Other additives have also been used throughout the centuries. But the great advances in science and technology in the twentieth century have made so many more potential additives available that regulation has become an absolute necessity. The first nutrient supplement, potassium iodide, was added to table salt in 1924 to overcome iodine deficiency encountered in many inland areas. Since then, a number of other chemicals have been added to certain foods specifically to prevent deficiency diseases. Nutrient supplements such as vitamins and minerals are still important today.
Preservatives are chemicals added to food formulations to inhibit or prevent the growth of microbes.
Propionic acid, sorbic acid, benzoic acid and their salts are used. Some inorganic compounds are also used as inhibitors. Sodium nitrate and sodium nitrite are used to stop the growth of harmful bacteria in food. Both of them give cured meat an attractive red colour. In diabetic and other special dietary foods, artificial sweeteners are preferred.