This document summarizes the nitrogen and sulfur cycles. It explains that humans ingest nitrogen through eating plants and animals, and it benefits humans by making proteins. If humans do not ingest sufficient nitrogen, they could die. It also explains that humans ingest sulfur through food, and it benefits humans by helping with arthritis, skin disorders, and playing a vital role in skin, hair, nails and joints. If insufficient sulfur is ingested, muscles and bones will be weak. Both elements are said to react in the body and cause lung disease. The document lists sources used to obtain this information.