Comparison of plasma ferritin concentration with the ratio of plasma transferrin receptor to ferritin in estimating body iron stores: results of 4 intervention trials

BACKGROUND

Efforts to develop global programs for the control of iron deficiency require simple, low-cost, and accurate indicators of iron status.

OBJECTIVE

We aimed to compare estimates of body iron (BI) stores, as calculated from either plasma ferritin concentration alone (BI-ferritin) or the ratio of plasma transferrin receptor (TfR) to ferritin (BI-TfR/ferritin).

DESIGN

Data were analyzed from 4 previously completed, randomized intervention trials that enrolled infants, schoolchildren, or pregnant women (total n = 1189, after excluding subjects with elevated C-reactive protein).

RESULTS

The correlation coefficients between BI-ferritin and BI-TfR/ferritin were >0.95 for all studies. The kappa index ranged from 0.5 to 1.0. All of the sensitivities of BI-ferritin for identifying persons with low iron stores (defined as BI-TfR/ferritin < 0 mg/kg body wt) were >0.90. All of the specificities were >0.90 except the study of pregnant women (specificity = 0.66). The effect sizes of iron intervention trials were significantly greater for change in iron reserves estimated by BI-TfR/ferritin than by BI-ferritin in 2 studies with larger effect sizes (1.11 compared with 1.00 and 1.56 compared with 1.44, respectively; P < 0.05) and 1 study with medium effect size (0.70 compared with 0.57; P < 0.05). However, there were no significant differences between estimates of these effect sizes for 1 study with a medium effect size and 1 study with a smaller effect size (0.78 compared with 0.83 and 0.37 compared with 0.35, respectively; P > 0.2).

CONCLUSION

Plasma ferritin concentration alone provides a good approximation of total BI reserves, as estimated by BI-TfR/ferritin, on the basis of high correlation, sensitivity, and specificity among nonpregnant persons with unelevated C-reactive protein.

Fraction of total plasma vitamin B12 bound to transcobalamin correlates with cognitive function in elderly Latinos with depressive symptoms

BACKGROUND

The fraction of total plasma vitamin B(12) bound to transcobalamin (holoTC/B12 ratio) may reflect tissue levels of the vitamin, but its clinical relevance is unclear.

METHODS

We assessed associations between cognitive function and total B12, holoTC, and holoTC/B12 ratio in a cohort of elderly Latinos (n = 1089, age 60-101 years). We assessed cognitive function using the Modified Mini-Mental State Examination (3MSE) and a delayed recall test; we diagnosed clinical cognitive impairment by neuropsychological and clinical exam with expert adjudication; and we assessed depressive symptoms using the Center for Epidemiological Studies Depression Scale (CES-D). We measured total B12 and holoTC using radioassays.

RESULTS

HoloTC/B12 ratio was directly associated with 3MSE score (P = 0.026) but not delayed recall score. Interactions between holoTC/B12 and CES-D score were observed for 3MSE (P = 0.026) and delayed recall scores (P = 0.013) such that associations between the ratio and cognitive function scores were confined to individuals with CES-D >/=16. For individuals with CES-D > or = 16, the odds ratio for clinical cognitive impairment for the lowest holoTC/B12 tertile was 3.6 (95% CI 1.2-11.2) compared with the highest tertile (P = 0.03). We observed no associations between cognitive function and total B12 or holoTC alone, except between holoTC and 3MSE score (P = 0.021), and no interactions between holoTC or total B12 and CES-D score on cognitive function.

CONCLUSIONS

HoloTC/B12 ratio is associated with cognitive function in elderly Latinos with depressive symptoms and may better reflect the adequacy of B12 for nervous system function than either holoTC or total B12 alone.

Position of the American Dietetic Association: nutrition and lifestyle for a healthy pregnancy outcome

It is the position of the American Dietetic Association that women of child-bearing ages should maintain good nutritional status through a lifestyle that optimizes maternal health and reduces the risk of birth defects, suboptimal fetal growth and development, and chronic health problems in their children. The key components of a health-promoting lifestyle during pregnancy include appropriate weight gain; appropriate physical activity; consumption of a variety of foods in accordance with the Dietary Guidelines for Americans 2005; appropriate and timely vitamin and mineral supplementation; avoidance of alcohol, tobacco, and other harmful substances; and safe food handling. Pregnant women with inappropriate weight gain, hyperemesis, poor dietary patterns, phenylketonuria, certain chronic health problems, or a history of substance abuse should be referred to a registered dietitian for medical nutrition therapy. Prenatal weight gain within the Institute of Medicine recommended ranges has been associated with better pregnancy outcomes. Most pregnant women need 2,200 to 2,900 kcal a day, but prepregnancy body mass index, rate of weight gain, maternal age, and appetite must be considered when tailoring this recommendation to the individual. The consumption of more food to meet energy needs, and the increased absorption and efficiency of nutrient utilization that occurs in pregnancy, are generally adequate to meet the needs for most nutrients. However, vitamin and mineral supplementation is appropriate for some nutrients and situations. This position paper also includes recommendations pertaining to use of alcohol, tobacco, caffeine, and illicit drugs.

To what extent can food-based approaches improve micronutrient status?

The main dietary sources of micronutrients are animal source foods, fruits, vegetables and legumes. Animal source foods are the only source of some micronutrients and the main dietary source of others. Micronutrient status and child development are improved by animal source food interventions in populations that habitually consume low amounts. Of particular concern is the high global prevalence of vitamin B12 depletion, which is associated with low animal source food intake. Some fruits and vegetables can supply vitamin A requirements even with the lower amounts of fat typically consumed in many countries. However, plant source foods are unlikely to supply enough iron, zinc and vitamin B12, even if strategies such as consuming ascorbic-acid rich foods to increase iron absorption are adopted. Identification of mineral-rich varieties of cereals and legumes may improve the future situation. Complementary foods for infants and young children are unlikely to meet micronutrient requirements, especially for iron and zinc, unless they are fortified. Other strategies to improve micronutrient status, such as fortification and supplementation, have limitations and should not replace food-based strategies. Moreover, food-based strategies will improve dietary quality in general and are consistent with the global need to lower the risk of chronic disease and overweight.

Young Zanzibari children with iron deficiency, iron deficiency anemia, stunting, or malaria have lower motor activity scores and spend less time in locomotion

Motor activity improves cognitive and social-emotional development through a child's exploration of his or her physical and social environment. This study assessed anemia, iron deficiency, hemoglobin (Hb), length-for-age Z-score (LAZ), and malaria infection as predictors of motor activity in 771 children aged 5-19 mo. Trained observers conducted 2- to 4-h observations of children's motor activity in and around their homes. Binary logistic regression assessed the predictors of any locomotion. Children who did not locomote during the observation (nonmovers) were excluded from further analyses. Linear regression evaluated the predictors of total motor activity (TMA) and time spent in locomotion for all children who locomoted during the observation combined (movers) and then separately for crawlers and walkers. Iron deficiency (77.0%), anemia (58.9%), malaria infection (33.9%), and stunting (34.6%) were prevalent. Iron deficiency with and without anemia, Hb, LAZ, and malaria infection significantly predicted TMA and locomotion in all movers. Malaria infection significantly predicted less TMA and locomotion in crawlers. In walkers, iron deficiency anemia predicted less activity and locomotion, whereas higher Hb and LAZ significantly predicted more activity and locomotion, even after controlling for attained milestone. Improvements in iron status and growth and prevention or effective treatment of malaria may improve children's motor, cognitive, and social-emotional development either directly or through improvements in motor activity. However, the relative importance of these factors is dependent on motor development, with malaria being important for the younger, less developmentally advanced children and Hb and LAZ becoming important as children begin to attain walking skills.

Application of nutrient intake values (NIVs)

The process of applying nutrient intake values (NIVs) for dietary assessment, planning, and implementing programs is discussed in this paper. In addition to assessing, monitoring, and evaluating nutritional situations, applications include planning food policies, strategies, and programs for promotion of optimal nutrition and preventing and treating malnutrition (both over- and undernutrition). Other applications include nutrition education, food and nutrient legislation, marketing and labeling, research, product development, food procurement and trade (import and export), food aid, and therapeutic (clinical) nutrition. Specific examples of how NIVs are used to develop food labels, fortification policies, and food-based dietary guidelines are described. Applications in both developed and developing countries are also described. In summary, NIVs are the scientific backbone of all aspects of nutrition policy in countries and regions worldwide.

Prevalent vitamin B-12 deficiency in twelve-month-old Guatemalan infants is predicted by maternal B-12 deficiency and infant diet

Approximately one-third of low-income women and children studied in Guatemala are reported to have deficient (<148 pmol/L) or marginal (148-220 pmol/L) plasma vitamin B-12 concentrations. Because vitamin B-12 deficiency can adversely affect infant development and cognitive function, the present study examined predictors of deficient plasma vitamin B-12 concentrations at the age of 12 mo. Analyses were performed on baseline data from a randomized clinical trial in 304 Guatemalan infants, 80% of whom were partially breast-fed, and their mothers. Exclusion criteria for infants included twins, severe stunting or moderate wasting, reported major health problems, severe developmental delay, hemoglobin <95 g/L, maternal age <17 y, and maternal pregnancy >3 mo. Data collected included socio-economic status, infant anthropometry, vitamin B-12 intake from complementary foods, and breast-feeding frequency reported by mothers. A complete blood count and plasma vitamin B-12, folate, ferritin, and C-reactive protein were measured. Deficient or marginal plasma vitamin B-12 concentrations were found in 49% of infants and 68% of mothers. The mean intake of maternal vitamin B-12 was 3.1 microg/d, and infants consumed 2.2 microg/d from complementary foods. In linear regression analysis, infant plasma B-12 concentration was strongly and positively associated with maternal plasma vitamin B-12 and B-12 intake from complementary foods (predominantly powdered cow's milk), and inversely associated with frequency of breast-feeding and larger household size (P < 0.0001). Vitamin B-12 supplementation of lactating women, food fortification, and education to improve infant's vitamin B-12 status are potential interventions that can improve the vitamin B-12 status of mothers and infants in this population.

Supplementation with iron and riboflavin enhances dark adaptation response to vitamin A-fortified rice in iron-deficient, pregnant, nightblind Nepali women

BACKGROUND

Nightblindness affects 16-52% of pregnant women in areas of Nepal and in some cases persists after vitamin A treatment. Iron and riboflavin affect vitamin A utilization and photoreceptor function, respectively, and pilot data in the study population showed a high prevalence of iron and riboflavin deficiencies.

OBJECTIVE

The objective was to assess the effect of supplemental iron and riboflavin on pupillary threshold (PT) and plasma retinol in nightblind, pregnant Nepali women given vitamin A-fortified rice.

DESIGN

Nightblind pregnant women were randomly assigned to receive, 6 d/wk under supervision for 6 wk, a vitamin A-fortified rice curry dish providing 850 microg retinal activity equivalents/d with either a 30-mg Fe and 6-mg riboflavin (FeR + VA) capsule or a placebo control (VA only) capsule. Hemoglobin, erythrocyte riboflavin, and plasma ferritin and retinol were measured before and after the intervention. Dark adaptation was assessed by PT score.

RESULTS

Women who were iron deficient at baseline (n=38) had significantly greater improvement in PT score with iron and riboflavin supplementation than without (P=0.05). Iron and riboflavin supplements significantly reduced the prevalences of riboflavin deficiency (from 60% to 6%; P<0.0001), iron deficiency anemia (from 35% to 15%; P<0.007), and abnormal PT (from 87% to 30%; P<0.05) from baseline. Mean increases in erythrocyte riboflavin (P<0.0001) and plasma ferritin (P=0.01) were greater in the FeR + VA group than in the VA only group.

CONCLUSIONS

Iron deficiency may limit the efficacy of vitamin A to normalize dark adaptation in pregnant Nepali women. Further studies are needed to assess the effect of simultaneous delivery of iron and vitamin A for the treatment of nightblindness.

Low plasma vitamin B-12 in Kenyan school children is highly prevalent and improved by supplemental animal source foods

The high prevalence of vitamin B-12 deficiency in many regions of the world is becoming recognized as a widespread public health problem, but it is not known to what extent this deficiency results from a low intake of the vitamin or from its malabsorption from food. In rural Kenya, where a previous study identified a high prevalence of inadequate vitamin B-12 intakes, this study examined whether plasma vitamin B-12 concentrations were associated with dietary sources of the vitamin at baseline and could be increased by supplementation with animal source foods (ASF). The 4 experimental groups in 503 school children were: 1) control (no food provided); 2) githeri (a maize and bean staple with added oil); 3) githeri + meat (githeri + minced beef); or 4) githeri + milk (githeri + milk). Feedings were isocaloric. Dietary data were collected at baseline, and biochemical data at baseline and after 1 and 2 y of feeding. Baseline plasma vitamin B-12 concentration was 193.6 +/- 105.3 pmol/L and correlated with % energy from ASF (r = 0.308, P < 0.001). The odds ratio for low plasma vitamin B-12 (<148 pmol/L), which occurred in 40% of children, was 6.28 [95% CI: 3.07-12.82] for the lowest vs. highest ASF intake tertile (P < 0.001). Feeding ASF (meat or milk) greatly reduced the prevalence of low plasma vitamin B-12 (P < 0.001). The high prevalence of low plasma vitamin B-12 concentrations in these children is predicted by a low intake of ASF, and supplemental ASF improves vitamin B-12 status.

Homocysteine, B vitamins, and the incidence of dementia and cognitive impairment: results from the Sacramento Area Latino Study on Aging

BACKGROUND

High concentrations of homocysteine have been linked to a greater risk of Alzheimer disease, dementia, and cognitive decline.

OBJECTIVE

We evaluated the association between homocysteine and 4.5-y combined incidences of dementia and cognitive impairment without dementia (CIND) in a cohort of 1779 Mexican Americans aged 60-101 y.

DESIGN

Homocysteine, red blood cell (RBC) folate, and plasma vitamin B-12 were measured at baseline. New cases of dementia or CIND were ascertained by neuropsychological and clinical examinations and expert adjudication. We used proportional hazards models to estimate the risk of homocysteine-associated dementia or CIND and the influence of RBC folate and plasma vitamin B-12 on that association.

RESULTS

High homocysteine concentrations were associated with a greater risk of dementia or CIND: hazard ratio (HR): 2.39; 95% CI: 1.11, 5.16. Plasma vitamin B-12 modified the association between homocysteine and the outcome. The rates of dementia or CIND associated with homocysteine for those in the lowest and highest tertiles of vitamin B-12, respectively, were significantly higher (HR: 1.61, P = 0.04) and lower (HR: 0.94, P = 0.015) than the risk for those in the middle tertile.

CONCLUSIONS

Homocysteine is an independent risk factor for both dementia and CIND. Higher plasma vitamin B-12 may reduce the risk of homocysteine-associated dementia or CIND.

Causes of nutrition-related public health problems of preschool children: available diet

The primary goal of this review is to examine the timing and nature of dietary inadequacy during the first 5 years of life. An important issue is that many children in developing countries are already nutritionally depleted by the end of the first year of life, because maternal undernutrition can cause low fetal accumulation of nutrient stores and secretion of inadequate amounts of some micronutrients in breast milk. Improvement of maternal diet and micronutrient status is required to remedy this situation. During the period of complementary feeding, most households may be able to provide their young children with sufficient energy and protein from home-produced complementary foods, but many do not feed foods with an adequate energy density or a sufficient number of meals per day. Inadequate micronutrient intakes and resulting deficiencies are common in preschoolers because of a lack of sufficient animal source foods, and have been associated with delayed child development. Dietary diversity is an especially important determinant of micronutrient intakes when animal source food intake is low. Interventions with animal source foods have produced improvements in growth, micronutrient status, cognitive performance and activity of children. Although much is now known about the role of inadequate diets in preschooler malnutrition, on a global scale the ability of households to apply this knowledge to improve the diets of their children is still limited.

Combined iron and folic acid supplementation with or without zinc reduces time to walking unassisted among Zanzibari infants 5- to 11-mo old

Iron and zinc deficiencies have been associated with delayed motor development in nutritionally at-risk children, albeit inconsistently. In this community-based, randomized double-blind trial, iron+folic acid (FeFA) (12.5 mg Fe + 50 mug folic acid), zinc (Zn) (10 mg), and iron+folic acid+zinc (FeFA+Zn) supplements or a placebo were given daily for 1 y to nutritionally at-risk children in Pemba, Zanzibar. The effects of these treatments on attaining unassisted walking were evaluated using survival analysis for 354 children aged 5-11 mo at the start of supplementation. Treatment effects on changes in hemoglobin (Hb) and zinc protoporphyrin (ZPP) and height-for-age (HAZ) and weight-for-age (WAZ) Z scores were evaluated using linear regression. Attained motor milestone was recorded every 2 wk for 1 y. Hb, ZPP, HAZ, and WAZ were measured at baseline and after 6 mo of treatment. FeFA with or without Zn reduced the time it took for children to walk assisted. Children who received any iron walked unassisted sooner than those who received no iron [median difference approximately 15 d, P = 0.035, risk ratio (RR) = 1.28, 95% CI = 1.02, 1.61] and this effect was stronger in those who had iron deficiency anemia (IDA) at baseline (median difference was approximately 30 d; P = 0.002; RR = 1.68; 95% CI = 1.21, 2.32). FeFA alone and Zn alone improved Hb and ZPP compared with placebo. There were no significant treatment effects on changes in HAZ or WAZ. The effects of treatment on time to walking may have been mediated by improvements in iron status or hemoglobin, but were not mediated through improvements in growth.