One element that is essential for projecting food demand growth is income distribution. One of the most robust relationships in economics is ‘Engel’s law’, after Ernst Engel, a German economist, who in the 19th century studied food consumption of the Belgian working class. The law establishes that as income increases, households’ demand for food increases less than proportionally. Hence, as households become richer, their share of expenditure on food decreases until reaching a ‘saturation’ point, after which food demand is hardly responsive to any income increases.

There is a strong positive relationship between the level of income and the demand for greater food variety. As incomes increase, demand for higher value foods such as meat, milk and eggs rises, compared with food of plant origin such as cereals. This is because livestock products are not only tasty and provide high-value protein but are also important sources of a wide range of essential micronutrients, in particular minerals such as iron and zinc, and vitamins such as Vitamin A.

Demand for meat is growing. Over the past 50 years, meat production has more than quadrupled. Globally, we consume 346.14 million tons of meat every year (2018). Around 80 billion animals are slaughtered each year. The average person in the world consumed around 43 kilogram of meat in 2014. This ranges from over 100 kg in the US and Australia to only 5 kg in India. In 2030, our consumption level will be around 453 million ~ a 44 per cent increase.

The projection for world meat demand appears to be uncertain. Though income explains a large proportion of variance, tasks are relatively unimportant. Growth in meat consumption accelerates as countries pass through middle-income stages. Greater equality in income distribution reduces average meat consumption. Therefore, part of the reason why growth in meat consumption accelerates as countries pass through the middle-income stages is because income distribution is more skewed at this stage of development. However, demand may vary from 375 to 570 million tonnes by 2050, that is an increase of 70-160 per cent compared to 2000.

The growing demand for livestock products will have an undesirable impact on environment. Livestock production has become a major environmental challenge. For example, there will be more large-scale, industrial production, often located close to urban centres, which brings with it a range of environmental and public health risks. When full commodity chain of livestock products is included, the sector contributes to global warming, imparts stress on land by grazing, increases demand for water for feed crop production and leads to water pollution by animal waste and chemicals.

Red meat production is a major contributor to global warming because of the methane emitted by cattle and sheep. The amount of greenhouse gases in fresh foods (in kg CO2-eq/Kg) is: Beef (26.61 kg), Lamb (25.58 kg), Pork (5.77 kg), Chicken (3.65 kg), fish (3.49 kg) and eggs (3.46 kg). Field-grown vegetables, on the other hand, produce the least emissions, according to research published in the Journal of Cleaner Production: Rice (2.55 kg), fruits and vegetables (2.13 kg), tree nuts (1.2 kg), cereals and pulses (0.51 kg) and field-grown vegetables (0.37 kg).

Livestock products contribute 18 per cent of total greenhouse gas emissions, accounting for 37 per cent of anthropogenic methane (23 times as warming as CO2 generated by human activity). Livestock industry generates 64 per cent of ammonia, which contributes significantly to acid rain, and generates, mostly from manure, 65 per cent of human-related nitrous oxide, which has 300 times the Global Warming Potential (GWP) of CO2.

Livestock is the world’s largest user of land, either directly through grazing or indirectly through consumption of fodder and feed grains. Around 30 per cent of the earth’s land surface ~ a massive 70 per cent of all agricultural land ~ is used for grazing farmed animals. Much of this grazing land would otherwise host natural habitats such as rainforests. And of the world’s land suitable for growing crops that would otherwise directly feed humans, a third is used to produce feed for farmed animals. A Worldwatch report says that persistent grazing makes bare ground impermeable to rain, which then carries away the most precious topsoil with it. Topsoil regenerates naturally ~ but at the agonizingly slow rate of approximately 2.5 centimeters every 500 years. Thus, overgrazing causes soil erosion, desertification and deforestation. Twenty per cent of the world’s grazing land has already been designated as degraded due to the rearing of animals for their meat.

Livestock population explosion is damaging the overgrazed grasslands surrounding China’s Gobi Desert, where dust storms are increasing dramatically. China has the largest sheep population of 187 million followed by India and Australia. Livestock production is responsible for 70 per cent of deforestation in the Amazon region of Latin American, where rainforests are being cleared to create pastures.

The conversion of cereal grains and other foods to livestock products involves large losses of edible energy. The losses are greatest for cattle, intermediate for pigs, and least for chickens and fish. Cattle in feedlots require roughly seven kilograms of grains concentrate per additional kilogram of live weight. For pigs, the ratio is less than four to one. Chickens, being much more efficient, uses scarcely two kilograms of grain for gaining one kilogram of weight. Fish, including both herbivorous and omnivorous species, require less than two kilograms of grain concentrate to gain additional kilogram.

On average, 40 per cent of global grain production is used to feed livestock, although in richer countries the proportion of grains used for animal feed is around 70 per cent. If all food crops grown globally were fed directly to humans instead of animals, around 70 per cent more food would be added to the food supply, which would be enough to feed 4 billion additional mouths. Estimate of water required to produce a kilo of beef vary from 13,000 liters up to 100,000 litres. Around 8 per cent of total human water use goes for irrigation of feed crop. On the other hand, the sector is the single largest contributor of water pollution. Key pollutants are animal waste, antibiotics and hormones during raising; fertilizer and pesticides for feed crops and sediment from eroded pastures.Farmed animals and fish are fed a wide variety of drugs to fatten them faster and to keep them alive in conditions that would otherwise kill them. These drugs enter the human food chain through direct consumption or through pollution of our waterways. Antibiotics reduce the amount of bacteria in animal intestines and prevent infection to which crowded stressed animals are predisposed. Routine antibiotic use leads to antibiotic-resistant bacteria thereby reducing antibiotic effectiveness when treating people suffering from infectious diseases. Farmers also use hormones on animals to increase growth and productivity, these hormones are known to cause several types of cancer and reproductive dysfunctions in humans.The WHO’s International Agency for Research on Cancer indicated that consumption of red meat is carcinogenic. The Washington-based Physicians’ Committee for Responsible Medicines has linked the high incidence of heart disease and diabetics among Indians to increased meat consumption. The British epidemic of bovine spongiform encephalopathy (BSE) or mad cow disease, which began in 1986 and had affected nearly two lakh cattle, jumps to beef-eating humans in the form of the always-fatal Creutzfeldt–Jacob Disease (CJD). The CDC reported that an average of 10 to 15 people have contracted CJD from meat in Britain each year since it was detected in 1994. Over the past 70 years, more than 300 zoonotic diseases have been detected. Every epidemic that has threatened humans has largely been zoonotic ~ Covid-19, HIV, Sars, Mers, Nipah, Ebola and Swine flu.

According to a 2012 report of the Department for International Development, UK, zoonoses are responsible for over 2.7 million deaths and over 2.5 billion cases of human illness every year. indeed, zoonoses are increasingly being considered as a potent threat to the stability of society. Our preference for meat-based diets has increased our close contact with domesticated and wild animals. As a result, frequency of virus transfer has increased 2 to 3 times in the past four decades, in a cycle of every three decades.

Eating a vegan diet could be the single biggest way to reduce environmental impact on earth and ill effects of diets on health. It reduces global warming; avoids toxic food contamination; reduces the risk of heart disease; prevents cancer and slows the ageing process. In general, a vegetarian is defined as a person who doesn’t eat meat, fish or even poultry. But science tells us that while an exclusive plant-based diet is said to reduce the risk of chronic diseases, persons living on such diet alone are at an increased risk for iron, zinc and vitamin B12 deficiency and anemia. Of course, eating fewer animal products can help us to get rid of these risks. Not all vegetarian diets are created equally. There are several approaches. Vegans, also called total vegetarians, exclude all animal products including eggs, milk, cheese, and perhaps even honey. Lacto vegetarians will include dairy products in their diet. Lacto-ovo vegetarians will eat dairy and eggs. Pescatarians will eat fish. Flexitarians, also called semi-vegetarians, may eat meat once a week or less. Indeed, it is green to go veggie (a vegetarian), but before doing that, it is important to learn about vegetarian nutrition so that the selected diet is balanced and adequate. We all must remember that ‘To eat is a necessary, but it is an art to eat intelligently.’