A group of 40 investors managing $1.25 trillion in assets have launched a campaign to encourage 16 global food companies to change the way they source protein for their products to help to reduce environmental and health risks. The investors wrote to the food companies urging them to respond to the “material” risks of industrial farming and to diversify into plant-based sources of protein. Among the companies targeted are Kraft Heinz, Nestle, Unilever, Tesco and Walmart.