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

Large Iodine Variability in Retail Cows' Milk in the U.S.: A Follow-Up Study among Different Retail Outlets

In a previous study, large variability in iodine content was found among samples of store brand retail milk at a single time point in a sampling taken from 24 nationwide U.S. locations for the USDA FoodData Central database, but the sampling plan was not designed to detect differences among locations. This follow-up study was carried out to evaluate iodine levels in retail milk across the U.S. over time. Milk samples (2% fat) were collected bimonthly in fourteen locations for one year and analyzed in duplicate. Control materials were used to support accuracy of results and ensure precision across analytical batches. The overall mean and standard error (SE) for iodine concentration were 82.5 (7.0) µg/240 mL serving, which was comparable to the previous national mean [85.0 (5.5) µg/240 mL]. A similar wide range among individual samples was detected (27.9-282 µg/240 mL). For some locations, the mean iodine concentration differed significantly from others, and differed from the national average by amounts ranging from -47 µg to +37 µg per serving. The between-sample range within location was large for some (up to 229 µg/serving) and minimal for others (as little as 13.2 µg/serving). These findings suggest iodine intake from some retail milk supplies could be over- or underestimated relative to the national average, even if the national average is suitable for population-wide intake estimates.

Large Variability of Iodine Content in Retail Cow's Milk in the U.S

Iodine intake is of contemporary public health interest. The recommended daily iodine intake is 150 µg for most adults, and milk is an important source of iodine in the U.S. diet. Iodine concentration in cow's milk is affected by diet and iodine supplementation levels, milking sanitation practices, and other factors. Current analytical iodine data in U.S. retail milk are crucial for evaluating population-wide health outcomes related to diet. Samples of whole (3.25% fat), 2%, 1%, and skim (0-0.5% fat) milk were procured from 24 supermarkets across the U.S. using a census-based statistical plan. Iodine was analyzed by inductively coupled plasma mass spectrometry, including certified reference materials and control samples to validate results. No difference in iodine content was found between milkfat levels (F3,69 1.033, p = 0.4). Overall mean (SEM) was 85(5.5) µg/serving (240 mL). However, the 95% prediction interval of 39-185 µg/serving for individual samples indicated high variability among individual samples. Given the recommended 150 µg iodine per day for most adults along with the study mean, one milk serving can provide approximately 57% of daily intake. Researchers, health care professionals, and consumers should be aware of iodine variability in milk, while additional research is needed to investigate the impact of iodine variability factors.

Characterization of the nutrient profile of processed red raspberries for use in nutrition labeling and promoting healthy food choices

BACKGROUND:

Red raspberries (Rubus idaeus L.) contain varied nutrients and phytochemicals important for healthy aging. Processing berries extends their shelf-life and culinary applications, although information on nutritional content among processed forms are limited.

OBJECTIVE:

The main objective of the project was to conduct a market basket study to characterize nutrient content and variation in processed red raspberry (RRB) products (i.e., individually quick frozen (IQF), purée, concentrates). Secondary objectives were to provide new data to the USDA nutrient composition database on processed RRB, which is now complete, and to evaluate RRB forms relative to regulatory (US FDA) criteria for food labeling based on Dietary Reference Intake (DRI) recommendations expressed as % Daily Values (DV).

METHODS:

Processed raspberry product samples were obtained in 2017 from retail outlets, processing plants and distributors, in and outside the USA. Samples were analyzed by pre-qualified laboratories using pre-approved AOAC methods and validated HPLC methods.

RESULTS:

Nutrient variance in domestic compared to imported product was observed, but on average IQF and purée with seeds are excellent sources of dietary fiber based on FDA criteria of providing ≥20% DV, IQF and purée are good (10–19% DV) sources of copper, thiamin, riboflavin and folate, and all forms were excellent or good sources of vitamin C and manganese. IQF and puréed red raspberries may also be considered a valuable fruit source of lutein/zeaxanthin.

CONCLUSIONS:

Processed RRB are nutrient rich options for including in a diet for healthy aging.

Comparison of Label and Laboratory Sodium Values in Popular Sodium-Contributing Foods in the United States

BACKGROUND

Nutrition labels are important tools for consumers and for supporting public health strategies. Recent, published comparison of label and laboratory sodium values for US foods, and differences by brand type (national or private-label) or source (store or restaurant [fast-food and sit-down]) is unavailable.

OBJECTIVE

The objective was to compare label and laboratory values for sodium and related nutrients (ie, total sugars, total fat, and saturated fat) in popular, sodium-contributing foods, and examine whether there are differences by brand type, and source.

DESIGN

During 2010 to 2014, the Nutrient Data Laboratory of the US Department of Agriculture collected 3,432 samples nationwide of 125 foods, combined one or more samples of the same food (henceforth referred to as composites), and chemically analyzed them. For this comparative post hoc analysis, the Nutrient Data Laboratory linked laboratory values for 1,390 composites (consisting of one or more samples of the same food) of 114 foods to corresponding label or website (restaurant) nutrient values.

MAIN OUTCOME MEASURES

Label and laboratory values and their ratio for each composite, for each of the four nutrients (sodium, total fat, total sugars, and saturated fat).

STATISTICAL ANALYSES PERFORMED

Nutrient Data Laboratory analysis determined the ratio of laboratory to label value for each composite, and categorized them into six groups: ≥141%, 121% to 140%, 101% to 120%, 81% to 100%, 61% to 80%, and ≤60%. For sodium, the Nutrient Data Laboratory analysis determined the distribution of the ratios by food, food category, brand type, and source.

RESULTS

For sodium, 5% of the composites had ratios of laboratory to label values >120% and 14% had ratios ≤80%. Twenty-two percent of private-label brand composites had ratios ≤80%, compared with 12% of national brands. Only 3% of store composites had ratios >120% compared with 11% of restaurant composites. Ratios ≤80% were more prevalent among sit-down restaurants (37%) compared with fast-food restaurants (9%).

CONCLUSIONS

This study shows that a majority of label and laboratory values sampled agree and underdeclaration of label values is limited. However, there is some disagreement. Periodic monitoring of the nutrient content of foods through laboratory analyses establishes validity of the food labels and helps identify foods and food categories where the label and laboratory values do not compare well, and hence may need laboratory analyses to support accuracy of food composition data.

Seasonal variability of the vitamin C content of fresh fruits and vegetables in a local retail market

BACKGROUND

Seasonal variation of vitamin C in fresh fruits and vegetables is not reflected in food composition database average values, yet many factors influence content and retention.

RESULTS

Fresh fruits and vegetables were sampled on three occasions in each season, from the same local retail outlets, for 1 or 2 years. Vitamin C was significantly higher in winter-sampled spinach (436 mg kg^-1 ) compared with spring (298 mg kg^-1 ) and summer/fall (180 mg kg^-1 ); in potatoes in summer/fall (156 mg kg^-1 ) versus winter/spring (106 mg kg^-1 ); and in oranges in winter (616 mg kg^-1 ), spring (592 mg kg^-1 ), and summer (506 mg kg^-1 ). Ranges were dramatic among sampling occasions for broccoli, oranges, potatoes, and spinach (700-1210 mg kg^-1 , 420-780 mg kg^-1 , 70-280 mg kg^-1 , and 90-660 mg kg^-1 respectively). Mean values for apples, bananas, tomatoes, and potatoes differed from the USDA National Nutrient Database for Standard Reference (SR) average by ≥10% of the daily recommended intake (90 mg). For broccoli, oranges, and spinach, vitamin C was substantially above or below the SR range in 50-100% of the samples. For spinach, the average content did not differ from SR, but vitamin C in winter was 55% higher than SR.

CONCLUSION

Database average values for vitamin C in fresh produce can significantly over- or underestimate the content in a specific food supply. © 2018 Society of Chemical Industry.

Human Milk Nutrient Composition in the United States: Current Knowledge, Challenges, and Research Needs

Human milk is considered to be the ideal food for infants. Accurate, representative, and up-to-date nutrient composition data of human milk are crucial for the management of infant feeding, assessment of infant and maternal nutritional needs, and as a guide for developing infant formula. Currently in the United States, the nutrient profiles of human milk can be found in the USDA National Nutrient Database for Standard Reference, and in books or review articles. Nonetheless, these resources all suffer major drawbacks, such as being outdated, incomplete profiles, limited sources of data, and uncertain data quality. Furthermore, no nutrient profile was developed specifically for the US population. The purposes of this review were to summarize the current knowledge of human milk nutrient composition from studies conducted in the United States and Canada, and to identify the knowledge gaps and research needs. The literature review was conducted to cover the years 1980-2017, and 28 research papers were found containing original data on macronutrients and micronutrients. Most of these 28 studies were published before 1990 and mainly examined samples from small groups of generally healthy lactating women. The experimental designs, including sampling, storage, and analytic methods, varied substantially between the different studies. Data of several components from these 28 studies showed some consistency for 1-6 mo postpartum, especially for protein, fat, lactose, energy, and certain minerals (e.g., calcium). The data for 7-12 mo postpartum and for other nutrients are very scarce. Comprehensive studies are required to provide current and complete nutrient information on human milk in the United States.

Development of Databases on Iodine in Foods and Dietary Supplements

Iodine is an essential micronutrient required for normal growth and neurodevelopment; thus, an adequate intake of iodine is particularly important for pregnant and lactating women, and throughout childhood. Low levels of iodine in the soil and groundwater are common in many parts of the world, often leading to diets that are low in iodine. Widespread salt iodization has eradicated severe iodine deficiency, but mild-to-moderate deficiency is still prevalent even in many developed countries. To understand patterns of iodine intake and to develop strategies for improving intake, it is important to characterize all sources of dietary iodine, and national databases on the iodine content of major dietary contributors (including foods, beverages, water, salts, and supplements) provide a key information resource. This paper discusses the importance of well-constructed databases on the iodine content of foods, beverages, and dietary supplements; the availability of iodine databases worldwide; and factors related to variability in iodine content that should be considered when developing such databases. We also describe current efforts in iodine database development in the United States, the use of iodine composition data to develop food fortification policies in New Zealand, and how iodine content databases might be used when considering the iodine intake and status of individuals and populations.

Modeled changes in US sodium intake from reducing sodium concentrations of commercially processed and prepared foods to meet voluntary standards established in North America: NHANES

Background: Approximately 2 in 3 US adults have prehypertension or hypertension that increases their risk of cardiovascular disease. Reducing sodium intake can decrease blood pressure and prevent hypertension. Approximately 9 in 10 Americans consume excess sodium (≥2300 mg/d). Voluntary sodium standards for commercially processed and prepared foods were established in North America, but their impact on sodium intake is unclear.Objective: We modelled the potential impact on US sodium intake of applying voluntary sodium standards for foods.Design: We used NHANES 2007-2010 data for 17,933 participants aged ≥1 y to model predicted US daily mean sodium intake and the prevalence of excess sodium intake with the use of the standards of the New York City's National Salt Reduction Initiative (NSRI) and Health Canada for commercially processed and prepared foods. The Food and Nutrient Database for Dietary Studies food codes corresponding to foods reported by NHANES participants were matched to NSRI and Health Canada food categories, and the published sales-weighted mean percent reductions were applied.Results: The US population aged ≥1 y could have reduced their usual daily mean sodium intake of 3417 mg by 698 mg (95% CI: 683, 714 mg) by applying NSRI 2014 targets and by 615 mg (95% CI: 597, 634 mg) by applying Health Canada's 2016 benchmarks. Significant reductions could have occurred, regardless of age, sex, race/ethnicity, income, education, or hypertension status, up to a mean reduction in sodium intake of 850 mg/d in men aged ≥19 y by applying NSRI targets. The proportion of adults aged ≥19 y who consume ≥2300 mg/d would decline from 88% (95% CI: 86%, 91%) to 71% (95% CI: 68%, 73%) by applying NSRI targets and to 74% (95% CI: 71%, 76%) by applying Health Canada benchmarks.Conclusion: If established sodium standards are applied to commercially processed and prepared foods, a significant reduction of US sodium intake could occur.

Validation of a sampling plan to generate food composition data

A methodology to develop systematic plans for food sampling was proposed. Long life whole and skimmed milk, and sunflower oil were selected to validate the methodology in Argentina. Fatty acid profile in all foods, proximal composition, and calcium's content in milk were determined with AOAC methods. The number of samples (n) was calculated applying Cochran's formula with variation coefficients ⩽12% and an estimate error (r) maximum permissible ⩽5% for calcium content in milks and unsaturated fatty acids in oil. n were 9, 11 and 21 for long life whole and skimmed milk, and sunflower oil respectively. Sample units were randomly collected from production sites and sent to labs. Calculated r with experimental data was ⩽10%, indicating high accuracy in the determination of analyte content of greater variability and reliability of the proposed sampling plan. The methodology is an adequate and useful tool to develop sampling plans for food composition analysis.

Sodium content of popular commercially processed and restaurant foods in the United States

PURPOSE

The purpose of this study was to provide baseline estimates of sodium levels in 125 popular, sodium-contributing, commercially processed and restaurant foods in the U.S., to assess future changes as manufacturers reformulate foods.

METHODS

In 2010-2013, we obtained ~ 5200 sample units from up to 12 locations and analyzed 1654 composites for sodium and related nutrients (potassium, total dietary fiber, total and saturated fat, and total sugar), as part of the U.S. Department of Agriculture-led sodium-monitoring program. We determined sodium content as mg/100 g, mg/serving, and mg/kcal and compared them against U.S. Food and Drug Administration's (FDA) sodium limits for "low" and "healthy" claims and to the optimal sodium level of < 1.1 mg/kcal, extrapolating from the Healthy Eating Index-2010.

RESULTS

Results from this study represent the baseline nutrient values to use in assessing future changes as foods are reformulated for sodium reduction. Sodium levels in over half (69 of 125) of the foods, including all main dishes and most Sentinel Foods from fast-food outlets or restaurants (29 of 33 foods), exceeded the FDA sodium limit for using the claim "healthy". Only 13 of 125 foods had sodium values below 1.1 mg/kcal. We observed a wide range of sodium content among similar food types and brands.

CONCLUSIONS

Current sodium levels in commercially processed and restaurant foods in the U.S. are high and variable. Targeted benchmarks and increased awareness of high sodium content and variability in foods would support reduction of sodium intakes in the U.S.

Sodium Content of Foods Contributing to Sodium Intake: Comparison between Selected Foods from the CDC Packaged Food Database and the USDA National Nutrient Database for Standard Reference

The sodium concentration (mg/100g) for 23 of 125 Sentinel Foods (e.g. white bread) were identified in the 2009 CDC Packaged Food Database (PFD) and compared with data in the USDA's 2013 National Nutrient Database for Standard Reference(SR 26). Sentinel Foods are foods identified by USDA to be monitored as primary indicators to assess the changes in the sodium content of commercially processed foods from stores and restaurants. Overall, 937 products were evaluated in the CDC PFD, and between 3 (one brand of ready-to-eat cereal) and 126 products (white bread) were evaluated per selected food. The mean sodium concentrations of 17 of the 23 (74%) selected foods in the CDC PFD were 90%-110% of the mean sodium concentrations in SR 26 and differences in sodium concentration were statistically significant for 6 Sentinel Foods. The sodium concentration of most of the Sentinel Foods, as selected in the PFD, appeared to represent the sodium concentrations of the corresponding food category. The results of our study help improve the understanding of how nutrition information compares between national analytic values and the label and whether the selected Sentinel Foods represent their corresponding food category as indicators for assessment of change of the sodium content in the food supply.

Sodium monitoring in commercially processed and restaurant foods

BACKGROUND

Most sodium in the US diet comes from commercially processed and restaurant foods. Sodium reduction in these foods is key to several recent public health efforts.

OBJECTIVE

The objective was to provide an overview of a program led by the USDA, in partnership with other government agencies, to monitor sodium contents in commercially processed and restaurant foods in the United States. We also present comparisons of nutrients generated under the program to older data.

DESIGN

We track ∼125 commercially processed and restaurant food items ("sentinel foods") annually using information from food manufacturers and periodically by nationwide sampling and laboratory analyses. In addition, we monitor >1100 other commercially processed and restaurant food items, termed "priority-2 foods" (P2Fs) biennially by using information from food manufacturers. These foods serve as indicators for assessing changes in the sodium content of commercially processed and restaurant foods in the United States. We sampled all sentinel foods nationwide and reviewed all P2Fs in 2010-2013 to determine baseline sodium concentrations.

RESULTS

We updated sodium values for 73 sentinel foods and 551 P2Fs in the USDA's National Nutrient Database for Standard Reference (releases 23-26). Sodium values changed by at least 10% for 43 of the sentinel foods, which, for 31 foods, including commonly consumed foods such as bread, tomato catsup, and potato chips, the newer sodium values were lower. Changes in the concentrations of related nutrients (total and saturated fat, total sugar, potassium, or dietary fiber) that were recommended by the 2010 Dietary Guidelines for Americans for reduced or increased consumption accompanied sodium reduction. The results of sodium reduction efforts, based on resampling of the sentinel foods or re-review of P2Fs, will become available beginning in 2015.

CONCLUSION

This monitoring program tracks sodium reduction efforts, improves food composition databases, and strengthens national nutrition monitoring.

Nutrition and Cost Comparisons of Select Canned, Frozen, and Fresh Fruits and Vegetables

A common call to action for addressing public health concerns of both obesity and hunger is improving access to and consumption of fruits and vegetables. Previous research has examined the nutritional merits of fresh, frozen, and canned fruits and vegetables. However, there are limited data on the cost-effectiveness of fresh compared with processed—that is, canned and frozen—food. This study examined the nutrition delivered in 8 common vegetables and 10 common fruits across multiple packaging options (fresh, frozen, and canned) relative to average costs. A method of scoring based on nutrient intake recommendations was used to calculate the nutrients per calorie, and average costs were obtained from the US Department of Agriculture’s Economic Research Service. Nutrient scores for the vegetables were similar across the 3 packaging options, whereas canned vegetables had a lower cost per edible cup compared with frozen and fresh. Nutrient scores were variable for the fruits across the 3 packaging options, and canned fruits were either lower or comparably priced per edible cup. The evidence from this study suggests that fruits and vegetables packaged as frozen or canned are cost-effective and nutritious options for meeting daily vegetable and fruit recommendations in the context of a healthy diet.

Monitoring the sodium content of restaurant foods: public health challenges and opportunities

We reviewed methods of studies assessing restaurant foods' sodium content and nutrition databases. We systematically searched the 1964-2012 literature and manually examined references in selected articles and studies. Twenty-six (5.2%) of the 499 articles we found met the inclusion criteria and were abstracted. Five were conducted nationally. Sodium content determination methods included laboratory analysis (n = 15), point-of-purchase nutrition information or restaurants' Web sites (n = 8), and menu analysis with a nutrient database (n = 3). There is no comprehensive data system that provides all information needed to monitor changes in sodium or other nutrients among restaurant foods. Combining information from different sources and methods may help inform a comprehensive system to monitor sodium content reduction efforts in the US food supply and to develop future strategies.

Sterol composition of shellfish species commonly consumed in the United States

Background

Shellfish can be a component of a healthy diet due to a low fat and high protein content, but the cholesterol content of some species is often cited as a reason to limit their consumption. Data on levels of non-cholesterol sterols in commonly consumed species are lacking.

Objective

Shellfish were sampled and analyzed to update sterol data in the United States Department of Agriculture (USDA) National Nutrient Database for Standard Reference.

Design

Using a nationwide sampling plan, raw shrimp and sea scallops, canned clams, and steamed oysters, blue crab, and lobster were sampled from 12 statistically selected supermarkets across the United States in 2007–08. For each species, four composites were analyzed, each comprised of samples from three locations; shrimp and scallops from six single locations were also analyzed separately. Using validated analytical methodology, 14 sterols were determined in total lipid extracts after saponification and derivatization to trimethylsilyethers, using gas chromatography for quantitation and mass spectrometry for confirmation of components.

Results

Crab, lobster, and shrimp contained significant cholesterol (96.2–27 mg/100 g); scallops and clams had the lowest concentrations (23.4–30.1 mg/100 g). Variability in cholesterol among single-location samples of shrimp was low. The major sterols in the mollusks were brassicasterol (12.6–45.6 mg/100 g) and 24-methylenecholesterol (16.7–41.9 mg/100 g), with the highest concentrations in oysters. Total non-cholesterol sterols were 46.5–75.6 mg/100 g in five single-location scallops samples, but 107 mg/100 g in the sixth, with cholesterol also higher in that sample. Other prominent non-cholesterol sterols in mollusks were 22-dehydrocholesterol, isofucosterol, clionasterol, campesterol, and 24-norcholesta-5,22-diene-3β-ol (4–21 mg/100 g).

Conclusions

The presence of a wide range of sterols, including isomeric forms, in shellfish makes the analysis and quantitation of sterols in marine species more complex than in animal and plant tissues. The detailed sterol composition reported herein provides data that may be useful in research on the impact of shellfish consumption on dietary risk factors.

Vitamin D and sterol composition of 10 types of mushrooms from retail suppliers in the United States

Vitamin D(2) (ergocalciferol) and sterols were analyzed in mushrooms sampled nationwide in the United States to update the USDA Nutrient Database for Standard Reference. Vitamin D(2) was assayed using HPLC with [(3)H]-vitamin D(3) internal standard and sterols by GC-FID mass spectrometric (MS) confirmation. Vitamin D(2) was low (0.1-0.3 μg/100 g) in Agaricus bisporus (white button, crimini, portabella) and enoki, moderate in shiitake and oyster (0.4-0.7 μg/100 g), and high in morel, chanterelle, maitake (5.2-28.1 μg/100 g) and UV-treated portabella (3.4-20.9 μg/100 g), with significant variability among composites for some types. Ergosterol (mg/100 g) was highest in maitake and shiitake (79.2, 84.9) and lowest in morel and enoki (26.3, 35.5); the range was <10 mg/100 g among white button composites but 12-50 mg/100 g among samples of other types. All mushrooms contained ergosta-5,7-dienol (22,23-dihydroergosterol) (3.53-18.0 mg/100 g) and (except morel) ergosta-7-enol. Only morel contained brassicasterol (28.6 mg/100 g) and campesterol (1.23-4.54 mg/100 g) and no ergosta-7,22-dienol. MS was critical in distinguishing campesterol from ergosta-7,22-dienol.