““The grass on your front lawn is a perfect example. Grass contains several vitamins and minerals, but they are largely inaccessible to humans because of grass’s cellulose content. Cellulose is a fiber that forms the walls of cells in most green plants. Ruminants, such as cows and sheep, have a specialized compartment in the stomach called a rumen; it produces an enzyme that breaks down cellulose, allowing the nutrients in the grass to be absorbed. Ruminants also have other chambers in their stomachs to help them assimilate the nutrients from grass. Humans don’t have rumens, multiple stomach chambers, or the enzymes to break down cellulose, so we can’t extract any nutrients from grass if we eat it. Fortunately, there is a solution to this problem: rather than eating the grass, humans can let animals do the hard work of assimilating the nutrients from grass, and then we can eat the animals.””
