Adolescence is a rapid stage of growth and development that is characterized by increased nutrition requirements [1] . Adolescence period is also characterized by independent decisions about diet with limited parental control [2] . The decisions about diet are the foundation of eating habits that could persist and be hard to change in adulthood [3] . Unhealthy eating habits may pose negative child’s health status, making nutrition education at school paramount to prevent obesity and NCDs, and promote healthy eating. Given that the adolescent stage is important in the development of adult NCDs, [4] it is vital to study nutrition knowledge of adolescents to help develop school-based intervention programs.

Adolescents compose a large proportion of the population globally. In developed countries they are exposed to media that advertises the Western diet which is composed of too much sugar, fat, and low fiber [5] . Increased fast-food consumption negatively impacts food habits and choices of adolescents [6] . The prevalence of obesity globally was 18% in children and adolescents aged 5 - 19 in 2016 and unhealthy diet cause obesity that is a risk factor for NCDs [6] . In Botswana 33.3% of the population are adolescents [7] . Adolescents in developing countries engage in unhealthy eating habits. Adolescents consume high energy snacks and beverages, and low vegetables and fruit especially in urban areas [8] .

Public health approaches to promoting healthy lifestyles can be individual, social, or environmental [9] . At the individual level, nutrition knowledge is important since it promotes a healthy lifestyle. The Information, Motivation and Behavioral Skill (IMBs) model asserts that information is a prerequisite for behavior change [10] . Knowledge is the application of information learned [11] . This means that an individual needs to be equipped with knowledge to impact behavior. Although it is well known that knowledge alone is not adequate to impact behavior, knowledge at adolescent stage is deemed essential, with the hope that it could impact eating habits [9] .

Nutrition knowledge and awareness may be affected by many factors, among them being residential area, age, gender, and socioeconomic status [12] . Older students with high academic performance had more nutrition knowledge than younger ones while obese students who were on diet had low nutrition knowledge, however, normal BMI was found to be associated with adequate nutrition knowledge [13] . In addition, taking a course on nutrition or health related subjects might also affect nutrition knowledge and awareness [14] . Students from low socioeconomic status and rural areas had low nutrition knowledge [15] indicating that there is a gap in Botswana literature, hence the need to share the results of this study.

While adolescents are reported to have good nutrition knowledge in South Africa [15] and low in Saudi Arabia, [16] . Adolescents in developing countries generally make wrong food choices because of lack of nutrition knowledge [17] . Further research is needed to evaluate the adolescents’ knowledge of nutrients and skills, and its association to Body Mass Index (BMI) and age.

For Botswana, a sub-Saharan developing country, adolescents residing in Gaborone the capital of Botswana exposed to unhealthy foods fast foods that I sold in tuck-shops and street vendors at school, supermarkets, and restaurants that sell fast foods [18] . For eating habits to be modified or changed adolescents should be equipped with adequate nutrition knowledge [11] . However, there is lack of published studies located in the literature that evaluated the level of nutrition knowledge of 13-15-year-old adolescents in public junior secondary schools in Gaborone, Botswana.

Nutrition knowledge and awareness needs to be explored to find out the level of understanding of children about nutrition and nutrients. This study is one of the first to be conducted in Botswana looking at nutrition knowledge and awareness on healthy eating behaviors among children who are 13-15 years. The results of this study may inform school education curriculums in terms of making nutrition subject compulsory to all students as compared to the current situation in schools where nutrition subject is optional in public schools. The study was a baseline for the development and evaluation of an intervention program for the fulfillment of a doctoral degree.

The survey response rate was 95.1% (252/264). The descriptive demographic data are presented in the tables below.

Socio-demographic characteristics of adolescents aged 13-15 years.

Most of the respondents were females (58.3%). Many of the respondents were aged 15 years (47.6%), 53.6% were from low socioeconomic status and 4.0% were from high. Most respondents had normal body mass index (74.6%), and only 10.7% were overweight, 6% obese ( Table 1 ).

Nutrition knowledge on food nutrients, food contents, healthy foods and drinks, healthiest food, energy expenditure and nutrition related issues.

The results show 34.1% of respondents knew what food nutrients are, only 13.5% knew what fiber is, while 69% knew the foods that are rich in vitamin C. Most respondents (66.3%) knew what milk is used for and 67.1% were able to identify the healthiest drink. Most of the respondents were able to identify the healthiest foods (≥ 50%) except for the question on orange juice, orange smoothie or both (40%). Regarding the answer to the question on what the amount of energy depends on, 61.1% knew the answer, while only 15.9% knew what the amount of energy depends on. Many respondents knew (65.1%) the nutrition related diseases and only 29.8% knew the benefits of healthy eating.

The overall pass mark of respondents using nutrition knowledge and awareness categories (N = 252).

According to the overall marks of the respondents to the nutrition knowledge questions, the results show that most of the respondents scored below 50% (56.3%), while only 7.1% got a very good score.

Concerning correlation between BMI and nutrition knowledge, the results show a significant correlation (p = 0.001).

Concerning correlation between age and nutrition knowledge, the results of this study show that there is no significant correlation between age and nutrition knowledge (p = 0.103).

The purpose of the current study was to determine the level of nutrition knowledge and awareness on healthy eating and food intake and if there was an association with age, BMI. To our knowledge this is the first study to determine the level of nutrition knowledge and its association with age and BMI among 13-15 years adolescents in public schools in Botswana. The results in the current study based on scores ( Table 2 ) showed that the overall pass grade on nutrition knowledge of adolescents aged 13-15 years in urban junior secondary schools was inadequate. In a total of 252 (95% response rate), most of the respondents had low nutrition knowledge (56.3%) and were not aware of food nutrients, food content healthiest foods and drinks, indicating that adolescents lack nutrition education. Only 7.1% got a very good score. Although nutrition knowledge is spread on social media, at school and families and other platforms [20] [21] , nutrition knowledge in adolescents in Gaborone remains low and still needs to be improved. The results are in line with other studies [22] found that adolescents in the urban slum of Dehli had poor knowledge (72%) and 4.15% performed better, while in urban Bengaluru district, adolescents had low nutrition knowledge (28%) and 18% had high knowledge [21] and in Ibadan Municipality in Nigeria, 58.7% had poor nutrition level [23] .

However, in other countries nutrition knowledge among adolescents was moderate to high. The results of the current study are inconsistent with a study conducted in Easten Cape South Africa, where 72.9% adolescents got a high scored [17] , in Italy 57.3% of adolescents had good nutrition knowledge [19] , in Brazil 53.6% knew that their diet is healthy [24] and In Bangladesh, Krira 57.3% [25] .

Based on the results of individual questions ( Table 3 ), most adolescents in the current study responded well except for nutrients found in egg and fiber. The results are in line with other studies where adolescents in secondary school in Al-Khobar, Saudi Arabia had low knowledge on fiber rich diet (27.5% in males and 24.2% in females) [16] . In addition, in Balearic Islands adolescents displayed inadequate knowledge especially on fat, carbohydrate, dietary fiber, foods rich in protein, contents of eggs and meats, milk, and foods that provide most energy [26] .

Again, on the aspect of nutrition related diseases ( Table 3 ), only 29.8% knew dangers of unhealthy eating, and the results are like [27] where 4.0% males and 4.7% female adolescents knew the dangers of unhealthy eating. Healthy eating messages should be inculcated in children’s minds at an early age [22] . Probably implying that nutrition education must be included in the school curriculums, and that parents should also teach their children healthy eating behaviors at home. In the current study, respondents were able to identify healthy foods and drinks. Inconsistent with a study that showed that respondents could not identify healthiest foods [15] .

Another question that adolescents answered poorly was on energy rich food (38.9%) ( Table 3 ). Few respondents knew energy rich foods and ways of expending energy, which is worrisome because lack of knowledge in this area could predispose respondents to obesity at present and in later life. The results of the current study are like studies [28] [29] reporting that adolescents failed to identify energy rich foods. But in another study, it was reported that adolescents knew the answers to the question on energy rich foods. Inadequate nutrition knowledge may have a negative impact on health. It may affect food choices and in turn food intake may lead to overweight/obesity [30] . Therefore, nutrition education must be promoted at all levels in the communities. One may expect that since adolescents are children of the digital age, and one may assume that they have access to nutrition information from various platforms and will possess adequate information, however the results showed the contrary. It is noteworthy that other factors that may have caused adolescents in this study to have low nutrition knowledge could be that majority of them were from low socio-economic status and public school where nutrition subject is optional. The current study is the first step in pointing out the need to spread information about healthy and unhealthy foods and drinks among adolescents at home, school, and community.

In terms of correlation ( Table 4 ), the current study showed that nutrition knowledge significantly correlated with BMI (p = 0.001). Adolescents with low nutrition knowledge are at risk of obesity [31] . However, in the current study most adolescents had normal BMI.

This could be the reason for this significant correlation. The current results are like other study in Lebanon [14] . However, inconsistent with other studies that reported an insignificant relationship between nutrition knowledge and BMI [31] - [33] .

Nutrition knowledge was not significantly associated with age in the current study ( Table 5 ), although [20] reported that nutrition knowledge increases with age. In a study conducted in Bangladesh, age was significantly associated with age (p = 0.005) [34] . Few studies were accessed that investigated this association, in Botswana more studies are needed in a larger population to determine this correlation.

Adolescents in urban junior secondary schools lacked nutrition knowledge. Nutritional knowledge is significantly correlated with BMI, and this may place these adolescents at risk for developing non-communicable diseases later in life. Nutrition education programs are urgently needed for teachers, parents, and children.

A limitation of the study was that it was conducted in junior secondary schools in one of the urban areas in Botswana. A larger study is needed in junior secondary schools in rural areas and other urban areas.