Vitamin D is a fat-soluble vitamin, essential for the regulation of calcium and phosphorus which supports cellular processes, bone mineralization, and neuromuscular function. It is also important for the functioning of several other body systems, including the immune, cardiovascular, and reproductive systems. Vitamin D deficiency is a global public health problem affecting all regions of the world, especially the Middle East. In addition to skeletal and dental problems, Vitamin D deficiency has been linked to a long list of diseases including some types of cancer, autoimmune diseases, allergic diseases, inflammatory bowel diseases, cardiovascular diseases, hypertension, diabetes, and several others. On the other hand, an excess intake of Vitamin D (hypervitaminosis D) can cause hypercalcemia and calcium deposition in a number of soft tissues in the body.
As very few food items are naturally rich in Vitamin D, and Vitamin D fortified foods are often not adequately consumed, exposure to the sun remains the most important natural source of Vitamin D. Despite the abundance of sunlight in Saudi Arabia, it has been estimated that approximately 80% of different Saudi populations have Vitamin D deficiency (defined as 25-hydroxyVitamin D <50 nmol/l). In addition, Vitamin D deficiency is notably much higher in females than males, probably due to some cultural and religious reasons. These findings highlight the critical need to raise public awareness of the problem and the means to prevent it. A number of studies in Saudi Arabia have recently examined the awareness of Vitamin D and its deficiency in children and adolescents, female college students, and hospital patients. In addition, primary care physicians and mothers have been examined for their awareness of Vitamin D supplementation for infants. However, none of the previous studies have examined the awareness and intake of Vitamin D in adults at the primary care setting. Moreover, the association between awareness and intake of Vitamin D was never the focus of these studies. The objective of the current study was to evaluate the awareness and intake of Vitamin D and their associations in adult males and females attending primary care centers in the Qassim region.
Materials and Methods
A cross-sectional study was done between June 2016 and August 2016 in patients who presented at 6 primary care centers in the Qassim region, Saudi Arabia. Ethical approval was obtained from the ethical committee of Qassim College of Medicine, Saudi Arabia. Informed written consent was obtained from all the participants.
A total 500 primary care patients were recruited using convenience sampling while they waited for their primary care appointments. The minimum sample size needed for the conduct of this research was calculated using the following statistical formula: n = 4P (1-p)/ME2 where n represented the sample size needed, P the prevalence of Vitamin D deficiency in Qassim region (according to the previous study in the same region), and ME reflected the margin of error allowed. Both patients and their family members who agreed to participate in the study were included. Completion of the questionnaire after an explanation of the objectives of the study had been given was taken as consent to participate in the study. Adult males and females, irrespective of the reason for attending the primary care center, were included. Excluded were those aged <18 years and those with severe mental or sensory disorders that affected convenient interactions.
Data were collected using a self-administered study questionnaire covering the following sections; demographics, medical history, awareness of Vitamin D, and intake of Vitamin D. The questionnaire developed after a review of similar studies was revised by a consultant dermatologist. A pilot study was conducted on 10 volunteers to ensure clarity and appropriateness of the questions and estimate the time required for completion of the questionnaire. Reliability coefficient was, however, not calculated.
Awareness of Vitamin D was defined as the ability to positively answer 4 questions about “ever hearing” of Vitamin D, awareness of the importance of Vitamin D for health, awareness of the symptoms of Vitamin D deficiency, and awareness of at least one source of Vitamin D, including diet and exposure to the sun. The intake of Vitamin D was defined as actual intake of at least two sources of Vitamin D, including sun exposure, Vitamin D-rich diet, and Vitamin D supplements.
Data were presented as frequencies and percentages. Demographic characteristics and medical history of the groups defined by the study outcomes were compared; overall awareness of Vitamin D and intake of Vitamin D. Chi-square or Fisher exact test, as appropriate, was used to detect significant differences. The association of overall awareness and the intake of Vitamin D, overall and stratified by gender, were done using Chi-square and Mantel–Haenszel Chi-square. All P values were two-tailed. P < 0.05 was considered as statistically significant. Statistical Package of the Social Science software (release 23.0, IBM Corp., Armonk, NY, USA) was used for all statistical analyses.
A total of 500 study participants were included in the current analysis. Demographic characteristics and medical history of the study participants are shown in Table 1. The most frequent age of the participants was between 26 and 50 years (49.4%), followed by ≤25 years (46.8%); very few were >50 years (3.8%). Approximately 54.6% of the participants were male and 57.8% were graduates. Approximately 18.1% of the female participants were either pregnant or breastfeeding. Approximately 41.8% of the participants had been told previously that they were Vitamin D deficient. History of Vitamin D deficiency was more frequent in females than males (55.1% and 30.8%, P < 0.001). Only 6.2% of the participants had a history of Crohn's disease, ulcerative colitis, or celiac sprue. Approximately 27.2% of the participants had a history of diarrhea in the previous 2 weeks.
The awareness of Vitamin D is shown in Table 2. The majority of the participants had heard of Vitamin D (91.4%) and believed in its importance for health (92.8%). Close to three-fourths (72.6%) of the participants were aware of the symptoms of Vitamin D deficiency such as tiredness, low mood, muscle, and bone pain. Approximately 81.4% and 70.4% of the participants were able to indicate sun exposure and diet (respectively) as sources of Vitamin D, with approximately 64.0% of them identifying both sources, and 87.8% mentioned at least one source. Family and friends (28.8%) as well as physicians (25.6%) were the most common sources of their information, while school (9.4%) and books (8.0%) were the least common sources of information about Vitamin D. As shown in Figure 1, approximately 65.8% of the participants had heard of Vitamin D, were aware of its importance, aware of the symptoms of its deficiency, and aware of at least one Vitamin D source.
The intake of Vitamin D is shown in Table 3. Approximately half (51.2%) of the participants reported eating Vitamin D-rich foods such as milk, oily fish, and eggs. The majority (83.5%) of the participants drank 1 or 2 cups of milk every day. Only 18.8% of the participants took Vitamin D supplements and 19.6% took multivitamins. More than half (57.2%) of the participants reported that they had exposed their faces, arms, or legs (at every opportunity) to sunlight within the last year. This was <5 min in 43.0% of the participants and between 5 and 15 min in 30.4% of the participants. Only 17.2% of the participants used sunscreen when they were exposed to sunlight. As shown in Figure 2, out of the three common sources of Vitamin D (diet, sun exposure, and supplements), 19.2% of the participants took none of them. On the other hand, 80.8% had at least one source, 41.2% had at least two sources, and only 5.2% had all the three sources.
The associations of patients' characteristics with both awareness of and intake of Vitamin D are shown in Table 4. The overall awareness [Figure 1] was significantly higher among the middle-aged compared to other age groups (76.9% vs. 54.9%, P < 0.001), females compared to males (78.9% vs. 54.9%, P < 0.001), graduates compared to nongraduates (71.3% vs. 58.3%, P = 0.003), and those with a history of compared to those with no previous history of Vitamin D deficiency (83.7% vs. 52.9%, P < 0.001). The intake of at least two sources of Vitamin D was significantly higher among males than females (85.7% vs. 74.9%, P = 0.002). As shown in Figure 3, this was caused by the lower sun exposure in females than males (41.9% vs. 70.0%, P < 0.001). Table 4 shows also marginally significant (P > 0.05 but < 0.010) trends of higher Vitamin D intake in pregnancy and breastfeeding (85.4% vs. 72.6%, P = 0.087) and in the case of no previous history of Vitamin D deficiency (83.5% vs. 77.0%, P = 0.070).
As shown in Figure 4, there was a significant association between overall awareness of Vitamin D and the intake of at least two sources of Vitamin D for all the included participants, with participants who were aware, having a higher intake (45.0% vs. 33.9%, P = 0.012). However, when the same association was repeated by gender, it was stronger and more significant in males (57.3% vs. 33.3%, P < 0.001) but nonsignificant in females (34.6% vs. 35.4%, P = 0.920).
The current study revealed that approximately two-thirds of the participants had heard of Vitamin D, were aware of its importance, of the symptoms of Vitamin D deficiency, and aware of at least one Vitamin D source. It is unrealistic to make a comparison of the current finding with the data previously reported in Saudi Arabia since the populations examined, outcome of interest, and tools used in the studies are different. Actually, one of these studies used a qualitative approach in studying the awareness. Nevertheless, individual awareness items in the current study are probably better than seen in previous studies in Saudi Arabia. For example, those who had heard of Vitamin D were approximately 90% in the current study compared with 70% of adult patients attending different clinics in the Western region and approximately 30%–64% of healthy children and adolescents in Riyadh. Similarly, those who were aware of sun exposure and/or diet as sources of Vitamin D were 88% in the current study compared with 51%–76% in previous studies. The better awareness of Vitamin D observed in the current study may be due to the higher educational level of the participants (more than half of our participants were graduates) and the more health-oriented primary care population than the populations, including children and adolescents, examined in previous studies. As expected, awareness in the current study was higher in the more educated participants. The better awareness observed in the current study in those who had a history of Vitamin D deficiency may be the result of greater exposure to information while seeking medical advice. In similar previous studies, relatives/friends and physicians were the main source of information on Vitamin D. However, the finding also highlights the minor role played by schools and the media in raising public awareness on Vitamin D.
Approximately 41.8% of our participants reported a positive history of Vitamin D deficiency. Certainly, we did not measure the levels of Vitamin D in our participants to confirm the actual prevalence of Vitamin D deficiency. As expected, the history of Vitamin D deficiency was more frequent in females than males. A recent meta-analysis of 13 studies done over the last 10 years in more than 24000 Saudi adults, children, and pregnant women showed that the prevalence of Vitamin D deficiency ranged between 50% and 95% with an average of 81%. Interestingly, all the studies included in this meta-analysis and reported gender-specific prevalence showed much higher prevalence of Vitamin D deficiency in females than males, even in childhood and adolescence.
The current study showed inadequate intake of Vitamin D. The most common source of Vitamin D in our participants was exposure to the sun (57.2%), followed by Vitamin D-rich foods (51.2%) and supplements (18.8%). Actually, only 5.2% took all the three sources and 41.2% had at least two sources. The finding is not surprising given the high Vitamin D deficiency and lower intake previously reported in Saudi Arabia. However, some previous studies could not confirm the association between the intake of some Vitamin D sources (especially dietary sources) and the presence of Vitamin D deficiency. As expected, the intake of Vitamin D in the current study was lower in females than males because of lower sun exposure rather than dietary sources or supplementations. The lower exposure of Saudi females to the sun has been documented before, even among children. This has been linked to cultural, lifestyle, and religious reasons that limit outdoor activities for women and demand the wearing of complete body cover usually of black material when in public. Besides, nongender specific factors in Saudi Arabia such as very hot weather that limit outdoor activities and the generally dark skin that limit the penetration of sunlight contribute to the problem of Vitamin D deficiency in Saudi Arabia.
The current finding showed awareness associated with Vitamin D intake in males but not females. The inability to translate awareness into action exhibited by females in the current study may be explained again by the same cultural, lifestyle, and religious reasons that limit sun exposure of females compared with males. Since these reasons are difficult to modify and since supplementation was very low in both genders, the current findings further highlight the critical importance of Vitamin D supplementation, especially in Saudi females and other at-risk groups. In support of this recommendation, we note that <20% of the participants in this study were taking Vitamin D supplementations or multivitamins. Furthermore, stricter regulations to ensure that dairy products, cereals, and orange juice are fortified may also be required in Saudi Arabia to counter the negligible dietary intake of Vitamin D.
To the best of our knowledge, the current study is the first to report gender-specific associations between awareness and intake of Vitamin D. This was done in a relatively large sample size recruited from 6 primary care centers. Nevertheless, there are some limitations albeit minor. Since the study design involved self-reported cross-sectional data collection, causation cannot be confirmed. In addition, the convenience sampling used in recruiting our participants may limit the generalization of findings. However, we believe that the findings add to the field of Vitamin D research in Saudi Arabia.
We are reporting a relatively good awareness, but low intake of Vitamin D in a group of adult males and females at a primary care setting. The awareness was associated with Vitamin D intake in males but not in females, mainly because of lower sun exposure in females than males. As supplementation was very low in both genders, and since cultural factors that limit females' exposure to the sun are not easily modifiable, the current findings further highlight the critical importance of Vitamin D supplementation, especially in females and other groups at risk in Saudi Arabia. In addition, there is a need to encourage schools and the media in their role in raising public awareness of Vitamin D.
There could be confounding factors in this study [Tables 3 and 4]. Moreover, it was unfortunate that multivariate analysis was not attempted. Certainly, the method used for the assessment of Vitamin D intake was subjective [Table 3]. This subjectivity may have led to some bias in the quantification of this variable despite all efforts by the investigators to avoid this. The measurement of awareness was done in primary health-care settings and so may not reflect the awareness in the general population.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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