ABSTRACT
Dehydration is linked to worse cognitive functions and preference for beverages that are linked to obesity and other health conditions. Saudi Arabia’s hot climate can exacerbate these effects and it is important to ensure that children in the region understand the benefits of adequate water intake. To evaluate secondary school student perceptions and practices regarding water intake, investigate how water intake is related to BMI and school performance, and compare international schools to national schools. This cross-sectional study surveyed understanding and practices relating to water intake of national and international secondary school students using a questionnaire based on a random selection of schools and students. One-hundred and sixty-two students from international schools (I) and 157 from national schools (N) responded. Most were aged 16 and 17 years old (I:61.1%, N:76.5%, p = .005). The average BMI of all students was 24.9 ± 6.013 (I:23.6 ± 4.658, N:26.1 ± 6.931, p < 0.001). Students understood beverages do not replace water intake (I:80.2%, N:75.8%, p = .337) and preferred water when thirsty (I:77.8%, N:75.2%, p = .549). However, water consumption was low with more than 50% of students drinking less than 1500 ml a day (I:54.3%, N:70.7%, p = .002). A positive correlation between BMI and water intake was observed only among international school students. Students have inadequate water intake despite understanding the importance of hydration. There are some differences between international school students and national school students that can be attributed to the availability and sources of water, though other factors cannot be excluded.
KEYWORDS: Water intake, BMI, secondary school students, academic performance
1. Introduction
Water is considered to comprise two-thirds of our body fluids and is essential to sustain life and to maintain all functions of the human body. Sufficient water intake is important to aid food ingestion and digestion, regulate body temperature, and maintain adequate blood circulation which carries nutrients and oxygen to cells. Chronic dehydration has adverse effects on cognitive and physical performance, as well as on general health [1]. Without any water intake, we cannot survive for more than a few days [2].
The amount of water intake required depends on a variety of factors, including age, body size, metabolism, physical activity and environmental conditions such as humidity and temperature [3]. As such, it is challenging to define an adequate intake of total water (from all sources), but it is estimated to range between 2700 to 3700 in adults [3]. Despite this scientific uncertainty, the benefits of good hydration are well established and numerous studies have concentrated in evaluating public awareness on the subject. In some cases, lack of awareness is evident, as shown in a study of 1,483 adults in China where two-thirds of the participants were unaware of water-intake recommendations by the Chinese Nutrition Society (1,200 mL/day) and one third did not meet these recommendations [4].
Although there are multiple sources of water, including food and fluids such as milk, drinking water, tea, coffee, and beverages [3], not all healthy. Of particular interest are sugar-sweetened beverages (SSBs) because these are linked to obesity [5,6]. Replacing SSBs with calorie-free beverages leads to reduced weight gain in children [7] and there is a strong relationship between water consumption and weight loss [8,9]. Individuals who drink water are likely to experience weight loss compared to those who drink sweetened beverages (with the exception of coffee), who are likely to experience weight gain [10,11]. However, even when awareness of the benefits of water is high, practice can still remain poor, as shown by a study of schoolchildren in China, where the majority of participants understood the benefits of drinking water and yet preferred sugary drinks [12]. There is, therefore, a need to educate the population on the benefits of healthy water intake and schools are the best place to start such programs. Also, an attempts should be made to improve access to water sources, especially at schools and working areas in hot, dry environments [1].
The issue of dehydration is more pronounced in hot climates [3], like Saudi Arabia. The General Directorate of Nutrition in Saudi Arabia recommends a water intake of 1.5 L (6 cups), though it acknowledges that specifying a minimal intake can lead to dehydration due to the numerous factors that affect fluid intake needs, such as physical activity, diet and health [13]. For adults, a total water intake of at least 3 L can be considered satisfactory [14]. In Riyadh, a considerably hot zone, children are at risk of dehydration because they spend long hours away from their parents’ supervision. However, there is limited literature on the level of awareness of the benefits of hydration or current practices among this group. A report involving 725 children (7–12 years old) from Al-Baha city, Saudi Arabia, revealed a high intake of sweets products and sweetened-carbonated soft drinks among children [15]. Another study from 2006 of 344 children (12–13 years old) in Riyadh City also reported that most fluid intake came from both carbonated soft drink and fruit juice/drink, with water only accounting for 37% of the fluid intake [16]. High intake of sugar-sweetened beverages is correlated with low water intake and obesity [17], and further studies are needed to examine water consumption and its determinates among Saudi children.
The aim of the study was therefore to evaluate children’s fluid intake practices and awareness of the importance of keeping themselves well hydrated. The objectives were to ascertain their knowledge on adequate hydration and healthy drinking, evaluate fluid intake practices, investigate the relation between body mass index (BMI) and water intake, explore correlations between water intake and students’ school performance, and compare the findings between national and international secondary schools. Compared to international schools, public national schools are not as well funded, do not have admission fees, and students are from low to middle socioeconomic class with lower level of education. As such, a comparison will allow to identify if these factors also affect water intake behavior. The null hypothesis was that there are no differences in knowledge and practices of healthy fluid intake between children at international schools and national schools.
2. Methods
2.1. Study design, setting, and participants
This was a questionnaire-based cross-sectional study of children attending national and international secondary schools in Riyadh city. The population of interest was secondary school children in Riyadh city, so all students from 1st, 2nd, and 3rd year of secondary schools were eligible to participate. There were no exclusion criteria (apart from unwillingness to participate).
Based on the proportional allocation technique, students were selected using the multistage stratified random sampling method. Firstly, two national and two international secondary schools were selected randomly from a list of all schools in Riyadh, Saudi Arabia. Then, from each selected school, all students from each educational grade (1st, 2nd, and 3rd year) in attendance the day of the data collection were asked to participate.
2.2. Measures
A self-administrated questionnaire with 25 questions was designed by a panel of doctors (including from the Public Health Department) for the assessment of students’ awareness and knowledge about the importance of water intake, as well as their drinking practices. The schools’ principal and teachers were also involved in the design to ensure that the questions were in alignment to the school’s policy and did not affect the privacy of the students. The questionnaire included basic demographic questions (age, self-reported grades).
The BMI was calculated from the height and weight. Weight and height were measured based on the World Health Organization guidelines [18]; students were asked to remove all objects from their pockets, be barefoot, and wear light clothing. We categorized BMI as <18.5 (Underweight), 18.5–24.9 (Normal), 25–29.5 (Overweight), and ≥30 (Obese).
2.3. Sample size
A pilot study of was performed to confirm that students understood the questionnaire and estimate sample size for the purpose of comparing children from national and international schools. Twenty students were randomly selected from two different secondary schools (national and international). We found out that 13 out of 20 (65%) in international schools and 9 out of 20 (45%) in public schools were aware of the importance of water intake. For a power of 90%, 95% confidence intervals, a proportion of 65% in one group and 45% in the other, a minimum sample size of 128 per school type was calculated based on the two-proportion formula [19]. To ensure the minimum sample size was reached, we chose two schools from each school-type cluster.
2.4. Statistical analysis
Data were entered and analyzed using the Statistical Package for Social Sciences version 21 (SPSS Inc., Chicago, IL, USA). Descriptive statistics (mean, standard deviation, and percentages) were used to describe the quantitative and categorical variables. Unpaired T-test for continuous variables and Pearson chi-square test was used to observe and quantify an association between categorical study and outcome variables. A p-value of <0.05 was set as significant, and 95% confidence intervals (CI) were used to report the statistical significance and precision of the results.
2.5. Ethics
The study was accepted and reviewed by The Institutional Review Board of the College of Medicine Research Center, Vice Deanship for Scientific Affairs, and College of Medicine, King Saud University. Written consent was obtained from all participants after they had been given a complete explanation of the aims of the research and the nature of the questionnaire.
3. Results
The study took place from February to April of 2018. Table 1 shows the demographics and characteristics of the participants. The schools that were randomly selected were the British International school, the Alrowad International school, the King Saud Secondary school, and the Prince Abdul Majeed Bin Abdulaziz secondary school in Riyadh. Three hundred and nineteen students completed the questionnaires, 162 from international schools and 157 from national. Average student age was similar between international schools (16.5 years ± 10.02 SD) and national schools (16.7 years ± 0.84, p = 0.094). However, the distribution of ages was different between schools with 16 and 17-year-old students comprising 61.1% of students in international schools compared to 76.5% in national schools (p = 0.005). Only 4 students had any chronic illnesses. The average BMI of all students was 24.9 ± 6.013, with the BMI of students at international schools (23.6 ± 4.658) being lower than that of students at national schools (26.1 ± 6.931), p < 0.001. International schools had a much higher percentage of students with BMI of 18.5 to 24.9 (58.6%) than national schools (38.2%). Lastly, the majority of students had very good or excellent grades, and that was true for both types of schools. Students in national schools counted their grades higher (8.759 ± 1.24) than students in international schools (8.1107 ± 1.51), p = 0.015.
Table 1.
Participants’ characteristics (n = 319)
| International school (N = 162) |
National school (N = 157) |
||
|---|---|---|---|
| n (%) | n (%) | P value | |
| Age | |||
| 15 years | 32 (19.8%) | 11 (7%) | <.005 |
| 16 years | 49 (30.2%) | 56 (35.7%) | |
| 17 years | 50 (30.9%) | 64 (40.8%) | |
| 18 years | 31 (19.1%) | 26 (16.6%) | |
| Chronic illness | |||
| Yes | 0 (0%) | 4 (2.5%) | .041 |
| No | 162 (100%) | 153 (97.5%) | |
| BMI | |||
| <18.5 (Underweight) | 16 (9.9%) | 18 (11.5%) | <.005 |
| 18.5–24.9 (Normal) | 95 (58.6%) | 60 (38.2%) | |
| 25–29.5 (Overweight) | 35 (21.6%) | 38 (24.2%) | |
| ≥30 (Obese) | 16 (9.9%) | 41 (26.1%) | |
| Grade | |||
| Excellent | 73 (45.1%) | 108 (68.8%) | <.005 |
| Very good | 51 (31.5%) | 35 (22.3%) | |
| Good | 30 (18.5%) | 14 (8.9%) | |
| Acceptable | 8 (4.9%) | 0 (0%) |
Water consumption was low with the most frequent amount being 1000 to 1500 ml in both international (36.4%) and national (39.5%) schools (Table 2). However, more students in international schools consumed larger amounts of water than students in national schools, Table 2 (p = 0.002). These results are reflected also in the ml/kg water consumption (Table 2). Most students also reported that the body needs 5–10 cups of water a day, though students in international schools were more likely to think so than students in national schools (p < 0.005).
Table 2.
Water drinking practices
| International school (n = 162) |
National school (n = 157) |
CI 95% | P values | |
|---|---|---|---|---|
| N (%) | N (%) | |||
| Daily water consumption | ||||
| 10 mL/Kg | 11 (6.8%) | 25 (15.9%) | .08-.153 | .005 |
| 20 mL/Kg | 33 (20.4%) | 42 (26.8%) | .19-.286 | |
| 30 mL/Kg | 62 (38.3%) | 60 (38.2%) | .329–438 | |
| 40 mL/Kg | 27 (16.7%) | 17 (10.8%) | .102-.181 | |
| 50 mL/Kg | 29 (17.9%) | 13 (8.3%) | .097-.174 | |
| Daily water consumption | ||||
| 500–1000 mL | 29 (17.9%) | 49 (31.2%) | .198–295 | .002 |
| 1000–1500 mL | 59 (36.4%) | 62 (39.5%) | .326-.435 | |
| 1500–2000 mL | 41 (25.3%) | 33 (21%) | .187-.282 | |
| 2000–3000 mL | 33 (20.4%) | 13 (8.3%) | .108-.188 | |
| Daily water requirements (cup = 200 ml) | ||||
| 1–5 cups | 10 (6.2%) | 47 (29.9%) | .138-.225 | <.005 |
| 5–10 cups | 98 (60.5%) | 78 (49.7%) | .495-.607 | |
| 10–15 cups | 47 (29%) | 29 (18.5%) | .193-.289 | |
| 15–20 cups | 7 (4.3%) | 3 (1.9%) | .015-.057 | |
| Water at home | ||||
| Tap water | 36 (22.2%) | 22 (14%) | .141-.229 | <.005 |
| Barrel water | 36 (22.2%) | 36 (22.9%) | .181-.276 | |
| Bottled water | 72 (44.4%) | 51 (32.5%) | .332-.441 | |
| Filtered water | 18 (11.1%) | 48 (30.6%) | .164-.256 | |
| Drink with meal | ||||
| Water | 74 (45.7%) | 31 (19.7%) | .278-.384 | <.005 |
| Juices | 38 (23.5%) | 39 (24.8%) | .195-.292 | |
| Soda | 34 (21%) | 72 (45.9%) | .281-.387 | |
| Other | 16 (9.9%) | 15 (9.6%) | .067-.135 | |
| Drink when thirsty | ||||
| Water | 126 (77.8%) | 118 (75.2%) | .714-.810 | .549 |
| Juices | 12 (7.4%) | 17 (10.8%) | .062-.128 | |
| Soda | 22 (13.6%) | 18 (11.5%) | .091-.167 | |
| Other | 2 (1.2%) | 4 (2.5%) | .007-.040 | |
| Frequency of water intake | ||||
| Regularly | 75 (46.3%) | 51 (32.5%) | .341-.451 | .012 |
| When thirsty | 87 (53.7%) | 106 (67.5%) | .549-.659 | |
| I drink water more during: | ||||
| summer | 152 (93.8%) | 146 (93%) | .901-.959 | .764 |
| winter | 10 (6.2%) | 11 (7%) | .041-.099 |
Most students reported that they drink water when they feel thirsty (with no difference between schools, p = 0.549), fewer students in national schools compared to international schools drunk water regularly (32.5% vs 46.3%), and most students in national schools preferred soda when having a meal (45.9%) compared to those in international schools (21.0%), who still preferred water (45.7%) (Table 2).
Students in international schools were more likely to drink barrel water compared to national schools (1.9%), which drunk bottled water (58%), p < 0.001 (Table 3), and the main areas providing water were cafeterias in both international schools (47.5%) and national (81.5%), p < 0.001.). A substantial percentage did not carry water bottles with them (42.6% in international schools, 74.5% in national schools, p < 0.001), and if they did, most only filled them once (37.4% in international schools, 52.4% in national schools, p = 0.140), despite the fact that most bottles were small (42.5% had less than 500 ml capacity in national schools).
Table 3.
Water supply in schools
| International school (n = 162) |
National school (n = 157) |
CI 95% | P value | |
|---|---|---|---|---|
| N (%) | N (%) | |||
| Type of water | ||||
| Tap water | 42 (25.9%) | 49 (31.2%) | .236-.338 | <.0001 |
| Barrel water | 59 (36.4%) | 3 (1.9%) | .152-.242 | |
| Bottled water | 54 (33.3%) | 91 (58%) | .399-.511 | |
| Filtered water | 7 (4.3%) | 14 (8.9%) | .041-.099 | |
| Source | ||||
| Cafeteria | 77 (47.5%) | 128 (81.5%) | .587-.695 | <.0001 |
| Cooler | 72 (44.4%) | 25 (15.9%) | .254-.358 | |
| Toilets | 8 (4.9%) | 2 (1.3%) | .015-.057 | |
| Others | 5 (3.1%) | 2 (1.3%) | .009-.045 | |
| I carry a water bottle | ||||
| Yes | 93 (57.4%) | 40 (25.5%) | .362-.473 | >.0001 |
| No | 69 (42.6%) | 117 (74.5%) | .527-.638 | |
| Frequency of filling bottle | ||||
| One time | 34 (37.4%) | 21 (52.5%) | .334-.509 | .14 |
| Two times | 32 (35.2%) | 15 (37.5%) | .277-.477 | |
| Three times | 15 (16.5%) | 2 (5%) | .077-.200 | |
| Four times | 10 (11%) | 2 (5%) | .048-.155 | |
| Bottle capacity | ||||
| 100–500 mL | 23 (24.7%) | 17 (42.5%) | .224-.386 | .063 |
| 500–1000 mL | 58 (62.4%) | 16 (40%) | .468-.642 | |
| 1000–1500 mL | 10 (10.8%) | 7 (17.5%) | .076-.197 | |
| 1500–2000 mL | 2 (2.2%) | 0 (0%) | .002-.053 |
Many students observed that they had never been reminded to bring a bottle of water with them during training (Table 4), though this was more frequent in national schools (89.5%), p < 0.001. The most frequent amount of water drunk after exercise was 100 ml to 600 ml, with a higher percentage in international schools drinking 300 ml – 600 ml. The vast majority of students preferred water after exercise and understood that water intake depends on physical activity.
Table 4.
Water intake practices during exercise and physical activities
| International school (n = 162) |
National school (n = 157) |
CI 95% | P value | |
|---|---|---|---|---|
| N (%) | N (%) | |||
| Course trainer reminding | ||||
| Always | 34 (21%) | 2 (1.3%) | .080-.153 | <.0001 |
| Sometimes | 31 (19.1%) | 4 (2.5%) | .078-.149 | |
| A few times | 14 (8.6%) | 11 (7%) | .051-.114 | |
| Never | 83 (51.2%) | 140 (89.2%) | .645-.749 | |
| Water intake after training | ||||
| Often none | 14 (8.6%) | 13 (8.3%) | .057-.121 | <.0001 |
| 100–300 mL | 45 (27.8%) | 81 (51.6%) | .341-.451 | |
| 300–600 mL | 86 (53.1%) | 53 (33.8%) | .381-.492 | |
| 600–900 mL | 17 (10.5%) | 10 (6.4%) | .057-.121 | |
| Water intake depends on physical activity | ||||
| Yes | 134 (82.7%) | 99 (63.1%) | .678-.778 | <.0001 |
| No | 28 (17.3%) | 58 (36.9%) | .222-.322 | |
| Preferred drink after activity | ||||
| Water | 142 (87.7%) | 136 (86.6%) | .830-.903 | <.0001 |
| Juices | 11 (6.8%) | 13 (8.3%) | .049-.110 | |
| Soda | 6 (3.7%) | 8 (5.1%) | .024-.073 | |
| Other | 3 (1.9%) | 0 (0%) | .002-.027 |
Students at both types of schools agreed that drinking beverages could not replace drinking water (Table 5). Most students also realized there is a correlation between BMI and water intake (Table 5), though a small percentage thought water can cause weight gain (17.9% in international schools, 11.0% in national schools, p = 0.067). Students also reported that their cognitive function is affected by dehydration, and that drinking water can prevent diseases.
Table 5.
Knowledge about water intake
| International school (n = 162) |
National school (n = 157) |
CI 95% | p value | |
|---|---|---|---|---|
| N (%) | N (%) | |||
| Beverages replace water | ||||
| Yes | 32 (19.8%) | 38 (24.2%) | .175-.296 | .337 |
| No | 130 (80.2%) | 119 (75.8%) | .731-.825 | |
| Is there a relationship between BMI and water intake? | ||||
| Yes | 104 (64.2%) | 106 (67.5%) | .603-.710 | .532 |
| No | 58 (35.8%) | 51 (32.5%) | .290-.397 | |
| Drinking more water: | ||||
| Increases BMI (Weight gain). | 19 (17.9%) | 12 (11%) | .10-.198 | .067 |
| Decreases BMI (Weight loss). | 44 (41.5%) | 62 (56.9%) | .424-.562 | |
| Maintain my BMI | 43 (40.6%) | 35 (32.1%) | .298-.431 | |
| >8 h dehydration affects mentality and understanding | ||||
| Yes | 129 (79.6%) | 111 (70.7%) | .701-.799 | .065 |
| No | 33 (20.4%) | 46 (29.3%) | .201-.299 | |
| Drinking enough water could prevent disease | ||||
| Yes | 147 (90.7%) | 144 (91.7%) | .876-.941 | .757 |
| No | 15 (9.3%) | 13 (8.3%) | .059-.124 |
Water consumption was different between students of different grades, but this was statistically significant only in international schools (p < 0.001), where more students with excellent grades drunk 1500–2000 ml per day (Table 6).
Table 6.
Relationship between daily consumption of water and self-reported grade
| Amount of water per day |
||||||
|---|---|---|---|---|---|---|
| International school grade | 0.5–1 L | 1–1.5 L | 1.5–2 L | 2–3 L | df | P-value |
| Excellent | 8 (4.9%) | 18 (11.1%) | 31 (13%) | 26 (16%) | 9 | <.001 |
| Very good | 13 (8%) | 24 (14.8%) | 10 (6.2%) | 4 (2.5%) | ||
| Good | 4 (2.5%) | 14 (8.6%) | 10 (6.2%) | 2 (1.2%) | ||
| Acceptable | 4 (2.5%) | 3 (1.9%) | 0 (0%) | 1 (0.6%) | ||
| National school grade | ||||||
| Excellent | 31 (19.7%) | 42 (26.8%) | 23 (14.6%) | 12 (7.6%) | 6 | .255 |
| Very good | 11 (7%) | 17 (10.8%) | 6 (3.8%) | 1 (0.6%) | ||
| Good | 7 (4.5%) | 3 (1.9%) | 4 (2.5%) | 0 (0%) | ||
Correlation analysis indicates that there is a positive relationship between BMI and water intake in international schools (r = .282, P < .001), but not so in national schools (r = .064, P = 0.424). A negative correlation between BMI and self-reported grade was observed in both international (r = −.192, P = .015) and national schools (r = −.196, P = .014).
4. Discussion
Knowledge and awareness of the importance of water intake among international school students appeared to be higher than among national school students, as they reported carrying their own water bottle, consume the proper amount of water, and consume water while having their meals rather than soft drinks or other beverages that are a known risk to obesity [10,11]. Although previous studies show that there is a link between BMI and water intake [8–10], our findings indicate that the correlation is weak and does not apply to all settings. The effect of confounding factors that are known to affect BMI, such as sedentary life style and dietary intake [8], cannot be ruled out.
An interesting observation is that students from national schools consume water more frequent in the form of bottled water from the cafeteria, while international school students consume bottled water less frequently. We presume that there are two reasons behind that. Firstly, international schools offered coolers and barreled water for free to their students. Secondly, more international school students bring their own water bottle (57.4%) than national school students (25.5%).
Despite this cohort not meeting the required water intake of 2000–3000 ml/day [3], most students had very good or excellent grades. This possibly relates to the fact that mild transient dehydration doesn’t affect cognitive function [3] and, thus, academic performance is not affected the same as in prolonged dehydration.
A limitation of this study is that there is no validated questionnaire measuring the level of awareness of water intake and its correlation with BMI in the literature, so we had to construct our own. However, we utilized a panel of experts and piloted the questionnaire on a small number of students prior to the main study. In addition, we did not explore the reasons behind non-completion of the questionnaires. Finally, we did not have any data on gender, so we could not report age and gender specific BMIs, nor evaluate if there was an unequal ratio of male to female children between the two types of schools.
5. Conclusion
Students understand the importance of water intake, generally prefer water when thirsty, and yet do not drink enough. There are some differences between international school students and national school students that can be attributed to the availability and sources of water, though other factors cannot be excluded. Finally, BMI does not always correlate with water intake.
6. Recommendations
Our results should be corroborated with studies that further explore students’ awareness and perception about their daily need of water and benefits of proper hydration. We encourage the Ministry of Health to collaborate with the Ministry of Education to establish programs that educate students on the importance of drinking water, and to ensure free water is provided to all students.
Acknowledgments
The authors would like to thank the school principals for giving permission to conduct this research at their schools. The authors would also like to express gratitude to the secondary school students in Riyadh, Saudi Arabia who participated in this study. The corresponding author would like to thank Ajman University (AU) for all supports.
Disclosure statement
No potential conflict of interest was reported by the author(s).
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