The effects of a dietary zinc supplement during lactation on longitudinal changes in maternal zinc status and milk zinc concentrations

Dietary zinc intakes, selected biochemical indices of zinc status, and milk zinc concentrations were determined at monthly intervals throughout lactation for 53 middle-income lactating women, 14 of whom received a daily supplement of 15 mg zinc. Overall mean dietary zinc intake for the non-supplemented group (NZS) was 10.7 +/- 4.1 mg/day (mean +/- SD). The mean dietary zinc intake of the zinc supplemented group (ZS) was 12.2 +/- 3.5 mg/day, with an additional 12.8 +/- 1.5 mg/day from the supplement. For the NZS group, the highest mean plasma zinc concentration of 79 +/- 10 mu/dl, which occurred at month 4, was significantly less than the mean for non-lactating control women (86 +/- 10 micrograms/dl). ZS plasma zinc levels had a pattern similar to that of the NZS group for months 1-7. The rate of decline in milk zinc during lactation was significantly less for the ZS group compared to that of the NZS group (p = 0.02). It is concluded that milk zinc concentrations are influenced by maternal zinc intake within a physiological range and that the effects of low maternal intakes are most apparent with prolonged lactation.     

Metabolic adaptations to low zinc intakes in premenarcheal girls

BACKGROUND: Zinc deficiency is increasingly recognized as an important cause of mortality and morbidity. Children in developing countries are at especially high risk because of relatively low zinc intakes and poor bioavailability. OBJECTIVE: We assessed the effect of 2-wk adaptation to low zinc intake (4 mg/d) on fractional zinc absorption, endogenous fecal zinc excretion, and urinary zinc excretion. DESIGN: Sixteen healthy 9-14-y-old girls were studied twice in random order after 2-wk adaptation to diets providing either 12 mg/d (high) or 4 mg/d (low) zinc. Fractional zinc absorption and endogenous fecal zinc excretion were measured with use of established stable isotope techniques. RESULTS: Plasma zinc was not significantly lower during the low dietary intake period (1.06 +/- 0.18 mg/L) than during the high dietary intake period (1.14 +/- 0.23 mg/L, P = 0.30). Endogenous fecal zinc excretion was significantly lower during the low intake period (1.08 +/- 0.62 mg/d) than during the high intake period (1.82 +/- 0.95 mg/d, P < 0.026), but there was no significant change in fractional zinc absorption (30.6% +/- 12.4% compared with 26.6% +/- 9.0%, P = 0.32) or urinary zinc excretion (0.68 +/- 0.35 mg/d compared with 0.59 +/- 0.24 mg/d, P = 0.30). Approximate zinc balance was significantly lower during the low-intake period than during the high-intake period (P = 0.007) and significantly (P < 0.0001) less than zero. CONCLUSION: Short-term zinc restriction in premenarcheal girls leads to a significant decrease in endogenous fecal zinc excretion, which was inadequate to restore normal zinc balance.     

Effect of germination of finger millet on nutritional value of foods and effect of food supplement on nutrition and anaemia status in Tanzanian children

Inadequate dietary intake, often combined with an infection can lead to malnutrition that often manifest as growth failure or deficiency of essentials nutrients including iron leading to iron deficiency anaemia. In an effort to investigate diet in relation to nutrition status of children, diet and dietary intake were investigated in rural Tanzania. The effect of germination of finger millet based food recipe on its nutritional value was evaluated. The food consisted of finger millet flour, kidney beans, ground peanuts and dried mangoes at predetermined proportions of 75:10:10:5 respectively. Dietary habits of young children were investigated and effects of a fortified food supplement and the cereal based recipe on nutrition status of children were investigated. The two diets were then supplemented to children for 6 months and changes on anaemia and anthropometrical indices of children were evaluated at follow up periods. To assess anaemia and iron status, haemoglobin (Hb), haematocrit (Hct), erythrocyte protoporphyrin (EP) and serum ferritin (SF); and weights and heights were measured to assess growth. A significant improvement in nutrient density was noted in processed cereals. Bioavailability of iron in cereal based diet increased from 0.75 +/- 18 to 1.25 +/- 41 mg/100 g (P = 008), viscosity was significantly raised by 12% and phytate concentration was reduced from 4.5 +/- 0.5 to 4.1 +/- 0.5 mg/g (P = 0.03). Significantly lower intake of iron was observed in schoolchildren with Hb < 11.5 g/dl) compared to those who were normal. Total iron intake was 22+/- 7 and 27 +/- 13 mg/day, respectively (P < 0.05). There was a significant correlation between iron intake and serum ferritin (r = 0.233, P < 0.05). After six months of supplementing children with the fortified beverage a significantly larger increase in haemoglobin concentration was shown in the fortified group than in the non-fortified group (a difference of 6.2 versus 3.2 g/dl respectively). Supplementing infants with the germinated cereal based food supplement showed a general improvement on Hb status and growth that was not significantly different to that in the control group (P > 0.05). In conclusion, consumption of foods with low iron bioavailability is a major cause of anaemia. Germination improves the nutritional value of foods however there is need to fortify such processed foods for infant feeding.     

Basal urinary zinc/creatinine ratio as an indicator of dietary zinc intake in healthy adult women

OBJECTIVE: To study, in healthy women, the correlation between the basal urinary zinc/creatinine ratio and dietary zinc intake. SUBJECTS: A group of 36 healthy female University students was evaluated. Mean age and body weight were, respectively, 25.6+/-3.3 years and 54.4+/-7.0 kg. METHODS: Basal urine was collected; Zn was determined by AAS and Creatinine (Creat) by the Jaffe method. A nutritional survey of seven days was recorded. Mean daily dietary intake of energy (DE) and zinc (DZn) were calculated according to the INCAP and English or German Food Composition Tables, respectively. RESULTS: Mean dietary daily intake were as follows (x +/- SD): Energy (kcal): 1606+/-570; zinc (mg): 9.1+/-3.8; basal urine Zn/Creat ratio: 0.41+/-0.24. Individual values of the Zn/Creat ratio correlated with dietary Zn (r=0.481, p=0.0339); data grouped according to ranges of dietary Zn fit the following equation: Zn/Creat=0.160+/-0.034 DZn (mg/day); (r=0.870, p=0.00497). CONCLUSIONS: These results showed that the basal urinary Zn/Creat ratio could be a useful indicator of dietary Zn intake in healthy adult women.     

Current dietary zinc intake has a greater effect on fractional zinc absorption than does longer term zinc consumption in healthy adult men

BACKGROUND: No studies have examined the independent effects of current and longer-term dietary zinc intakes on zinc absorption. OBJECTIVE: We determined the effects of current compared with longer-term zinc intake on fractional zinc absorption (FZA). DESIGN: We studied 9 men whose usual zinc intakes were >11 mg/d. FZA was measured at baseline, depletion (0.6 mg Zn/d for 1 wk and 4 mg Zn/d for 5 wk), and repletion (11 mg Zn/d for 4 wk with 20 mg supplemental Zn/d for first 7 d). During 2 successive days after each dietary period, subjects consumed either adequate-zinc meals (11 mg Zn/d) with a zinc stable isotope tracer for 1 d, followed by low-zinc meals (4 mg Zn/d) with zinc tracer, or vice versa. Five days after oral dosing, a zinc tracer was infused intravenously. FZA was measured with the use of a modified double isotope tracer ratio method with urine samples collected on days 5-7 and 10-12 of absorption studies. RESULTS: Plasma and urinary zinc did not vary by dietary period. Mean FZA was greater from low-zinc meals than from adequate-zinc meals (60.9% +/- 13.8% compared with 36.1% +/- 8.9%; P < 0.0001), whereas mean total absorbed zinc was greater from adequate-zinc meals than from low-zinc meals (3.60 +/- 0.91 compared with 2.48 +/- 0.56; P < 0.0001), regardless of the longer-term dietary period. CONCLUSIONS: FZA was inversely related to current zinc intake, but there was no detectable effect of longer-term dietary zinc. If longer- term zinc intake does modify FZA, such changes are smaller than those caused by current zinc intake, or they occur only after more severe zinc depletion.     

1991-2009年中国九省区膳食营养素摄入状况及变化趋势(十) 7～17岁儿童青少年膳食锌的摄入状况及变化趋势

目的了解1991-2009年中国九省区儿童青少年膳食锌的摄入状况、食物来源以及变化趋势。方法利用"中国健康与营养调查"的资料,选取1991、1993、1997、2000、2004、2006和2009年7轮调查中的7～17岁儿童青少年为对象,采用连续3 d 24 h膳食回顾询问法收集膳食资料。结果中国九省区儿童青少年平均每日锌摄入量从1991年的10.4mg下降到2009年的9.1mg。1991年和2009年中国九省区儿童青少年膳食锌摄入量低于平均需要量(EAR)的比例分别为66.6%和79.6%。膳食锌主要来源于谷类食物、动物性食物、坚果和蔬菜水果。结论我国儿童青少年人群中普遍存在锌摄入不足的问题,需要进行适当干预以增加膳食锌摄入量。[营养学报,2013,35(2):131-133]     

Dietary calcium intakes of urban children at risk of lead poisoning.

Dietary calcium is well known to decrease gastrointestinal lead absorption and thereby reduce the risk for lead poisoning. Because children in economically deprived urban centers are especially likely to have excessive lead exposure, we surveyed dietary calcium intakes of 314 children from the greater Newark, New Jersey, area. The areas of Newark and adjacent communities studied had been previously identified as containing significant sources of environmental lead by geographic information systems technology. An abbreviated National Cancer Institute Health Habits and History Questionnaire, modified to focus on foods high in calcium, was used to determine dietary calcium. Calcium intakes were then compared to the new Dietary Reference Intake (DRI) guidelines. The respondents were primarily the parents of African-American and Hispanic children ranging in age from 1 to 8 years, with a mean age of 3.5 years. The most recent blood lead concentration was 11.4 +/- 0.8 microg/dL (mean +/- standard error), and 48.6% had concentrations at or above the current guideline of 10 microg/dL. Quintiles of calcium intake were: 221 +/- 13; 488 +/- 9; 720 +/- 6; 885 +/- 6; and 1,389 +/- 49 mg/day. Fifty-five of 175 (31.4%) children aged 1-3 years had calcium intakes below the DRI, as did 82 of 139 (59.0%) children aged 4-8 years. The percentage of mothers reporting lactose intolerance in their children was 2.5%. The observation that the children in the highest quintile easily exceeded the DRIs for calcium suggests that urban parents who include dairy foods in their childrens' meals can provide a diet that meets the DRI guidelines. Children in the lowest quintiles are at risk of increased absorption of the environmental lead to which they are inevitably exposed, as well as other problems associated with a low intake of dietary calcium. The data suggest that both lead exposure and low dietary calcium continue to pose significant health risks to urban minority children.     

Influence of dietary and socio-demographic factors on the iron status of married adolescent girls from Indian urban slums

To explore the influence of dietary factors of iron bioavailability and socio-demographic conditions on blood iron status of married adolescent girls (MAG), a cross-sectional study was conducted in 173 MAG (15-19 years old) from urban slums near Pune city, India. Diet was assessed by two random 24-h recalls. The age, weight, height, education, family size, income, physical work, and number of days of menstrual loss were recorded. Fasting blood was analyzed for hemoglobin and serum ferritin. Mean intakes of micronutrients were 40-75% less than the recommended dietary intakes for Indian adolescent girls. High intake of phytates (171+/-6 mg/day) and low intakes of vitamin C (25+/-1 mg/day) resulted in low bioavailable iron intakes. The mean bioavailable iron intake was 0.76+/-0.3 mg/day, which is one-half of the basal iron requirement of adolescent girls. The prevalence of iron deficiency (serum ferritin<12 microg/l) was 25.1%, and anemia (hemoglobin <12 g/l) was seen in 46.4% of MAG. A multiple regression model adjusted for energy intake indicated that intakes of beta-carotene and riboflavin were associated with hemoglobin (P<0.001) and those of zinc, riboflavin and thiamin associated with serum ferritin (P<0.01). Multiple regressions including socio-demographic factors revealed that the family size, number of menstrual days lost and total bioavailable iron intake were the influencing factors for low iron status. In conclusion, there is a need to increase intakes of vitamin C and other micronutrients of the MAGs and to improve iron bioavailability through diet modifications.     

Zinc biofortification of rice in China: a simulation of zinc intake with different dietary patterns

A cross-sectional survey of 2819 adults aged 20 years and above was undertaken in 2002 in Jiangsu Province. Zinc intake was assessed using a consecutive 3-day 24-h dietary recall method. Insufficient and excess intake was determined according to the Chinese Dietary Recommended Intakes. Four distinct dietary patterns were identified namely "traditional", "macho", "sweet tooth", and "healthy". Intake of zinc from biofortified rice was simulated at an intermediate zinc concentration (2.7 mg/100 g) and a high zinc concentration (3.8 mg/100 g) in rice. Average total zinc intake was 12.0 ± 3.7 mg/day, and insufficiency of zinc intake was present in 15.4%. Simulated zinc intake from biofortified rice with intermediate and high zinc concentration decreased the prevalence of low zinc intake to 6.5% and 4.4%, respectively. The effect was most pronounced in the "traditional" pattern, with only 0.7% of insufficiency of zinc intake remaining in the highest quartile of the pattern. Zinc intake was inversely associated with the "sweet tooth" pattern. Zinc biofortifed rice improves dietary zinc intake and lowers risk for insufficient zinc intake, especially for subjects with a more "traditional" food pattern, but less for subjects with a "sweet tooth" food pattern.     

Food consumption and nutrient intake in a sample of Italian secondary school students: results from the INRAN-RM-2001 food survey

The present study was designed to estimate the average food and nutrient intake in a sample of Italian students living in the District of Rome. In the school year 1999-2000 all students belonging to the first, second or third year of nine randomly selected secondary public schools were contacted for filling in a food frequency questionnaire (3982 subjects). The next year, 233 of them (125 males and 108 females), randomly extracted, participated in a detailed food survey. Food intake was assessed on the basis of 12 (four consecutive days in three different periods) 24-h dietary records. The average daily intakes of fruit (107 +/- 100 g/day), vegetables (186 +/- 74 g/day) and legumes (16 +/- 29 g/day) were lower than recommended. The percentage of energy intake from fat (39%) and that from saturated fats (12%) were high. On the other hand, the percentage of energy intake from carbohydrates was low (45%) even if that from sugar (14%) was rather high. The students' diet was characterized by low intakes of fibre (16 +/- 6 g/day) and calcium (710 +/- 247 mg/day) in both males and females. Iron intakes were lower than 12 mg/day in a very high percentage of females (80%), suggesting that iron deficiency may be present in this population group. Results indicate that the diet of these students is both unbalanced in terms of macronutrients and deficient for some micronutrients, suggesting the need for intervention.     

Effect of zinc intake on copper excretion and retention in men

To determine the influence of zinc intake on copper excretion and retention, nine men consumed diets containing 2.6 mg of copper/day and 1.8, 4.0, 6.0, 8.0, 18.5 or 20.7 mg of zinc/day for one- or two-week periods in a 63-day study. Copper and zinc in the diet and copper in plasma were determined weekly; fecal copper was determined daily and averaged within each week. The weekly mean (+/-SEM) plasma copper concentrations (81 +/- 3.3 to 100 +/- 5.8 micrograms/dl) remained within the normal range throughout the study. Fecal copper and apparent copper retention were influenced by the level of dietary zinc and the duration it was fed. When 18.5 mg of zinc/day was fed for two consecutive weeks following a lower zinc intake, fecal copper was elevated and apparent copper retention was reduced after a one-week lag. Thus, an intake of zinc only 3.5 mg/day above the RDA for men reduced apparent retention of copper at an intake of 2.6 mg/day.     

Selenium and zinc status are suboptimal in a sample of older New Zealand women in a community-based study

The importance of selenium and zinc in the immune functioning of the aged is widely recognized. Seniors in New Zealand are at particularly high risk of low selenium status because of the low selenium soil environment. The zinc status of the New Zealand elderly has never been assessed. In this cross-sectional study, the biochemical selenium, zinc and lipid levels, physical functional capacity and dietary intakes of 103 randomly selected free-living New Zealand women (mean age +/- SD, 75 +/- 3 y) were assessed. Among nonusers of selenium supplements (n = 80), 80% [95% confidence interval (CI): 70; 88%] had plasma selenium levels (0.85 +/- 0.23 micromol/L) below 1.00 micromol/L [ approximately 10% below mean plasma selenium necessary for full expression of glutathione peroxidase (GPx) activity in New Zealand subjects]. Plasma selenium was strongly correlated with GPx: r = 0.56; P < 0.0001. For nonusers of zinc supplements (n = 88), serum zinc concentrations were 12.4 +/- 1.4 micromol/L, with 12% (95% CI: 6; 21%) having levels below the cut-off value (10.7 micromol/L). Estimated mean daily selenium and zinc intakes were 34 +/- 10 microg and 8.7 +/- 2.0 mg, respectively. Subjects in the highest tertile of a functional capacity index had higher biochemical zinc and selenium values than those in the lowest tertile (P < 0.05). The correlation between plasma selenium and GPx indicates that selenium intake in these women is still insufficient for full expression of GPx activity. Lower serum zinc levels also appear to be prevalent. Because a suboptimal trace element status may be more common among those with a poor physical functioning, promotion of the consumption of nutrient dense foods or supplements to improve selenium and zinc status of elderly women in New Zealand may be beneficial.     

Red meat and a fortified manufactured toddler milk drink increase dietary zinc intakes without affecting zinc status of New Zealand toddlers

Evidence suggests that New Zealand (NZ) children are mildly zinc deficient and may respond to dietary change. A 20-wk randomized intervention trial was therefore conducted to determine whether an increased intake of red meat or consumption of a fortified manufactured toddler milk drink (FTMD, fortified with zinc and other micronutrients) would increase dietary zinc intakes and improve the biochemical zinc status of 12- to 20-mo-old NZ toddlers. Toddlers were randomized to a red meat intervention (n = 90), FTMD intervention (n = 45), or nonfortified milk placebo (n = 90). Study foods were provided. Adherence was assessed via monthly 7-d meat or milk recording diaries. Hair and serum zinc concentrations, and length and weight were measured at baseline and postintervention. Nutrient intakes were assessed via 3-d weighed food records at baseline, wk 4, and wk 18. At baseline, 38% of participants had low serum zinc concentrations despite seemingly adequate dietary zinc intakes (<4% below the Estimated Average Requirement). Dietary zinc intakes significantly increased by 0.8 mg/d (95% CI: 0.5, 1.1) in the meat group and 0.7 mg/d (95% CI: 0.2, 1.1) in the FTMD group compared with a decrease of -0.5 (95% CI: -0.8, -0.2) mg/d in the placebo group. No corresponding increases in serum or hair zinc concentrations were observed. Dietary zinc intakes achievable via interventions based on red meat or a FTMD are unlikely to improve biochemical zinc status in NZ toddlers. These results also question cutoffs used to define zinc deficiency in toddlers.     

Zinc intake of US preschool children exceeds new dietary reference intakes

BACKGROUND: The recent dietary reference intakes publication provides updated information on the physiologic and dietary requirements for zinc and proposes new tolerable upper intake levels. OBJECTIVE: We analyzed dietary intake data of US preschool children to determine the prevalence of inadequate and excessive intakes of zinc. DESIGN: Diets of 7474 nonbreastfeeding preschool children in the Continuing Survey of Food Intakes by Individuals (1994-1996 and 1998) were analyzed for the intakes of zinc and other dietary components, and factors associated with zinc intake were examined. RESULTS: The mean intakes of zinc by children aged < 1 y, 1-3 y, and 4-5 y were 6.6, 7.6, and 9.1 mg/d, respectively. Less than 1% of children had usual zinc intakes below the adequate intake or estimated average requirement. The percentages of children with intakes exceeding the tolerable upper intake level were 92% (0-6 mo), 86% (7-12 mo), 51% (1-3 y), and 3% (4-5 y). Controlling for age and energy intake, zinc intake was greater in 1998 than in 1994 (P < 0.0001) and was positively associated with participation in the Women, Infants, and Children Program (P < 0.001) and with the lowest income category (P < 0.001). CONCLUSIONS: Preschool children in the United States have dietary zinc intakes that exceed the new dietary reference intakes. Zinc intakes increased during the 4 y of the study. The present level of intake does not seem to pose a health problem, but if zinc intake continues to increase because of the greater availability of zinc-fortified foods in the US food supply, the amount of zinc consumed by children may become excessive.     

Association between dietary conjugated linoleic acid and bone mineral density in postmenopausal women

OBJECTIVE: To determine if dietary conjugated linoleic acid (CLA) is associated with bone mineral density (BMD) of different skeletal sites in postmenopausal women. METHODS: A cross-sectional analysis in 136 Caucasian, healthy, postmenopausal women, mean age 68.6 years. BMD and soft tissue were assessed by dual energy x-ray absorptiometry (DXA). Energy, calcium, protein, fat, CLA and other relevant nutrients were estimated using 3 day dietary records. Supplement use was recorded as well. Current and past physical activity were determined using the Allied Dunbar National Fitness Survey for older adults. RESULTS: CLA (63.1 +/- 46.8 mg, mean +/- SD) was a significant predictor of Ward's triangle BMD (p = 0.040) in a multiple regression model containing years since menopause (18.5 +/- 8.4 y), lean tissue, energy intake (1691 +/- 382 kcal/day) dietary calcium (873 +/- 365 mg), protein (70.6 +/- 18.6 g), fat (57.9 +/- 23.9 g), zinc (19.2 +/- 13.6 mg), and current and past physical activity, with R(2)(adj) = 0.286. Subjects were also divided into groups below (Group 1) and above (Group 2) the median intake for CLA. Group 2 had higher BMD in the forearm, p = 0.042, and higher BMD in the hip, lumbar spine and whole body, however statistical significance was not reached. CONCLUSION: These findings indicate dietary CLA may positively benefit BMD in postmenopausal women. More studies are warranted examining the relationship between dietary CLA and BMD.     

Effect of a rapeseed oil substituting diet on serum lipids and lipoproteins in children and adolescents with familial hypercholesterolemia

OBJECTIVE: Familial hypercholesterolemia (FH) is a predominantly inherited disorder, which contributes to a defect of the LDL-cholesterol receptor. For adults with familial hypercholesterolemia (FH), it is known that a supplementary diet of monounsaturated fatty acids reduces elevated levels of total cholesterol and LDL-cholesterol and may further increase HDL-cholesterol. In particular the reduced intake of dietary fat reduces total serum cholesterol and LDL-cholesterol in the range of 10% to 15% and inhibits LDL-oxidation. Once the diagnosis of familial hypercholesterolemia is made in early childhood a supplementary diet with rapeseed oil should be started as early as possible to prevent development of atherosclerosis and subsequent complications. So far there are no reports of a lipid lowering diet enriched with rapeseed oil in children and adolescents. METHODS: Seventeen children and young adolescents (male = 6, female = 11, ages 4 to 19 years) diagnosed with FH were enrolled in this study. They received dietary training and a classical low fat/low cholesterol diet enriched with rapeseed oil over five months. In the first two months they received orally mean 15 g/day (8-23 g/day), for the remaining three months mean 22 g/day (15-30 g/day) rapeseed oil. The calculation of the three-days dietary protocols showed the following characteristics: 29.5% calories from fat, 14.3% calories from protein and 54.6% calories from carbohydrates. The subjects had six sessions of dietary counseling, and serum lipids levels and lipoprotein(a) were estimated; each month's diet adherence was controlled by a dietitian and discussed with the patients and their families during this five-month study. RESULTS: During five months of rapeseed oil diet serum triglycerides decreased by 29% (119.2+/-62.8 mg/dL vs. 84.9 mean +/- 39.7 mg/dL), VLDL-cholesterol by 27% (23+/-12 mg/dL vs. 17+/-8 mg/dL), total cholesterol by 10% (233+/-35 mg/dL vs. 213+/-36 mg/dL), LDL-cholesterol by 7% (151+/-31 mg/dL vs. 142+/-31 mg/dL). HDL-cholesterol (59+/-15 mg/dL vs. 57+/-11 mg/dL) and Lp(a) (29.8+/-36.3 mg/dL vs. 32.6+/-40.7 mg/dL) were not changed significantly. The diet was well accepted; in most families a sustained change was reported. CONCLUSIONS: Our results indicate that in children and adolescents with FH a lipid-lowering diet with rapeseed oil has a similar effect on total serum cholesterol and LDL-cholesterol compared to classical cholesterol reduction diets (step I). However, an additional pronounced effect on lowering of triglycerides and VLDL-cholesterol can be observed.     

The effects of zinc supplementation on serum zinc and cholesterol concentrations in hemodialysis patients.

OBJECTIVE: To examine the effect of zinc sulfate supplementation on the concentrations of serum zinc and serum cholesterol in hemodialysis (HD) patients. SETTING: Outpatient dialysis center in a large metropolitan city. DESIGN: Randomized, double-blind, before-after trial. PATIENTS: Twenty-eight maintenance HD patients were selected. Twenty (15 women and 5 men) completed the study. Subjects were identified for inclusion in the study by the following criteria: HD treatment for a minimum of 6 months, no signs of gastrointestinal disorders, and no record of hospitalizations for reasons other than vascular access complications within the last 3 months. INTERVENTIONS: Patients were given a daily supplement of 7.7 micromol zinc sulfate (50 mg elemental zinc) or a cornstarch placebo capsule for 90 days. Patients completed 2-day food records, at day 0 and day 90 of the study, which included 1 dialysis day and 1 nondialysis day. MAIN OUTCOME MEASURE: Fasting, predialysis serum samples were collected on days 0, 40, and 90 to determine serum zinc and total cholesterol (TCHOL) concentrations. Dietary parameters, including zinc, protein, and energy intake, were also analyzed on days 0 and 90. RESULTS: Initial concentrations of serum zinc indicated subjects were below the normal range for serum zinc standards (12 micromol/L [80 microg/dL]). After supplementation, subjects in the zinc-supplemented group showed significant increases in serum zinc concentrations from 0.79 microg/mL at day 0 to 0.96 microg/mL at day 90. Serum TCHOL concentrations were initially low among subjects in the control (2.914 +/- 0.158 mmol/L [112.7 +/- 6.1 mg/dL]) and zinc-supplemented (3.155 +/- 0.354 mmol/L [122.0 +/- 13.7 mg/dL]) groups. Serum TCHOL concentrations in the control group increased slightly throughout the study period but did not reach statistical significance. A progressive increase in serum TCHOL concentration was observed in the zinc-supplemented group from the beginning (3.155 +/- 0.354 mmol/L [122.0 +/- 13.7 mg/dL]) to the end (4.445 +/- 0.478 mmol/L [171.9 +/- 18.5 mg/dL]) of the study (r =.63, P <.05). Mean serum high-density lipoprotein (HDL) cholesterol concentrations for the zinc-supplemented group were 0.959 mmol/L +/- 0.11 (37.1 mg/dL +/- 4.3), 0.825 mmol/L +/- 0.08 (31.9 mg/dL +/- 3.2), and 0.908 mmol/L +/- 0.10 (35.1 mg/dL +/- 3.9) from the beginning to the end of the experimental period. The mean serum HDL cholesterol concentrations for the control group were 0.760 mmol/L +/- 0.075 (29.4 mg/dL +/- 2.9), 0.760 +/- 0.08 (29.4 mg/dL +/- 3.0), and 0.799 mmol/L +/- 0.13 (30.9 mg/dL +/- 4.9) from the beginning to the end of the experimental period. A progressive increase in low-density lipoprotein (LDL) cholesterol concentration was observed for the zinc-supplemented group throughout the study. Mean LDL cholesterol concentrations for the zinc-supplemented group were 2.19 mmol/L +/- 0.39 (85 mg/dL +/- 15.0), 3.30 mmol/L +/- 0.36 (127.8 mg/dL +/- 14.1), and 3.53 mmol/L +/- 0.53 (136.7 mg/dL +/- 20.6) from the beginning to the end of the study period. When serum zinc concentration was correlated with serum LDL cholesterol concentration, a significant correlation was found (r =.62, P <.03) for the zinc-supplemented group and no significant difference was found for the control group. No significant differences in LDL cholesterol concentrations were found within the control group from the beginning to the end of the study. Dietary intake of zinc, cholesterol, total fat, and saturated fat remained constant and did not statistically influence serum values. Reported energy intake increased significantly in the zinc-supplemented group from 5,799 kJ/24 h (1,385 kcal/d) at day 0 to 7,042 kJ/24 h (1,682 kcal/d) at day 90. CONCLUSION: Zinc supplementation is an effective means of improving serum levels of zinc and cholesterol in the HD patient.     

Erythrocyte metallothionein response to dietary zinc in humans.

The response of erythrocyte metallothionein to dietary zinc in human subjects was evaluated in a controlled metabolic protocol including standard indices of zinc status. Fifteen male subjects, age 27 +/- 3.6 y, participated in a 90-d, four-phase study consisting of acclimation (7 d; 15 mg Zn/d), treatment (6 wk; either 3.2, 7.2 or 15.2 mg Zn/d), depletion (12 d; 0.55 mg Zn/d) and supplementation (30 d; self-selected diet plus 50 mg Zn/d) phases. During the treatment phase erythrocyte metallothionein decreased in the group fed 3.2 mg Zn/d. Erythrocyte metallothionein decreased during the depletion phase (46 +/- 10%) to below the normal concentration in all groups and increased in the supplementation phase. Plasma zinc concentration decreased in the group fed 3.2 mg Zn/d during the treatment phase relative to the acclimation phase. Erythrocyte zinc decreased in all groups during the depletion phase relative to the treatment phase, and then increased during the supplementation phase. These data suggest that erythrocyte metallothionein can be used as a measure of status in severe zinc depletion and that comparing the change in erythrocyte metallothionein over a 6-wk period can differentiate between low and adequate levels of dietary zinc intake.     

Magnesium, zinc, and copper status in women involved in different sports

The dietary intake, serum levels, and urinary excretion of magnesium, zinc, and copper were studied in 78 women involved in different sports (karate, handball, basketball, and running) and in 65 sedentary women. Seven-day, weighed-food dietary reports revealed that no group of female athletes reached the minimal intake recommended for magnesium (280 mg/day) and zinc (12 mg/day), although their values were superior to those of the control group. The estimated safe and adequate minimal intake of copper (1.5 mg/day) was amply surpassed by the basketball players and runners but was not reached by the handball players. Serum levels and urinary excretion of magnesium, zinc and copper di not seem related either to their intake or to the type of physical activity performed. The influence of other factors such as nutritional status, bioavailability, intestinal absorption mechanisms, and muscle-level modifications might explain the differences between the different groups of female athletes.     

Nutrition knowledge and dietary composition in Italian adolescent female athletes and non-athletes

This study aims to investigate dietary composition and nutrition knowledge of 60 athlete and 59 non-athlete adolescent females (age, 14-18 years), using a 3-day food recall and a questionnaire on nutrition. The reported daily energy intake was similar in athletes and non-athletes, but less than the recommended and the estimated requirements. In the athletes, the energy supply from breakfast was higher than in the non-athletes (18.5 +/- 6.6 vs. 15.0 +/- 8.2%, p < .005). Energy intake from carbohydrates was higher (53.6 +/- 6.2 vs. 49.8 +/- 6.3%, p < .05) and that from lipids was lower (30.4 +/- 5.5 vs. 34.2 +/- 5.2%, p < .001) in athletes than in non-athletes. Athletes also showed higher fiber (20.0 +/- 5.8 vs. 14.1 +/- 4.3 g/day, p < .001), iron (10.6 +/- 5.1 vs. 7.5 +/- 2.1 mg/day, p < .001) and vitamin A (804 +/- 500 vs. 612 +/- 456 micrograms/day, p < .05) reported intake than non-athletes. Calcium, iron, and zinc intake were less than 100% RDA in both groups. Athletes gave a slightly higher rate of correct answers on the nutrition knowledge questionnaire (77.6 vs. 71.6%, p < .01) than non-athletes. In conclusion, the overall recalled dietary intake and nutrition knowledge of the studied adolescent females show some misconceptions and nutrient deficiencies, but the results in athletes are quite better than in non-athletes, suggesting a favorable role of sport practice on dietary habits and nutrition knowledge.