In the recent years, the use of dietary supplements has increased worldwide. According to the 1994 United States (US) Dietary Supplement Health and Education Act, a dietary supplement is defined as a product in the form of a pill, a capsule, a tablet, or a liquid containing one or more dietary ingredients (e.g., vitamins, minerals, herbs, amino acids, or other botanicals) that is intended to be taken orally as a nutritional supplement. Sales of these supplements have led to significant commercial activity, with an estimated total expenditure of US$ 36.7 billion in the US in 2014; of which US $14.3 billion was spent on vitamin/mineral supplements.
Dietary supplements are used extensively worldwide. In a previous study, 48.8% of the US population were found to have used dietary supplements between 2007 and 2010, and 48% and 56% of men and women, respectively, without chronic diseases had consumed multivitamin supplements on a weekly basis. A US national health survey found that 34% of children and adolescents took vitamin and mineral supplements, even though they may not have been medically indicated for them. Furthermore, populations in other developed countries report the average rate of multivitamin supplement usage as 20%–30% or higher. In Canada, this rate was 40.1%, while in Japan, the overall rate was 32%. In South Korea, more than 62% of adults reported using dietary supplements; 14% and 9% of them had used multivitamins and Vitamin C, respectively. A public survey conducted in India reported that 68.3% of the participants took multivitamin supplements.
Despite the popularity of supplements, few studies have documented their use by college students, who tend to be young and highly educated, and therefore, may exhibit usage patterns different from those of the general population. In a study conducted at five US universities between 2009 and 2010, college students appeared more likely than the general population to use supplements, and many students reported the weekly use of multiple types of supplements. Specifically, 66% of college students reported taking supplements. Of these, 42% took multivitamin and mineral supplements and 18% took Vitamin C supplements. Among a population of students in Malaysia, 43% took supplements, while in India, 49.6% of health science students reported using supplements, most commonly multivitamins, Vitamin C, and Vitamin B complex. Prevalence rate of 27.4% of supplement use was reported in Jordan and 42% by South African students; a study of medical college students in Nigeria found that approximately 86% used dietary supplements, mostly Vitamin C and multivitamins.
General studies on the use of supplements in the Arab world are very few, and there are hardly any Saudi studies on vitamin and mineral supplement use. However, there is report of an increased usage of supplements in the general population of the Gulf countries. In Qatar, 49.6% of college students reported taking at least one nutritional or herbal supplement at some point in their life, and 56.2% of these students had ingested vitamins and minerals. A study of students at Ajman University in the United Arab Emirates reported that 39% took dietary supplements.
Several studies have evaluated the association between the use of vitamin and mineral supplements and student characteristics including gender, physical activity, smoking, and socioeconomic and marital status. In general this was found to be higher in females and those with a higher monthly income. Furthermore, people with healthier lifestyles were more likely to take vitamin and mineral supplements. It has been found that physically active people and nonsmokers consume more supplements than others. The Qatari study found no significant association between marital status and the use of supplements.
Few reports have evaluated the general use of supplements in the Saudi population. One of these studies conducted along the northern border of Saudi Arabia found that more than 62% of the study population had taken vitamin supplements. Furthermore, a study involving professional athletes in Saudi Arabia reported that 52% of the respondents took multivitamin supplements, particularly Vitamin C (82.6% of supplement users). Another study that targeted Saudi Arabian adolescents found that the rate of dietary supplement usage was as high as 59.4%.
To the best of our knowledge, no published study had dealt with the use of supplements by college students in the Eastern Province of Saudi Arabia. Furthermore, since previous studies had reported higher rates of supplement use in females, the present study was designed with the aim of measuring the prevalence of the use of vitamin and mineral supplements by female college students at Imam Abdulrahman Bin Faisal University (IAU) in Dammam, Saudi Arabia. It was also to determine the characteristics associated with supplement consumption in this population.
Materials and Methods
This cross-sectional study was conducted between September and November 2016. The target population comprised all female medical students at different levels. The total number of students contacted was 620 including first preparatory year students and 2nd-year and 4th-year medical students. Data were collected using a self-administered questionnaire, developed by the researcher based on the tools of previous studies, and after a review of current related literatures. The opinions of three experts were sought and obtained on content validity. A pilot study of 25 medical students not included in the main sample was conducted to review the clarity and applicability of the questionnaire. A Cronbach's alpha test of reliability yielded a value of >0.748.
The questionnaire consisted mainly of two sections. The first section was on demographic data and lifestyle of the students. In this section, physical activity was categorized as 1 = regular exercise 3 times a week or more, 2 = occasional exercise, and 3 = not at all. In addition, smoking status was categorized as 1 = regular smoker, 2 = social smoker (only smoke cigarettes on occasions such as going out with friends and weddings), 3 = I tried smoking, but I did not like it, 4 = ex-smoker, and 5 = never smoked a cigarette in my life.
The second section was about supplement use.
Ethical approval for this study was obtained from the research committee of the Family Medicine joint residency program in the Eastern Province of Saudi Arabia, and the institutional review board of IAU. The purpose of the study was explained to the students, who also received reassurance that their involvement in the study would have no adverse repercussions. Informed written consent was obtained from all respondents prior to study, and participants were given the option to refuse to participate. All information obtained from questionnaires was kept confidential.
Data coding, entry, and statistical analysis were done using Statistical Package for the Social Sciences Version 16.0 (SPSS Inc. Released 2007. SPSS for Windows, Version16.0. Chicago). Statistical significance was set at P < 0.05. Chi-square test was used to verify an association between supplement usage (current, previous, or never) and sociodemographic characteristic categories as well as smoking and exercise habits and to detect a difference in the distribution of those characteristics at three study levels (Monte Carlo statistical technique and Fisher's exact test were used if more than 20% of cells had an expected count of <5).
A backward logistic regression analysis was done to identify independent factors associated with supplement use. Here, factors with an alpha = 0.05 were added, and those with an alpha = 0.1 were removed. The dependent variable was supplement use, which was coded as ever used, 1 or never used, 0. The independent variables were student year ( first, second, or fourth), marital status (single or married), family monthly income (<5000 SR, 5000–15000 SR, or more than 15,000 SR), physical exercise (never, regular, or occasional), and smoking status (never or ever).
All students (620) were approached; of these, 474 students completed the questionnaires. The response rate was 76.5%. Their ages ranged from 17 to 22 years, with an average of 18.9 ± 1.24 years. Table 1 describes student characteristics; 90.3% of students were single and more than half (53%) of them reported that they belonged to high-income families (≥15000 SR). Only 10.3% of the students reported that they had a habit of regular exercise. Notably, 4th-year students significantly more frequently reported a higher family monthly income and a habit of regular exercise, compared with the other students. Only 0.4% of students reported a regular smoking habit, whereas 1.3% were social smokers, 3.8% had tried smoking, and 0.4% were ex-smokers, but the vast majority (94.1%) had never smoked, with no difference among the different academic years.
Regarding the prevalence of the use of vitamin and mineral supplements, 44.6% of the participants used supplements; 24.1% had currently used supplements and 20.5% had previously used supplements. However, 55.4% had never taken supplements [Figure 1]. Vitamin D was the most common supplement taken by our population (50.3%), followed by multivitamins (41.3%), iron (36%), and Vitamin C (27.1%). Zinc (14.7%) and Vitamin B complex (14.6%) were the supplements least frequently taken [Figure 2].
Notably, the use of supplements correlated significantly with the student year: approximately 33% of the 4th-year students were current users, compared with only 21% of the 1st-year students (P < 0.032). Furthermore, students with the habit of regular exercise were more likely to take supplements (38.8%), and this association was statistically significant among those who had previously taken supplements and exercised occasionally (P < 0.015). Furthermore, the majority of the students with higher income took supplements (a total of 53.1%); among them, 29.1% were current users, a higher proportion than what was observed among students with lower income. This association of monthly income with supplement use was statistically significant (P < 0.038). By contrast, supplement use was not associated significantly with marital status or smoking status [Table 2].
A logistic regression model identified the following factors as having statistically significant associations with the use of supplements: with reference to high family income (the most common category), those of intermediate income used almost 35% less supplements (odds ratio [OR] [95% confidence interval (CI) = 0.651 (0.429, 0.988)]), and those with the habit of regular exercise habit took about twice as many supplements (OR [95% CI] = 2.152 [1.045, 4.433]) (reference: no exercise) [Table 3].
The present study found that the use of vitamin and mineral supplement was common among the participating university students. Specifically, 44.6% of the participants had taken vitamin and mineral supplements at some point and 24% of them currently took supplements. This prevalence was lower than the reported prevalence among female college students in Qatar (56.5%) and higher than the rates reported in Jordan (30.2%). Vitamin D was the most common supplement taken by the study participants. Earlier studies in Malaysia, India, Jordan, and Tehran identified multivitamins, multivitamin/minerals, and Vitamin C as the most commonly used supplements. However, several previous studies conducted in the Eastern Province of Saudi Arabia corroborated the prevalence of Vitamin D deficiency in the population. One such study, conducted by Elsammak et al., observed marked deficiencies in the serum Vitamin D levels of both male and female blood donors. Another study, conducted by Al-Elq, observed a very high prevalence of Vitamin D deficiency in medical students (96.0%). However, it is not known whether the high use of Vitamin D supplements in this study had any association with the previously observed high prevalence of Vitamin D deficiency.
The finding that students with a high family income were more likely to use supplements endorse the findings of other studies conducted in Jordan, Malaysia, Korea, and Canada. Furthermore, the finding that participants who had a habit of regular exercise were more likely to take supplements was similar to the results of other studies. One explanation given by a Canadian study was that people who exercised frequently possibly used supplements to increase their energy levels and improve athletic performance.
This study which explored the use of supplements by female college students had some notable limitations. First, the study involved only female medical students at one university, and therefore, may not be representative of all Saudi medical students. Second, a better response rate could reduce the nonresponse bias and yield a more accurate representation of the prevalence of the use of supplements.
This study was the first to provide data on the use of vitamin and mineral supplements by college students in the Eastern Province of Saudi Arabia. Notably, the prevalence of usage was relatively high, and Vitamin D was the most frequently used supplement. Furthermore, regular physical exercise and a high family income were found to be associated significantly with a higher use of supplements.
It is crucial to assess the knowledge of users about supplements efficacy, side effects and supplement-drug interaction in future studies. In addition, using qualitative method to evaluate the participants' views on the consumption of supplement is recommended. Moreover, it is recommended that further studies be undertaken to explore the use of supplements by both genders in the general population.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
The authors acknowledge the help of the family medicine faculty members of IAU who helped in validation of the questionnaire contents. Furthermore, the effort of Dr. Reem AlShamlan, Dr. Leenah Turkistani, Dr. Ranya Sabri, Dr. Abeer AlShamlan, and Dr. Nada AlZamil who participated in data collection is highly appreciated.
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