Nutrient concentrations in common western foods and estimated daily intakes - Minerals - Brief Article

Nutrition Research Newsletter, Oct, 2001

The recommended daily allowance or adequate intake component of the Dietary Reference Intake guidelines for nutrients are based on various kinds of evidence. One kind of evidence is the estimated intakes of a given nutrient from the food supply by apparently healthy persons. Therefore, estimated dietary intakes provide critical information for those establishing or updating recommendations. The present study was designed to estimate intake of 12 different minerals and permit direct calculation of molar to molar elemental ratios in individual foods and total diet to facilitate evaluation of mineral pairs with demonstrated competitive metabolism (e.g., calcium and iron). Estimated intakes were determined for Americans from eight age-sex groups: infants, toddlers, male and female adolescents, adults, and seniors.

A well-established model, including 234 foods, was used to estimate dietary mineral intakes. Food items were purchased from local fast-food restaurants or commercial groceries and were national brands except for fresh fruits, meats, vegetables, and milk. Foods needing further preparation or cooking were processed in the metabolic unit kitchens of the UDSA Grand Forks Human Nutrition Research Center, according to appropriate recipes in a common cookbook. Food samples (5 g each) were digested in triplicate in batches, each comprised of 18 to 20 foods of similar physical matrix. Standards, such as wheat flour, were digested in duplicate, and blanks in triplicate. Integrity of mineral analysis was evidenced by agreement between the analytical and the certified values listed in the reference materials. Estimates of average daily intakes of analyzed minerals were determined based on average daily intake of each analyzed food for each age-sex group as estimated by the Total Diet Study model.

Eleven of the representative foods were mineral-rich (i.e., ranked highest in mineral concentration for three or more minerals): oat ring cereal, granola with raisins, peanut butter, peanuts, bran cereal with raisins, pecans, liver, biscuits, American cheese, cream substitute, and shredded wheat cereal. For all age-sex groups, grain products (mainly cornbread, pancakes, biscuits and muffins) accounted for >50% of total daily aluminum intake. Infant foods supplied 47% of infants' boron intake. For toddlers, boron intake from fruits and fruit juices combined was twice that from milk/ cheese. For adolescents, milk/cheese foods were the single largest source of boron. For adults and seniors, the largest source was beverages (mainly instant regular coffee).

For all groups, milk/cheese products were the primary sources of calcium. A notable source of calcium for infants was infant food. Grain products were the secondary sources of calcium except for adolescent males. For all groups except infants, meat/poultry/fish was the most important food category relevant to copper intake. Grain products provided the highest amount of dietary iron for all groups except infants. Beverages contributed the most magnesium to the diets of adults and seniors. Milk/cheese products contributed the most to dietary phosphorus and potassium intakes of infants, toddlers, and adolescents; meat/poultry/fish products contributed the most of both minerals for adults and seniors.

There is little or no apparent correspondence between mineral-dense foods and representative foods that supply the largest amounts of most minerals. For example, for adolescent females, none of the mineral-dense foods analyzed are among the 10 highest contributors to the total intake for three or more minerals. Also, foods that make the single highest contribution to total individual mineral intake are often not readily apparent. For example, the primary source of sodium for all groups except infants are foods represented by white bread.

C. Hunt, S. Meacham. Aluminum, boron, calcium, copper, iron, magnesium, manganese, molybdenum, phosphorus, potassium, sodium, and zinc: Concentrations in common Western foods and estimated daily intakes by infants; toddlers; and male and female adolescents, adults, and seniors in the United States. JADA 101(9): 1058-1060 (September 2001) [Correspondence: Curtiss D. Hunt, Ph.D, US Dept of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Research Center, Grand Forks, ND 58202-9034].