Editorial: What is a nutrient?

Nutrient:a substance that an organism must obtain from its surroundings for growth and the sustenance of life. old days of food composition work, we took certain comfort in the simple characterization of the food components we measured--they were nutrients. But if they were not nutrients, they could still be neatly classified as antinutrients, toxicants, or just interesting non-nutrients. Of course, components are not so simply characterized these days. Polyphenols, measured in at least two of the studies in this issue of JFCA, were referred to as antinutrients in the not-too-distant past. In recent years, we rarely see that kind of characterization. Many of the polyphenols are now characterized as beneficial bio-active non-nutrients, with the occasional suggestions that some could even be called nutrients. The same is true for isoflavones and coumestrol, for which we have more new data in this issue. her confounding situation exists with functional characterizations of food components. Letʹs take what many papers in the scientific literature refer to as "antioxidant nutrients". The provitamin A carotenoids show up on this list, but some of the most potent antioxidant carotenoids cannot be classified this way because they have no provitamin A activity, i.e. they are not antioxidant nutrients. o have the reverse situation. Any essential divalent cation, for example iron, can be an antinutrient or toxicant, by inducing deficiencies of other essential divalent cations even at therapeutic levels, or by straightforward poisoning at toxic levels. By preventing absorption of nutrients in a meal, dietary fibre or various fractions of dietary fibre are characterized as antinutrients. ese and other reasons, many scientists have called for, and some have created, new definitions for the word nutrient. From a chemical and physiological point of view this is reasonable. It is also reasonable from a research point of view. Is dietary analysis different from an exposure or risk assessment? Not really. Is a food composition database different from an additive, contaminant or toxicant database? No, not fundamentally. Do we miss assessment opportunities in clinical and epidemiological research by not having extensive compositional data--beyond nutrients--in our food databases? Surely we do. ational food composition database developers are including many food components in their databases. As long as all the samples and values are properly documented, there is no down-side to this activity; there is huge potential benefit. The new edition of the German Food Composition and Nutrition Tables by Souci, Fachmann and Kraut, reviewed in this issue of JFCA, is a good example of printed tables presenting a more comprehensive picture of the chemical composition of foods. This is to be encouraged and applauded.