Food is the basic need for all living organisms to continue their life cycles. Food security achievement is the key development priority for all developing countries such as Bangladesh (Parvin and Ahsan, 2013). Food security is a global concern for every individual; one in nine people around the world (805 million) go hungry every day (FAO, 2014a). Moreover, the hidden type of hunger that is caused by deficiencies in micronutrients such as iron, Vitamin A, and Zinc affects two billion people worldwide (FAO et al., 2014). In Bangladesh food insecurity situation is more severe; overpopulation along with decrease of the land-to-human ratio (Shaheen and Islam, 2012) have made the need for food security of utmost necessity. Since Bangladesh liberation in 1971, the government has been  trying hard to control the population growth and triumph over the food insecurity (Parvin and Ahsan, 2013, WFP, 2004). Food and Agriculture Organization (FAO, 2009) explains food security as a situation ‘when all people at all times have physical, social, and economic access to sufficient, safe, and nutritious food to meet their dietary needs and food preferences for an active and healthy life’. The definition introduces the food security as a complex situation that involves physical and biological aspects of food production, distribution, and utilization considering food stability throughout the time (WFP, 2004). Thus, food security embraces four key dimensions of food availability, access, utilization, and stability

(FAO, 2008).
Bangladesh is an agrarian country where more than half of the population are engaged directly in agriculture for survival (Jolliffe et al., 2013). Besides, a lion share of the national economy comes from the agriculture sector (GDP-14.17%) (BBS, 2017). Bangladesh has nearly achieved self-sufficiency in food production (Mannaf and Uddin, 2012), especially in the case of rice. The production of rice (staple food of Bangladesh) was assumed to be tripled over the last 30 years (Hossain, 2014, Shaheen and Islam, 2012). The staple food of most people in Bangladesh is rice and more than 70 percent of their daily calories comes from rice  (Magnani et al., 2015). Hence, food security is considered synonymously with self-sufficiency in rice production (Hossain, 2013). In addition, Bangladesh has made remarkable progress in producing wheat, potatoes, and vegetables (Hossain, 2013, 2014). It is also worth mentioning that Bangladesh has made tremendous improvement in ensuring the food availability. However, about 32 percent of people live below the poverty line and  do not have sufficient access to food (FAO, 2011a). This shows that the other dimensions of food security still lag behind. Moreover, it is shocking that even with the sufficient food production, 26 percent of people are still chronically food insecure (Shaheen and Islam, 2012). So, it is imperative to assess the present status of food security in Bangladesh and to find out the drawbacks, especially in case of food access, utilization, and stability. Consequently, we need to study the future challenges of food security and to investigate the strategies to deal with them. Therefore, in this study we attempted to have an overview on the current food security situation of Bangladesh to address the above-mentioned drawbacks and to formulate some recommendations to improve the food security situation in Bangladesh.
Data sources
The study was conducted using a systematic design to investigate the records of food security in Bangladesh. Therefore, the data were mainly from the secondary sources. The main data were obtained from Bangladesh Bureau of Statistics (BBS), World Bank, Household Income and Expenditure Survey (HIES), Bangladesh Demographic and Health Survey (BDHS), Bangladesh Economic Review, Bangladesh Integrated Household Survey (BIHS), as well as other published and unpublished documents. In this study, we explored the information that covered all the four dimensions in this area, i.e., food availability, food access, food utilization, and food stability using a systematic literature review.

Food security status of Bangladesh
Availability of food: The major food crops are quite available in Bangladesh, especially rice, which is considered as the staple food of Bangladesh (Hossain, 2014, Shaheen and Islam, 2012). The rapid development and improvement of different high yielding crop varieties and technologies along with better agricultural extension system made it possible to ensure year round availability of food for people (Hossain, 2014). During 1970s and 1980s, it was dificult for the government of Bangladesh to assure the vailability of two meals per day for the mass people. However, as Table 1 shows, rice production has been increasing in Bangladesh, so that the advancement and distinct proress is quite visible (Lagos and Hossain, 2016).
Besides self sufficiency in rice production, production of other crops such as potatoes, vegetables, and fruits boasted remarkbly. Unfortunately, wheat as the second staple food of Bangladesh had a decreased production trend (BDP, 2015). This shows the dependency of Bangladesh people on rice as a starchy staple and lack of the necessary facilities to produce different foods to ensure the complete nutritional food security (Hossain, 2013). Beside the crop sector, Bangladesh has made notable  progress in fish and livestock production. Bangladesh is the fourth fish producing country in the world (FAO, 2016). The increased production and supply of fish, meat, milk, and egg (as shown in Table 2) contributes to the overall availibilty of food to the general people (BER, 2014).
Considering the progress in food production, the per capita availability of foods has also increased (Table 3). It is evident that major availability was met in the case of cereals (e.g., rice) and potato. The availability of vegetables, fish, meat, and milk also increased notably; whereas, further measures are required in case of egg, pulses, oilseeds, and fruits' production (BDP, 2015).
Access to food: Despite making tremendous success in food production, Bangladesh is still experiencing limited access to sufficient food. Although 60 percent of people living in the rural areas are directly or indirectly engaged with agriculture (Hossain, 2014), land distribution inequalities led to pepeole's disproportionate access to food. Small farmers (owing 0.5-1.49 acres of land) are the major population of Bangladesh, who consist of 44.6 percent of the farming communities (Ahmed et al., 2013). These small farmers mainly have access to cereals and other basic food items are not sufficiently available for them. Poverty is another factor that makes access to food difficult and ultimatley create food insecurity (Bishwajit et al., 2014). Bangladesh has made significant progress in reducing poverty rates (FAO, 2014b) and improved its extreme poverty situation (Graph 1) with the passage of time but changes were not significant.
Due to slow growth of gross national product (GNP) and high population growth, still one-third of the population live below the poverty line in Bangladesh (Hossain, 2014). This trend seemed a bit sluggish in the urban areas (Hussain et al., 2014, Magnani et al., 2015). Indicators such as wages and income are the key factors in accessing the food by the poor (Hossain, 2014). Majority of the labor forces belong to the farming community (Graph 2) and therefore, their income and wages are very low compared with other professions in this country (Ahmed et al., 2013, Magnani et al., 2015) .
Price hikes and market instability have worsen the condition of the households and affected their food access (Hossain, 2014). Sudden price hikes in 2007s-2008s deteriorated the condition of people who spent over half of their income in purchasing starchy staple and discouraged them to invest in agriculture (Bishwajit et al., 2014, Hossain, 2014). Likewise, seasonal food shortage, especially in the northern Bangladesh affected the availability of and accessibility to food by the poor and the middle-level households (Bishwajit et al., 2014).
Food utilization and nutrition: Another dimension of food security in Bangladesh is deficiency in proper nutrition and utilization of food. Although food consumption has been increased in the last few decades, adequate uptake of nutritious food is far below the standard. The national average per capita food consumption was 913.8 grams in 1995-96, but it was increased up to 1000.0 grams in 2010, which was higher than the normal food intake (934 grams/person/day) for a regular person. The extent of food consumption was significantly higher in the rural areas (1000.5 gm/person/day) than the urban settings (985.5 gm/person/day) in 2010 (HEIS, 2010). Despite the fact that urban people consume less amount of food, their overall nutrition is better than the rural people. The main portion of food intake by the rural people comes from cereals, especially rice. The average calorie intake of the rural people is higher than the urban people, which is due to the high calorie of rice. Graph 3 shows that the average per capita calorie intake has increased in the last few decades at rural, urban, and national levels. Calorie intake is comparatively higher in the rural settings than the urban settings (HEIS, 2010). Graph 3 clearly shows the sudden rise of calorie intake from 2005 to 2010. The average poverty rate has decreased to 31.5 percent in 2010 compared with 40.0 percent in 2005 as the per-capita expenditure has increased for the entire population (Gimenz et al., 2014). So, people are getting more concerned about food quality and nutrition. They spend more on high quality food. The same progress is also noticed in the rural areas of the country.
It was found that the major percentage of calorie came from rice (71.1) followed by vegetables (8) and oils (7.4) in 2010. On the other hand, people used to acquire very less amount of calorie from eggs (0.4%) and fruits (0.4 %) (Ahmed et al., 2013) . Furthermore, the amount of protein intake was higher in the urban settings (69.11 gram) in comparison with the rural settings (64.24 gram). The highest amount of protein came from cereals (35.15 gram) followed by fish (9.70 gram); whereas, very low amount came from milk and milk products (Table 5). The major vulnerable groups (i.e., children and women) find this situation more difficult and are still undernourished; especially the reproductive-aged women and children less than 5 years (BDHS, 2014). This situation implicates the imbalanced nutrition consumption and lack of food security in food utilization and nutrition.
Food stability: Food stability is a new dimension in food security. Stability in food availability, food access, food utilization including nutrition and food safety are crucial factors in food security. Therefore, it is highly important to retain the stable condition in food market chain and food supply. To hit this target, trade plays an important role in stabilizing the food supplies and market. It reduces the consumption fluctuations and relieves the country from the costly burden of stock holding interventions. In the cases that trade cannot fulfill the goal of food market stabilization, maintaining food security stocks to a reasonable level depending upon the internal and external situations can play a vital role. Moreover, the government is expected to stabilize the food access throughout the year by employing the food safety net or social protection strategies (Nath, 2015).
Key challenges in achieving food security in Bangladesh
Bangladesh is not food secure and the probable future challenges may make the situation more critical. However, climate change is considered as one of the key challenges for food security (Muniruzzaman, 2013). Food security is directly dependent on the agricultural sector and climate change influences the agriculture rigorously (Amir and Ahmed, 2013). The changing patterns of hazards and natural calamities such as irregular and untimely rainfalls, uneven temperature fluctuation, salinity rise, ill-timed drought, river erosion, and floods (MoEF, 2010) have made Bangladesh more vulnerable to food insecurity in the coming days (FAO, 2003, Mondal, 2010). An expected estimation counts that climate change may cause up to US$26 billion loss to Bangladesh’s agricultural sectors during the 2005-2050 (Yu et al., 2010). This loss may be more in rice production and leads to 3.9 percent reduction in rice production per year (Asaduzzaman et al., 2010). The effect of climate change is harsher with regard to the majority of farmers, since they belong to the smallholding farming community (Ahmed et al., 2013, Quasem, 2011). Besides, the increasing conversion rate of agricultural land to non-agricultural land could have adverse impacts on food security (Muniruzzaman, 2013, Quasem, 2011). One-third of the agricultural land was lost in the last 30 years due to the unplanned urbanization in this country (Rashid, 2012). This losing pace does not seem to slow down considering the overpopulation and tendency of people to convert into urbanized citizens (Shaheen and Islam, 2012). The population of Bangladesh is predicted to reach about 260 million in the mid-21^st century (Streatfield and Karar, 2008), which will bring about severe food shortage in the coming years (Muniruzzaman, 2013). In addition, the global food prices began to rise slowly from 2004 and have fluctuated much since 2007, highlighting the vulnerability of global food supplies and re-vitalizing interest in farming and related issues after a long period of neglect (Foley, 2011, Tilman et al., 2011). This situation also affects the food security condition of those who live in the suburbs of the country (Shakib, 2012). Since the majority of the Bangladeshi population are poor, they will face a tough challenge to afford the food costs in the future (Mondal, 2010, Muniruzzaman, 2013).  In order to ensure the food security of people, better planning should be conducted about these challenges in the future. Currently, the initial and most important need of Bangladeshi people is food security, which should be met by taking appropriate measures
Opportunities for food security in Bangladesh
Protection of the existing arable land should be the first priority of the authorities to ensure the sufficient crops for the production of Bangladesh. The land distribution policy should be more agriculture and farmer oriented. Cultivable waste land should be distributed among the people who do not have land to be used for agricultural purposes (Mondal, 2010). Maximum but sustainable use of agricultural land should be ensured to get most crop production. The present yield gaps can also be exploited using simple interventions such as better seed, nutrients, and water management (Mueller, 2012). Investment in sustainable agricultural and fisheries' productivity growth should be ensured to get sustainable supply of food over the long term. This includes investment in innovations, such as climate-resilient varieties that can enable the sectors to respond to the challenges posed by climate change (OECD, 2017). Bangladesh already has many research institutes working on this issue, but the studies should be problem specific to ensure better utilization of resources (Mondal, 2010). Since most of the farmers in Bangladesh are smallholders (Ahmed et al., 2013), political strategies, focused investments, and planned measures should be implemented to enable these farmers to develop their farming activities and use new innovations (FAO, 2011b, Vorley et al., 2012). The experienced farmers require economic and financial support to use their knowledge. Therefore, measures should be taken to improve the food access in short term using the targeted strategies (OECD, 2017). In other words, food access in the market and the economic affordability of foods are crucial factors. However, income inequalities have made food access difficult economically. The food intake should concern both enough calorie intake and nutritional adequacy to ensure good health and reduce morbidity rates (Mittal and Sethi, 2009).
Conclusions and Recommendations
Food security is the most challenging issue in Bangladesh. With the pass of time, we observed remarkable progress in the food security situations including food grain production, poverty reduction, food consumption, as well as energy and calorie intake with a notable improvement in child and women nutrition. Agriculture is dominated by cereals in Bangladesh and people lack dietary diversification. In other words, they do not have access to other nutrients in their major meals. Subsequently, nutritional aspects of human health have remained neglected in this country. Moreover, Bangladesh has experienced many challenges including climate change, poverty, loss of land, overpopulation, market instability, and post-harvest losses in achieving food security at the national to the local levels. The government of Bangladesh has already made some measures to achieve food security, but many more strategies are required to achieve complete food security. Thus, the following recommendations are suggested for the future policy actions.

Acknowledgements
The first author is grateful to Dr. Avishek Datta, the Associate Professor in the Department of Food, Agriculture, and Bioresources, School of Environment, Resources and Development, Asian Institute of Technology in Thailand for his kind cooperation in developing the research idea. 
Authors’ contributions
D Roy designed the study, reviewed the literature, organized the information, developed the draft, and edited the manuscript. DS Dev wrote and edited the manuscript. S Sheheli had the main responsibility for the final content. All authors read and approved the final manuscript.
Conflicts of interests
The authors declare no conflict of interests.