Invited Commentary A celebration of 100 years of vitamin research but time to revitalise the science

In 1912, the Polish biochemist Kazimierz Funk introduced the term ‘vitamine’ (‘vital amine’) for dietary factors that could prevent diseases such as beri-beri, pellagra or scurvy. Although these diseases were known for centuries, their origins remained a mystery. It was Christiaan Eijkman, a Dutch physician and pathologist, who in 1897 started to investigate an outbreak of beri-beri in prisons in Java (now Indonesia). He observed that chickens fed on a diet of polished rice developed similar symptoms to the prisoners receiving a comparable diet. Eijkman demonstrated that unpolished rice and rice peelings prevented and even reversed beri-beri symptoms. It was Eijkman’s collaborator Gerrit Grijns who identified thiamin or vitamin B1 as the active anti-beri-beri compound. Its structure was finally elucidated and it was synthesised in 1936. In 1929, Eijkman shared the Nobel Prize in Physiology or Medicine with Frederick Gowland Hopkins. This was one of the first Nobel prizes awarded for research achievements on individual vitamins, their structure, biological function and relationship to disease, and many more followed (see Table 1). One may call this period of the first half of the twentieth century the ‘golden age’ of nutrition research. It should be mentioned that this year also celebrates the seventy-fifth anniversary of the Nobel Prize given to Albert Szent-Györgyi in 1937 for his research on ‘hexuronic acid’ that was later demonstrated by his fellow Joseph Svirbely to be the antiscorbutic factor that we now call ascorbic (for ascorbutus) acid or vitamin C. In opposition to Funk’s presumption that all vitamins would represent amines, McCollum and Kennedy introduced a classification based on solubility. They coined the terms ‘fat-soluble A’ and ‘water-soluble B’ to distinguish the vitamins present in milk and also noted that fractions A and B probably contained more than a single active compound. Altogether, it took over 50 years until all vitamins relevant for human nutrition were isolated in chemically pure form. An important step along the way was the discovery that some microorganisms also required organic growth factors, and it soon became clear that these factors were identical to those required by mammals. This finding opened the way to replace the time-consuming animal experiments by microbial assays, increasing the speed of analysis and work progress. Nevertheless, the isolation of vitamins quite often required brute-force methods and took years. In the case of biotin, the work started with 250 kg of dried egg yolk from which 1·1 mg of a highly active crystalline material was isolated. Starting material for the isolation of folate was 4 tons of spinach leaves. The final proof that the isolated compounds indeed caused biological effects was enabled by the chemical synthesis of the compounds. Chemical synthesis also opened the way for food fortification. This started with niacin in 1938 and soon led to the eradication of pellagra in the USA. However, identifying the biochemical processes that explained the essentiality of the compounds was still a huge challenge. Our knowledge that all B vitamins as well as vitamins C and K serve as cofactors in enzymatic reactions and determine the activities of hundreds of enzymes is the result of the hard work of thousands of dedicated scientists. This also holds true for those vitamins that have other functions by serving as antioxidants or as ligands for nuclear receptors or in light-transducing proteins. Although much time has passed since the heyday of vitamin discovery and many more studies have addressed vitamin functions in human and animal nutrition, there are still uncertainties as to how much of the vitamins should be consumed by an individual to provide optimal health. These uncertainties are reflected, for example, in the dietary recommendations for vitamin intake as provided by various national bodies and scientific committees. Most interestingly, for some vitamins, the recommendations may vary up to 2·5-fold even between European countries with similar socio-economic status. This is one of the results of the analysis of Troesch et al. published in this issue of British Journal of Nutrition . The authors compared mean dietary vitamin intakes based on food consumption data across a variety of countries and came to the conclusion that the majority of consumers did not achieve the intakes recommended. According to Troesch et al., this gap is most pronounced for the fat-soluble vitamins and for folate. Of course, not reaching the reference intake of a vitamin does not mean that there is a vitamin deficiency, as the recommendations always have a statistically defined safety margin. The key question is of course whether this situation is something to worry about and so to start campaigns to increase vitamin intake or whether we have to reassess the recommendations. Troesch et al. based their analysis on food intake data from the USA, the UK, The Netherlands and Germany. Their British Journal of Nutrition (2012), 108, 574–576 doi:10.1017/S000711451200181X q The Authors 2012