Content of minor and trace elements, and organic nutrients in representative mixed total diet composites from the USA.

As part of an international nutrition project sponsored by the International Atomic Energy Agency (see footnote), Vienna, Austria, a number of bench-mark mixed total diet composites from the United States were collected and analyzed for minor and trace elements. In this segment of the project, the daily dietary intakes of the minor elements Ca, Cl, K, Mg, N and P and the trace elements Al, As, Au, Br, Cd, Co, Cr, Cs, Cu, Fe, Hg, I, Mn, Mo, Ni, Pb, Rb, Sb, Sc, Se, Sn, Sr, V, Zn and W were determined in mixed total diet composites of foods collected in the FDA Total Diet Study (FDA-TDS). These diets are representative of foods consumed by 25-30-year-old males (representing the mixed population groups in the United States), the highest of eight intake groups in the TDS scheme. In order to link the US mixed diet composite results from this study group to the more comprehensive information generated by the FDA-TDS, the results are compared with the same age-sex group published by the FDA-TDS scheme. The FDA-TDS scheme is based on individual analysis of the 201 food items, with resultant calculation of the daily intake representative of various age-sex groups. The comparison shows excellent agreement for 21 elements which have been investigated by both approaches. Additional elements are reported in the US mixed diet composites from the present study which demonstrate a valuable supplement to the data obtained by FDA-TDS scheme. Further the mixed total diet composite approach has also proven useful for the assessment of dietary intake of proximates (protein, fat, carbohydrates), fiber and phytate. In addition, vitamins thiamin, riboflavin, niacin, B6, B12, pantothenic acid, folic acid and biotin were also assayed in these composites.

Certification of nutrients in Standard Reference Material 1846: infant formula.

In 1996, the National Institute of Standards and Technology (NIST) released Standard Reference Material 1846 (Infant Formula), which can be used as a control material for assigning values to in-house control materials and for validating analytical methods for measurement of proximates, vitamins, and minerals in infant formula and similar matrixes. The SRM was manufactured by preparing a spray-dried formula base containing fat, protein, carbohydrates, and minerals and then combining that formula base with a dry-blend vitamin premix that supplied the vitamins. The Certificate of Analysis for SRM 1846 provides assigned values for concentrations of proximates (fat, protein, etc.), vitamins, and minerals for which product labeling is required by the Infant Formula Act of 1980 and by the Nutrition Labeling and Education Act of 1990. These assigned values were based on agreement of measurements by NIST and/or collaborating laboratories. Certified values are provided for vitamins A (trans), E, C, B2, and B6 and niacin. Noncertified values are provided for solids, ash, fat, nitrogen, protein, carbohydrate, calories, vitamin D, delta-tocopherol, gamma-tocopherol, vitamin B1, vitamin B12, folic acid, pantothenic acid, biotin, choline, inositol, calcium, phosphorus, magnesium, iron, zinc, copper, sodium, potassium, and chloride. Information values are provided for iodine, manganese, selenium, and vitamin K.

Analysis of milk-based infant formula. Phase IV. Iodide, linoleic acid, and vitamins D and K: U.S. Food and Drug Administration-Infant Formula Council: collaborative study.

In 1982, the U.S. Food and Drug Administration, the Infant Formula Council and its member companies, contract laboratories, and other government laboratories began a study of analytical methods for the nutrients listed in the Infant Formula Act of 1980. Phases I, II, III, and V have been completed. The present report provides data on Phase IV, in which 13 laboratories collaboratively studied an ion-selective electrode method for analyzing iodide, a gas chromatographic method for linoleic acid, and 2 liquid chromatographic (LC) methods each for vitamins D and K. Data were insufficient to evaluate one each of the LC methods studied for vitamins K and D. The relative standard deviations (RSD) are sufficient for the nutrient levels found in infant formula. RSDs (%) for repeatability (RSDr) and reproducibility (RSDR), respectively, were as follows: iodide, 4.0-11.4 and 13.5-18.2; linoleic acid, 1.0-1.6 and 3.5-5.1; vitamin K1, 3.2-16.0 and 6.2-19.4; and vitamin D3, 4.2 and 35.0. The recommendation to adopt the method for vitamin D was supported by the results of a ministudy. All laboratories were capable of using these methods with little training. The methods for determination of iodide, linoleic acid, and vitamins D and K in ready-to-feed milk-based infant formula have been adopted first action by AOAC International.

Analysis of milk-based infant formula. Phase V. Vitamins A and E, folic acid, and pantothenic acid: Food and Drug Administration-Infant Formula Council: collaborative study.

In 1982, the U.S. Food and Drug Administration, the Infant Formula Council and its member companies, contract laboratories, and other government laboratories began a study of analytical methods for the nutrients listed in the Infant Formula Act of 1980 (P.L. 96-359). Four phases of the study have been completed and are discussed in earlier reports. The present report provides data on Phase V, in which 13 laboratories collaboratively studied individual methods for folic acid, pantothenic acid, and vitamin E, in addition to 2 methods for vitamin A. Vitamins A and E are determined by liquid chromatography. Folic acid and pantothenic acid are determined by microbiological methods using acidimetric and/or turbidimetric assays as the determinative step. In most cases, relative standard deviations for repeatability, RSDr, and reproducibility, RSDR, are as good as those that would be predicted from other collaborative studies. RSDr and RSDR values obtained for the 5 methods are 9.35 and 25.44% for folic acid, 4.59 and 10.23% for pantothenic acid, 8.46 and 11.69% for vitamin E, 3.62 and 9.72% for vitamin A (retinol isomers), and 4.9 and 10.5% for vitamin A (retinol). The 5 methods have been adopted first action by AOAC International.

Comparison of in vitro, animal, and clinical determinations of iron bioavailability: International Nutritional Anemia Consultative Group Task Force report on iron bioavailability.

Relative bioavailability of two iron fortificants, electrolytic Fe and ferric orthophosphate, was related to that of the reference ferrous sulfate with in vitro and rat model depletion-repletion methods in four laboratories to compare values directly with those obtained in a parallel human study. In vitro testing was performed on Fe compounds with both solubility and dialysis in a simulated in vitro gastrointestinal digestion system. Two depletion-repletion techniques, hemoglobin-regeneration efficiency (HRE) and an official method of the Association of Official Analytical Chemists (AOAC), were examined. AOAC relative biological values (RBV) of electrolytic Fe were 0.66 and 0.78 and of FePO4 were 0.25 and 0.34. HRE values were 0.78 and 0.58 for electrolytic Fe and FePO4, respectively. When compared with FeSO4 in a radiolabeled farina-based meal fed to humans, the RBV of FePO4 was 0.25 and electrolytic Fe 0.75. Results obtained with the AOAC method serve as the most reliable prediction of Fe bioavailability in the human although in vitro dialysis is a promising screening technique.

Survey of vitamin content of fortified milk.

This paper summarizes work done by 4 different laboratories on the vitamin content of milk. Riboflavin, vitamin A, and vitamin D were assayed in whole, 2%, and skim milks that had been fortified. In general, the adherence to label claim decreased with decreasing fat content. This may be due to methods and stage of vitamin addition prior to processing.

Preparation of a mixed human diet material for the determination of nutrient elements, selected toxic elements and organic nutrients: a preliminary report.

Using 201 foods from the United States Food and Drug Administration's Total Diet Study (FDA TDS), a mixed diet composite (USDIET-I) was prepared to represent the intake of 25-30-year-old males in the United States. Proximate analyses, phytate determination, and assays for nutrient elements and selected toxic elements, as well as organic nutrients were carried out on this composite. As part of a quality control exercise for a coordinated research program, atomic absorption spectrophotometry, inductively coupled atomic emission spectrometry, colorimetry and neutron activation analysis were used to determine up to 30 elements in this diet material. A comparison of the daily intakes of As, Ca, Cd, Cu, Fe, Hg, K, Mg, Mn, Na, P, Se and Zn from the composite USDIET-I shows excellent to good agreement with FDA TDS values calculated from results of single food analyses. These USDIET-I results demonstrate the feasibility of the mixed diet concept as a viable approach for a reliable assessment of daily intakes, especially for a number of elements such as Cd, Cr, Hg and Mo that occur at low concentrations in individual food products. Simultaneously, stability of some organic nutrients during storage was also investigated. Initial findings suggest that this program may also be useful in the development of reference materials for organic nutrients, for which there is a great need. These aspects are discussed.

Methods of analysis for infant formula: Food and Drug Administration and Infant Formula Council Collaborative Study, Phase III.

Phase III of the collaborative study of methods of assay for nutrients in infant formulas was conducted. The study included assay of chloride, phosphorus, proximates (ash, fat, protein, total solids, and carbohydrates), thiamine, total pantothenates, and vitamins A, B12, and E. Most of the methods were those in Official Methods of Analysis, 13th edition, with slight modifications, or methods of the Infant Formula Council. On the basis of the results obtained by the collaborators, the methods for chloride, phosphorus, proximates, thiamine, and vitamin B12 have been adopted official first action. Methods for total pantothenates, vitamin A, and vitamin E were not recommended for adoption at this time because of anticipated improvements in methodology in the foreseeable future.

National Bureau of Standards reference materials as organic nutrient standards: a preliminary study.

A preliminary study was conducted to determine if the available National Bureau of Standards (NBS) Standard Reference Materials (SRM) Non-Fat Powdered Milk, Oyster Tissue, Wheat Flour, Rice Flour, Spinach, and Albacore Tuna would be suitable for use as organic nutrient standards. These materials were assayed for folates, total pantothenates, vitamin B6, thiamine, riboflavin, niacin, and protein. Vitamins A, E, D, K, and C were also assayed but, for the most part, were not detected. Based on results from this study, it appears that at least some of the NBS SRMs would be useful as organic nutrient standards.

Methods of analysis for infant formula: Food and Drug Administration and Infant Formula Council Collaborative Study.

Because the U.S. Infant Formula Act of 1980 requires manufacturers to produce formula containing a specific minimum amount of nutrients, it became necessary to establish analytical methods for the nutrients listed in the Act. The Food and Drug Administration, the Infant Formula Council, its member companies, contract laboratories, and other government laboratories undertook a collaborative study of available methods; the specific nutrients studied to date include vitamins A, B6, C, riboflavin, and niacin, and the elements calcium, magnesium, iron, zinc, copper, manganese, sodium, and potassium. The coefficients of variation in most cases have been as good as those that could be predicted from other collaborative studies. The methods studied for these nutrients have been adopted official first action except the method for vitamin A.

Total diet study: determination of iodine intake by neutron activation analysis.

Composite food samples from adult, infant, and toddler market baskets of the Food and Drug Administration's (FDA) Total Diet Study for Fiscal Year 1980 were analyzed for iodine by neutron activation analysis (NAA) at the FDA NAA laboratory at the National Bureau of Standards. The mean iodine content of the total diets was 412, 397, and 410 micrograms, per day for adult (2,900 kcal per day), infant, and toddler diets, respectively. These intakes correspond with 275%, 882%, and 586% of the adult, infant, and toddler Recommended Dietary Allowances, respectively. Dairy products and iodate-containing breads were major dietary sources of iodine. The iodine values for total diets reported here, determined by NAA, are from 11% to 15% higher than those determined by colorimetric analysis at FDA's Kansas City Field Office Laboratory.

Proximate and elemental analysis of infant formula.

The Nutrient Surveillance Branch has been conducting a survey of infant formula products for Fiscal Year 1981. Each product has been carefully analyzed and the results compared to the label declaration and the minimum-maximum limits specified by the American Academy of Pediatrics' Committee on Nutrition (CON/AAP). Proximate and elemental analyses were made. Protein, fat, ash, and total solids (moisture) were determined by AOAC methods. Osmolality, density, and fatty acids (linoleic) were also determined. Carbohydrates were calculated by difference and caloric content was calculated by using the general Atwater factors. Elemental analysis for Ca, P, Mg, Fe, Zn, Cu, Mn, Na, and K were performed by induction coupled plasma absorption spectroscopy. Chloride was assayed by potentiometric titration with AgNO3. A summary of the findings from the infant formula survey have been compared with CON/AAP recommendations. In general, there were only a few exceptions where the label claims and the CON/AAP requirements were not met. However, in none of these cases was the difference considered to be of public health significance.

Analytical methods for foods in the next decade.

With each passing decade new problems arise for the regulatory analytical chemist. The push for low detection limits from percent to parts per million to parts per billion brought the need for new and improved analytical instrumentation followed by questions of reliability at such low values. Each question has been met by new instruments or techniques and critical studies. The question for the 1980s is not how to achieve low detection limits but how to reliably and rapidly perform analyses at low values. During the 1960s the emphasis was on the single component/element techniques. We seem now to be entering the computer-controlled era. In each analytical specialty, computer-controlled instruments are offered which greatly aid the analyst in producing an accurate, reliable analysis in a shorter time. The advantage of larger numbers of analyses per unit of time with, in some cases, reduced personnel are not to be overlooked in this age of economy. To the AOAC collaborative study this means a reduction in the number of laboratories who can participate. It also means greater standardization of methodology, and the chemist's laboratory ability becomes less of a factor in producing reliable analyses. Specific analytical examples are discussed to illustrate the trend for the 1980s.

Neutron activation analysis of total diet food composites for iodine.

The iodine content of Total Diet food composites was measured using neutron activation analysis. The interfering element chlorine was separated using a modified combustion and gas phase procedure. The average recovery was 94.8% (standard deviation 2.9) for the 10 matrices that were tested. In addition, iodine was measured in National Bureau of Standards Standard Reference Materials, which have no certified values for this element. Preliminary findings of iodine content of adult Total Diet market baskets collected during Fiscal Year 1980 in different regions of the United States ranged from 292 to 901 micrograms/day for a 2900 kcal intake.

The toxicity of brominated sesame oil and brominated soybean oil in miniature swine.

Miniature swine were fed brominated sesame oil at dietary levels of 0, 5, 25, 50 or 500 mg/kg of body weight for 17 weeks and brominated soybean oil at levels of 0, 5, 50 or 500 mg/kg of body weight for 28 weeks. Growth rate and food intake were decreased only at the high dose level in the brominated sesame oil study. In both studies, signs of lethargy and ataxia occurred in pigs fed the highest dose, and were probably due to a dose-related increase in serum bromine concentrations. Marked elevations in lactic dehydrogenase (LDH), serum glutamic-oxalacetic transaminase (SGOT) and serum glutamicpyruvic transaminase (SGPT) values were seen at the highest dose level with both substances and these enzyme activities were increased at the 50 mg/kg dose level in the brominated sesame oil study. Histopathologic lesions were confined to animals given the highest dose level of either oil. Marked fatty degeneration of the hepatic plate cells and renal tubular epithelial cells were seen in both studies. In the brominated sesame oil study, neutral fat was moderately increased in the myocardium of the pigs fed 500 mg/kg. However, marked diffuse accumulation of LDH, marked diffuse fatty degeneration and focal degeneration, and/or necrosis of individual or small groups of cardiac muscle fibers were seen in the group fed brominated soybean oil at 500 mg/kg. A moderate to marked testicular atrophy was also observed in this group. A dose-related accumulation of total and hexane-soluble bromine was observed in all tissues examined in both studies; the highest concentrations occurred in adipose tissue of the pigs given the highest dose level. Kidneys, livers, hearts and thyroids of these groups also contained large amounts of bromine. In pigs given the 50 mg/kg dose level, total and hexane-soluble bromine concentrations were higher in the brominated sesame oil study than in the longer brominated soybean oil study and may be responsible for the elevations in LDH, SGPT and SGOT activities in this group.