Elaine R Monsen

Food Iron Absorption Measured by an Extrinsic Tag

The paper describes the use of an extrinsic tag of inorganic radioiron to determine the total absorption of nonheme iron from a complete meal. The method was developed by measuring the iron absorbed from vegetable foods containing biosynthetically incorporated (55)Fe (intrinsic tag) and from (59)Fe added as a small dose of inorganic iron to the same meal (extrinsic tag). In studies with maize, black bean, and wheat, a consistent extrinsic: intrinsic radioiron absorption ratio averaging 1.10 was observed. Similar results were obtained with either ferrous or ferric iron as the extrinsic tag, and with doses of the latter ranging from 0.001 to 0.5 mg iron added to a test meal containing 2-4 mg of food iron. Adding the radioiron at different stages in preparation of the test meal also had little effect. Separate administration of the extrinsic tag was less satisfactory when small portions of a single food were employed, but with a complete meal, the separate dose was preferable. The extrinsic tag provided a valid measure of absorption despite marked differences in the iron status of the subject, and with wide changes in absorption imposed by adding desferrioxamine or ascorbic acid to the test meal. These findings indicate that there is a common pool of nonheme iron, the absorption of which is influenced by various blocking or enhancing substances present in the meal.

Weight loss leads to a marked decrease in nonresting energy expenditure in ambulatory human subjects

The extent to which the resting and nonresting components of 24-hour energy expenditure decrease after weight reduction has not been prospectively assessed in ambulatory, weight-stable, reduced-obese humans. Accordingly, 24-hour energy expenditure was estimated as the weight-stabilizing (+/- 50 g/d) daily caloric intake of a defined liquid diet in a cross-sectional study of ten reduced-obese subjects after a 23.2% +/- 9.4% weight loss and 18 obese subjects at baseline weight. A regression analysis demonstrated an 18% decrease in the mean daily energy requirement of the reduced-obese subjects compared with that of subjects of the same relative body weight who had never dieted. Strong linear relationships were noted between estimated 24-hour energy expenditure and fat-free mass (FFM), and between resting metabolic rate (RMR) and FFM in the subjects at baseline weight. In six reduced-obese men, the 24-hour energy expenditure was only 75.7% +/- 5.6% of the value predicted by regression analysis for the decreased FFM. In these six subjects the RMR was 97.4% +/- 7.5% of that predicted for the decreased FFM, suggesting that essentially all the energy savings relative to FFM in the reduced-obese state occurred in nonresting energy expenditure. In a subsequent group of seven subjects studied longitudinally before and after a 21.5% +/- 2.3% weight loss, the decrease in nonresting energy expenditure accounted for 582 +/- 276 kcal/d or 71% of the decrease in estimated 24-hour energy expenditure. These data suggest a decrease in the nonresting energy expenditure of ambulatory reduced-obese individuals, which is greater than previously appreciated.(ABSTRACT TRUNCATED AT 250 WORDS)

Iron status of elderly Americans

Studies of iron nutriture in the elderly are limited and very few include observations on individuals over the age of 75. The two Health and Nutrition Examination Surveys carried out by the United States Department of Health, Education and Welfare demonstrate that the mean iron intake of Americans is adequate until the age of 75. However, with changes in the major food sources there is a decrease in iron derived from meat and a concomitant rise in the proportion supplied by breakfast cereals. Alterations in dietary iron bioavailability++ that may result from this have not been studied. Physiological data suggest that the elderly do not represent a target population for iron deficiency since iron requirements are no greater than those of adult men and lower than those of children and menstruating women. Furthermore, there is little direct evidence of a high prevalence of iron deficiency in the elderly, but the laboratory measurements that have proved useful in defining iron status in younger people have not been standardized for or extensively used in older people. Anemia is still the most important known consequence of significant iron deficiency. However, the application of Hb or hematocrit standards used in younger people to the elderly as well as the assumption that anemia can be equated with iron deficiency invalidates the conclusions of many surveys. Hb and hematocrit measurements are not suitable screening tests for iron deficiency in the elderly and there is an urgent need for a clearer understanding of the physiological and nutritional factors responsible for lower Hb values in older people, particularly older Blacks.

Absorption of dietary and supplemental folate in women with prior pregnancies with neural tube defects and controls

BACKGROUND The Public Health Service of the United States recommends that all women capable of childbearing consume .4 mg (400 microg) folic acid per day to decrease the risk of having a pregnancy affected by a neural tube defect such as spina bifida or anencephaly. Three strategies are available to women to achieve this goal: use of dietary supplements; use of fortified foods; and/or increased intake of naturally occurring folate from foods. Identification of the most effective vehicle for delivery of folate to all women is critical in order to prevent these devastating congenital defects. OBJECTIVE To investigate the difference in response to an oral load of folate both from naturally occurring food sources and synthetic supplements among women with prior pregnancies affected by neural tube defects and controls. METHODS We compared the absorption of test doses of 400 microg pteroylglutamic acid (unconjugated or synthetic folic acid found in supplements) and 400 microg pteroylpolyglutamic acid (conjugated or food folate) in 10 women with a history of neural tube defect affected pregnancies and eight controls with normal birth outcomes. The folate test dose was given as either 32 fluid ounces of orange juice or a folic acid single supplement pill. All participants received each test dose at separate clinic visits. The response to each test dose was measured by constructing an area under the curve (AUC) from the serum folate levels at 1, 2 and 3 hours post dose and applying a t-test to compare within and between cases and controls. We also compared red cell folate, vitamin B12, zinc and homocysteine between cases and controls. RESULTS Within group comparisons showed that the area under the curve was significantly greater for the pteroylglutamic acid dose compared to the pteroylpolyglutamic acid dose for both cases and controls (p=0.02 and p=0.03, respectively). In a between group comparison, control women had a greater serum folate response to both forms of the vitamin compared to the case women, but the difference reached statistical significance only for the pteroylglutamic acid dose (p=0.02). Other measured nutrients differed between cases and controls, but did not reach statistical significance. CONCLUSION We conclude that for all women synthetic folic acid as supplements or fortified foods may be the best way to increase acute folate levels in the blood, and thus delivery to the developing embryo. Further, since case women had a diminished response to both forms of the vitamin, and some case women had almost no response, we speculate that women with prior affected pregnancies may need a larger dose of folate to elicit a plasma response equivalent to the general population.

Health Screening and Health Promotion Programs for the Elderly

As the population of elderly people worldwide continues to grow, successful aging has risen to the top of the health policy agenda. The definition of successful aging includes the maintenance of physical and mental function, as well as continued social engagement. Given this definition, maintaining health-related quality of life (HR-QOL) should be a key goal for nutrition and physical activity programs targeted toward the elderly. HR-QOL encompasses physical functioning necessary for unassisted living, as well as broader domains of mental functioning and overall life satisfaction. This review examines the relationship between health parameters and HR-QOL, and assesses the degree to which these relationships are addressed in existing screening and promotion programs. In many cases, nutrition screening and evaluation tools have focused on biomedical measures, such as bodyweight, body fat, or plasma lipids, without taking QOL into account. While HR-QOL has been considered in a few health promotion campaigns, a more balanced perspective on wellness and health among the elderly is needed for the design of effective policies and programs. Successful aging can depend on such factors as race, ethnicity, education, and access to economic and social resources. Intervention programs reviewed include those that address nutritional status, physical activity, and mental health issues among community-dwelling elderly. A comprehensive approach to promoting health in aging would incorporate indicators of wellbeing, and would specifically address nutrition and physical activity issues alongside HR-QOL. Public health policies reviewed here are designed to create an infrastructure to promote healthy aging and offer support to the growing elderly population.

Iron Fortification of Infant Foods A Decade of Change

A survey of iron-fortified commercial foods commonly marketed for consumption by infants was conducted in 1972 and again in 1982. Positive changes had occurred in infant formulas and cereals during that decade, in availability of fortifying iron, level of fortification, and label infor mation. Miscellaneous iron-containing products, cookies, and crackers were unreliable sources of dietary iron in both 1972 and 1982. Availability of fortifying iron in regular cereals had improved by 1982, though 10 percent lacked the label information. Fortified infant formulas and cereals contribute iron of high bioavailability to the typical infant diet in amounts equal to the USRDA. Food manufacturers need to continue to apply knowledge gained through research to sustain the lessened but still highly prevalent incidence of anemia in 1-2-year old children.

Absorption of iron protein-calorie deficient rats and immediate effects of re-feeding an adequate protein diet

Five-week-old rats fed 0.5% protein diet for at least 6 weeks, as well as the progeny of female rats fed either 18 or 5% protein diet during pregnancy and lactation, were studied for iron absorption. In the former, iron retention varied from 2.8 to 4.7% of the ingested dose. Raising the dietary protein level fed these malnourished rats to 18% produced prompt and marked enhancement of iron retention which varied with duration of re-feeding with adequate protein. Compared with the progeny of adequately fed mothers, the offspring of malnourished dams demonstrated prominent reduction in iron absorption at weaning. Re-feeding with high-protein diet elicited prompt increase in body weight with concomitant enhancement of the proportion of ingested iron retained.

Effect of sex and exercise on liver and plasma lipids of the rat

The effect of voluntary exercise on plasma and hepatic lipids was studied in 24 week old male and female Long-Evans rats who were fed a high sucrose (73% of calories) diet containing saturated fat and cholesterol for a 10 week period. Blood lipids were analyzed at week 0, 2, 5 and 10 and liver lipids at week 0 and 10. Half of the animals were housed in individual activity wheels where the females voluntarily ran 4.3 miles/day and the males voluntarily ran 2.4 miles/day. Compared to the males, the females 1. exhibited a greater lipogenic response to the diet, 2. showed a greater lowering of plasma and liver triglyceride and plasma cholesterol ester with exercise, and 3. developed with exercise a higher relative heart weight. Exercise was successful in the males in producing a 75% reduction in the level of hepatic cholesterol ester seen in the non-exercising males. The importance of this study is seen in the lipid-lowering effects of voluntary exercise which avoids food and water deprivation and thus the stress concurrent with forced exercise regimes.

Effects of dietary cholesterol and voluntary exercise on histopathology, plasma and hepatic lipids of the male rat

SummaryTo avoid the stress of imposed activity, male weanling rats were allowed to exercise voluntarily in individual activity wheels. The exercising animals, which were compared to sedentary controls, ran over 26 km/wk (over 2 miles/day). Half of the animals in each group were fed a 10% coconut oil diet; the other half were fed the same diet with 1% added cholesterol.Plasma cholesterol was monitored throughout the 23-week regime. Consistently lower plasma cholesterol values were shown by the exercising animals during the first weeks of the study, the differences being statistically significant at the end of the 8th week. Dietary cholesterol sharply elevated plasma cholesterol, which reached a peak at the 5th week, then declined to basal levels by the 10th week.Both neutral glycerides and cholesterol levels of the livers were elevated considerably by the addition of cholesterol to the diet. Exercising, however, had a lowering effect on both liver cholesterol and neutral glycerides. The weights of the hearts of the exercising rats were increased, while those of the other organs selected were unchanged.Histologic examination of sections of livers showed fat infiltration of hepatic cells varying in severity, depending on the diet. Greater damage to liver cells was noted when cholesterol was added to the basal diet. Fat infiltration was lessened considerably in exercising rats on the basal diet; exercising partially overcame the effects of added cholesterol.

The effects of graded dietary levels of cholesterol and cholic acid on plasma and hepatic lipids and histopathology of the young male rat

SummaryYoung male rats were maintained on a basal diet containing 20% coconut oil with cholesterol added at 0, 0.25, 1 or 4% and cholic acid at 0, 0.25 or 0.5% weight. Determinations were made of plasma cholesterol and neutral glyceride levels throughout the regimen. After 10 weeks, the rats were killed and their livers, hearts, testes and adrenal glands were weighed. Histologic preparations were made from sections of livers, hearts and aortae. Analyses were made of liver lipids.A decrease in food intake with concomitant lessening in body weight gain occurred when both cholesterol and cholic acid were added to the diet; simultaneously relative liver and adrenal weights were increased. A definite interaction was observed between the dietary cholesterol and cholic acid as evidenced by a considerable elevation in plasma cholesterol levels which showed a peak of 67–110% above the initial values at the 3rd week. No consistent alteration was seen in plasma neutral glyceride values. Both hepatic cholesterol levels and relative liver weights were increased as a result of feeding cholesterol and cholic acid. Liver cells sustained severe injury from fat infiltration. Myocardial cells, which were little affected from added cholesterol, became somewhat vaeuolated with areas of fiber degeneration when cholic acid was in the diet.