Polish-born American biochemist Casimir Funk introduced the term vitamine in 1912. Researchers later identified vitamins needed by the body to prevent deficiency diseases such as beriberi, rickets, scurvy, and pellagra. As better nutrition was developed and the quality of life improved, these diseases almost disappeared from industrialized countries (see Human Nutrition). But by the end of the 20th century, other nutritional disorders emerged. Studies conducted in the United States in the 1990s showed that more than 97 million Americans were overweight and risked health problems, such as heart disease and diabetes mellitus, commonly associated with obesity.