Food security is a crucial aspect of human well-being. There are only seven years remaining to achieve the Sustainable Development Goal (SDG) 2 “Zero Hunger”, but the task is becoming more challenging due to factors such as climate change, regional conflicts, and economic shocks. According to The Sustainable Development Goals Report 2022, an increasing number of people have been affected by hunger since 2014 and the COVID-19 pandemic makes it worse [1]. The FAO [2] estimated that more than 700 million people suffered from hunger in 2021, an increase of 46 million since 2020 and 150 million more than that in 2019. In particular, people affected by severe food insecurity increased in 2021, accounting for 11.7% of the global population, which highlights the impacts of COVID-19 on the most vulnerable people. Regarding the nutrition status worldwide, rural residents are suffering from various forms of malnutrition while urban residents are exposed to a higher risk of overweight and obesity. In 2020, 22% (149.2 million) of children under the age of five were affected by stunting and 6.7% (45.4 million) suffered from wasting. The prevalence of overweight among children under five increased to 5.7% (38.9 million) in 2020 [2]. Additionally, high food prices have been affecting many countries since 2016. The crisis in Ukraine adds further uncertainty to the affordability of a healthy diet since both Ukraine and Russia are major agricultural producers and exporters [3]. For example, the crisis affects the planting, harvesting, and transportation in Ukraine, which leads to a reduction in the supply market [4]. The global supply chains have been disrupted by the conflicts and agricultural trade has been hampered, especially the export from Russia and Ukraine [5]. Moreover, agricultural input costs have experienced a significant rise due to the conflicts between Ukraine and Russia, which negatively impact crop yields ^[4][6][4,6]. Given the growing threats to global food security, it is essential that all levels of society pay closer attention and that interdisciplinary solutions are sought urgently.

Various actions have been implemented to improve food security. Governments propose various policies to improve food security, such as food price controls and agricultural subsidies for small-scale farmers, and preferential tariffs for agricultural enterprises [7]. Non-government organizations keep investing to improve food and nutrition for the most vulnerable. Some cross-sectors collaborate to improve food security, such as public–private partnerships [8]. The FAO [9] emphasizes the engagement of small- and medium-sized enterprises in the agrifood systems transformation. Many papers also argue the positive effects of investment on food security. However, enterprises’ investment is usually motivated by maximizing profit, which is not necessarily consistent with the goal of food security improvement. How to guide agricultural investment towards food insecure countries and take advantage of these investments to improve food security is worthy of attention.

2. Agricultural Investment and Food Security

Food security is a hot topic in the literature and involves various aspects of socio–economic development. Both developing countries and developed country face food security issues but manifest in different ways. In developing countries, hungry people usually cannot afford sufficient, safe, and healthy food, while food insecurity usually refers to overweight and obesity in developed countries ^[2][10][2,10]. To improve the food security level, some papers focus on general agricultural interventions and others investigate the impacts of certain improvement projects. Bizikova, et al. [11] find input subsidies, cash transfers, food vouchers, and extension services are effective interventions to improve food security at an individual level. However, the performance of these interventions also varies across different design and operating plans. Rana et al. [12] highlight crop management strategies, such as utilizing fertilizers, caring for the seasonality, and introducing control systems to increase yield productivity based on the literature review from the botanical perspective. Deligios et al. [13] introduce an irrigation water management system that combines evaporative cooling practice with precision irrigation technique, which increases yields and improves water productivity. Shamah-Levy et al. [14] focus on food security governance at national level and point out that fragmentation of governance agencies and oligopoly problems in the agricultural sector threaten food security in Mexico. West et al. [15] evaluate one specific intervention program, OzHarvest’s six-week Nutrition Education and Skills Training program, and suggest that ensuring all citizens’ access to nutritious food is the key to improve food security. Furthermore, another strand of literature investigates the determinants of food security aiming at explaining the underlying mechanism. Feleke et al. [16] focus on household food security and find that technology adoption, farm size, and land quality could positively affect household food security. Allee et al. [17] explore national determinants and find that per-capita cereal production, governance level, and logistics performance are key drivers of food security improvement. Food security measurement is the key to conducting research related to food security. Because food security is a relatively broad concept and includes four dimensions: access, availability, utilization, and stability according to the FAO’s definition. Scholars usually choose different indicators to capture different dimensions of food security based on their research objectives. Some papers develop their own indicators to measure more site-specific food security ^[18][19][18,19]. Based on the existing indicators, there are mainly two types of evaluation methods: micro-level and macro-level methods. At the macro level, that is at the national level, the most common indicators include the Global Hunger Index (GHI), the Food Insecurity Experience Scale (FIES), the prevalence of undernourishment, and food demand and supply ^[17][20][21][17,20,21]. The other kind is a household or individual indicator, such as nutrients intake (calorie, carbohydrates, and protein), dietary diversity, and food distribution within the family ^{[22][23][24][25][26]}[22,23,24,25,26]. These micro-level indicators are usually used to measure food utilization and food stability.  Regarding the discussion on investment and food security, many papers have provided evidence of the positive effects of agricultural investment on food security improvement. The underlying mechanism is mainly explained through three channels. First, investment improves food production efficiency and positively affects food security in host countries. The investment brings capital directly and improves agricultural Total Factor Productivity (TFP) through the spillover effect of knowledge and technology ^[27][28][29,30]. For example, large scale land investments bring modern agricultural techniques and close the crops yield gaps in host country, which contributes to the increase in food production and feeds more people in the host country ^[29][31]. Furthermore, increased agricultural production directly improves household consumption, including the intake of protein, vitamins, and carbohydrates ^[30][32]. Second, investment would promote economic development at the national level, and therefore provide employment opportunities for local residents ^[31][32][33,34]. Large-scale land investments could provide agricultural and non-agricultural jobs when it matches with local community ^[30][33][32,35]. Investment in commercial farms helps small-holders get access to modern inputs and improve their income levels ^[34][36]. Third, some studies suggest that agricultural investment positively affects food supply chains in host countries, which would promote regional and international trade in agricultural sectors ^[35][37].