have shown that DHS users generally have healthier lifestyle behaviours, better health status [13] and tend to consume more nutrient dense diets, i.e. low in energy and high in micronutrients [14–17], relatively little, however, is known about the socio-demographic, lifestyle, dietary characteristics and pattern of DHS consumption among hospitalized patients. A study by Goldstein et al. reported that DHS consumption is associated with higher income and non-smoking status [8], while a recent local study by Chow et al. reported that the independent predictors of traditional Chinese medicine (TCM) and DHS use were Chinese ethnicity, tertiary education and age less than 65 years [18].
2
HCPs: healthcare professionals.
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Therefore, in order to understand the spectrum of DHS use among hospitalized patients, this study aims to: (i) profile the characteristics of patients who use DHS, (ii) evaluate the association between DHS use and socio-demographic, lifestyle and dietary habits and (iii) investigate whether DHS users report the use of DHS to HCPs, their perceptions and pattern of DHS use. 2. Methods 2.1. Participants A cross-sectional survey was conducted in the medical speciality wards of a large tertiary hospital. The study population consisted of patients newly admitted to medical wards for the period November 2011 to January 2012. Convenience sampling was used. Eligibility criteria for study participants included: age 21 years and above, medically stable, cognitively intact, conversant in English, Mandarin or Malay language; or with primary caregiver present to answer the questions. After obtaining informed consent, patients were interviewed by a single dietitian using a standardized 40-item questionnaire. Concurrently, patients’ medical records were reviewed for medical diagnoses. This study was approved by the SingHealth Centralised Institutional Review Board. 2.2. Questionnaires The study adopted the definition of DHS by Health Sciences Authority [3]. Since no validated questionnaire was available, the questionnaire was initially developed based on literature review. It was tested on a group of individuals whereby feedback was gathered and the questions were adapted to ensure the appropriateness in our multiethnic patient population. It was available in the English language. There were five sections in the questionnaire: (i) Socio-demographic characteristics (age, gender, ethnic group,
educational level and monthly household income). (ii) Lifestyle behaviours (exercise, alcohol consumption and
smoking status). (iii) Dietary behaviours for the past 12 months: consumption frequency of milk, wholegrain bread, brown rice or other cooked whole grains, fruit and vegetables) adapted from Diet History Questionnaire version II from the National Institutes of Health, USA [19]. (iv) Report of DHS use to HCPs, perceptions about and pattern of DHS use. (v) Type of DHS consumed for at least 4 weeks in the past 12 months. Seven categories of common DHS were included, namely multi-nutrient supplements, single nutrient, mineral/ mineral combinations/trace elements, herbals or botanicals, amino acid, fibre supplements, food constituents and others (e.g. fish oil, glucosamine, probiotics, etc).
2.3. Statistical methods Descriptive analysis (e.g. mean, percentage) was used to determine the characteristics of study participants while Chisquare test was used to assess the association between DHS and patient’s socio-demographic, lifestyle and dietary behaviours. Student’s independent t-test (two-tailed) was used to analyse between-group differences (DHS users/non-DHS users). A p-value of <0.05 is considered statistically significant. Statistical analyses were carried out using SPSS version 17.0 (SPSS, Chicago).
3. Results 3.1. Socio-demographic and lifestyle characteristics A total of 100 patients were recruited into this study and the characteristics of the patients are shown in Table 1. In general, 42% of study population (n = 42) reported using DHS. Percentage of female patients who consumed DHS was 54.8%, slightly higher than the percentage of male patients (45.2%). Ethnic distribution of DHS users was 73.8% Chinese, 16.7% Malay and 9.5% Indian. This distribution was not significantly different from non-DHS users. Majority of the DHS users (64.3%) attained higher education, i.e. secondary level and above. There was a statistically significant difference in smoking status between DHS users and non-users. In the DHS users group, only 2.4% were smokers compared to 17.2% in the non-DHS users group (p = 0.02). For the other lifestyle characteristics, there were no significant differences between the two groups. While a larger proportion of DHS users did not smoke as much as one cigarette a day for as long as a year (97.6%) and did not drink alcohol over the past 12 months (90.5%), more than half (57.1%) also reported not doing any weekly exercise for more than 15 min during their free time. 3.2. Dietary habits and DHS use Dietary habits of patients in this study, particularly consumption of selected food items, were analysed. As shown in Table 2, DHS users were more likely than non-DHS users to report consumption of two to three servings of fruit per day (p = 0.02), at least one cup of milk per day (p = 0.03) and at least once a day of whole grain bread (p < 0.05).
Table 1 Socio-demographic and lifestyle characteristics of the study population. Characteristics (N = 100)
Age, years
DHS users (n = 42)
Non-DHS users (n = 58)
mean SD
mean SD
57.9 12.3 n (%)
55.8 15.8 n (%)
Gender Men 19 (45.2) Women 23 (54.8) Ethnic group Chinese 31 (73.8) Malay 7 (16.7) Indian 4 (9.5) Others 0 (0) Education Nil 3 (7.1) Primary school 12 (28.6) Secondary school 18 (42.9) Tertiary 9 (21.4) Monthly household income Refuse to disclose 22 (52.4) <$4000 11 (26.2) $4000–7999 6 (14.3) $8000 and above 3 (7.1) Exercise Yes 18 (42.9) No 24 (57.1) Alcohol consumption Yes 4 (9.5) No 38 (90.5) Smoking status* Yes 1 (2.4) No 41 (97.6) *
p = 0.02.
25 (43.1) 33 (56.9) 44 (75.9) 8 (13.8) 5 (8.6) 1 (1.7) 6 (10.3) 20 (34.5) 20 (34.5) 12 (20.7) 25 (43.1) 20 (34.5) 10 (17.2) 3 (5.2) 15 (25.9) 43 (74.1) 8 (13.8) 50 (86.2) 10 (17.2) 48 (82.8)
P.W. Yong et al. / PharmaNutrition 2 (2014) 135–140 Table 2 DHS use and consumption of selected food groups. Food group
DHS users (n = 42) n (%)
Non-DHS users (n = 58) n (%)
Fruit (all kinds, fresh, canned and frozen) 2–3 servings/day 13 (31.0) 7 (12.1) 29 (69.0) 51 (87.9) <2–3 servings/day Vegetables (all kinds, raw, cooked, canned and frozen) 2–3 servings/day 20 (47.6) 24 (41.4) <2–3 servings/day 22 (52.4) 34 (58.6) Milk At least 1 cup/day 9 (21.4) 4 (6.9) 33 (78.6) 54 (93.1) <1 cup/day Whole grain bread (whole wheat, rye and oatmeal) At least once a day 13 (31.0) 9 (15.5)
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(15.1%). In comparison, only 7.5% of patients cited the doctor or pharmacist as their source of information on DHS. p-value
3.4. Report of DHS use to HCPs Out of 42% (n = 42) of DHS users, 52% (n = 22) did not inform HCPs of their DHS use. The top two reasons for not informing were that ‘they were not asked by HCPs’ (36.4%) and ‘not important to report DHS use’ (31.8%) (Fig. 1).
p = 0.02
p = 0.54
4. Discussion p = 0.03
p < 0.05
p = 0.87
3.3. DHS consumption Up to 42% of patients (n = 42) surveyed were DHS users, and of these, half were taking more than one type of DHS at the same time. The types and number of DHS consumed by participants for at least 4 weeks over the previous 12 months are listed in Table 3. The top four commonly used DHS were fish oil/v – 3(35.7%), calcium (33.3%), glucosamine (16.7%) and vitamin C (16.7%). Most of the patients took DHS for general well-being reason (64.3%) as well as for disease prevention and treatment purpose (21.4%). In contrast, the two major reasons given by non-users were ‘worried about safety or side effects of DHS’ (32.8%) and ‘I am eating well’ (24.1%). Majority of the DHS users (73.8%) perceived that taking DHS made them feel better while 23.8% felt that there was no difference and only one DHS user indicated worsening effect with DHS use. Friend/relative and family members (children and/or spouse) (56.6%) were the most common source of information on DHS followed by health food retailer or salesperson
To the best of our knowledge, the present study is the first investigation into DHS use and its relationship with demographics, lifestyle and dietary characteristics among hospitalized patients. We found that more than 40% of the total 100 patients admitted to the medical wards took DHS for at least 4 weeks during the past year. Our results most closely match that of a previous finding among multi-ethnic hospitalized medical patients in Asia [9]. In that study, 42% reported using herbs within the past year. However, when compared with other Western studies, those reports showed higher rates of 60–80% of DHS use in patients admitted to the general internal medicine or geriatric services [7] and the internal medicine resident teaching clinics [20] respectively. This could be explained by the difference in sample characteristics, observed time period and possibly sampling bias as more than 10% of patients refused to participate in those studies for unknown reasons [7,20]. As far as the predictors of DHS use are concerned, studies among general population have identified a familiar pattern of DHS users: female, middle-aged or older, better educated and with higher income [8,13,16,21,22]. Such finding was similarly reported in most published studies among pre-surgical patients [23–26]. In the study carried out in medical wards in Israel, there was also a significant association between DHS use with female, higher education and higher income level [8]. In comparison, our study found that the women and study participants with higher education level were more likely to take DHS although this finding
Table 3 DHS consumed over previous 12 months. Type of DHS
DHS users (n = 42) n (%)
Number of DHS taken (n = 84) n (%)
Multivitamin and/or multimineral supplement Antioxidant vitamins B vitamin complex Single vitamin Vitamin C Vitamin A Vitamin E Single minerals Calcium Herbals/botanicals Traditional Chinese medicine Lingzhi Ginseng Other TCM Evening primrose oil Aloe vera Garlic Black seed oil Other herbalsa Food constituents and others Fish oil/omega-3 Glucosamine Othersb Amino acid Fibre
4 (9.5) 2 (4.8) 2 (4.8)
4 (4.8) 2 (2.4) 2 (2.4)
7 (16.7) 2 (4.8) 1 (2.4)
7 (8.3) 2 (2.4) 1 (1.2)
14 (33.3)
14 (16.7)
5 2 5 2 2 2 2 4
5 2 5 2 2 2 2 4
a b
(11.9) (4.8) (11.9) (4.8) (4.8) (4.8) (4.8) (9.5)
15 (35.7) 7 (16.7) 6 (14.3) 0 (0) 0 (0)
Other herbals: milk thistle, mushroom extract, Nopal cactus, traditional Malay medicine. Other food constituents: immune system enhance product, acidophilus, cod liver oil, enzyme product, plant sterol, royal jelly.
(6.0) (2.4) (6.0) (2.4) (2.4) (2.4) (2.4) (4.8)
15 (17.9) 7 (8.3) 6 (7.1) 0 (0) 0 (0)
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P.W. Yong et al. / PharmaNutrition 2 (2014) 135–140
Fig. 1. Reasons given for not reporting DHS use to HCPs.
was not statistically significant. This can be due to their greater access to healthcare information [25] but this does not necessarily mean that they are able to correctly classify efficacy and safety of DHS [27]. We were, however, unable to compare the difference in income level between DHS users and non-users as almost half of the participants (47%) did not want to disclose their monthly household income. As for lifestyle characteristics, most cohort studies found that DHS users were more physically active and less likely to smoke regularly or drink alcohol [13–16]. Our findings were comparable with the study by Goldstein et al. [8]. We found that DHS consumption was significantly higher among non-smokers than smokers, possibly due to their higher health awareness although this cannot be verified within the scope of this analysis. There was, however, no statistically significant difference in the alcohol consumption and physical activity levels between DHS users and non-users. These differences could be explained by the differing criteria for classification of ‘alcohol user’ and ‘being physically active’. In general, DHS users are often observed to differ from nonusers by consuming more nutrient dense diets, i.e. higher in micronutrients as indicated by higher intake of fruit, vegetables and dairy products [16,21,28]. Our study is the first study that looked into the relationship between dietary characteristics and DHS use in patient population. We found that DHS users had significantly higher intake of fruit, milk and wholegrain bread, suggesting that they tend to make a healthier choice when compared with non-DHS users. However, there was no statistically significant difference in the consumption of cooked whole grains and vegetable between DHS users and non-users. The reasons could be due to different dietary assessment method used [29] and the variation in grouping of food. For example, in our study, both fruit and vegetables were examined separately whereas in the study by Robson et al., they were grouped together [30]. Our results suggest that most patients used DHS for general well-being which is consistent with societal trends toward increased autonomy for one’s health [31,32]. Nevertheless, we observed that some of the reasons for DHS use appeared to be related to disease prevention and treatment, which suggested that DHS are being taken with the same intent as for drugs [33]. When patients perceive DHS are safe and have added benefits, they are more likely to take them [34]. This study expands on previously reported disclosure rates of CAM/DHS to HCPs in Singapore [6,18]. Our findings are consistent with studies in other countries which reported low patient disclosure rates of DHS use to HCPs as well as poorly documented
inquiring by HCPs. While a Malaysian study found that less than 10% of herbal therapy users disclosed use to their physician [9], the study from Israel also reported that the medical team was unaware of DHS consumption in 77% of the cases. In cases whereby the medical team was aware of DHS use, it was due to patients volunteering the information themselves [8]. Similarly, Young et al. found that 74% of patients did not inform their physician about their DHS use and only 20% of patients’ charts had documented inquiring about DHS use [7]. Similar to those of other investigators [8,31,35], the main reason for non-disclosure was that ‘the doctor never asked’ and patients believed ‘it was not important for the doctor to know’ as the second most popular response. This lack of communication is an area of concern because we found that the main reason of non-disclosure was due to the lack of inquiry by HCPs who may then overlook the potential adverse drug–DHS interactions. In a survey of veteran outpatients taking prescription medications, 45% of DHS users had the potential for a drug–DHS interaction [36]. This is further exacerbated by patient’s belief that DHS are safe as they are ‘natural’ [37–39]. For instance, DHS users consumed more than two-fold the Recommended Dietary Allowance (RDA) for vitamin A and 17-fold for vitamin C on a daily basis without realizing the potential toxicity of mega supplements [40]. Numerous adverse effects and interactions attributed to DHS were based on case reports or high quality clinical trials. For example, cases of bleeding were reported with combined use of warfarin and fish oil [41], known to have anticoagulant effects. A prospective 5-year National Institutes of Health (NIH)-AARP Diet and Health Study showed an increased risk of prostate cancer with increased multivitamin use [42], while a recent 10-year prospective EPIC-Heidelberg cohort study demonstrated a statistically significant increased myocardial infarction risk among users of calcium supplements [43]. Our study has a number of limitations including the limited sample size and potential for recall bias. Estimates of frequency may be imprecise as convenience sampling instead of randomized sampling was used. Generalizability is limited by the fact that the patients enrolled were all hospitalized in the medical wards. Results may be different in other subgroups of patients such as surgical patients and possibly children. There is the possibility of self-selection bias in this study since information could not be obtained from non-respondents. However, the number of nonrespondents was only 5%. We also acknowledged that there is a wide range of DHS but we tried to include DHS more likely to have been consumed in our population.
P.W. Yong et al. / PharmaNutrition 2 (2014) 135–140
Nonetheless, the strength of this study is that all the patients enrolled were interviewed by a single dietitian with a standardized questionnaire which probably reduced the chance of variability and there was no language barrier during the interview. The definition of DHS was explicit while ratio of female to male patients was proportionate. The ethnic distribution was also representative of the local population. In conclusion, DHS users in our study were more physically active, less likely to smoke regularly or drink alcohol and had significantly higher intake of fruit, milk and wholegrain bread when compared to non-users. However, in view of the low disclosure rate of DHS, HCPs should be obliged to ask their patients, especially those with multiple co-morbidities on prescription medications about their DHS use. More studies are needed to determine if there is any relationship between DHS use and the disorders for which patients are admitted, and the potential adverse consequences from DHS–drug interactions. Conflicts of interest None disclosed. Layperson’s summary The use of dietary health supplement has increased considerably over the last decade in the general population. This phenomenon is even more worrisome in hospitalized patients due to their multiple co-morbidities and the potential interaction with medications. In our study, we found that up to 42% of our 100 patients surveyed were dietary health supplements users. They took more than one type of dietary health supplements at the same time and the most commonly consumed were fish oil, calcium, glucosamine and vitamin C. The reason of using dietary health supplements was mainly for general well being but some patients reported using it for disease prevention and treatment. More than half of the patients felt better after using dietary health supplements. Dietary health supplement users tend to have healthier lifestyle behaviours. They were less likely to smoke regularly and had significantly higher intake of fruit, milk and wholegrain bread when compared to non-users. However, we found that more than half of the patients did not disclose their use of dietary health supplements to the healthcare professionals. The main reason was that they were never asked and believed it was also not important to do so. This study highlights the level of dietary supplementation in patients admitted to the medical wards in an acute tertiary hospital. It is important for healthcare professionals to ask their patients about the use of dietary health supplements due to the potential adverse consequences from dietary health supplements–drug interactions. The authors wish to thank all study participants for their time and enthusiasm.
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