Lemons have long been valued for more than lemonade. We know that ancient Egyptians prized this oil for its purported ability to act as an antidote to fish and meat poisoning. And, like lime, it was a staple on 17th century Royal Navy ships to help prevent scurvy. Today, we know lemon can help contain and treat infectious diseases, especially colds and fevers. Its scent also helps to increase concentration, and neutralizes unpleasant odors. Some hospitals use lemon oil to help calm frightened or depressed patients. It also boosts the immune system by stimulating production of white and red blood cells. Lemon oil is a must for every aromatherapy kit.