Plants produce their own food through photosynthesis, while animals obtain food from plants, either directly by eating plants or indirectly by eating animals that eat plants. There are five main steps in the nutrients process: ingestion, digestion, absorption, assimilation, and egestion. Ingestion involves taking substances into the body through the mouth. Digestion breaks down large food molecules into smaller molecules. Absorption is when digested food passes into the bloodstream. Assimilation converts absorbed nutrients into tissues. Egestion removes undigested waste from the body.