O. Aksonova, D. Torianik, L. Pavlotska, A. Borysova
Kharkiv State University of Food Technology and Trade, Kharkiv, Ukraine
ABSTRACT. A significant portion of vitamin D, which is essential for important processes of vital activity, a person gets from food. The purpose of this study was to assess the level of consumption by young males and females of foods containing vitamin D3.
One hundred and two first-year students (females — 78.4 %, males — 21.6 % between the ages of 17 and 22) participated in the study voluntarily. Data collection was carried out by questioning. The frequency of consumption and food preferences for 22 products containing vitamin D were assessed. The evaluation was carried out on a 5-point rating scale. Statistical processing of the questionnaires was carried out using the SPSS program.
The results are analyzed for approval of the points of the questionnaire. It turned out that the coefficient of Alpha Cronbach is 0,912 and 0,896 for consumption and food preferences respectively. This indicates a high consistency of the items on the questionnaire about the frequency of consumption and food preferences of foods rich in vitamin D. The consumption of foods rich in vitamin D is at a pain lower level than the respondents' desire to consume them. The reasons for low consumption may be price unavailability of the product. For some products, there is a very high difference of ratings, which indicates that the level of well-being of the respondent have a great influence on food preferences. Food preferences in this case, most likely, play a secondary role.
The results obtained suggest that foods rich in vitamin D are not among the preferences of young people who took part in the study. It should be noted that, low intake of foods rich in vitamin D may also be related to the global trend. This fact is of concern because the lack of vitamin D in young people leads to negative consequences, including the emergence of diseases of various kinds.
Key Words: vitamin D, first-year students, 5-point rating scale.
Introduction. The need for nutrition is the basic need of all living things. The amount of food eaten, its composition, quality level, rituals associated with food are specific to each individual. Food habits can be determined by a variety of external factors and one of the most significant is the social factor, that is, the fundamental possibility of access to certain nutrients [1].
Food security, which refers to reliable access to food, can contribute to a deficit of various nutrients. On the other hand, overweight and obesity can also be due to food security [3].
High mortality from cardiovascular disease in Eastern Europe is often due to poor nutrition. The study of food habits in the adult population of Russia, Poland and the Czech Republic in 20022005 HAPIEE (Health, Alcohol and Psychosocial Factors In Eastern Europe) showed a food imbalance: consumption of complex carbohydrates, pulses or nuts did not meet the WHO recommendations — was not enough, and consumption saturated fatty acids, sugars and protein was too high. Only 16 % of Polish subjects responded to the recommendations of WHO on the consumption of polyunsaturated fats. Consumption of fruits and vegetables was lower than recommended [4]. Studies [5] also showed the problem of lack of vitamin D in the diets of the adult population of Korea.
The situation is not better in Ukraine. According to information posted on the union's website on the standard of living of the population of Ukraine, by the end of 2015, 23.8 % of the country's population was under the poverty line, and in the first half of 2017 this figure increased to 25.4 %. Among all expenditures of households, 93.7% were consumer expenditures (in the first half of 2016 — 93.3 %). Foodstuffs spend about 50% of the budget. The cost of food for one person in the first half of 2017 amounted to an average of 54 UAH per day against 46 UAH in the first half of 2016. At the same time, consumption of some products, including milk and dairy products, has decreased [6].
According to the State Statistics Service of Ukraine in January–September 2018, food products went up by 3.1 %. Prices for bread, pasta, fish and fish products, meat and meat products increased by 12.7–8.2 %; by 4.2–1.4 % — soft drinks, dairy products, butter, rice, sunflower oil [7]. This leads to the exclusion of some food from the diet.
If in 2014 there was 1.6 kg of fish per Ukrainian, which is a significant source of vitamin D, in 2017 this figure was already 1.2 kg. It should be noted that not all varieties of even sea fish contain high amounts of vitamin D. In 2017, on average, one Ukrainian ate 20 eggs per month, that is, less than one egg per day [8]. Based on the order of the Ministry of Health of Ukraine «About the approval of the norms of the physiological needs of the population of Ukraine in basic nutrients and energy» per adult person should be 5 gg of vitamin D. [9]. Simple calculations show that to provide an adult with enough vitamin D per day, you need to eat either 2 eggs or eat fish or seafood regularly, and statistics show that this does not happen.
The above facts indicate a violation of the nutritional structure of the population of the country due to low food security, which leads to a decrease in living standards and, accordingly, the growth and prevalence of various pathologies due to the lack of certain nutrients and vitamins, in particular, vitamin D.
The results presented in [10–12] show the link between prevalence of chronic noncommunicable diseases and unhealthy preferences in food. Studies of recent years emphasize the important role of vitamin D in human physiology. Thus, its inadequate consumption can lead to an increased risk of type 1 diabetes, hypertension and other diseases, not to mention its crucial role in maintaining the necessary level of calcium in the body [13].
According to the literary data [14], the vitamin deficiency in the diet is on average 20–30 percent. Moreover, this deficit does not depend on the region of residence and is all-season.
In [15] it is stated that the vast majority of Ukrainians have a deficit of vitamin D. For the adult population, this figure is 81.8%, and for schoolchildren — 88.5%. Only 4.6% of residents have [25(OH)D] levels in serum within normal limits.
Vitamin D contributes to the absorption of calcium in the intestines and supports the necessary levels of calcium and phosphate in the blood to ensure bone mineralization and prevent hypocalcemic tetany. It is also necessary for bone growth and the process of bone remodeling. A sufficient level of vitamin D prevents the development of rickets in children and osteomalacia in adults. Together with calcium, vitamin D is also used for prophylaxis and as part of the complex treatment of osteoporosis. [16, 17].
The aim of the work was to investigate the dietary habits of KHSUFTT students regarding the use of food rich in vitamin D.
Vitamin D belongs to the group of fat-soluble vitamins. It is naturally present only in a very limited amount of food [18, 19, 20], and synthesis in the human body is possible only under the influence of short-wave ultraviolet radiation (a wavelength of 290–315 nm).
Vitamin D, which enters the human body with food and in the form of nutritional supplements, as well as formed during exposure to the sun, is biologically inert. To activate and convert to the active form of D-hormone [1.25 (OH) 2 D] in the body, two stages of hydroxylation must occur. The first stage of hydroxylation occurs in the liver and converts vitamin D to 25-hydroxyvitamin D [25 (OH) D] – calcidiol. The second stage of hydroxylation occurs predominantly in the kidneys (with the participation of the enzyme CYP27B1 – alpha hydroxylase), and it results in the synthesis of the physiologically active D-hormone, 1,25-dihydroxyvitamin D [1,25 (OH) 2D] –calcitriol [16].
According to several researchers, vitamin D functions are not limited to calcium-phosphorous metabolism control, but also affects other physiological processes in the body, including modulation of cell growth, neuromuscular conduction, immunity and inflammation [17, 20]. Recent studies link the levels of vitamin D in the body with allergic diseases [21].
Vitamin D deficiency [18] is defined as serum 25 (OH) D levels of less than 20 ng / ml. Many experts [18, 20, 22] tend to think that levels between 20–30 ng / ml should be regarded as vitamin D “deficiency”, and the optimal level is more than 30 ng / ml, especially for elderly patients.
Currently, insufficiency and for the most part 25 (OH) D deficiency is a pandemic affecting a large part of the general population, since vitamin D deficiency, as defined by 25 (OH) D levels of less than 30 ng / ml and less than 20 ng / ml, is highly prevalent around the world [23].
Materials and Мethods. To date, there is experience in assessing the level of intake of vitamin D using questionnaires. [24,25]. However, it would be interesting to consider not only the frequency of eating foods that contain vitamin D, but also the attitude towards them. In the 2017–2018 academic year, the first-year students were surveyed at Kharkov State University of Food and Commerce. 102 people were surveyed, among them females — 78.4%, males — 21.6% between the ages of 17 and 22. Questionnaires were completely anonymous, participation was voluntary.
Participants were asked to determine the food preferences and frequency of consumption of 22 different foods containing substantial amounts of vitamin D in accordance with the literature data [26] (see Table 1).
It was proposed to evaluate taste preferences in relation to the above-mentioned products on a 5-point rating scale with anchors “very much” (4 points), “like” (3 points), “I have nothing against” (2 points), “rather not like than like” (1 point),“ not at all like ”(0 points). Evaluation of the frequency of consumption in food also occurred on a 5-point rating scale with anchors “I eat very often” (4 points), “I eat, but not often” (3 points), “sometimes I eat” (2 points), “very rarely I eat” (1 point), “I don’t eat at all” (0 points).
Statistical processing of the questionnaires was performed using the SPSS program for Windows (IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp.). The consistency of the questionnaire questions was assessed with the help of Alpha Cronbach. The mean values and variances of the estimates for each product were also calculated.
Results and Discussion. Any questioning involves the reliability of the result, which is achieved by correctly compiling the questions of the questionnaire. Despite the fact that the questionnaire offered to the respondents contained questions of the same type, it obviously should have given a reliable result. To confirm this, the Alfa Cronbach coefficient was calculated in the SPSS program, which again confirmed the assumption that the questionnaire was reliable. Moreover, the reliability of the questionnaire practically does not change when adding or deleting questionnaire items. It turned out that the coefficient of Alpha Cronbach is 0.912 and 0.896, respectively.
Means of frequency of consumption and food preferences are shown below (see Fig. 1).
Table 1
Foods that contain high amounts of vitamin D
Fig. 1. of frequency of consumption and food preferences. (1) Frequency of consumption. (2) Food preferences.
Analysis of the means of the results of the survey for each product shows that there is some correlation between consumption and food preferences. Although, the consumption of foods rich in vitamin D is at a lower level than the desire of respondents to consume them. Food preferences and consumption of products such as fish oil and chicken eggs are almost completely the same. Some products, such as black and red caviar, are ready to be consumed by respondents, but do not. The reasons for lower consumption than we would like could be both the price unavailability of the product and the lack of confidence in its quality.
Table 2 shows in order of increasing variances of the questionnaire items and the corresponding product codes.
Table 2 shows in order of increasing variance of the questionnaire items and the corresponding product codes. The results show that for products such as fish oil, there is no difference in the assessment of both the frequency of consumption and the product preferences. For products such as river perch, there is a very high difference of estimates. From our point of view, all of the above, including statistics from official sources and the results of our research, suggests that not only food preferences, but also the level of well-being of a particular individual affect the level of vitamin D intake. Moreover, food preferences in this case, most likely, play a secondary role. It should be noted that, low intake of foods rich in vitamin D may also be related to the global trend, which shows a low level of healthy eating habits among young people [27, 28, 29]. Research [30] shows that most U.S. Americans and Canadians do not meet the 2011 Inst. of Medicine recommended daily allowance (RDA) for vitamin D for their age groups from foods. Therefore, the authors of this paper suggest that, it is likely that additional food fortification or vitamin D supplementation is required to achieve the RDA. Paper [31] concluded that most European countries lack current recommendations for vitamin D. The exception is Finland, but the experience of this country cannot be a suitable strategy for the whole of Europe. The authors suggest that standardization of measurements in vitamin D studies will strengthen the evidence base on which policies can be developed to promote nutritional recommendations, food fortification, vitamin D supplementation in the form of dietary supplements and reasonable sun exposure. However, this policy must necessarily take into account the national, cultural and dietary habits of the population of a particular country.
Table 2
Variances of items of the questionnaire
Conclusion
Thus, the analysis of the questionnaires showed that the survey conducted provides a fairly high degree of reliability of studies of the frequency of consumption and food preferences of the respondents to products containing significant amounts of vitamin D.
The results obtained allow us to distinguish the groups of products that cause the greatest rejection, and vice versa, are included in the list of food preferences. Also installed products used most often and almost never used.
Despite the positive attitude of a fairly high percentage of respondents to such products as black and red caviar, salmon, they are used insufficiently, which can be tied primarily to food insecurity, namely, the high price and distrust of the population to the quality of the product.
The results obtained suggest that products that are richest in vitamin D are not in the range of preferences of respondents who participated in the study. This fact is of concern because the lack of vitamin D in young people leads to negative consequences, including the emergence of allergic diseases.
Unfortunately, the data suggest that it is highly likely that the ability to meet the need of the body for adequate doses of vitamin D is only difficult with food. Therefore, from our point of view, fortification of food with vitamin D is relevant and necessary for Ukraine. A recent study [32] has shown that consumers are ambiguous on the fortification of food products with the vitamin D. Further studies suggest the establishment of a correlation between the products consumed, which contain significant amounts of vitamin D and the presence of allergic diseases among respondents.
Data Availability
The data used to support the findings of this study are available from the corresponding author upon request.
Conflicts of Interest
The authors declare that there are no conflicts of interest regarding the publication of this paper.
Acknowledgements
The authors gratefully acknowledge all 102 students of Kharkiv State University of Food Technology and Trade for their support and cooperation to voluntarily participate in this study.
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Надійшла до редакції 04.06.2019 р.