Lemon is the fruit of the common lemon tree. Lemons differ from other fruits in high citric acid content. Lemon contains a significant amount of vitamin C, which is twice as high as that of mandarins, but slightly below that of oranges. Lemon is an important dietary supplement, flavoring as well as lemonade ingredient. Lemonade is originally a natural lemon drink and is named after a lemon. Smell Fresh Properties valued in folk medicine A tonic, high vitamin content is good for the complexion and helps reduce nausea. Aromatherapy properties Lemon oil acts as a mood enhancer.