National Food And Nutrient Analysis Program Research Articles

USDA’s National Food and Nutrient Analysis Program (NFNAP) produces high-quality data for USDA food composition databases: Two decades of collaboration

For nearly 20years, the National Food and Nutrient Analysis Program (NFNAP) has expanded and improved the quantity and quality of data in US Department of Agriculture’s (USDA) food composition databases (FCDB) through the collection and analysis of nationally representative food samples. NFNAP employs statistically valid sampling plans, the Key Foods approach to identify and prioritize foods and nutrients, comprehensive quality control protocols, and analytical oversight to generate new and updated analytical data for food components. NFNAP has allowed the Nutrient Data Laboratory to keep up with the dynamic US food supply and emerging scientific research. Recently generated results for nationally representative food samples show marked changes compared to previous database values for selected nutrients. Monitoring changes in the composition of foods is critical in keeping FCDB up-to-date, so that they remain a vital tool in assessing the nutrient intake of national populations, as well as for providing dietary advice.

Comparison of Selected Nutrients in Raw, Whole Egg from USDA Data Releases (1976 – 2010)

BackgroundEggs are an important component of the US diet. The USDA released nutrient data for raw, whole eggs based on compilations in 1976, 1988–89, 2000–01 and 2010.MethodsThe 1976 compilation was primarily from literature data, the 1988–89 samples were from samples provided by egg producers nationwide, and the 2000–01 and 2010 samples were part of the Nutrient Data Laboratory (NDL) National Food and Nutrient Analysis Program (NFNAP).Except for the 1976 literature compilation, samples from the other years were analyzed by commercial and university laboratories approved by NDL for nutrient analysis of food samples.ResultsThere were only minor changes in total fat and protein, calcium, iron, phosphorus and sodium over this time period. There was a 22% decrease in cholesterol from 1976 to 1988–89, no significant change from 1988–89 to 2000–01. The mean cholesterol content decreased 51 mg/100 g (12%; p < 0.0001), from 423 mg/100 g in 2000–2001 to 372 (range 344–405) in 2010. Over the same period, average Vitamin D3 increased by 60%, to 2.05 mg [80 IU]/100 g (range 0.97–12.1). Samples from 2010 contained 0.65 mg 25‐OH‐D3/100 g (range 0.43–1.32).There was a 43% decrease in vitamin B12 from 1976 to 2010.ConclusionRecommendations on egg intake may allow for more eggs in the diet resulting in increase in egg consumption. USDA is planning on a future NFNAP sampling to monitor egg nutrients with a special interest in cholesterol, vitamin D3 and vitamin B12.Support or Funding InformationThis work was supported by the USDA Agricultural Research Service. Partial support was received from the National Institutes of Health, agreement #Y1CN5010, and from the Egg Nutrition Center

Comparison of Select Nutrients in the Nutrition Facts Panel to Analytical Values in Greek Yogurt

Yogurt has been consumed for approximately 7,000 years and is still a popular consumer commodity. Greek yogurt has seen a dramatic increase in consumption in recent years. The Nutrient Data Laboratory uses the National Food and Nutrient Analysis Program (NFNAP) and the label data on cartons or websites for populating the nutritive value of foods in the USDA National Nutrient Database for Standard Reference. The objective of this study was to observe if there were differences in select nutrients between the Nutrition Facts Panel (NFP) and analytical data. Through the NFNAP program, 11 Greek yogurt samples were analyzed chemically by standard AOAC methods for protein, total lipid, calcium, sodium, and cholesterol and compared to their corresponding NFP. As per the FDA 80/120 rule for class 2 nutrients, percent differences between the two methods were calculated. The percent differences were used to calculate the frequency of differences in two categories: 蠄80% than label for protein and calcium; 蠅120% than label for total fat, cholesterol and sodium. Results showed that all types of Greek yogurt were 蠄80% for protein, and 10 types were 80% for calcium. For total lipid and sodium, none of the types were 蠅120%. However, cholesterol in two types was 蠅120%. While the majority of the labels provide accurate nutritive value information, some caveats exist. Knowledge about these limitations can provide dietitians, health professionals and consumers a more pragmatic perspective.

Fifteen Years Of The Usda's National Food And Nutrient Analysis Program: Improving National Food Composition Data

Since 1997, the National Food and Nutrient Analysis Program (NFNAP), a USDA‐NIH collaboration, has improved the data quantity and quality in USDA food composition databases through the analysis of nationally representative samples of foods and beverages. The focal database is the USDA National Nutrient Database for Standard Reference (SR), the authoritative food composition database in the US and the international research community. An updated sampling plan based on 2010 US Census data is being implemented to account for recent demographic changes. Foods are collected nationwide from retail locations, composited, and sent with QC materials to commercial labs/cooperators for analysis. Results, self‐weighted by market share, often show wide variation among retail brands, restaurant chains, and botanical varieties when compared to values of unknown/non‐representative sampling or to older data. Sodium in French fries, for example, varies widely among top restaurant chains sampled under NFNAP (46–521 mg/100g, p<.0001). As manufacturers reformulate their foods in response to public health concerns (e.g., trans fatty acids, sodium) it is imperative for food composition databases to keep current. Since its inception, 1440 foods (representing almost 100,000 data points) have been added or updated in SR; these data are critical to health researchers, nutrition policy makers, the food industry and consumers.

USDA Updates Nutrient Values for Fast Food Pizza

Consumption of quick service pizza has increased as Americans are spending more on food away from home. Pizza is consistently a primary Key Food in the USDA National Food and Nutrient Analysis Program (NFNAP) because it is a contributor of more than 14 nutrients of public health significance to the U.S. diet. The USDA Nutrient Data Laboratory collected national samples of the two leading fast food pizza chains to monitor and update changes in this popular food. Two brands of pizza - cheese (regular, thick, and thin crust) and pepperoni (regular and thick crust) pizzas were collected in 12 nationwide locations in 2003 and again in 2010. Sample units of pizzas were prepared for analysis of proximates, vitamins, minerals and fatty acids using NFNAP protocols. Analytical samples and quality control materials were analyzed by USDA-qualified laboratories using Association of Official Analytical Chemists (AOAC) approved methods. Nutrient data were statistically evaluated (significance set at p<0.05) to compare similar pizzas from different years. Based on these analyses, values for various nutrients changed. For example, both brands of cheese, thin crust pizzas showed a significant increase in sodium (p<0.014). Across all pizza types, brand A pizzas showed a significant increase in iron (p<0.0009-0.036) and potassium (p<0.001-0.013). Total sugars, fiber, cholesterol, and fat values significantly increased or decreased by brand and pizza type. These analyses provide current, accurate, nationally representative data for high consumption foods in the U.S. and are included in the USDA Nutrient Database for Standard Reference 24 as part of an effort to monitor changes in nutrient profiles for popular foods.

ARS, USDA Updates Food Sampling Strategies to Keep Pace with Demographic Shifts

The National Food and Nutrient Analysis Program (NFNAP) was implemented in 1997 as a collaborative food composition research effort between USDA and NIH. The goal of this program is to obtain nationally representative estimates of the nutritional components of important foods consumed in the US for inclusion in the USDA National Nutrient Databank System; to date, analytical food composition data generated for over 1800 foods have vastly improved overall data quality in the database. The NFNAP sampling approach was updated in 2001 using 2000 US Census data and recently updated to use 2010 Census population estimates. This design, like the 2001 design, employs a three-stage, stratified, probability-proportional-to-size (PPS) sample selection process; 1) county selection (based on population density); 2) supermarket outlets within selected counties (based on annual sales); and 3) specific brands of foods (based on market share data). In the first stage, Census regions (4), divisions and states were used to obtain a self-weighting sample of population centres, ensuring geographic dispersion across the 48 conterminous states; 48 locations were selected, with nested subsets of 24, 12 and 6 locations. Due to demographic changes in the population and congressional redistricting it was necessary to revise the sampling scheme to reflect these changes. With the increased penetration of warehouse-type retail outlets into the grocery industry, the sampling frame must be adjusted to include these purchase locations. Food samples which are collected nationally according to a statistically rigorous sampling approach are consistent with national representativeness and allow better estimates of the mean and variability than convenience sampling or less rigorous options.

Development of sample handling procedures for foods under USDA's National Food and Nutrient Analysis Program

The National Food and Nutrient Analysis Program (NFNAP) was implemented in 1997 to update and improve the quality of food composition data maintained by the United States Department of Agriculture (USDA). NFNAP was designed to sample and analyze frequently consumed foods in the U.S. food supply using statistically rigorous sampling plans, established sample handling procedures, and qualified analytical laboratories. Methods for careful handling of food samples from acquisition to analysis were developed to ensure the integrity of the samples and subsequent generation of accurate nutrient values. The infrastructure of NFNAP, under which over 1500 foods have been sampled, mandates tested sample handling protocols for a wide variety of foods. The majority of these foods were categorized into several major areas: (1) frozen foods; (2) fresh produce and/or highly perishable foods requiring refrigeration; (3) fast foods and prepared foods; (4) shelf-stable foods; (5) specialized study and non-retail (point of production) foods; and (6) foods from remote areas (e.g. American Indian reservations). This paper describes the sample handling approaches, from the collection and receipt of the food items to the preparation of the analytical samples, with emphasis on the strategies developed for those foods. It provides a foundation for developing sample handling protocols of foods to be analyzed under NFNAP and for other researchers working on similar projects.

Stability of vitamin C in frozen raw fruit and vegetable homogenates

Retention of vitamin C in homogenized raw fruits and vegetables stored under routine conditions prior to analysis was investigated. Raw collard greens ( Brassica oleracea var. viridis), clementines ( Citrus clementina hort. ex Tanaka), and potatoes ( Solanum tuberosum) were chosen, being representative of foods to be sampled in USDA's National Food and Nutrient Analysis Program (NFNAP), and having different expected stability of ascorbic acid (AA). Samples were homogenized in liquid nitrogen, assayed immediately, then stored at −60 °C and analyzed at time points up to 49 weeks. Vitamin C (as total AA after reduction of dehydroascorbic acid) was analyzed using a validated method with quantitation by HPLC/ultraviolet detection. An orange juice control sample was included in each run. Vitamin C concentrations were stable in clementines and the orange juice, but decreased in collards and potatoes [16.8 and 10.9 mg/100 g (14.7% and 30.4%), respectively, after 49 weeks]. Significant losses had occurred after 12 weeks. These results suggest similar matrices must receive careful attention to sample handling protocols before analysis or AA values may not reflect the concentration in the food as consumed. The control sample was critical to allowing assessment of storage effects independent of analytical variability. Fruits and vegetables for the NFNAP will be analyzed without storage until a practical stabilization protocol is validated.

Tropical Fruits and Nectars Typically Consumed in Latino Communities Are Excellent Sources of Vitamins A, C and Other Nutrients

Latinos are the largest minority group in the U.S. The Nutrient Data Laboratory (NDL) is sampling and analyzing foods commonly consumed by Latin Americans in order to improve the quality and quantity of data on ethnic foods in the USDA National Nutrient Database for Standard Reference (SR). Guanabana, guava, mango, and tamarind nectars were sampled from retail stores using NDL’s National Food and Nutrient Analysis Program’s (NFNAP) nationwide, probability-based method. Nectars were sent to qualified labs for analysis of proximates, sugar, fiber, vitamins, minerals, and carotenoids. Findings include the following per 1 cup (251 ml): guava nectar, 10% DV for fiber; and mango nectar, 35% DV for vitamin A. All nectars are excellent sources of vitamin C (30-82% DV). NDL and Minnesota’s Nutrition Coordinating Center created a list of tropical fruits typically consumed in Latino communities. The NFNAP sampling method was not feasible due to the low probability of finding these fruits in retail stores. Cherimoya, jackfruit, mango, papaya, and mamey sapote were purchased from U.S. wholesalers, then composited and analyzed. All five fruits are excellent sources (32-138% DV) of vitamin C per 140 g (FDA serving, approximately 1 cup). Other standouts are mango for vitamin A and folate (45% and 21% DV, respectively); mamey sapote for potassium (21% DV); and cherimoya and mamey sapote for fiber (20% and 26% DV, respectively). Papaya has 2173 μg lycopene per 140 g. These new analytical values will enable researchers, clinicians, and consumers to more accurately assess the nutrient intakes of Latin Americans. INTRODUCTION The USDA National Nutrient Database for Standard Reference (SR) is an important source of nutrient composition data for foods consumed in the U.S. As the Latino population in the U.S. increases, there is a greater need to serve this population by adding nutrient data to SR for foods they commonly consume. Many people seek the fruits they consumed in their native countries, resulting in increased tropical fruit imports such as mangos and papayas (Pollack, 2001). The general population is able to enjoy more tropical fruits with the greater availability resulting from the increased demand. Four tropical nectars and 5 tropical fruits were analyzed in order to update SR with quality nutrient data for foods commonly consumed by Latinos. METHODS Tropical nectars and whole fruits were sampled and nutrient components analyzed using the following procedures: Nectar •National Food and Nutrient Analysis Program (NFNAP) – probabilitybased, nationwide retail sampling. •Obtained two brands of each of following types of nectar: guanabana (soursop), guava, mango, and tamarind. •Food Analysis Laboratory Control Center (FALCC) at Virginia Polytechnic Institute and State University prepared samples according to standard protocols and shipped composited samples to pre-qualified analytical laboratories along with quality control materials. Fruit •Types of fruit were selected based on recommendations by the Nutrition Coordinating Center, at University of Minnesota from results of the multicenter epidemiologic Hispanic Community Health Study. •NFNAP probability-based sampling method not feasible due to limited availability. •Ordered from U.S. wholesalers via Internet; arrived at various stages of ripeness and allowed to fully ripen before composited at FALCC. •Fruits studied and their scientific names and countries of origin (according to the wholesaler) were cherimoya, Annona cherimola, Chile and U.S. (CA); jackfruit, Artocarpus heterophyllus, U.S. (FL); mamey sapote, Pouteria sapota, U.S. (FL); mango, Mangifera indica, Mexico and U.S. (FL); and papaya, Carica papaya, Brazil, Mexico and U.S. (FL). Laboratories conducted analyses of proximate components, sugars, dietary fiber, vitamins, minerals and carotenoids in all of the nectars and fruit using AOAC or other published methods. CONCLUSION Nutrient composition information assists consumers in making more informed food choices to positively impact their health. All four nectars were added to USDA’s SR in earlier releases. The cherimoya was updated with the new data in the recently released SR22 (USDA, 2009). The remaining four tropical fruits will be updated in SR23. A few more types of tropical fruits commonly consumed by Latinos will be sampled and analyzed in the future. New data will aid in the assessment of nutrient intakes of Latin Americans and help health professionals provide dietary guidance to this population .

Total Fat, n‐3 Fatty Acids and Vitamin D3 in Selected Fish Species Sampled Under USDA's National Food and Nutrient Analysis Program (NFNAP)

As part of the USDA's National Food and Nutrient Analysis Program (NFNAP), new analytical data were determined for the 20 most frequently consumed raw fish identified for FDA's voluntary nutrition labeling. Samples of 21 fish species were purchased from 12 supermarkets nationwide according to a statistical sampling plan. The samples were processed at Virginia Tech (a cooperator of USDA's Nutrient Data Laboratory), and detailed information on each sample was recorded. Sample composites and QC materials were analyzed by qualified laboratories. Because fish are a natural source of n‐3 fatty acids and vitamin D3, data for these nutrients and total fat are being reported. Results for n‐3 fatty acids show that the highest amounts were found in salmon and rainbow trout, closely related species, and lower amounts were in shrimp, scallops, and tuna. Preliminary results for vitamin D3 in wild salmon species show that values vary from 10 mcg/100g or less in foreign caught samples to between 10 and 20 mcg/100g in domestic caught samples. Nutrient profiles for these species will be released to the USDA National Nutrient Database for Standard Reference (http://www.ars.usda.gov/nutrientdata), which is used to support the USDA/NHANES food consumption surveys, food and nutrition policy, and consumer education.Support by USDA, NIH #Y1CN5010, FDA, and the Beverage Institute for Health &amp; Wellness (Coca‐Cola, Inc.)

Vitamin D3 content of fortified yogurt and milk as determined for the USDA National Food and Nutrient Analysis Program (NFNAP)

In response to recent interest in vitamin D composition of foods, USDA‐NDL is updating and expanding data in the National Nutrient Database for Standard Reference. In 2007, the USDA sampled vitamin D3 fortified yogurt and milk from 12 and 24 supermarkets, respectively, selected from a nationwide statistical sampling. The four types of yogurt collected were from two national manufacturers while the milk samples were processed in dairies in the vicinity of the supermarkets. The samples along with QC material were analyzed for vitamin D3 by HPLC with UV detection. All of the yogurt samples met the label claim (15% or 20%DV). Three of the four types of yogurt had vitamin D3 values at 100 ‐ 150% of label claim, with the fourth type above 150% but not exceeding 175%. Each serving of yogurt had 1.6 to 3.0 µg vitamin D3. Five types of fortified milk were collected; skim, 1%, 2%, whole and 1% chocolate. All the products should provide 25%DV of vitamin D3 / 8 oz serving (2.6 µg). Actual vitamin content varied from zero to 47%DV, nearly double the label claim. Overall, about 77% of the products fell within or very close to the expected 100 ‐ 150% of label, however, about 17% of the values were lower than 100%. The vitamin D content of milk was more variable than yogurt. Accurate, current data for vitamin D are important to the assessment of intake by the US population.Support by USDA, NIH #Y1CN5010 and the Beverage Institute for Health &amp; Wellness (Coca‐Cola)

Development and validation of control materials for the measurement of vitamin D 3 in selected US foods

As part of the United States Department of Agriculture's (USDA) National Food and Nutrient Analysis Program (NFNAP), food composition data for vitamin D in the USDA National Nutrient Database for Standard Reference are being updated and expanded, focusing on high priority foods and validated analytical methodology. A lack of certified reference materials and analytical methods validated for these key foods required the development of five matrix-specific control composite materials (CC) (canned salmon and vitamin D 3 fortified cereal, orange juice, milk, and cheese). Each of six experienced laboratories (research and commercial) analyzed vitamin D 3 in five subsamples of each CC in five separate analytical batches, with one subsample of each material in each run. Research laboratories performed recovery studies, mass spectrometric analysis, and other studies to validate quantitation in each matrix. Initial results showed a wide disparity between the six laboratories (RSDs of 26–46%). Extensive collaboration resolved several problems related to calibration standards, extraction solvents and the internal standard, achieving final values with RSDs of approximately 10%, validated by mass spectrometry tests that confirmed lack of matrix interferences in these foods.

Control materials for validating measurement of vitamin D in key foods for the USDA National Food and Nutrient Analysis Program (NFNAP)

Data for vitamin D in the National Nutrient Database for Standard Reference are being updated. High priority foods including fish and vitamin D fortified orange juice, breakfast cereals, milk, American cheese, and yogurt were sampled (n=446) according to a nationwide plan, to be analyzed by qualified laboratories. A lack of certified reference materials required development of control materials to ensure accurate measurements. Matrix‐specific food homogenates (e.g. salmon, orange juice) were prepared and analyzed by six laboratories experienced in determining Vitamin D. Initial results showed wide disparity among the laboratories (CV = 26–46%). Subsequent recovery studies, mass spectrometric analysis, verification of standards, optimization of extraction solvents resulted in reliable values. The three labs chosen for future analyses obtained statistically similar results. These data were used to assign mean values and tolerance limits for four of the control materials. Due to inconsistent data for salmon, further work is required to validate those results.This research was supported by USDA, NIH, and the Beverage Institute for Health &amp; Wellness (Coca‐Cola).

The National Food and Nutrient Analysis Program: A decade of progress

The National Food and Nutrient Analysis Program (NFNAP) was designed to expand the quantity and improve the quality of data in the United States Department of Agriculture (USDA) food composition databases through the collection and analysis of nationally representative samples of foods and beverages. This paper describes some of the findings from the NFNAP and its impact on the food composition databases produced by USDA. The NFNAP employs statistically valid sampling plans, comprehensive quality control, and USDA analytical oversight to generate new and updated analytical data for food components. USDA food consumption and composition data were used to target those foods that are major contributors of nutrients of public health significance to the U.S. diet (454 Key Foods). Foods were ranked using a scoring system, divided into quartiles, and reviewed to determine the impact of changes in their composition compared to historical values. Foods were purchased from several types of locations, such as retail outlets and fast food restaurants in different geographic areas as determined by the sampling plan, then composited and sent for analysis to commercial laboratories and cooperators, along with quality control materials. Comparisons were made to assess differences between new NFNAP means generated from original analytical data and historical means. Recently generated results for nationally representative food samples show marked changes compared to database values for selected nutrients from unknown or non-representative sampling. A number of changes were observed in many high consumption foods, e.g. the vitamin A value for cooked carrots decreased from 1225 to 860 RAE/100 g; the fat value for fast food French fried potatoes increased by 21% (14.08–17.06 g/100 g). Trans fatty acids in margarine have decreased as companies reformulate their products in response to the required addition of trans fatty acids content on the nutrition label. Values decreased from 19.7 g/100 in 2002 to 14.8 g/100 in 2006 for 80%-fat stick margarines and to 4.52 g/100 g for 80%-fat tub margarines. These changes reflect improved strategies for sampling and analysis of representative food samples, which enhance the reliability of nutrient estimates for Key Foods and subsequent assessments of nutrient intake.

Reference materials to evaluate measurement systems for the nutrient composition of foods: results from USDA’s National Food and Nutrient Analysis Program (NFNAP)

Over a 6.5-year period a total of 2554 values were reported by nine laboratories for 259 certified or reference nutrient concentrations in 26 certified reference materials (CRM) submitted to contract laboratories, blinded, as part of the qualifying process for analytical contracts and in the routine sample stream as part of the National Food and Nutrient Analysis Program. Each value was converted to a Z'-score, reflecting the difference from the assigned value related to the combined expected analytical uncertainty plus the uncertainty in the CRM value. Z'-scores >/3.0/ were considered unacceptable. For some nutrients (Na, folate, dietary fiber, pantothenic acid, thiamin, tocopherols, carotenoids, monounsaturated, and polyunsaturated fatty acids), >20% of Z'-scores were >/3.0/. For total fat, vitamin C, and niacin >25% of Z'-scores were >/2.0/. Components for which CRM data were best (more than 90% of Z'-scores </2.0/) were Mg, P, Mn, Se, and vitamin B12. In some cases deviations from assigned values were not uniform across laboratories and materials. For Na almost all high Z'-scores were for low-Na matrices, suggesting analytical problems related to concentration. Figure Z'-scores for vitamins in certified reference materials.

Summary of reference materials for the determination of the nutrient composition of foods

Certified reference materials (CRMs) play a critical role in validating the accuracy of nutrient data for food samples. A number of available food CRMs of dif- fering matrix composition have assigned concentrations for various nutrients, along with associated uncertainty inter- vals (UIs) for those values. These CRMs have been used extensively in the United States Department of Agricul- ture's (USDA) ongoing National Food and Nutrient Anal- ysis Program (NFNAP) to monitor the accuracy of assays of key foods and nutrients consumed in the United States. A total of 690 assigned values for individual nutrients, including proximates, vitamins, macroelements, microele- ments, fatty acids, amino acids, and selected phytochemi- cals (e.g., carotenoids), were compiled from the certificates of analysis for 63 CRMs, and the specified UI in each case was expressed as a percentage of the assigned certified or reference concentration. Across all nutrients, 63.5% of the UIs were less than 10% of the assigned value, 25.5% were 10-20%, and 11% were greater than 20% of the assigned value. The UIs for proximates, minerals, and trace elements were most consistently less than 10% of the assigned value. The relative uncertainties were significantly higher for vitamins, suggesting greater challenges in measuring and certifying these components. These high UIs (greater than 10% assigned value) in the best available reference mate- rials are likely to be indicative of the precision and accu- racy that can be obtained by current measurement systems for these components. These data suggest that care must be taken in choosing CRMs to monitor food composition analysis, including evaluating what levels of uncertainty are required in assigned values and which analytical mea- surement systems for food components need closer exam- ination and improvement.

Quality-control materials in the USDA National Food and Nutrient Analysis Program (NFNAP)

The US Department of Agriculture (USDA) Nutrient Data Laboratory (NDL) develops and maintains the USDA National Nutrient Databank System (NDBS). Data are released from the NDBS for scientific and public use through the USDA National Nutrient Database for Standard Reference (SR) ( http://www.ars.usda.gov/ba/bhnrc/ndl ). In 1997 the NDL initiated the National Food and Nutrient Analysis Program (NFNAP) to update and expand its food-composition data. The program included: 1) nationwide probability-based sampling of foods; 2) central processing and archiving of food samples; 3) analysis of food components at commercial, government, and university laboratories; 4) incorporation of new analytical data into the NDBS; and 5) dissemination of these data to the scientific community. A key feature and strength of the NFNAP was a rigorous quality-control program that enabled independent verification of the accuracy and precision of analytical results. Custom-made food-control composites and/or commercially available certified reference materials were sent to the laboratories, blinded, with the samples. Data for these materials were essential to ongoing monitoring of analytical work, to identify and resolve suspected analytical problems, to ensure the accuracy and precision of results for the NFNAP food samples.

Tocopherol and tocotrienol contents of raw and processed fruits and vegetables in the United States diet

Tocopherol and tocotrienol contents of raw fruits and vegetables and processed products were determined by saponification and normal phase liquid chromatography. All samples were either locally obtained or collected as part of the US Department of Agriculture's National Food and Nutrient Analysis Program (NFNAP). All fruits, vegetables and processed products were selected from the USDA Key Foods list. The study included 32 raw and processed fruits, 22 raw vegetables, various tomato products, baked beans, cooked potatoes, frozen broccoli and frozen green peas. α-Tocopherol ( α-T) was detectable in all products and usually represented the vitamin E form present in highest quantity. γ-Tocopherol ( γ-T) was higher than α-T only in cantaloupes, figs, red raspberries, cauliflower, button mushrooms, lettuce, and green peas. α- and γ-Tocotrienols ( α- and γ-T3) were measurable in several fruit and vegetables but at levels usually less than 0.1 mg/100 g.

Phylloquinone and dihydrophylloquinone contents of mixed dishes, processed meats, soups and cheeses

Assessment of dietary intakes of phylloquinone (VK-1) and dihydrophylloquinone (dK) has been limited by an overall deficit of food composition data, especially for mixed dishes and processed foods. Ninety-eight geographically representative food samples, obtained as part of the National Food and Nutrient Analysis Program (NFNAP), were analyzed for VK-1 and dK using reversed phase HPLC with fluorescent detection. The VK-1 concentrations of the mixed dishes, processed meats, soups, and cheeses ranged from zero (non-detectable, ND) to 11.1 μg/100 g; the dK concentrations ranged from zero (ND) to 22.4 μg/100 g. No dK was detected in the cheese samples. Minimal variation in VK-1 content was observed between the cooked and uncooked samples. Mixed dishes, processed meats, soups, and cheeses contain relatively small amounts of phylloquinone and dK when compared with vegetables and certain plant oils. However, since these foods may frequently be consumed in large amounts, they may be important dietary contributors of vitamin K.

The USDA's National Food and Nutrient Analysis Program: update 2002

The National Food and Nutrient Analysis Program (NFNAP) was designed in 1997 to develop robust and nationally representative estimates of the mean nutrient content of important foods in the food supply and significantly improve the quality of food composition data in the US Department of Agriculture's National Nutrient Databank. The underlying aims defining the process behind the NFNAP are: (1) evaluation of existing data; (2) identification of Key Foods and nutrients for analysis; (3) development of nationally based sampling plans; (4) analysis of samples; and (5) compilation and calculation of representative food composition data. Supported by a self-weighting stratified sampling design, the NFNAP approach has been applied to other sampling programs for the analysis of specific nutrients (e.g., fluoride-containing beverages and foods) and ethnic foods (e.g., American Indian foods). For select nutrients of potential health significance, additional sampling approaches allow for the estimation of serving-to-serving variability (e.g., highly processed foods). Under NFNAP, over 500 foods of the targeted 1000 important foods in the US food supply have been analyzed. Unrivaled research on food sampling, sample handling, and analytical methodology (e.g., for study of perishable nutrients in fresh produce) is integral to this effort. The NFNAP data are current, reflective of the market and nationally representative of the US food supply and therefore a crucial resource to health researchers, architects of nutrition policy, the nutrition and medical communities, and the food industry. They are released through the Web site: www.nal.usda.gov/fnic/foodcomp