Nutrient labeling

Neurotransmitters are produced in our brains from the contents of our diets by means of a many-step process. First, nutrients (labeled i in Fig. i—i), such as amino acids, sugar, fats, and peptides (strings of amino acids bound together), are extracted and absorbed from the food we eat and are transported out of the arterial blood supply to the brain—that is, they are actively carried through the blood—brain barrier and transported into the neurons. Enzymes (2) convert these nutrients into different neurotransmitters. The neurotransmitter molecules are actively transported into what are called synaptic vesicles (3), or very tiny spheres with hollow centers into which about 10,000 molecules of a typical neurotransmitter can be stored for later release from a neuron. 

Vitamin analysis in food has a variety of purposes it is used to provide quality assurance for supplemented products to study changes in vitamin content attributable to food processing, packing, and storage to provide data for food composition tables and to check compliance with contract specifications and nutrient labeling regulation [16]. This section gives a short overview of techniques for the analysis of the vitamin content in food and some of the problems associated with these techniques. 

Chemical Analyses. Today, many foods are being analyzed routinely by highly sophisticated chemical procedures. The laboratories in government agencies, universities, and large food manufacturing concerns are often equipped to perform these analyses when needed to determine nutrient compositions in order to (1) enforce or comply with the laws on nutrient labelling or (2) provide data for nutritional research. 

In the United States the analytical methods approved by most states are ones developed under the auspices of the Association of Official Analytical Chemists (AOAC) (3). Penalties for analytical deviation from guaranteed analyses vary, even from state to state within the United States (4). The legally accepted analytical procedures, in general, detect the solubiUty of nitrogen and potassium in water and the solubiUty of phosphoms in a specified citrate solution. Some very slowly soluble nutrient sources, particularly of nitrogen, are included in some specialty fertilizers such as turf fertilizers. The slow solubihty extends the period of effectiveness and reduces leaching losses. In these cases, the proportion and nature of the specialty source must be detailed on the labeling. 

In the United States, additional ramifications maybe expected from FDA s announcement of final regulations for new food labeling requirements under the directive of the Nutrition Labeling and Education Act of 1990 (2). Among other things, these regulations limit health claims that can be made on food labels. They also require new information on nutrient content, and limit the use of descriptors such as low and free in association with calories, fat levels, and other food product characteristics. 

Commonly, a juice drink contains 10% fruit juice, which usually is a blend of several fruits. The 1990 Federal Nutrition and Labeling Act requites declaration of juice content so that the consumer can make a more informed choice (3). With cocktails and juice drinks, added sugars, acids, flavorings, colorings, and nutrients can be used to provide a wide variety of stable products of uniform quaUty. Because drinks requite less juice than 100% juice products, the drinks can be sold at a lower price. 

Information about a food s potassium content is required on the nutrition facts panel only if the food contains added potassium as a nutrient or if claims about it as a nutrient appear on the label. In all other cases, it is voluntary. The recommended daily value for potassium is 3500 mg. The following labels have been designated for foods high potassium (700 mg or more per serving) good source of potassium (350—665 mg per serving) more or added potassium (at least 350 mg more per serving than the reference food) (43). 

Other expansions of FDA s authority include the Dmg Price Competition and Patent Term Restoration Act of 1984, commonly known as the 1984 Amendments or the Waxman-Hatch Act, which was passed to attain quicker marketing of safe, effective, and less expensive generic dmgs and the Safe Medical Device Amendments of 1990, which was passed to correct perceived weaknesses in the implementation of the 1976 Device Amendments. Congress further expanded FDA authority over nutrition labeling and health and nutrient content claims on food labels with the Nutrition Labeling and Education Act of 1990. 

Generation of data on the nutrient content of agricultural products and foods forms the basis for estimating nutrient intakes of populations via dietary surveys, nutritional labelling for consumer protection, nutrition education for consumer food choice, home and institution menu planning and food purchase, and for research in nutrient requirements and metabolism, toxicant chemical composition is used to assess effects of farm management practices, crop culture, and food processing on chemical content and implications for human health. 

Much of the analytical data on the nutrient content of foods is generated using official methods of analysis (e.g. AO AC International). An evaluation of AO AC Methods of Analysis for Nutritional Labelling is available (Sullivan and Carpenter 1993). While these methods have often been studied for a variety of food matrices, applicability over the entire range of food matrices has not been formally studied in most cases. In addition, RMs are not available over the entire range of food matrices (Wolf... 

According to this label, which nutrient is NOT found in cereal ... 

Experiments to examine rhizodeposition can vary markedly in scale and complexity depending on the information required, the equipment available, and the plants concerned. In general, experiments to study exudates and other material lost from young roots are the simplest and are carried out in the laboratory under controlled conditions. Plants are grown in nutrient solution culture, sometimes with sand or other solid support systems, and compounds released into the culture solution are collected and analyzed chemically. The experiments are mainly short-term and the roots can be kept sterile if required. Techniques are also available to label plants growing in these systems with C and to monitor the presence of the isotopes in the rhizodeposits. 

The in vitro procedure was tested in "critical" experiments designed to make direct comparisons of in vivo and in vitro estimates of exchangeability and potential bioavailability and to test the use of in vitro exchangeability values in in vivo experiments. (8). Three foods which were expected to show different levels of calcium solubility and exchangeability, collards, soybeans and spinach, were intrinsically labeled with 45Ca in nutrient solution culture. They were used together with 47 Ca as an extrinsic label in both in vitro and in vivo experiments. 

Quantitative measurement of diffusional uptake and carrier-mediated transport of nutrients and drugs in experimental animals was greatly facilitated with the introduction of Olden dorfs brain uptake index (BUI) [42].Test and reference tracers are injected as an intraarterial bolus into the carotid artery of the anaesthetized animal. After 5 s the animal is killed and the brain is removed for radioactivity counting. This method measures the ratio of the unidirectional brain extraction, E, of the test substance and of the reference ([ H]-water, [ " C]-butanol), which are labelled with different isotopes, during a single passage through the brain capillary bed ... 

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