Estimation of Carbon Dioxide Emissions from a Traditional Nutrient-Rich Cambodian Diet Food Production System Using Life Cycle Assessment

: Traditional Cambodian food has higher nutrient balances and is environmentally sustainable compared to conventional diets. However, there is a lack of knowledge and evidence on nutrient intake and the environmental greenness of traditional food at different age distributions. The rela-tionship between nutritional intake and environmental impact can be evaluated using carbon dioxide (CO 2 ) emissions from agricultural production based on life cycle assessment (LCA). The objective of this study was to estimate the CO 2 equivalent (eq) emissions from the traditional Cambodian diet using LCA, starting at each agricultural production phase. A one-year food consumption scenario with the traditional diet was established. Five breakfast (BF1–5) and seven lunch and dinner (LD1–7) food sets were consumed at the same rate and compared using LCA. The results showed that BF1 and LD2 had the lowest and highest emissions (0.3 Mt CO 2 eq/yr and 1.2 Mt CO 2 eq/yr, respectively). The food calories, minerals, and vitamins met the recommended dietary allowance. The country’s existing food production system generates CO 2 emissions of 9.7 Mt CO 2 eq/yr, with the proposed system reducing these by 28.9% to 6.9 Mt CO 2 eq/yr. The change in each food item could decrease emissions depending on the type and quantity of the food set, especially meat and milk consumption.


General Background
Traditional Cambodian food has not been popularized even though it provides a high nutrient intake of calories, minerals, and vitamins. In addition, this traditional food is environmentally sustainable compared to conventional food consumption, considering carbon dioxide (CO 2 ) emissions based on land and water use for agricultural production [1,2]. However, there is a lack of knowledge and evidence on nutrient intake and environmental greenness in favor of traditional food at various age distributions in Cambodia. To confirm the nutritional intake with environmental greenness, it is essential to evaluate traditional Cambodian food consumption patterns for CO 2 emissions. Food production systems impact both the environment and human health. The environmental impact is caused by human activities emitting carbon dioxide emissions that contribute to climate change [3,4]. The carbon dioxide emissions of Cambodia amount to 65.6 Mt CO 2 equivalent, contributing 0.13% to global data [5] of CO 2 from agriculture, industry, etc. greenhouse gas emissions with agricultural production, and life cycle assessment (LCA) is one of the best ways to understand environmental effects.
LCA is an analysis tool that is used to indicate the environmental impact of an agriculture or production system. Various foods have been studied for their environmental impact depending on the quantity of food set as a diet menu, nutrient pattern, and food consumption pattern [22][23][24]. Through environmental impact assessments, traditional Cambodian foods can be adapted to suit young and environmentally aware populations.

Objective of the Study
The type and quantity of food consumption not only affects human health through malnutrition and but also has environmental impacts. Carbon dioxide emissions are linked to the type and quantity of food consumption. This study uses LCA to study both the nutritional value and environmental impact of traditional Cambodian diets. This was completed using 12 sets of traditional Cambodian food, including five breakfast (BF) sets and seven lunch and dinner (LD) sets. The nutritional content of each diet, including calories, minerals, vitamins, and associated carbon dioxide emissions, were evaluated.

Nutrient Requirement
Carbohydrates, proteins, fats, and oils are sources of calories from food. Carbohydrates are the primary energy source from cereals and cereal products (rice, rice noodles, bread, etc.). They consist of 45-65% of the total calorie intake; however, 25% of the total calories come from sugar. Proteins come from fish, meat, and beans, with a daily consumption of 0.8 g (10% to 20% of total calories) multiplied by the weight (kg) of the human body. Moreover, fat is divided into saturated fat (fat) and unsaturated fat (oil), which consists of 25-30% of the total calories. However, saturated fat is separated from animal sources that consume less than 7% of the total calories [25][26][27][28][29][30]. Therefore, minerals and vitamins are derived from vegetables, milk, and/or fruits [31]. In a case study in Cambodia, the food consumption for calories was normal; however, the food consumption for minerals and vitamins was unbalanced. Consumers had mineral and vitamin deficiency problems [26,31,32]. The food quantity was calculated based on the food contents of calories, minerals, and vitamins contained in one set of traditional Cambodian food. Food self-sufficiency in rice has ensured adequate calories per person per day from domestic production. The food set is dependent on the quantity of food and food items that were able to reduce malnutrition and environmental issues and related to agricultural production and food consumption. Therefore, the food set was divided into two groups according to consumer age of G1 and G2 in Cambodia.

Food Dietary
The food set of traditional Cambodian food consisted of food items and the of food serving size. Food items included staple food (rice and/or wheat), meat (beef, chicken, pork, and/or fish), poultry eggs, vegetable cooking oil, vegetables, spices, fruit, and milk. Cambodian cuisine includes a soup menu, stir-fry menu, a roasting menu, and a toasting menu [33]. The food serving size was based on food for calories, vitamins, and minerals and consumer age. Therefore, the food set was consumed two to three times a day to fulfill food needs for calories, vitamins, and minerals. Many Cambodian dishes are served with rice, noodles, or bread, depending on the menu and individual preference. The cuisine taste is balanced between salty, sweet, sour, bitter, and spicy [1,33,34]. Malnutrition is induced by unbalanced of diet habits, so a quantity of staple foods, meat, poultry eggs, cooking oil, vegetables, fruits, and milk was provided. Adequate nutrition is an essential human need, affecting health and well-being through dietary intake from food for calories and food for minerals and vitamins [16][17][18]. The food set was calculated to estimate the food needed for calories, minerals, and vitamins according to the food serving size, consumers' age, estimated land use, water use, and carbon dioxide emission equivalent.

Calculation of Food for Calories, Food for Minerals and Vitamins, and Food Consumption
The concept of this study focused on the necessary food serving size and food items to meet requirements for calories and minerals and vitamins, which are a priority to decrease malnutrition and reduce environmental impact. According to the Cambodian population by age, participants were divided into two consumer groups (G1 and G2). The food set included five breakfast (BF1-5) and seven lunch and dinner (LD1-7) food sets to calculate the food consumption and food items that were converted to food production. Therefore, the food production system was analyzed using land requirements and water use according to the yield of production, product requirements, and/or quantity of animals. After that, the land requirement and animal quantity were calculated to estimate the greenhouse gas (GHG) emissions of carbon dioxide equivalent (CO 2 eq) ( Figure 1). human need, affecting health and well-being through dietary intake from food for calories and food for minerals and vitamins [16][17][18]. The food set was calculated to estimate the food needed for calories, minerals, and vitamins according to the food serving size, consumers' age, estimated land use, water use, and carbon dioxide emission equivalent.

Calculation of Food for Calories, Food for Minerals and Vitamins, and Food Consumption
The concept of this study focused on the necessary food serving size and food items to meet requirements for calories and minerals and vitamins, which are a priority to decrease malnutrition and reduce environmental impact. According to the Cambodian population by age, participants were divided into two consumer groups (G1 and G2). The food set included five breakfast (BF1-5) and seven lunch and dinner (LD1-7) food sets to calculate the food consumption and food items that were converted to food production. Therefore, the food production system was analyzed using land requirements and water use according to the yield of production, product requirements, and/or quantity of animals. After that, the land requirement and animal quantity were calculated to estimate the greenhouse gas (GHG) emissions of carbon dioxide equivalent (CO2 eq) ( Figure 1).  Figure 2 illustrates the system boundary through the production stage referred to as the quantity of food production to calculate the land and water use. Moreover, the emission of carbon dioxide equivalents was calculated based on production. Production was focused on cereals, vegetables, fruit plantations, and animal raising (cattle, poultry, pig, and fish) based on the land area used for planting and raising animals for food consumption. Based on traditional Cambodian food (one food set), the serving size was set to calculate the food consumption of cereals (staple food, such as rice and wheat), meat, eggs, cooking oil, vegetables, fruits, and milk. The staple food, vegetable, and fruit consumption were converted to food production to calculate the plantation's land area. Moreover, meat, egg, and milk consumption were converted to food production to calculate the number of animals reared. The number of animals depended on the weight of the animal carcass and the yield of egg and milk per animal. The cattle, poultry, pig, fish, egg, and milk yield were 120 kg/head. 1.14 kg/head, 50 kg/head [9], 1 kg/head, 98 eggs = 4.878 kg/animal [9], and 1650 kg/animal [35], respectively.  Figure 2 illustrates the system boundary through the production stage referred to as the quantity of food production to calculate the land and water use. Moreover, the emission of carbon dioxide equivalents was calculated based on production. Production was focused on cereals, vegetables, fruit plantations, and animal raising (cattle, poultry, pig, and fish) based on the land area used for planting and raising animals for food consumption. Based on traditional Cambodian food (one food set), the serving size was set to calculate the food consumption of cereals (staple food, such as rice and wheat), meat, eggs, cooking oil, vegetables, fruits, and milk. The staple food, vegetable, and fruit consumption were converted to food production to calculate the plantation's land area. Moreover, meat, egg, and milk consumption were converted to food production to calculate the number of animals reared. The number of animals depended on the weight of the animal carcass and the yield of egg and milk per animal. The cattle, poultry, pig, fish, egg, and milk yield were 120 kg/head. 1.14 kg/head, 50 kg/head [9], 1 kg/head, 98 eggs = 4.878 kg/animal [9], and 1650 kg/animal [35], respectively. The Cambodian population was divided into two groups by consumer age category (G1: age nine years and below; G2: age ten years and over) to calculate the food required for calories and the food required for minerals and vitamins ( Table 1). The recommended nutrient intakes as food for calories and food for minerals and vitamins were studied in terms of staple food, meat, egg, cooking oil, vegetable, fruit, calcium as milk, and fish consumption. The food item was defined using existing and proposed scenarios to account for the carbon dioxide emission equivalent. In this study, two scenarios are discussed: the existing scenario is based on Cambodia data [9] and the proposed scenario is dependent on the food set (Table 2). The amount of carbohydrates, proteins, and fats or oils consumed was equal to 100% of the food consumed by calories. According to the Ministry of Health, Labor, and Welfare and the Food and Agriculture Organization (FAO), fats or oils and proteins accounted for 30% and 10% of calories consumed, respectively. Therefore, the rest came from carbohydrates (60%). Consumers consumed carbohydrates, proteins, and fats or oils depending on the food nutrient composition [25][26][27][28][29][30].
Foods consumed for minerals and vitamins varied according to the age of the population. Therefore, 100 g/day was the minimum consumption of vegetables and fruits for G1, and 400 g/day was the minimum consumption of vegetables and fruits for G2. The amount of milk consumed was between 50 and 300 mL/day, and it was consumed to meet calcium (Ca) requirements. The Cambodian population was divided into two groups by consumer age category (G1: age nine years and below; G2: age ten years and over) to calculate the food required for calories and the food required for minerals and vitamins ( Table 1). The recommended nutrient intakes as food for calories and food for minerals and vitamins were studied in terms of staple food, meat, egg, cooking oil, vegetable, fruit, calcium as milk, and fish consumption. The food item was defined using existing and proposed scenarios to account for the carbon dioxide emission equivalent. In this study, two scenarios are discussed: the existing scenario is based on Cambodia data [9] and the proposed scenario is dependent on the food set ( Table 2). The amount of carbohydrates, proteins, and fats or oils consumed was equal to 100% of the food consumed by calories. According to the Ministry of Health, Labor, and Welfare and the Food and Agriculture Organization (FAO), fats or oils and proteins accounted for 30% and 10% of calories consumed, respectively. Therefore, the rest came from carbohydrates (60%). Consumers consumed carbohydrates, proteins, and fats or oils depending on the food nutrient composition [25][26][27][28][29][30].
Foods consumed for minerals and vitamins varied according to the age of the population. Therefore, 100 g/day was the minimum consumption of vegetables and fruits for G1, and 400 g/day was the minimum consumption of vegetables and fruits for G2. The amount of milk consumed was between 50 and 300 mL/day, and it was consumed to meet calcium (Ca) requirements.  The food for calories, minerals, and vitamins was calculated depending on the total food consumption and nutrient composition. The nutrient composition includes values for carbohydrate; protein; fat; calcium; iron; zinc; and vitamin A, D, B, and C (Table A1).
The items in traditional Cambodian food are defined by the Cambodian food consumption pyramid. Staple foods such as rice, rice noodles, or wheat are referred to as carbohydrates. Meat or fish and eggs are referred to as proteins, and cooking oil is referred to as fat. Moreover, vegetables, fruits, milk, and fish are referred to as sources of vitamins and minerals. The quantity of food eaten per person was divided into three meals-breakfast, lunch, and dinner-according to the total of food consumed for calories [1,26,31].
The traditional Cambodian food set consists of food for calories and food for minerals and vitamins ( Table 2). The food for calories included breakfast (BF) and lunch and dinner (LD) menus that contained staple foods, meats, eggs, and/or cooking oil. The food eaten for minerals and vitamins contained vegetables and spices (VESP), fruit, and milk. Therefore, staple food consisted of rice and wheat. The meat was composed of beef, chicken, pork, and/or fish, which is referred to as protein.
The annual intake included the food sets of BF1-5 and LD1-7. Ordinarily, consumers consume food sets three times per day, with BF once per day and LD twice per day. BF was set to 73 times the annual intake/set/yr, and the total annual intake of BF was 365 times/yr. LD was set to 104 times the annual intake/set/yr, and the total annual intake of LD was  (Table 2). Therefore, the annual intake changed depending on the number of food sets selected from the BF and LD. Consequently, the quantity of food produced changed according to the annual intake.
This study was focused on one food set of traditional Cambodian food. Imported foods were not included in this mass balanced because wheat and milk production did not satisfy food needs. Cambodia is a tropical country where wheat cannot be cultivated. The milk production was not enough for consumption because of its limited and low production.
The carbon dioxide equivalent estimation was calculated with SimaPro ® v8.0.4 using the global warming potential for a 100-year time horizon as the environmental impact category. The LCA methodology in this study followed the study framework in ISO14040.

Results
Traditional Cambodian food sets consist of 12 food sets categorized into five breakfast food sets (BF1-5) and seven lunch and dinner (LD1-7) food sets, which include food for calories, minerals, and vitamins. The food sets of food for calories consist of staple food, food menu, cooking oil, and food eaten for minerals and vitamins, such as vegetables, spices, fruits, and milk. Therefore, the food set called BF1 included chicken congee, fruit, and milk. BF2 consisted of Khmer fish noodle soup, fruit, and milk. BF3 included rice with fried pork, fruit, and milk. BF4 included beef noodle soup, fruit, and milk. Finally, BF5 included a Khmer sandwich, fruit, and milk. LD1 included samlor kako Khmer stew, fruit, and milk. LD2 included beef lemongrass sour soup, fruit, and milk. LD3 included samlor brahaer Khmer stew, fruit, and milk. LD4 included fried fish with ginger, fruit, and milk. LD5 included braised fish with tomato, fruit, and milk. LD6 included waterlily sour soup, fruit, and milk. Lastly, LD7 included stir-fry beansprouts, fruits, and milk. The serving size depended on the consumer's age. For G1, it was 200-205 g/set, and for G2 it was 330-335 g/set (Table 3). Therefore, the nutrient requirements include typical food eaten for calories, minerals, and vitamins (Table A2). Nutrition value is dependent on the food composition, such as carbohydrates, protein, fat, calcium, iron, zinc, vitamin A, vitamin B, vitamin C, and vitamin D (Table A1). Normally, consumers consume three food sets per day to satisfy the nutrient requirements for their daily life. Traditional Cambodian food (one set of food) consists of food eaten for calories and food eaten for minerals and vitamins and is dependent on food composition and the quantity of food items eaten. Food eaten for calories (carbohydrate, protein, and fat), minerals (Ca, Fe, and Zn), and vitamins (A, D, B1, B2, B3, B6, B9, B12, and C) is divided into two major categories (BF and LD) and two age groups ( Table 3). The average calorie count of one food set for G1 consumers was 307 kcal/set, which consisted of 50 g of carbohydrate, 11 g of protein, and 6 g of fat. The same food set contains minerals (82 mg   In the proposed scenario, rice, rice noodles, wheat, chicken, pork, fish, egg, cooking oil, vegetables, fruit, and milk were eaten in amounts of 1.   Instead of the food set selection, three sets listed as BF1 + LD1 + LD3 were consumed every day. The results showed foods eaten for calorie intake and foods eaten for mineral and vitamin intake. Thus, food selection could change according to consumers' preferences. In one day, the G1 consumers consumed 907 kcal of food for calories, which included 153 g of carbohydrates, 35 g of protein, 14 g of fat. Food eaten for minerals included 257 mg of Ca, 5.6 mg of Fe, and 3.3 mg of Zn. Food eaten for vitamins included 328 µg of A, 5.5 µg of D, 0.7 µg of B1, 0.7 mg of B2, 11 mg of B3, 0.9 mg of B6, 82 µg of B9, 1.5 µg of B12, and 77 mg of C. For G2 consumers, the calorie intake per day was 1620 kcal, which included 280 g of carbohydrates, 67 g of protein, and 22 g of fat. Food eaten for minerals included 402 mg of Ca, 9.9 mg of Fe, and 5.9 mg of Zn, and food eaten for vitamins included 588 µg of A, 93.5 µg of D, 1 µg of B1, 1.1 mg of B2, 21.1 mg of B3, 1.6 mg of B6, 150 µg of B9, 2.4 µg of B12, and 108 mg of C. In the proposed scenario, rice, rice noodles, wheat, chicken, pork, fish, egg, cooking oil, vegetables, fruit, and milk were eaten in amounts of 1.  Figure 4).   [8,9] and proposed scenarios to fulfill the nutrient requirements.
The Cambodian GHG emissions of carbon dioxide equivalent from the proposed food set were 6.9 Mt/y. The highest emission was 1.2 Mt for LD2, and the lowest was 0.3 Mt for BF1 and BF2. Therefore, BF4, LD7, and LD1 had emissions of 0.9 Mt, 0.8 Mt, and 0.7 Mt, respectively. Both BF4 and LD4 had emissions equal to 0.5 Mt, and BF5, LD3, LD5, and LD6 had emissions equal to 0.4 Mt ( Figure 5).  [8,9] and proposed scenarios to fulfill the nutrient requirements.
The Cambodian GHG emissions of carbon dioxide equivalent from the proposed food set were 6.9 Mt/y. The highest emission was 1. The mass balance of the existing and proposed scenarios according to land use, water use, and CO2 emissions showed the supply to be 8.6 Mt, including an import of 0.2 Mt and an export of 0.6 Mt. Based on the supply, 4.1 Mha for land use, 17.1 Gt for water use, and 9.7 Mt CO2 eq for emitted CO2 emissions were required. However, the result for the proposed scenario showed that the consumption was 5.1 Mt, including the import of wheat and milk products. Depending on the supply required, 2.3 Mha for land use, 6.8 Gt for water use, and 6.9 Mt CO2 eq for CO2 were emitted ( Figure 6). For the proposed scenario, the result showed the consumption of staple foods, meat, eggs, vegetables, fruits, and milk to be 1.  (Table 5).  The mass balance of the existing and proposed scenarios according to land use, water use, and CO 2 emissions showed the supply to be 8.6 Mt, including an import of 0.2 Mt and an export of 0.6 Mt. Based on the supply, 4.1 Mha for land use, 17.1 Gt for water use, and 9.7 Mt CO 2 eq for emitted CO 2 emissions were required. However, the result for the proposed scenario showed that the consumption was 5.1 Mt, including the import of wheat and milk products. Depending on the supply required, 2.3 Mha for land use, 6.8 Gt for water use, and 6.9 Mt CO 2 eq for CO 2 were emitted ( Figure 6). For the proposed scenario, the result showed the consumption of staple foods, meat, eggs, vegetables, fruits, and milk to be 1.  (Table 5).  (Table 5).
For the total GHG emissions of carbon dioxide equivalent in the existing scenario,   (Table 5).
For the total GHG emissions of carbon dioxide equivalent in the existing scenario, the total emissions of carbon dioxide were 9.7 Mt CO 2 eq/yr, in which staple foods, meat, eggs, vegetables, fruits, and milk had values of 5.   (Table 5).
For the total GHG emissions of carbon dioxide equivalent in the existing scenario, the total emissions of carbon dioxide were 9.7 Mt CO2 eq/yr, in which staple foods, meat, eggs, vegetables, fruits, and milk had values of 5.

Discussion
In the proposed scenario, the food consumed for calories per one set had an average of 307 to 540 kcal/set (Table 3; Figure 3), which was higher than the average in the existing scenario. Moreover, the amount of food consumed for minerals and vitamins in the proposed scenario was the higher than in the existing scenario [12,26].
One set had food consumed for calories from 591 to 793 kcal/set, containing 100 to 112 g of carbohydrate, 16 to 30 g of protein, and 12 to 24 g of fat. Then, the minerals included 4 to 12 mg of Fe, and the vitamins included 61 to 799 µg of A, 29 to 477 µg of B9, and 24 g of C [1,[36][37][38].
The food consumed for calories was defined by the consumer age and physical activity [26][27][28][29][30]. From 1 to 9 years of age, the food consumed for calories was between 1180 and 1825 kcal/day [24]. From 1 to 5 years of age, the food consumed for calories was between 950 and 1300 kcal/day. Therefore, from 6 to over 80 years old, the food consumed for calorie intake was defined according to the physical activity level [28]. Food consumed for minerals and vitamins was defined between the minimum and maximum requirements [29,37]. The individual intake guideline includes 5-12 g of carbohydrate/set/kg body weight, 1.2-1.8 g of protein/set/kg body weight dependent on physical activity, and 20-30% of the total calories required [39]. The food consumed for calories and the food consumed for minerals and vitamins was beyond the minimum and maximum requirements (Table A2).
In the existing scenario, food items consisted of rice, wheat, meat, eggs, cooking oil, vegetables, fruits, calcium as milk, and fish. The Cambodian data in 2017 [9] showed that the food supply of each food item was equal to the demand and other (processing, feed, seed, non-food, and stock) was equal to the production and import, excluding export. The rice was required 6.17 Mt/y of supply. The wheat, beef, chicken, pork, fish, eggs, cooking oil, vegetables, fruits, and milk accounted for 0.04 Mt, 0.07 Mt, 0.04 Mt, 0.10 Mt, 0.69 Mt, 0.02 Mt, 0.05 Mt, 0.55 Mt, 0.77 Mt, and 0.06 Mt, respectively. We do not have data concerning rice noodles yet (Figure 4; Table A3). According to the Ministry of Health and the Foundation for International Development/Relief, individuals of ages from 6 to 17 years old in a rural area consumed 74.6% carbohydrates, 11% proteins, and 14.4% fats. However, in an urban area they consumed 70.5% carbohydrates, 11.8% proteins, and 17.7% fats [26]. Moreover, the annual food intake per person was 300 kg of rice, 27 kg of meat, 27 kg of fish, and 91 kg of vegetables [34]. The total food consumption in the proposed scenario was less than in the existing one.
According to the food set, land and water use for plantation and raising and emissions of carbon dioxide equivalent (CO 2 eq) were estimated. For the existing scenario, the rice produced 6.17 Mt and required 2.79 Mha of land use [8,9] and 13.88 Gt of water use [19]. Data for rice noodles have not yet been reported [8,9]. The consumption of wheat, meat, egg, vegetables, fruit, and milk was 0.04 Mt, 0.09 Mt, 0.02 Mt, 0.60 Mt, 0.77, and 0.06 Mt, respectively, with land uses of 0.11 Mha, 0.93 Mha, 0.04 Mha, 0.09 Mha, 0.06 Mha, and 0.06 Mha, respectively, and water uses of 0.02 Gt, 2.86 Gt, 0.01 Gt, 0.08 Gt, 0.12 Gt, and 0.15 Gt, respectively (Table 5; Figure 7).
In the proposed scenario, the average for G1 and G2 per week was emitted CO 2 eqs of 5.42 kg/week and 9.47 kg/week, respectively (Table A5), which were lower than the values for the Mediterranean and new Nordic diets. However, the Mediterranean and new Nordic diets had emitted carbon dioxide emissions of 23.56 kg CO 2 eq/week and 25.8 kg CO 2 eq/week, respectively. These emissions were calculated from the individual food categories of beef, egg, milk, margarine, potatoes, pasta, assorted fruits, and tap water [24]. Therefore, the carbon dioxide emissions per product, including cereal, rice, beef, chicken, pork, fish, egg, butter, vegetable, fruit, and milk, were 0.50 kg, 2.55 kg, 26.61 kg, 3.65 kg, 5.77 kg, 3.49 kg, 3.46 kg, 9.25 kg, 0.37 kg, 0.42 kg, and 1.29 kg, respectively [19]. The emissions from fast food, pizza, were 3.5 kg CO 2 eq/kg pizza, in which cheese, meat, and solid fat made up 43%, 21%, and 21%, respectively [40]. Therefore, the dairy emissions were 0.37 kg CO 2 eq. Therefore, the global warming potential of carbon dioxide emissions were 1.09 kg for a ready meal and 0.99 kg for homemade chicken. The ready meal, tomato pasta, caused 0.12 kg, and the home made meal caused 0.11 kg [41]. However, in the proposed scenario the CO 2 eq kg/kg was higher than the emissions from ready meal, tomato pasta, and homemade chicken.
The global GHG emissions by sector were 49.4 billion t CO 2 eq, which included energy, industry, waste, and agriculture and land use at amounts pf 73.2%, 5.2%, 3.2%, and 18.4%, respectively. The global land use for livestock (meat and dairy) and crops was 77% and 23% of all agricultural land, accounting for 18% and 82% of calories supplied, and 37% and 63% of the protein supply, respectively [19]. Consequently, the global GHG emissions from non-food and food were 74% and 26%, respectively. The supply chain emissions, livestock and fish farms, crops, and land uses were 18%, 31%, 27%, and 24% of food, respectively. In the supply chain, the GHG emissions were high, accounting for high carbon dioxide equivalents from farms per kilogram of product. Instead of beef, the total GHG emissions were 60 kg CO 2 eq/kg product, which included land use, animal feed, farm, processing, transport, packaging, and retail of 16.3 kg, 1.9 kg, 39.4 kg, 1.3 kg, 0.3 kg, 0.2 kg, and 0.2 kg, respectively. Moreover, the total GHG emissions from pig meat, poultry meat, fish (farm), other vegetables, and other fruits were 7.2 kg, 6.1 kg, 5.1 kg, 0.5 kg, and 0.7 kg, respectively [19]. In Cambodia, the 2016 carbon dioxide emissions equivalent was 65.6 Mt, which included emissions from agriculture, land use change and forestry, transport, and other (bunker fuel, industry, waste, building, electricity, and heat, fumes from energy production, construction energy, and other types of fuel combustion) of 21.0 Mt, 30 Mt, 5.0 Mt, and 9.6 Mt, respectively [20]. Therefore, in Cambodia the 2016 GHG emissions for agriculture, land use change and forestry, other fuel combustion, waste, and fugitive emission and industry were 17.09 Mt, 5.37 Mt, 2.8 Mt, 0.28 Mt, and 0 Mt for methane emissions, respectively, and 3.89 Mt, 1.88 Mt, 0.67 Mt, 0.26 Mt, and 0 Mt for nitrous oxide, respectively [20]. According to Ritchie and Roser, the per person methane emissions of CO 2 eq based on their global warming potential value over a 100-year timescale was 1.62 Mt. Therefore, the total methane emissions from the rice field were 0.38 Mt [19,21,35,42,43]; in Cambodia, the total emissions from the paddy field were 0.45 Mt for methane emissions and 9.37 Mt for carbon dioxide emissions. Moreover, the total emissions (enteric) from all animals were 0.18 Mt for CH 4 emissions, and the CO 2 eq was 3.74 Mt [9].
In a comparison between the existing and proposed scenarios, the results showed that the carbon dioxide emissions are expected to reduce from 9.7 Mt in the existing scenario to 6.9 Mt in the proposed one. The land use requirement is reduced from 4.1 Mha in the existing scenario to 2.3 Mha in the proposed scenario, and the water use requirement is reduced from 17.1 Gt in the existing scenario to 6.8 Gt in the proposed one.

Conclusions
This research focuses on food consumption for traditional Cambodian food. The food set was defined as the quantity of rice, rice noodles, wheat, beef, chicken, pork, fish, eggs, cooking oil, vegetables, spices, fruits, and milk consumed. Depending on the food consumption in the proposed scenario, the land and water use requirements were reduced by 43.90% and 60.23%, respectively, for agricultural plantation and raising animals to meet the nutrient requirement intake.
The assessment was performed using existing practices and the proposed scenario was divided into BF and LD sets. In these sub-categories, food was divided into two scenarios: food eaten for calories and food eaten for minerals and vitamins. In the proposed scenario, the food eaten for calories, minerals, and vitamins satisfied the food requirements. The carbon dioxide emissions for the traditional Cambodian food set were decreased by 28.87%. Therefore, the food eaten for calories, minerals, and vitamins met the food set quantity requirements. The food set emissions were calculated from the food item intake.
In the proposed scenario, there is an opportunity to reduce land and water use, and the CO 2 of the agricultural production system met the nutrient requirements for human health. Furthermore, the LCA-based analysis showed the effectiveness of adopting a diet rich in traditional Cambodian foods to reduce the environmental load for CO 2 emissions. This method calculates dietary intake based on food eaten for calories, minerals, and vitamins.

Conflicts of Interest:
The authors declare no conflict of interest.    Table A3. Illustration of food supply balanced with food demand plus others and equal to food production and import excluding export (existing data) [8,9]. Note: (Production + Import)-Export = (Demand + Other); Demand + Other = Supply; "Other" meant for other use purposes as processing, feed, seed, stock, and non-food. Total emission as CO 2 eq (Mt CO 2 eq) TE CO 2 eq = RI Prod × E RICO 2 eq 0.85 Total emission as CO 2 eq (Mt CO 2 eq) TE CO 2 eq = RN Prod × E RNCO 2 eq 0.17 Table 5 * Rice production; ** Rice noodle production. Table A5. Inventory data of total wheat production (import basis).