PLANT-BASED DIETS

ENVIRONMENTAL REASONS TO EAT A PLANT-BASED DIET 

Consuming animal products is resulting in four main environmental issues:

1.    Resource inefficiency

Factory farming of animals for food requires an enormous amount of energy, land, and water to grow feed crops for these intensively produced animals (2). Based on current typical industrial methods, to produce just 1kg of beef, you need 20kg of feed, 15,500 L of water (which is approximately 90 full bathtubs), 15 x as much land as the production of 1kg of cereals and 70 x as much land as the production of 1kg of vegetables. To produce 1 kcal of food energy from beef, 40 kcal of fossil fuel energy input is required. 

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In terms of food energy (kilocalories), producing meat is extremely inefficient because livestock consume a lot more calories than they produce for human consumption (2). For example, to produce just 1 kg of high-quality animal protein, livestock are fed nearly 6 kg of plant protein. Additionally, livestock feed consumes ~43% of the food energy produced by the world’s total harvest of edible crops, after post-harvest losses.  This is a huge amount of calories which could be used to feed the human population. Moreover, 55% of US-produced corn, 40% of the worldwide grain harvest, and more than 85% of soybeans produced worldwide end up as animal feed. Even 37% of the total yearly fish harvest is used as feed in the aquaculture, pork, and poultry industries (5). Given that around 1 billion people are chronically undernourished (6), it is essential that we use these resources in a more efficient way, because the planet cannot feed both increasing human and farmed animal populations. 

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2.    Resource scarcity

The increasing demand for meat, and thus feed grain, is increasing the pressure on already scarce grazing land (2,7). Over-exploitation of arable land is damaging the soil, converting once fertile land into desert, in a process known as desertification. Overgrazing is also resulting in deforestation, at a rate where a slice of rainforest the size of a football field is mowed down every second (8). Not only is overgrazing resulting in less land to grow crops, the loss of wildlife habitats is threatening biodiversity globally. 

Water scarcity is also a major problem (9). 2 billion people worldwide experience water scarcity and the agricultural sector accounts for 70% of all freshwater consumption. It has been suggested that reducing the proportion of animal-based food and increasing that of plant-based food in the diet can halve an individual’s water footprint (2). This is because for each cubic metre of water used in production, lentils and wheat, for example, produce up to 17 and 19 x more food calories respectively and up to 5 x more edible protein, compared to beef.

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3.    Increase in global greenhouse gas (GHG) emissions

The livestock sector is responsible for a large proportion (18%) of total global GHG emissions (2) [* admin note #1]. This is 4% more than the GHG emissions produced from global transport. The major sources of these livestock-related GHGs are enteric fermentation (methane produced by digestion), animal manure and fertilisers used for feed production. Specifically, livestock production is responsible for 37% of global methane emissions, 65% of global nitrous oxide emissions, 9% of global carbon dioxide emissions, and 64% of ammonia emissions and contributes to air, soil, and water pollution, acid rain, and damage to the ozone layer (7).

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4.    Increase in water and air pollution 

Animal manure and the excessive quantities of fertilizers used to produce animal feed are polluting groundwater, streams and rivers (5). The high nitrogen and phosphorous content of run-off (from manure-fertilized fields) have resulted in the widespread eutrophication (over-enrichment with nutrients) and subsequent algae blooms in several lakes and estuaries over the past 30 to 40 years. 
As eutrophication reduces oxygen to levels insufficient to support aquatic life, large areas (e.g. Gulf of Mexico) have become dead zones. Livestock production can additionally pollute freshwater with sediment (through soil erosion), pesticides, antibiotics, heavy metals, and pathogens such as Salmonella and Escherichia coli. Factory farms are also sources of aerial pollutants that can damage the health of workers and those living near them. A chicken shed holding 100,000 broiler meat birds can emit up to 77 kg of polluting dust per day (2).

HEALTH REASONS TO EAT A PLANT-BASED DIET

Over the past several decades, plant-based nutrition has exploded in popularity and more-so recently with the rise of technology and social media. Both the British Dietetic Association (10) and the American Academy of Nutrition and Dietetics (11) recognise that the plant-based diet is suitable for every age and stage of life including pregnancy, lactation, infancy, childhood, adolescence, and for athletes. Whilst there may be some differences in the literature as to what the optimal diet for human health is, in general, it has been suggested that healthy eating may be best achieved with a diet that encourages whole, plant-based foods and discourages meats, dairy products, and eggs (as well as all refined and processed foods) (3). This is because plant-based diets have been associated with many health benefits (3, 4), including:

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·        supporting sustainable weight management

·        lowering ischemic heart disease mortality rates

·        lowering the risk for most chronic diseases

·        decreasing the incidence and severity of high-risk conditions, including obesity, high blood pressure, high blood sugar (diabetes) and high cholesterol levels

·        reducing the number of medications needed to treat chronic diseases

·        decrease the risk of cancer

·        even possibly reversing advanced coronary artery disease and type 2 diabetes

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These advantages of plant-based diets arise because plants typically have a large amount of phytochemicals and fibre (4), which are arguably the two most important categories of nutrients

in promoting health and fighting disease. Interestingly both these nutrients are completely absent in animals, and are only found in plants. Additionally, by removing animal products you reducing consumption of several harmful constituents found in them (4) [** admin note #2], such as:

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·        saturated fats, which promote CVD

·        dietary cholesterol, which when a high-intake is consumed, may also promote CVD

·        insulin-like growth factor-1 which has been associated with promoting cancer proliferation

·        heme iron, which when consumed in excess may increase the risk of colorectal cancer, promote atherosclerosis, and reduce insulin activity

·        chemical contaminants formed from high temperature cooking of cooked animal products, which have been shown to be carcinogenic, pro-inflammatory, pro-oxidative and also contribute to chronic disease

·        carnitine in meat, which may lead to atherosclerosis, heart attack, stroke and death

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Moreover, by not eating animal products, you are not consuming the huge amounts of antibiotics given to livestock. In fact, half of all antibiotics produced in the world are used for livestock, to prevent infections and diseases inherent in the conditions in which they are kept (2). Factory farming has resulted in several recent human health challenges, including the commonly known diseases, BSE (which emerged due to the intensification of the dairy industry) and bird flu (which emerged due to the intensification in the global chicken industry). Additionally, this over-use of antibiotics is causing a major global health crisis known as antibiotic resistance in many common pathogens which cause disease in humans. This means that the spectre of untreatable infections in humans is increasing.

Nonetheless, it is important to note that although plant-based diets are associated with several health benefits, different types of vegetarians or vegans may not experience the same effects on health, as you can also be an unhealthy vegan or vegetarian. For example, a lot of junk food is vegan, such as Oreos and Pringles original. Additionally, vegans need to take a B-12 supplements, and may be low in calcium, iron, vitamin D and fatty acids if they do not eat a balanced and nutritious diet. So, the key is to focus on eating a balanced and healthy plant-based diet (3,4) [*** admin note #3]