Potatoes, Including French Fries, Contribute Key Nutrients to Diets of U.S. Adults: NHANES 2003-2006

Many adult Americans fail to meet nutrient requirements. The objective of this study was to examine 24-hour dietary recall data from NHANES 2003–2006 to test the hypothesis that white potatoes (not sweet potatoes) contributed important nutrients within energy needs to adults’ diets. Potato content of survey foods was determined using US Department of Agriculture (USDA) recipe databases (Standard Reference [SR]-Link files). SR codes were linked to USDA food composition data to determine nutrient content. Daily nutrient intakes among consumers of potatoes (including french fries [FF]), and consumers of FF alone, were determined by applying the composition database to respondent’s recall data. Sample weighted data were analyzed; t-tests assessed differences between age-sex groups. Approximately 35% of adults consumed potatoes; 12% consumed FF. Intakes were lowest in adults aged 51+ y (P < .01). More males, compared to females, consumed potatoes (P<.05) and FF (P< 0.01). Males consumed larger amounts of potatoes (127 g/d) and FF (85 g/d) (P< .01). In all age-sex groups, potatoes and FF provided 7-11% of total energy (within daily energy requirements); 3-14% of daily fat (>75% MUFA+PUFA); >15% dietary fiber, >13% vitamin B6 and potassium; >5% thiamin, niacin, phosphorus, magnesium and copper; and <5% sodium. Potatoes provided >10% vitamin C for all age-sex groups and >5% vitamin K and iron for most groups; FF provided >5% vitamin E and folate intakes for all. These cross-sectional data showed that potatoes and FF, in amounts consumed by adults, contributed important nutrients in line with dietary recommendations.


INTRODUCTION
Many adult Americans fail to meet dietary recommendations [1].Across a range of income groups, adult Americans overconsumed energy from solid fats (saturated and trans fatty acids), added sugars, and alcoholic beverages, and underconsumed low-energy-dense fruits and vegetables (including those from dark-green, red-orange, and starchy subgroups) [1,2,3].Intake of sodium was too high, and intake of fiber was too low [4].These dietary patterns are problematic because healthful eating patterns, including the Dietary Approaches to Stop Hypertension (DASH) Eating Plan (as recommended in the 2010 Dietary Guidelines for Americans [2010 DG]) [5,6] are considered necessary to achieve and maintain a healthy weight, promote overall health, and to help reduce the risk of chronic disease [6].Nutrient densefoods, such as fruits and vegetables, are major contributors of shortfall nutrients, including potassium, dietary fiber, folate, vitamins A, C, and K, and magnesium, [4,6].Of these, potassium and dietary fiber are public health concerns; folate is of particular importance for women of childbearing age [6].Potatoes are nutrient-dense vegetables.They are low in fat and high in potassium, dietary fiber and vitamin C [7].In contrast, commercially prepared french fries (FF), *Address corresponding to this author at the San Jose State University, One Washington Square, San Jose, CA 95192-0058, USA; Tel: 408-924-3105; Fax: 408-924-3114; E-mail: Marjorie.freedman@sjsu.educooked in oil are more energy dense.Although white potatoes (as contrasted to sweet potatoes), including FF, are the most commonly consumed vegetables by American adults aged 19+ years [8], little is known about their contribution to total daily nutrient and energy intakes.We hypothesized that white potatoes, including FF, contribute shortfall nutrients within energy needs to adults' diets.We further hypothesized that potatoes, and FF, can be incorporated into diets consistent with the 2010 DG.To test this hypothesis, the National Health and Nutrition Examination Survey (NHANES) data was used to examine, in adult consumers, potato and FF consumption patterns, and the contribution of these foods to total daily nutrient intakes.

Data Source
The NHANES is an ongoing cross-sectional data collection initiative conducted by the National Center for Health Statistics of the Centers for Disease Control [9].Using a stratified, multistage, area probability sample survey design, NHANES is used to collect information about the nutrition and health status of a nationally representative sample of the noninstitutionalized US population.For this study, data collected from participants of the NHANES 2003-2004 [10] and the NHANES 2005-2006 [11] were combined.To produce reliable statistics representative of the US population, NHANES oversampled adults older than 60 years, African-Americans, and Hispanics.The sample design, methodology, and protocol used to collect NHANES data during these years were similar to those used in previous survey years.Detailed information about the survey design, questionnaires, and examination methodology can be found on the National Center for Health Statistics Web site (http:www.cdc.gov/nchs/nhanes.htm).

Study Sample
This cross-sectional analysis included 9490 participants aged 19 years and older with dietary recalls deemed reliable by the NHANES staff.Because secondary data analysis was conducted and personal identifiers were absent, this study was deemed exempt by the Institutional Review Board of San Jose State University.

Dietary Intake
Dietary data (including detailed descriptions of all food and quantities eaten) were collected by trained interviewers using 24-hour recall method and with automated data collection systems that included multiple passes [12].Two days of intake were collected.For this study, only data from the in-person interview (first recall) were used to ensure consistency.Only recall data judged to be complete and reliable by National Center for Health Statistics staff were include in these analyses.Methods for determining the nutrient contributions of potatoes were identical to that previously described [13].In short, the USDA Nutrient Database for Standard Reference (SR)-Link file (the recipe database) of the Food and Nutrient Database for Dietary Studies, version 2.0 and 3.0 (2006 and 2008, Food Surveys Research Group, Beltsville, Md), was used to determine the gram amounts of potatoes contained in survey foods consumed in NHANES.Standard Reference nutrient database codes in the SR-Link file were used to identify ingredients of survey foods.White potatoes, (as contrasted to sweet potatoes), were contained in more than 100 different survey foods mentioned by an unweighted sample of survey participants with complete, reliable 24-hour recall dietary data on day 1.The most frequently mentioned white potato products were deep-fried, commercially prepared french fries (FF), mashed potatoes, potato salad, baked potatoes, home fries, hash browns, and oven-baked fries (which included other commercially fried oven-baked potato products such as potato puffs).Mixed meat, poultry or fish dishes (that contained potatoes) were mentioned fewer than 25 times.

Nutrient Content
The nutrient content of potatoes contained in survey foods was determined by linking the SR codes for potatoes listed in the SR-link files (Release 18 and 20) [14,15], to the USDA National Nutrient Database for Standard Reference.Recipe calculations of nutrient composition values (nutrient amounts per 100 g weight of the food consumed) accounted for the gram weight of moisture or fat lost (or gained) in cooking.Recipe calculations also adjusted nutrient composition values for nutrient losses using the USDA A greater percentage of younger adults as compared to older adults consumed FF (P < .01).In both age groups, a greater percentage of males compared to females consumed FF (P < .05).Mean daily intake of potatoes was higher in males compared to females in both age groups (P < .01)(Table 2).French fry consumption was highest in younger males as compared to younger females, and compared to older males (P < .05).Intake of FF was lowest in older females as compared to older males, and compared to younger females (P < .01).Only 14% of female consumers aged 51+ years who reported eating potatoes on the recall day consumed FF.
Consumption of potatoes comprised less than 8% of the total energy consumed daily by each age-sex group of consumers.These foods provided 3% to 7% of total daily fat intake, 75% of which was monounsaturated (MUFAs) and polyunsaturated (PUFAs) fatty acids.Potatoes provided almost 20% of dietary fiber among older adult consumers; potatoes provided 14% to 17% of dietary fiber among younger adult consumers (Table 3).Among all groups of consumers except older females, potatoes provided over 10% of the total daily intake of vitamins B 6 and C, potassium, magnesium, and copper.Consumption of potatoes also provided over 5% of total daily intake of thiamin, niacin and phosphorus among all age-sex groups, and total folate, vitamin K and iron in all adults aged 19 to 50 years.Among all consumers, potatoes provided less than 3% of the dietary sodium on the day consumed.
French fries contributed about 10% of the total daily energy of all adults.Less than 14% of total fat intake was contributed by FF; the majority (75%) of fatty acids were comprised of MUFAs and PUFAs.Almost 20% of dietary fiber was provided by FF among consumers aged 19 to 50 years, and about 17% was provided among consumers 51+ years (Table 4).Among all agesex groups, FF provided at least 10% of vitamin B 6 and potassium; vitamin K among all groups except older females; and magnesium among younger females.Among all age-sex groups, FF provided at least 5% of thiamin, niacin, total folate, vitamin E, phosphorus, iron and copper; vitamin K among females aged 51+ years; and magnesium among all groups except younger females.Consumption of FF provided less than 5% of total daily sodium intake.

DISCUSSION
This study assessed, using NHANES 2003-2006 data, consumption of all potato products, and FF, among adults aged 19+ years, and the nutrient contribution of these foods to daily diets.About onethird of all adults consumed potatoes on the day of the survey.The amount consumed (110 g/day) was less than two-thirds cup of starchy vegetable (as defined by "ChooseMyPlate.gov")[17,18].Among the highest consumers, mean intake of potatoes (126.5 g/day) was less than three-quarters cup.Examination of recommended energy intakes based on age and physical activity [6,19] indicates that at a sedentary activity level (the most conservative choice), the recommended intake of starchy vegetables is 4 to 6 cups/week (or 0.57 to 0.86 cups/day).Thus, in this study, mean intake of potatoes (0.73 cups/day) among males in both age groups was within levels recommended by the 2010 DG while among females, mean intakes of potatoes (0.56 and 0.51 cups/day in younger and older women) were lower than recommended (0.71 and 0.57 cups/day, respectively) [6,16].Mean intake of FF among all consumers (72 g/day; 0.42 cups/day), and among the highest male consumers (88.2 g/day; 0.51 cups/day) was within levels recommended by the 2010 DG for starchy vegetables [6].This study did not assess intake of other starchy vegetables such as corn and green peas, which, if consumed in large amounts, could result in starchy vegetable intake exceeding recommended levels.This does not appear likely, since corn and peas, as compared to potatoes, are typically consumed in much smaller amounts [4].Among all consumers, daily consumption amounts of FF reflected the Food and Drug Administration (FDA) Reference Amount Customarily Consumed (RACC) portion size of 70 g [20], which is equivalent to a "small" portion of FF at a quick-serve restaurant [21].With respect to energy, potatoes provided 6.7% to 8% of total daily energy among consumers on the day of the recall; FF provided 9.4% to 10.5%.Based on agesex categories, intakes were within Estimated Energy Requirements [22], supporting inclusion of potatoes and FF into adult diets, as recommended by the 2010 DG, and illustrated in "ChooseMyPlate.gov"[6,17].
The Institute of Medicine established the acceptable range for total fat intake for adults 19+ years between 20 to 35% of total energy [22].On the day potatoes were consumed, total energy from fat (from all dietary sources) was about 36%; on the day FF were consumed, fat energy (between 36% and 38%) slightly exceeded the acceptable range.Potatoes contain less than 1% of total fat energy [18], and do not appreciably contribute to fat energy intake.However, 45% of energy in FF comes from fat [18].On the day potatoes were consumed, they provided 7% of total fat energy among younger adults and about 4% among older adults; FF provided between 12% and 14% of the total daily fat energy of all adult consumers.Among younger female consumers (whose percentage of total energy intake from FF was 10.5%, and highest among all agesex groups), the fat in FF provided 5% of total daily energy.For these females, however, 84% of total daily fat energy on the day when FF were consumed came from foods other than FF (although this study did not determine what that sources were.)Current government policy indicates types of fat are more important in influencing disease risk than total energy from fat (6).
The 2010 DG recommends consuming healthful MUFAs and PUFAs, and reducing intake of saturated fats to less than 10% of energy [6].Since 25% of the fat in FF was saturated fat, FF provided 0.6% and 1.2% of total daily saturated fat energy on the days potatoes and FF were consumed.Fifty percent of the remaining unsaturated fats were MUFAs.Prior to reformulation of cooking oils, elaidic acid (t9-C18:1), a partially hydrogenated MUFA, was used to fry potatoes, and thus, contributed trans fat to the diet.In fact, when elaicdic acid was used to commercially fry FF, these foods contributed 8% of the trans fat from processed foods [23].The contribution of FF to trans fat intake today is minimal.Mozaffarian et al. [24] examined the levels of trans (and saturated fat) in major brand-name restaurant foods (including fried potatoes) reformulated to reduce trans fat content from 1993 through 2006, and from 2008 through 2009.They reported that trans fat content was reduced to less that 0.5 g per serving in 80% of restaurant foods analyzed.Overall, the content of trans fats and saturated fats combined was reduced in 96% of restaurant foods; the average total reduction was 3.9 g per serving.The most current USDA Nutrient Database for Standard Reference (Release 23) [18] provides further evidence that trans fats in FF have decreased significantly [15] and that FF no longer contribute trans fat to the diet.National Cancer Institute data (collected using NHANES [2003][2004] indicating that fried white potatoes provided 4.8% of solid fats to the diets of the U.S. population ages 2+ years is thus outdated [25], as it examines intake prior to changes in cooking oils.Examination of more recent NHANES data is needed to accurately quantify the contribution of FF to solid fat intake among adults. Potassium is a nutrient of public health concern [6].The 2010 DG recommends increasing potassium intake, especially from foods, as dietary potassium lowers blood pressure by blunting sodium's effects [5,6].One small baked potato contains 738 mg potassium/128 energy, and provides 15% of the Adequate Intake (AI) of potassium [18].Potatoes can be part of the Dietary Approaches to Stop Hypertension (DASH) Eating Plan, which focuses on increasing potassium intake [5,6].For adult consumers, potatoes contributed between 13% and 17% of daily dietary potassium.Potatoes also provide magnesium, another important component of the DASH Eating Plan [5,6].Finally, the 2010 DG continues to recommend sodium reduction [6].The top 5 sources of sodium (accounting for 30% of dietary sodium) in diets of US adults aged 19+ years were yeast breads, chicken and chicken mixed-dishes, pizza, pasta and pasta dishes, and cold cuts.Potatoes contributed 1.8% of the sodium consumed among all US adults [25].On the day consumed, potatoes and FF contributed less than 5% of sodium intake to adult diets.However, overall sodium intake in all age-sex groups exceeded the recommended intake of 2300 mg/day for adults aged 19 to 50 years and 1500 mg/day for adults aged 51+ years.Continued efforts to reduce dietary sodium in the food supply are being sought [26].Consumers should also reduce salt in cooking and at the table [6].
Dietary fiber is another nutrient of public health concern [6].Baked potatoes contain 2.2 g dietary fiber/100 g (or 2.4 g dietary fiber/RACC of 110 g); FF contain 3.5 g dietary fiber/100g (or 2.4 g dietary fiber/RACC of 70 g) [18,20].Baked potatoes thus provide 8.8%, and FF provide 9.6% of the DV of fiber (25 g/2000 energy).Despite the significant contributions of potatoes and FF to daily dietary fiber intake (e.g., 14% and 19%, respectively), overall dietary fiber intake among all age-sex groups was low.The AI for fiber is 14g/1000 energy [22].At energy levels reported by consumers in this study, potatoes provided 5% to 12%, and FF provided 7% to 9% of the AI for fiber.Potatoes are key contributors to dietary fiber in all age-sex groups, but especially in older women.All Americans should be encouraged, however, to increase consumption of dried beans and peas, fruits and vegetables, and fiber-containing whole grains [6].
Finally, folate and iron are nutrients of particular concern to women of childbearing age [6].Despite folic acid fortification in the US, many women of childbearing age fail to meet recommended folate intakes [6].All women capable of becoming pregnant are recommended to consume synthetic folic acid from fortified foods and/or supplements, in addition to food forms of folate.A medium-sized baked potato (173 g) provides 48 mcg of total folate (7.8% of the DV).On the day consumed, potatoes and FF contributed 5% of dietary folate to diets of women of childbearing age.A medium-sized baked potato provides 1.9 mg of iron, an amount equivalent to one-half cup of cooked chopped spinach [18].Although absorption of the non-heme iron contained in potatoes is enhanced by naturally occurring vitamin C (9.6 mg/100 g), potatoes should not be recommended as a good source of dietary iron.However, potatoes can be recommended as part of overall healthful diets for women of childbearing age.
Analyses of NHANES data are limited by the crosssectional design that precludes any causal inferences.Participants providing 24-hour dietary recalls depend on memory; subjects may under-or over-report intake.Further, reported intakes may not reflect usual intake.Overall, however, the very large sample sizes, such as those available through the NHANES, have been accepted as producing reasonably accurate group estimates of nutrient intakes [27].Finally, results may not reflect current intake, and they likely do not accurately represent solid fat consumption due to changes in commercial cooking oils used to prepare FF.
In conclusion, NHANES 2003-2006 data showed consumption of potatoes and FF were consumed in moderate amounts in adults.Overall energy intake on the day these foods were consumed was within daily energy requirements among all consumers.Although FF (as contrasted to other forms of potatoes) provide fat energy, 84% of total daily fat energy came from foods other than FF on the day FF were consumed.Furthermore, on the day consumed, potatoes and FF contributed at least 10% of 3 essential nutrients (dietary fiber, vitamin B 6 , and potassium) to the diets of all age-sex groups surveyed, and at least 5% of 7 essential nutrients (thiamin, niacin, phosphorus, magnesium, vitamin K, iron and copper) to the diets of most age-sex groups.French fries provided 5% or greater folate to the diets of all women, including those of childbearing age, and 5% or greater of vitamin E to the diets of all groups; potatoes provided 10% or greater of vitamin C to the diets of all age-sex groups surveyed.Among all consumers, sodium from potatoes provided less than 5% of total sodium intake, although total sodium intake was high.Overall, analysis of NHANES cross-sectional data showed that on the day of consumption, potatoes and FF provided to adults shortfall nutrients, and nutrients of public health concern (dietary fiber, potassium, folate, magnesium, vitamins C and K), within mean energy intakes consistent with mean Estimated Energy Requirements.When consumed in moderate amounts, potatoes, including FF, can be part of healthful diets consistent with 2010 DG and associated eating plans.

ACKNOWLEDGEMENT
The authors acknowledge Tom Wolever and Fergus Clydesdale who reviewed the paper and provided constructive comments. ABBREVIATIONS

Table 1 : Percent of US Adults Aged 19 Years and Older Consuming all Potatoes and FF, NHANES 2003-2006 Age and sex group No. Percent of population consuming all potatoes Percent of population consuming FF
Data are presented as sample-weighted means ± SE and percentages using SUDAAN, based on a single 24-hour dietary recall.P < 0.01 between adults aged 19 to 50 years compared to adults aged 51 years and older.
a P < 0.05 and b P < 0.01 between sex groups in the same age range.c d P < 0.01 between age groups but the same sex.

Table 2 : Mean Gram Intake of all Potatoes and FF by Consumers of these Foods Among Adults Aged 19 Years and Older Participating in the NHANES 2003-2006
Data are presented as sample-weighted means ± SE and percentages using SUDAAN, based on a single 24-hour dietary recall.a P < 0.05 and b P < 0.01 between sex groups in the same age range.c P < 0.01 between adults aged 19 to 50 years compared to adults aged 51 years and older.d P < 0.05 and e P < 0.01 between age groups but the same sex.

Table 3 ). Continued. Adults aged 19-50 y Adults aged 51 y and older Nutrient Total daily intake
Data are presented as sample-weighted means ± SE and percentages using SUDAAN, based on a single 24-hour dietary recall collected from 916 male and 1054 female adults aged 19 to 50 years, and from 744 male and 719 female adults aged 51 years and older.

Table 4 ). Continued. Adults aged 19-50 y Adults 51 y and older Nutrient Total daily intake Intake from food group
Data are presented as sample-weighted means ± SE and percentages using SUDAAN, based on a single 24-hour dietary recall collected from 415 male and 439 female adults aged 19 to 50 years and from 136 male and 110 female adults aged 51 years and older.