A comparison of the bioavailability of ferrous fumarate and ferrous sulfate in non-anemic Mexican women and children consuming a sweetened maize and milk drink.

BACKGROUND/OBJECTIVES: Ferrous fumarate is recommended for the fortification of complementary foods based on similar iron absorption to ferrous sulfate in adults. Two recent studies in young children have reported that it is only 30% as well absorbed as ferrous sulfate. The objective of this study was to compare iron absorption from ferrous fumarate and ferrous sulfate in infants, young children and mothers. SUBJECTS/METHODS: Non-anemic Mexican infants (6-24 months), young children (2-5 years) and adult women were randomly assigned to receive either 4 mg Fe (women) or 2.5 mg Fe (infants and young children) as either [(57)Fe]-ferrous fumarate or [(58)Fe]-ferrous sulfate added to a sweetened drink based on degermed maize flour and milk powder. Iron absorption was calculated based on incorporation of isotopes into erythrocytes after 14 days. RESULTS: Within each population group, no significant differences (P > 0.05) in iron absorption were found between ferrous fumarate and ferrous sulfate. Mean iron absorption from ferrous fumarate vs ferrous sulfate was 17.5 vs 20.5% in women (relative bioavailability (RBV) =86), 7.0 vs 7.2% in infants (RBV = 97) and 6.3 vs 5.9% in young children (RBV = 106). CONCLUSIONS: Ferrous fumarate is as well absorbed as ferrous sulfate in non-anemic, iron sufficient infants and young children, and can be recommended as a useful fortification compound for complementary foods designed to prevent iron deficiency. Further studies are needed to clarify its usefulness in foods designed to treat iron deficiency.

Sensorial evaluation of nutritional supplements (PROGRESA) enriched with 3 different forms of iron in a rural Mexican community.

As part of the efforts to reduce iron deficiency anemia (IDA), the Mexican Federal program PROGRESA distributes complementary foods to toddlers and pregnant women living in extreme poverty. Complementary foods were originally fortified with hydrogen-reduced iron, which proved a limited efficacy. The supplement was reformulated to provide higher iron bioavailability. This investigation aims to assess the sensory changes and the acceptance of new versions of the complementary foods fortified with either reduced iron, ferrous fumarate, or ferrous sulfate, stored at room temperature for 2, 4, and 6 mo. Complementary foods were presented without flavor (plain) or flavored with either chocolate or vanilla. The complementary foods were evaluated in toddlers and their mothers using a hedonic scale. The percentage of overall acceptance for the baby foods was higher in toddlers (80% to 88%) than in their mothers (63% to 68%). The complementary foods with a better acceptance were those fortified with reduced iron (63% to 68%) and ferrous fumarate (61% to 80%) independently of the flavoring added. The acceptance of the beverage intended for women was better for those fortified with reduced iron (52% to 63%) or ferrous fumarate (44% to 63%) in their vanilla-flavored version. For women, the most accepted sources of iron were reduced iron (50% to 60%) and ferrous fumarate (50% to 58%).

[13C]linoleic acid oxidation and transfer into milk in stunted lactating women with contrasting body mass indexes.

BACKGROUND: The fat concentration of human milk is associated with maternal adiposity, but there is no clear understanding of the mechanisms controlling milk fat concentration. OBJECTIVE: We evaluated the effect of postpartum body mass index (BMI; in kg/m(2)) on the metabolic distribution of an oral dose of [13C]linoleic acid in lactating women. DESIGN: Ten lactating women stratified by BMI (either <22.5 or >23.5) at 5 mo postpartum received orally 2.5 mg [13C]linoleic acid/kg body wt. Exhaled air, milk, and plasma samples were collected in relation to tracer administration. Linoleic acid was determined by gas chromatography. Dietary intake, serum, milk composition, [13C]linoleic acid enrichment in milk and plasma, and exhaled 13CO2 (by isotope ratio mass spectrometry) were assessed. RESULTS: Women with a higher BMI exhaled more 13CO2 than did women with a lower BMI (22.8 +/- 9.4% compared with 8.6 +/- 3.5% of dose, P < 0.03). Cumulated 72-h transfer of [13C]linoleic acid to milk was not significantly different between groups (14.8 +/- 6.5% compared with 17.7 +/- 6.7% of dose). Within the first 9 h after dose administration, 51.6 +/- 4.9% of the total isotope transfer into milk had passed in women with a higher BMI, but only 24.0 +/- 15.3% had passed in those with a lower BMI (P = 0.02). CONCLUSIONS: Women with a lower BMI, who were reputed as having less body fat, oxidized and secreted into milk less dietary linoleic acid within 12 h after tracer administration than did women with a higher BMI. In both groups, a large proportion of [13C]linoleic was retained in the maternal compartment, most likely fat tissue, in a slow turnover pool, and released slowly in later hours.

Contribution of dietary and newly formed arachidonic acid to human milk lipids in women eating a low-fat diet.

BACKGROUND: Polyunsaturated fatty acids in milk are derived from direct intestinal absorption, endogenous synthesis, or maternal body stores. Arachidonic acid (AA) intake is frequently low in undernourished women, but milk secretion of this fatty acid is similar to that in well-nourished women. OBJECTIVE: The objective was to evaluate the contribution of dietary and endogenously synthesized AA to its total secretion in the milk of women eating a low-fat diet. DESIGN: Ten lactating women who habitually ate a low-fat diet (17% of energy) received 2.5 mg [(13)C]linoleic acid (LA)/kg body wt orally 5 mo postpartum. LA and AA concentrations and (13)C enrichment were measured in milk samples collected before and after the tracer application. Total lipid, LA, and AA contents were determined in diet composites. Fatty acids were assessed by gas chromatography and (13)C enrichment by isotope ratio mass spectrometry. RESULTS: The cumulative 72-h recovery of [(13)C]LA in milk was 16.3 +/- 6.4% of the dose; only 0.01% of the label was found as [(13)C]AA. The calculated transfer of dietary LA and AA into milk was 32.8 +/- 18.0% and 11.8 +/- 6.6%, respectively. AA originating from conversion of dietary LA contributed only 1.1% to the total milk AA secreted. CONCLUSIONS: Little milk AA originates from conversion of LA; 70% of LA and 90% of AA secreted in milk were not derived from direct intestinal absorption. Our results suggest that maternal body stores are the major source of milk LA and AA in these women.

Growth faltering is prevented by breast-feeding in underprivileged infants from Mexico City.

This study was designed to test whether breast-feeding protects infants reared in unfavorable environments from growth-stunting by averting acute infections. The body weight and length, feeding mode and morbidity of 170 healthy infants were assessed at 15-d intervals from birth to 6 mo. Birth weight and length were not different between groups, but at 6 mo, breast-fed infants were heavier and tended to be taller (P = 0.1) than infants fed formula. Relative to NCHS values, infants had lower mean birth weights than a sample of American and European BF infants. At 6 mo, the weight of BF infants caught up to the weight of NCHS standards, while infants fed formula fell to around -1 NCHS-Z-score for weight and length. The cumulative 6-mo weight increments were negatively related to the number of episodes of diarrhea, and positively to duration of lactation (P = 0.03, R(2) = 0.17). The 6-mo length gain was negatively related to infections but not to duration of lactation (P = 0.004, R(2) = 0.19). Never-ill infants attained a better weight (P = 0.04) and length (P = 0.02) than infants who suffered one or more episodes of diarrhea. Weight and length gain of infants suffering at least one episode of diarrhea was positively related to breast-feeding and socioeconomic status. Weight increments of 15-d were positively related to breast-feeding and negatively to the introduction of solids. In conclusion, breast-feeding positively affected the growth performance of the recipient infants by averting infections and possibly by improving nutrient intake during infections.

Interrelation among dietary energy and fat intakes, maternal body fatness, and milk total lipid in humans.

The relationship between maternal dietary intakes of energy or fat maternal body composition and the milk fat concentration is an important element in understanding the role of breast-milk in infant nutrition. In most studies in both developing and developed countries, no relation between maternal energy intake and milk fat content was observed. In only one published study, in which maternal fat intake comprised a very low 5% of calories, was a short term reduction in milk lipid observed in some subjects. On the other hand, a positive relation between maternal fatness and milk fat is evident in both well-nourished and under-nourished women when appropriate methodologies have been used. Low milk fat concentrations are associated with higher milk volumes probably because infant demand determines milk intake, compensating, at least partially, for low milk fat. No impairment of infant growth was associated with low milk fat, in studies where it has been measured. The mechanism for the relationship between body fat and milk fat is a fertile field for additional investigation.

A high dietary lipid intake during pregnancy and lactation enhances mammary gland lipid uptake and lipoprotein lipase activity in rats.

Rats fed a diet with high fat concentration produce larger amounts of milk with a higher lipid concentration than rats fed a lower fat diet. This investigation was designed to study the relationship between dietary fat intake, mammary gland lipid uptake and lipogenesis in rat dams fed, during pregnancy and lactation, one of two purified diets, with equal energy density, containing 2.5 (LL) or 20 g fat/100 g diet (HL). Milk lipid concentration and fatty acid composition were determined at d 14 of lactation. Mammary gland lipogenesis, lipoprotein lipase (LPL) activity and the uptake of [1-(14)C]triolein by the mammary gland and its transfer to the pups was measured. The intestinal absorption of oral (14)C-lipid, (14)CO(2) production and the amount of (14)C-lipid transferred to the pups (milk clot + pups carcass) were significantly higher in the HL group than in the LL group (P < 0.05). Mammary gland lipogenesis was 75% lower and LPL activity was 30% higher in the HL group (P < 0.05). Medium-chain fatty acids (C6-C14) excretion was 46% lower and that of long-chain fatty acids was 142% (P < 0.001) higher in the HL group than in the LL group. The higher milk lipid excretion in the rats fed a high-fat diet resulted from a larger uptake of dietary lipid by the mammary gland, indicated by a larger transfer of (14)C-lipid to the pups and by a higher LPL activity in the mammary gland.

Changes in cathepsin D activity of maternal tissues during lactation and weaning in rats.

BACKGROUND: A loss of proteins from maternal tissues during lactation has been demonstrated. Protein loss could be explained by intracellular proteolysis. METHODS: Cathepsin D activity was studied in the liver, muscle and mammary gland of lactating and weaned rat dams. Lactation was studied at maximal milk production (L-14) and at the final stage of lactation (L-21). RESULTS: Basal activity (virgin rats) was three times higher in liver and mammary gland than in muscle. At both stages, L-14 and L-21, cathepsin D activity increased in liver (50%) as well as in the gland (164%), but no change was observed in muscle, when compared with controls. Twenty-four hours after litter separation, enzyme activity in the liver decreased to basal levels, while in the mammary gland cathepsin D activity showed a significant decrease but remained higher than control levels. CONCLUSION: Our results show that liver exhibits adaptive changes in the catabolism of proteins in response to the increased demands imposed by lactation on the maternal organism, and when the stimuli disappear activity returns to basal levels. The high activity in mammary gland indicates fast turnover of structures and biomolecules as an answer to the high synthetic activity in this tissue. Activity remained higher in the weaning rats, as a result of the regression process which the mammary gland is undergoing.

Early and late effects of breast-feeding: does breast-feeding really matter?

Breast-feeding protects the newborn against infectious diseases in developing as well as in industrialized countries. Protection is conferred against gastrointestinal and respiratory tract diseases as well as against otitis media. This protection provided by specific (antibody dependent) and broad, nonspecific protective factors in human milk (proteins, glycoproteins, and lipids) is associated with lower global morbidity and mortality of breast-fed infants as compared with formula-fed infants. While protection against diseases that develop later in life, such as insulin-dependent diabetes mellitus, inflammatory bowel disease, and childhood cancer, has been reported, well-planned prospective studies are essential in order to confirm these observations. Similar studies are essential in order to ascertain the small but consistently reported higher cognitive ability of breast-fed infants.

Qualitative analysis of human milk produced by women consuming a maize-predominant diet typical of rural Mexico.

The milk composition of women on a typical rural Mexican diet was compared with that secreted by American women, consuming a diet typical of affluent countries. Milk concentrations of free fatty acids, cholesterol, total amino acids, and selected key minerals were analyzed at 4 or 6 months postpartum. The total milk fat concentration was lower in the Otomi (22.7 +/- 6.7 mg/g milk) than in the American women (31.3 +/- 5.4 mg/g milk, p = 0.001). Although the absolute concentration did not differ, cholesterol, expressed in terms of total lipid, was higher in the Otomi milk (3.9 +/- 1.1 vs. 3.1 +/- 0.7 mg/g fat, p = 0.005). Saturated medium-chain (C10:0-C14:0) and unsaturated intermediate-chain fatty acids (C16:1 and C18:2) were higher in the Otomi than in the American milk (p < 0.03). The concentrations of C16:0, C18:0, and C18:1 were significantly lower in Otomi than in American milk. The milk concentrations of protein and nonprotein nitrogen were comparable between the two groups. The concentrations of serine, proline, cystine, methionine, and tryptophan were higher in the Otomi than in the American milk (p < 0.05-0.001). The concentrations of valine and isoleucine were significantly lower in the Otomi milk (p = 0.05). Expressed per gram of milk protein, the cystine, methionine, lysine, and tryptophan concentrations were higher, and the glutamine/glutamate, valine, isoleucine, and arginine levels were lower in the Otomi milk. The concentrations of phosphorus and copper were lower in the Otomi than in the American milk at 4 months postpartum (p = 0.05). These differences in milk fatty acid and amino acid patterns and mineral content are unlikely to affect infant growth, but may have other biological consequences yet to be ascertained.

Maternal energy balance and lactation performance of Mesoamerindians as a function of body mass index.

The effect of maternal energy balance in conjunction with body energy reserves on lactation performance has not been fully elucidated in humans. Energy balance was computed from changes in weight and body composition over 6 mo postpartum in 21 Otomi Indian women with relatively low postpartum body mass indexes (BMIs; in kg/m2, 21.4 +/- 0.9) and 19 with relatively high BMIs (25.7 +/- 1.9). Body fat was determined by deuterium dilution. Milk production was estimated by 24-h test weighing. Macronutrient content of human milk was measured by standard techniques. In both groups weight declined over the 6 mo postpartum (P = 0.04). In the lower BMI group only, body fat (kg, % of wt) decreased significantly (P = 0.04). Milk fat concentration was positively correlated with body fat at 3 and 6 mo (r = 0.32 and 0.40; P = 0.04 and 0.01, respectively). Energy balance was not associated with milk production or composition, nutrient secretion into milk, or infant growth velocity, except at 6 mo, when energy balance was positively correlated with milk energy and fat concentration in the lower BMI group (r = 0.55; P = 0.01). Fat concentration was lower in the lower BMI group (P = 0.04). Because of the inverse correlation between milk production and milk fat at 3 and 6 mo (r = -0.47 and -0.43, respectively; P = 0.01), fat secretion into milk did not differ between groups. Infant growth velocities did not differ significantly between groups. In conclusion, negative energy balance in conjunction with lower energy reserves did not adversely affect lactation performance or infant growth in this population of Otomi Indians.

Breast-feeding lowers the frequency and duration of acute respiratory infection and diarrhea in infants under six months of age.

It remains unclear whether breast-feeding protects infants against acute respiratory infection (ARI). To determine if breast-feeding protects against ARI as it does against diarrhea, 170 healthy newborns were followed for 6 mo. Feeding mode, incidence and duration of ARI and diarrhea were recorded biweekly. Infants were classified as fully or partially breast-fed, or formula-fed. Incidence and prevalence were computed monthly. The effects of duration of breast-feeding and potential confounders were analyzed by multiple and logistic regression analyses. Incidence and prevalence of ARI were significantly lower in fully breast-fed infants than in formula-fed infants from birth up to 4 mo, as was the mean duration of individual episodes (5.1 +/- 3.5 vs. 6.4 +/- 3.6 d, respectively). Incidence of ARI was negatively associated with duration of breast-feeding and positively associated with the presence of siblings (P < 0.05). The prevalence of ARI was associated only with the duration of breast-feeding (P < 0.05). Infants that were never breast-fed and that had one or more siblings were more likely to have an episode of ARI than those fully breast-fed for at least 1 mo. Incidence, prevalence, and duration of individual episodes of diarrhea were also lower in breast-fed infants. Incidence (r = -0.17, P < 0.02) and prevalence (r = -0.19, P < 0.008) were negatively associated with duration of full breast-feeding. Introduction of solid food was not associated with further episodes of diarrhea. The present results demonstrate protection against ARI as a result of breast-feeding similar to that for diarrhea, i.e., lower incidence and percentage of days ill, and episodes of shorter duration.

Maternal lipid intake during pregnancy and lactation alters milk composition and production and litter growth in rats.

The relationship between dietary fat content and milk composition, production and litter growth was studied in rats fed during pregnancy and lactation purified diets of equal energy density containing 2.5 or 20 g fat/100 g diet. A subsample of rats (HL-EP group) fed the high lipid (HL) diet but pair-fed on an energy basis with the low lipid (LL) diet group was also studied in a separate experiment. Food intake, dam body weight and litter weight were recorded daily. Rats were milked on d 14 of lactation. Milk lipid, lactose and protein concentration and milk production were measured. Lactating rats fed the HL diet had significantly higher energy intakes (P < 0.01) and milk production (P < 0.05) than rats fed the LL diet. Milk lipid concentration and daily milk volume and lipid production were significantly higher in the HL group. The HL-EP dams had significantly higher milk lipid, protein and lactose concentrations (P < 0.05) and tended to have higher daily lipid and energy outputs (P = 0.08) than LL rats. Birth weights of pups were similar among groups, but from d 6 on, the pups from the HL and HL-EP groups were significantly heavier (P < 0.05) than pups from the LL group. This investigation presents evidence that the milk fat concentration and the daily output of fat, protein and lactose of lactating rats are altered by dietary fat manipulations, which in turn affect growth of the litter.

Total energy expenditure and physical activity level of lactating Mesoamerindians.

Energy-sparing mechanisms may be elicited to meet increased energy requirements imposed by lactation on women who reside in poor, rural communities in developing countries. The objectives of this study were to measure total energy expenditure and its components, basal and activity energy expenditure, and to investigate their relationships with lactation performance in a total of 40 rural Mesoamerindians stratified according to postpartum body mass index. Total energy expenditure and fat-free mass were measured by the doubly labeled water method, and basal metabolic rate was determined by indirect calorimetry at 3 and 6 mo postpartum. Physical activity level was taken as the ratio of total energy expenditure to basal metabolic rate. Milk energy output, which is not included in total energy expenditure, was computed from 24-h milk intake (test-weighing) and energy concentration of milk (bomb calorimetry). Anthropometric measurements revealed negligible mobilization of tissue stores. Mean (+/- SD) total energy expenditures were 8912 +/- 1296 kJ/d and 9253 +/- 1298 kJ/d for the lower and higher body mass index groups, respectively. Adjusted for fat-free mass, total energy expenditure was higher in the lower body mass index group (P = 0.05). Adjusted for fat-free mass, basal metabolic rate did not differ between groups. Physical activity level was significantly higher in the lower body mass index group (P = 0.03). Lactation performance did not differ between groups and was not associated with total energy expenditure or its components. Despite the maintenance of energy balance and heightened energy requirements of lactation, energy-sparing mechanisms were not evident in these lactating Mesoamerindians.

PIP: The authors measured total energy expenditure and its components, basal and activity energy expenditure, and investigated their relationships with lactation performance among 40 rural Mesoamerindians stratified according to postpartum body mass index. Total energy expenditure and fat-free mass were measured by the doubly-labeled water method, and basal metabolic rate was determined by indirect calorimetry at 3 and 6 months postpartum. The ratio of total energy expenditure to basal metabolic rate identified the physical activity level, while milk energy output was computed from 24-hour milk intake test and the energy concentration of milk. Anthropometric measurements identified negligible mobilization of tissue stores. Mean total energy expenditures were 8912 kJ/day and 9253 kJ/day for the lower and higher body mass index groups, respectively. Adjusted for fat-free mass, total energy expenditure was higher in the lower body mass index group, although the basal metabolic rate did not differ between groups. The physical activity level was significantly higher in the lower body mass index group. Lactation performance did not differ between groups and was not associated with total energy expenditure or its components. Despite the maintenance of energy balance and heightened energy requirements of lactation, energy-sparing mechanisms were not evident in these lactating Mesoamerindians.

Early growth faltering of rural Mesoamerindian breast-fed infants.

Early growth faltering has been described in breast-fed infants 4-6 months of age from less-developed communities. The timing and magnitude of growth faltering, however, depends on the appropriateness or comparability of the reference used to evaluate growth performance. In this paper we compared the growth performance of a group of rural Mesoamerindian breast-fed infants from birth through 6 months of age to that of a reference group of breast-fed infants reared under favourable nutritional and environment conditions in the United States. The validity of this assessment is based upon the comparability of infant feeding mode. Mean weights and lengths and corresponding weight-for-age and length-for-age percentiles and z-scores were significantly lower among the Mesoamerindian (Otomi Indian) infants (p = 0.001). Mean weight-for-length percentiles and z-scores did not differ between groups. Weight gain (g/day) was significantly lower among the Otomi infants throughout the entire 6 months (p = 0.001). Length velocities of the Otomi infants were lower than reference infants at 3-6 months (p = 0.001). The growth pattern of the Otomi infants differed from that of the reference group: decreases in growth velocities and weight-for-age and length-for-age z-scores were significantly more precipitous for the Otomi infants between 4 and 6 months of age (p = 0.001). We conclude that growth faltering was evident among the Otomi infants between 4 and 6 months of age, relative to a reference growth of breast-fed infants.

PIP: During 1986-89, for the first 6 months of life biweekly measurements were taken of the weight and length of 114 breast fed, healthy Mesoamerindian (Otomi) infants living in rural Capulhuac, Mexico, and their mothers were asked about infant feeding. Results were compared with a reference sample of 45 predominantly breast fed infants from Houston, Texas. The Otomi infants had birth weights and lengths lower than the National Center for Health Statistics (NCHS) medians, perhaps due to suboptimal gestational weight gains. They had significantly lower growth velocities (i.e., weight gain/day throughout entire 6 months and length gain/month for 3-6 months) than the reference infants (p = 0.001). They also had significantly lower NCHS percentiles and NCHS z-scores for weight-for-age and length-for-age than the Texas infants (p = 0.001). For example, at 6 months, the weight and length velocities of the Otomi were about 70% of the reference infants. The mean weight-for-length percentiles and z-scores were not significantly different between the 2 groups, however. Between 4 and 6 months of age, the decreases in growth velocities and NCHS weight-for-age and NCHS length-for-age z-scores of the Otomi infants were much more steep than those for the reference group (p = 0.001); for example, the decrease in weight-for-age was 0.44 for Otomi infants compared to 0.29 for the reference group, and the decrease in length-for-age was 0.43 and 0.18, respectively. In conclusion, the Otomi Indian breast fed infants experienced growth faltering between 4 and 6 months.

Protein requirements of marginally nourished lactating women.

Few experimental data regarding protein requirements of lactating women are available. This study was designed to determine the protein requirement of seven healthy lactating women from a poor Mexican community who were 2-6 mo postpartum and had a mean body mass index of 21.8 +/- 2 kg/m2. Nitrogen balances were performed at intakes of 0.8, 1.0, and 1.2 g.kg body wt-1.d-1 of a mixed protein diet (70% derived from vegetable sources). A balance at 1.2 g.kg body wt-1.d-1 of a high-quality mixed protein (80% from animal sources) was the reference. The experimental diets were designed to resemble the habitual diet in terms of energy and macronutrients. The balance responses to nitrogen intake were -35.5 +/- 12.6, -10.5 +/- 14.8, and 7.8 +/- 19.2 mg N.kg body wt-1.d-1, respectively. Equilibrium balance was attained at 178.9 +/- 25.8 mg N (1.1 g protein.kg body wt-1.d-1), close to current recommended dietary allowances, albeit the dietary protein was mostly from vegetable sources.