Vitamins and related growth factors belong to the few chemicals with a positive appeal to most people; the name evokes health, vitality, fitness, strength . . . . each one of us indeed needs his daily intake of vitamins, which should normally be provided via a balanced and varied diet. However, current food habits or preferences, or food processing and preservation methods do not always assure a sufficient natural daily vitamin supply, even for a healthy human being; this is all the more true for stressed or sick individuals. Although modern society is seldom confronted with the notorious avitaminoses of the past, they do still occur frequently in overpopulated and poverty- and famine-struck regions in many parts of the world. Apart from their in-vivo nutritional-physiological roles as growth factors for man, animals, plants and micro-organisms, vitamin compounds are now being introduced increasingly as food/feed additives, as medical-therapeutical agents, as health-aids, and also as technical aids. Indeed, today an impressive number of processed foods, feeds, cosmetics, pharmaceuticals and chemicals contain extra added vitamins or vitamin-related compounds, and single or multivitamin preparations are commonly taken or prescribed. These reflections do indicate that there is an extra need for vitamin supply, other than that provided from plant and animal food resources. Most added vitamins are indeed now prepared chemically and/or biotechnologically via fermentation/bioconversion processes. Similarly, other related growth factors, provitamins, vitamin-like com pounds, i. e.
