A few related points
Three weekly balanced diets, equivalent to one another for energetic and nutrient content, have been planned: an omnivorous one, a vegetarian one and a vegan one. For each one, the Life Cycle Assessment (LCA) method has been applied in order to calculate the environmental impact, expressed in 'points'.
In particular, recent studies show that plant-based diets are environmentally better than meat-based diets(Leitzmann, 2003; Pimentel and Pimentel, 2003; Reijnders and Soret, 2003).
If the impact of single foods is analysed, we see that:
1. Beef is the single food with the greatest impact on the environment.
2. The other high impacting foods are cheese, fish and milk.
If we only take into account fossil fuel consumption, production of one calorie from beef needs 40 calories of fuel; one calorie from milk needs 14 fuel calories, whereas one calorie from grains can be obtained from 2.2 calories of fossil fuels (Pimentel and Pimentel, 2003; Reijnders and Soret, 2003).
Animal farming and agriculture are responsible for 70% of freshwater consumption on the planet, whereas only 22% of water is used by industry and 8% is used for domestic purposes (World Watch Institute, 2004).
This is the reason why, during the yearly 'Water Week' which took place in Stockholm in August 2004, the foremost specialists in water resources explicitly linked the issue of water shortage with eating habits and explained that the planet's freshwater reserves will no longer be sufficient to feed our descendants with the present Western diet: 'Cattle feed on grains; even those which are left to graze need much more water than is necessary to grow cereals.
Nevertheless, consumers in the developed countries, and even in developing ones, are asking for more meat. It will be almost impossible to feed coming generations on the same diet which we now have in Western Europe and in North America.' The executive director of the Stockholm International Water Institute added that the rich countries will be able to buy their way out of the dilemma by importing 'virtual water', that is, food (cattle feed or meat) from other countries, even from water-poor ones.
Owing to their lighter impact, confirmed also by our study, vegetarian and vegan diets could play an important role in preserving environmental resources and in reducing hunger and malnutrition in poorer nations (Gussow, 1994; Fox, 1999).