Effects of vegetable proteins on iron and zinc absorption and availability in humans

This review discusses research on the effects of vegetable protein diets on iron and zinc absorption and availability. Constituents of vegetables can have either a positive or negative effect on iron absorption. Although the use of soy protein to extend beef patties was found to decrease nonheme iron absorption in some studies, the use of soy-extended beef on a regular basis was not found to deleteriously affect the iron status (serum ferritin levels) of adult men, menstruating females or school age subjects. Factors such as phytic acid level, dietary fiber content or protein source of vegetable protein diets have been implicated in decreasing the utilization of iron and zinc by humans. The effect of the molar ratio of phytate on the zinc of the diet is controversial: some studies find a decrease in zinc absorption with an increase in the phytate to zinc molar ratio; other studies find zinc absorption more dependent on the total amount of zinc in the meal than on the presence of phytic acid. Since many people meet their energy and protein requirements from vegetable sources, attention should be given to the mineral availability of these diets.     

Effect of copper supplementation on lipid profile of Venezuelan hyperlipemic patients

It has been assumed that most Western diets satisfy the requirement of copper/day because of ubiquitous presence of this element in most foods. Recent studies have shown that dietary copper (Cu) may often fall below the estimated daily requirements, what could determine a deficiency of this trace element. This deficiency is associated with hypercholesterolemia and hypertrigliceridemia, both in human and experimental animals. In the present intervention study was examined the effect of the administration of 5 mg of Cu/day in 73 patients (treated group), of both genders, with ages between 26 and 48 years, with high serum levels of total cholesterol and triglycerides without pharmacological treatment and compared with 73 hyperlipemic subjects non-treated with copper (control group) who were matched by gender, age, body weight, smoking habits, calories and fat intake, and physical activity. Before copper administration, a sample of blood was obtained for serum determinations of copper, zinc and lipids. At the end of the experimental period (45 days), a new sample of blood was taken for the corresponding determinations. The results suggest the existence of a marginal deficiency of the trace element in 38% of the subjects and demonstrate that copper supplementation decreases (p < 0.05) serum levels of total cholesterol (r = -0.976), triglycerides (r = -0.972), LDL-cholesterol (r = -0.961) and zinc (r = -0.980) with a slight increment (r = 0.894) of HDL-cholesterol. These findings demonstrate that copper can be used in the treatment of the patients with hypercholesterolemia and hypertriglyceridemia. The mechanisms by which Cu determines these changes are not known.     

Effects of a diet high in plant sterols,vegetable proteins,and viscous fibers (dietary portfolio) on circulating sterol levels and red cell fragility in hypercholesterolemic subjects

Plant sterols, soy proteins, viscous fibers, and nuts are advised for cholesterol reduction, but their combined effect on plant sterol absorption has never been tested. We assessed their combined action on serum sterols in hyperlipidemic subjects who were following low-saturated fat diets before starting the study and who returned to these diets post-test. The 1-mon test (combination) diet was high in plant sterols (1 g/1,000 kcal), soy protein (23 g/1,000 kcal), viscous fiber (9 g/1,000 kcal), and almonds (14 g/1000 kcal). Fasting blood was obtained for serum lipids and sterols, and erythrocytes were obtained for fragility prior to and at 2-wk intervals during the study. The combination diet raised serum campesterol concentrations by 50% and β-sitosterol by 27%, although these changes were not significant after Bonferroni correction; near-maximal rises were found by the end of the first week, but no change was found in red cell fragility despite a 29% reduction in the LDL cholesterol level. No significant associations were observed between changes in red cell fragility and blood lipids or sterols. We conclude that plant sterols had a minimal impact on serum sterol concentrations or red cell fragility in hyperlipidemic subjects on diets that greatly reduced their serum lipids.     

Body iron reserves of rural and urban Guatemalan women of reproductive age

Body iron reserves (using serum ferritin as an index), hematological status, and other indicators of iron nutrition were evaluated in three groups of non-pregnant nulliparous women with ages comprised between 14 and 29 years (mean = 19 years). The first group (n = 33) included residents of the rural coastal area (less than 750 m above sea level) (group RCG); the second (n = 32) from the rural highlands (751-1,500 m) (group RHG); and the third group (n = 104) from urban Guatemala City (1,500 m) (group UG). The women in the UG group belonged to the middle or high socioeconomic stratum. Median values in serum ferritin levels (ng/ml) for each group were: RCG = 11.5 (undetectable 50.6); RHG = 17.2 (1.9-83.1) and UG = 20.2 (3.9-56.7). The difference between RCG and UG was statistically significant (P less than 0.05). The percentage of women with serum ferritin levels less than or equal to 9 ng/ml (iron deficiency) was 45 in the RCG, 25 in the RHG and 12 in the UG group. In addition, the prevalence of subnormal hemoglobin levels (below mean - 1 SD) was 46% in the RCG, 12% in the RHG and 8% in the UG. There were no cases of subnormal blood folate levels. As results indicate, the women studied had low iron reserves, the rural coastal group being the most affected. They also evidenced the high prevalence of iron deficiency in the region and the need for public health actions to overcome this nutrition problem.     

Changes in serum lipids in rats treated with oral cooper

Disturbances in lipid metabolism during copper deficiency in rats are well recognized. Copper deficiency is associated with the spontaneous retention of hepatic iron. Previous studies have reported that hypercholesterolemia and hypertriglyceridemia are associated with elevated hepatic iron concentrations in copper deficient rats. There was a direct relationship between the magnitude of blood lipids and the concentration of hepatic iron. Based on these data, it has been hypothesized that iron was responsible for the development of lipemia of copper deficiency. In this study was determined the effect of increasing doses of Cu(10, 20 and 50 ppm) in the diet, on the serum total lipids, total cholesterol, triglycerides (triacylglicerols), phospholipids, non-esterified fatty acids (NEFA) and liver iron and zinc concentrations in normal rats. The results were compared with normal rats that received a balanced diet containing 0.6 and 6 ppm of Cu, respectively. The results show that Cu-supplement diminished the cholesterol and triglyceride serum levels, increased the level of phospholipids, NEFA and concomitantly decreased the hepatic concentrations of Fe and Zn. There was a statistically significant (p < 0.05) simple correlation between triglycerides and liver Fe (r = 0.917; R2 = 64.03%), cholesterol and liver Zn (r = 0.872; R2 = 76.07%), cholesterol and liver Fe (r = 0.995; R2 = 99.10%), liver Fe and liver Cu (r = -0.612), liver Fe and liver Zn (r = 0.837), liver Cu and liver Zn (r = -0.612), and serum triglycerides and liver Zn (r = 0.967). The mechanism(s) by which Fe and Zn determine these changes is not known; none of the enzymes that act in cholesterol and triglyceride metabolism and biosynthesis require Fe and/or Zn. The increase of NEFA is due to changes in the process of lipolysis and re-esterification of the fatty acids in blood. However, additional studies are needed for the precise mechanisms of this interrelationships to be clarified.     

Index of nutritional quality per volume: a new indicator to evaluate the nutritional quality of food preparations and diets

The purpose of this study was to propose a new dietary index to evaluate the nutritional quality of common dishes and diets: the index of nutritional quality per volume (INQV). In its expression, this index takes into account the nutrient density (amount of nutrient/1,000 g of diet) and the nutrient density per reference volume. The last one is the ratio between the recommended allowances of the nutrient and the volume that it is possible to consume during the day, when the diet is offered freely. Zinc was used as example in the analysis. A total of 14 dishes of habitual consumption in Chile were studied in relation to its consumption by 30 preschool children. The volume that children were able to consume was determined by differential weighing between the amount offered and the amount left on the dish, during a period of 180 days. The percentage of water and energy value were established by means of chemical analysis performed according to the AOAC, and the zinc concentration by atomic absorption spectrophotometry. The results of the INQV were then compared with those of the index of nutritional quality (INQ), which considers zinc density/1,000 kcal, and zinc and energy requirements. This comparison demonstrated that the INQV values were lower than those of the INQ in dishes with energy densities lower than 1.0 kcal/g. The opposite tendency was observed in the case of those dishes with energy densities higher than 1.0 kcal/g. The analysis herein presented demonstrates the usefulness of the INQV in diets which are voluminous and with low energy densities, commonly consumed by the low socioeconomic strata of developing countries.     

Hemoglobin-fortified biscuits: bioavailability and its effect on iron nutriture in school children

School-age children in Chile received 30 g of wheat-flour biscuits daily through a National School Lunch Program. To improve iron nutrition, these biscuits were fortified with 6% of a bovine hemoglobin concentrate. Hemoglobin iron bioavailability, measured with a double isotope technique, showed that heme-iron absorption in fortified biscuits was high (19.7%). In a pilot field trial, a cohort of 215 school-children received fortified biscuits (30 g) daily during two school periods, and their iron nutrition status was compared with that of children who received non-fortified biscuits (n = 212). Acceptability of both types of biscuits was excellent. Initially, both groups had comparably good iron nutrition. The fortified children presented higher mean ferritin values at the end of the first and second school periods. Good iron stores (serum ferritin greater than or equal to 20 micrograms/lt) were present in 92% and 79% of the fortified and control subjects, respectively (P less than 0.004). The high-iron bioavailability, the good organoleptic characteristics and the biological effect on iron nutriture make this product an appealing alternative to combat iron deficiency.     

Folate and iron in fertile age women from a Venezuelan community affected by incidence of neural tube defects

The objective of this transversal study was to determine folate and iron nutritional status of women in fertile age from Municipio Jiménez, Lara State, Venezuela. The sampling was probabilistic by conglomerates from the urban and rural areas, selecting 15 conglomerates from which women between 12 and 45 years (269), were studied. After signing informed consent, participating were interviewed for personal data, antecedents related to folate and iron, socioeconomic data (Graffar-Mendez Castellano method and unsatisfied basic needs). In blood sample was determined Hemoglobin, and Erythrocytic Folate (FE). Serum was obtained to determine Ferritin and Serum Folate (FS). 53.53% of the sample presented low FS levels, 10.78% were FS deficient. Severe FE deficiency was present in 80.7% of the cases, moderate deficiency affected 5.9%. For both tests, median was higher for women in treatment with Acido Fólico or pregnant (p = 0.000), median for FE was higher for adults (p = 0.001) and in non poor women (p = 0.011). There were no significant differences for coffee, alcohol, anticonceptive consumption, urban or rural resident or socioeconomic strata. The prevalence of anemia was 11.2% being significantly more frequent in adults than in adolescents (p = 0.029) and in urban women (p = 0.042). Low ferritin were found in 37.3% of the sample, the effect of different variables was not statistically significant. In conclusion, there is a high prevalence of iron and folate deficiencies in women of fertile age from Municipio Jiménez, which could constitute a conditioning factor for the appearance of neural tube defects.     

Modulating influence of dietary lipid intake on the prostaglandin system in adult men

We evaluated the effect of moderate dietary changes on the prostaglandin system by measuring the urinary excretion of 7α-hydroxy-5,11-dioxo-tetranorprostane-1,16-dioic acid (PGE-M). In a crossover design, twenty-four free-living male subjects in good health (24 to 54 years of age) were fed two diets: (i) Regular (R) diet, 41% energy (en%) from fat, P/S 0.59, M/S 0.96; (ii) Experimental (E) diet, 19 en% from fat, P/S 1.31, M/S 1.48. Diet R contained 13.9 g/day of neutral detergent fiber (NDF) and about 600 mg/day of cholesterol per 3200 kcal; Diet E contained 35.5 g/day NDF and about 280 mg/day cholesterol. Each controlled-diet period lasted ten weeks. The menu cycle was 7 days, and all diets were calculated to provide adequate amounts of essential nutrients. The PGE-M excretion rates were determined in 24-hr urine by stable-isotope dilution gas chromatography-mass spectrometry in the selected ion-monitoring mode. Low-fat Diet E, with an intake of 6.6 en% from polyunsaturates, was associated with an average 14.2% reduction in PGE-M daily output, compared to high-fat Diet R with a 9.3 en% from polyunsaturates (P=0.046). These results support the view that dietary lipid changes can significantly alter thein vivo production of E-series prostaglandins. We cannot conclude, however, if this apparent diet effect was brought about by the change in linoleate intake alone or was the result of complex biochemical interactions among individual fatty acids, both saturated and unsaturated.     

Prevalence of anemia during pregnancy: results of Valencia (Venezuela) anemia during pregnancy study

To determine the prevalence of anemia during pregnancy in Venezuelan pregnant women. By using a cross-sectional study, 630 Venezuelan pregnant women in their third trimester at labor from the Valencia Anemia during Pregnancy Study were studied. Anemia during pregnancy was defined according to WHO guidelines (Hb < 11 g/dl), iron deficiency was considered when serum ferritin level was < 12 ng/ml, and when serum folate level was < 3 ng/ml, it was considered as folate deficiency. 630 pregnant women (mean [+/- SD] age, 24 +/- 6.4 years) having an average of Hb 11.38 +/- 1.47 g/dl [95%CI = 11.27 to 11.50] were studied. No patient had hemolytic anemia nor clinical infections. Almost all patients were from low or very low socioeconomic status. Prevalence of anemia was 34.44% (severe: 1.8%, moderate: 15.2%, and mild: 83%). Iron deficiency anemia (IDA) was present in 39.2% (95%CI = 32.7 to 45.7), prevalence of folate deficiency anemia (FDA) was 11.98% (95%CI = 7.6% to 16.3%). Combined anemia (IDA and FDA) occurred in 11.52% (95%CI = 7.27% to 15.7%). Multivariate analysis showed that multiparous (odds ratio -OR-: 1.95, 95%CI = 1.28 to 2.97, p = .002) and supplement use of iron (OR: .55 (95%CI = .33 to .91, p = .02) are associated with IDA. The factors associated with FDA were: supplement use of folic acid (OR: .37 (95%CI = .19 to .71, p = .003) and appropriate prenatal control (OR: .51 95%CI = .27 to .96, p = .04). Prevalence of anemia during pregnancy was found to be high. Educational efforts should be stressed in order to encourage improvements in the prenatal care visits.     

Serum zinc in Brazilian children of families of low income

Serum zinc was measured in 103 Brazilian children from low income families, 3 months to 6 years of age, with the purpose of characterizing their zinc nutritional status. Serum albumin was determined in some of the children studied. They were grouped in three categories according to the adequacy of height for age and weight for height indices related to the growth curves determined for Brazilian children. There were 30 normal, 18 acutely malnourished and five chronically malnourished children. This criteria was complemented by the Gomez criteria. Thirty healthy adults of both sexes served as a reference group for the analytical procedures. In the adults, serum zinc was 107.5 +/- 14.5 micrograms/dl, similar to values observed by other investigators, and significantly higher than in all of the children studied. Serum zinc of normal children was 98.3 +/- 15.7 micrograms/dl. It decreased with the degree of malnutrition, being significant for second degree acutely malnourished (87.8 +/- 9.2 micrograms/dl; p less than 0.05) and chronically malnourished children (68.7 +/- 8.9 micrograms/dl; p less than 0.001). Serum zinc and albumin correlated significantly (r = 0.51; n = 37; p less than 0.01), particularly in the severely malnourished children (r = 0.63; n = 8; p less than 0.05).     

Quality of the diet of women with severe and morbid obesity undergoing gastric bypass and sleeve gastrectomy

The objective of this study was to evaluate the changes of dietary intake and quality of the diet in patients undergoing gastric bypass and sleeve surgery. In 36 women with severe and morbid obesity it was assessed their nutrient intakes and dietary quality before and 6 months after bariatric surgery through three-day food records. Vitamin and mineral intakes from supplements were strictly controlled. Energy and nutrient intakes were significantly decreased 6 months after surgery bypass compared to the pre-surgery period with the exceptions of calcium and vitamin C. No differences were observed between groups. The Dietary quality index was also similar in both groups. Dietary intakes of calcium, iron, zinc, copper, folic acid, vitamin C, and vitamin E were below 100% of adequacy from at the 6th month after the surgery. Nevertheless, by considering both diet and supplements supply, nutrient adequacy of all but calcium and folic acid was above 100% in both groups. Gastric bypass patients presented greater values. In conclusion, these patients present an important reduction of their energy and nutrient intakes, with no major impact of the type of surgery. Supplement characteristics are crucial to cover nutritional needs.     

Erythrocyte protoporphyrin during recovery from malnutrition in rats

Interrelationships between Erythrocyte Protoporphyrin (EP), dietary Iron/Protein ratio (Fe/Prot) and Fe liver content (Feh) were studied during nutritional recovery in an experimental model: weanling female Wistar rats (To) were depleted with a protein-free diet (LP), losing 20% of their initial body weight. Then they were recovered until 45 days of age (T45) with diets containing: casein: 20 g/100 g; Fe (ammonium Fe citrate) (ppm.): 0, 75 or 100 (groups A1, A2 and A3, respectively). Hematocrit, Hemoglobin (Hb) (g/dL). Erythrocyte Protoporphyrin (EP) (microgram/dL Red Blood Cells) and Feh (microgram) were determined at To, LP and T45. Results were compared with control rats (C) fed with 20% of casein and Fe, 50 ppm. EP: a) decreased in C from To to T45 (99 +/- 24; 36 +/- 9; p < 0.01); b) increased in A1 and A2 at T45 (123 +/- 21; 93 +/- 29, respectively, p < 0.01) while A3 did not show significant difference (45 +/- 7) regarding to C: c) correlated inversely with Feh. According to the inverse correlation between EP and Fe/Prot (r = -0.99), we found that 92 ppm was an adequate Fe amount to prevent EP increase. These results confirm that during recovery from undernutrition EP depends on iron liver content, being an adequate indicator of iron nutritional status; therefore, EP would be useful as a predictor of the optimum Fe/Prot ratio for nutritional recovery.     

Food habits and culture factors in pregnant adolescents

The purpose of this study was to identify the food habits of pregnant adolescents and their perception about which, of her cultural concepts, have higher influence. 54 subjects between 12 and 19 years old from Guadalajara City were included and socioeconomic, dietetic data, as food frequency consumption and cultural concepts about feeding were also explored. Chi square was used for identifying association between variables. The fat intake was lower in late vs. Early and middle stage of adolescence (57 vs. 71 g/d, p = 0.05). The iron, calcium and zinc intake was also deficient in the early/middle stage; meanwhile, the folic acid consumption was very low in the late stage of adolescence. Corn tortillas were the most consumed cereal and food (93-96%); junk food and sodas (62 and 55%) prevailed in the early/middle stage. About local costumes, "tacos", "pozole" and burgers were the most referred (74.1%). They also mentioned that fat (36.7%), junk food (30%), chili (26.7%), sodas (23.3%), processed meals (26.7%) and salt (10%) were harmful. They also believed that vegetables (77%), fruits (60 %), milk (21%), broths (17%), and meat (12.5%) were beneficial; and, 96% considered that chicken and bean broths were nutritious (myth). There were some prohibited foods (taboos) during pregnancy: chili (48%), junk food (20%), and salt (16%). Prejudices were more common among later adolescents (60.9%) (p = 0.03). The erratic food habits and the conceptual confusion of these adolescents cause a low intake of nutrients and place them in a nutritional risk.     

Effect of the quality and quantity of dietary proteins on vitamin A depletion rate, and biological availability of vitamin A precursors

The effect of quantity and quality of protein from cereal and legume sources on the rate of vitamin A depletion was evaluated through changes in retinol serum levels and liver stores in male and female Wistar strain rats. A total of 64 animals were distributed into four groups and fed ad libitum with diets adequate in all nutrients, except vitamin A. The protein in the diets was derived from 91% common maize (Diet A); 91% Opaque-2 maize (Diet B), 64% common maize plus 27% precooked common black bean flour (Diet C), and 64% Opaque-2 maize with 27% bean flour (Diet D). The total depletion period lasted 60 days and four rats per group were sacrificed at 15, 30 and 60 days. A total of 4 animals were sacrificed at 0 day to count with a basal serum and hepatic retinol concentration value. The 16 depleted remaining rats were used for the carotene bioavailability study with dehydrated carrots. During the first 15 days the greater rate of depletion was observed in animals fed the highest protein quality diet made from Opaque-2 maize and beans (Diet D), which also caused the greatest weight increase. The least depletion rate and lowest weight gain was obtained with the common corn diet (Diet A). Diets B and C caused intermediate depletion rates, with Diet B (Opaque-2 maize) being more effective than Diet C in spite of its lower protein content. At the end of 60 days all groups presented depletion levels not statistically different. Thus, these results confirm that protein quantity and quality from basic staple foods influence mobilization of retinol liver reserves. The 16 remaining depleted rats were then divided into four groups and fed a standard 14% casein diet to which 25, 50 and 75% of the retinol requirements was added to obtain a reference standard biological response. The fourth group was fed with an amount of dehydrated and ground carrot containing 67.1 mg % of total carotenoids. After seven days, serum and hepatic retinol were obtained, from which a regression equation of liver retinol to diet retinol was calculated (microgram % liver retinol per 100 g of rat) = 2.47 + 0.063 (microgram retinol/g diet) (r = 0.585). From this equation the bioavailability of carrot carotenoids was established with a value of 21.8% comparable to the FAO/WHO value previously reported.     

Prevalence of nutritional deficiencies in Mexican adolescent women with early and late prenatal care

The objective was to evaluate the prevalence of specific nutritional deficiencies in a group of pregnant adolescents according to the gestational age when they started to receive prenatal care. A group of 163 pregnant adolescents that attended the Instituto Nacional de Perinatología (Mexico City) for the first time to receive prenatal care was evaluated. An anthropometrical evaluation was performed and a blood sample taken to determine hemoglobin, ferritin, erythrocyte folate and plasma zinc to all cases. The mean age was 15 years (11 to 17 years). The mean gestational age when starting prenatal care was 27 +/- 7 gestation weeks and most of them tended to have low weight (97 +/- 12% expected weight for height and gestational age). Eight of every ten adolescents had anemia and iron deficiency. Late prenatal care (> or = 25 weeks) was associated with the risk of presenting anemia OR 5.11 (CI 95% 2.4-10.7) iron deficiency (OR 3.5; CI 95% 1.7 to 7.1) and zinc deficiency (OR 2.9; CI 95% 1.1 a 7.6). In relation to folate deficiency, the opposite effect was observed (OR 0.10; CI 95% 0.02 a 0.48). Lack of opportune prenatal care was associated with the presence of iron and zinc depletion. Probably iron deficiency contributes to an erythrocyte folate accumulation.     

Food based approaches to improve vitamin and mineral nutrition adequacy

This paper, using the nutrient density concept and the development of Food-Based Dietary Guidelines (FBDG), explores the nutritional adequacy of food patterns based on the main staples around the world--maize, wheat, rice and potato. The nutritional adequacy of the vitamins A, C, folates and the minerals iron, zinc and calcium in diets composed by these staples is analyzed. Projected diets modified by the addition of foods high in vitamins and minerals, based on food table composition information, are analyzed for changes in nutritional adequacy, in order to cover the nutritional requirements of all family members. This theoretical exercise shows that diets diversified by the addition of relatively small quantities (27-70 g) of foods like fruits, vegetables, legumes and meat improve substantially the nutritional adequacy of the vitamins A, C, folates, iron and zinc. In the case of calcium, the addition of a dairy source becomes essential. From the practical point of view, the implementation of the food based approach requires a national effort in order to support the production of nutrient rich foods and to promote consciousness of nutrient bioavailability, so that people may obtain all nutrient potential from foods. Simultaneously, the need of fortification programs at the national level is recognized. This is the case for critical nutrients, where requirements might be above the potential in available foods. A similar situation occurs in the case of vulnerable groups like pregnant women and infants, who need supplementation to ensure nutritional adequacy of their diets. In conclusion, the use of FBDG is a good alternative for improving the nutritional adequacy of diets based predominantly on staple foods. However, food fortification and supplementation programs directed to vulnerable groups are necessary and complementary practices to the FBDG implementation.