Higher Intakes Of Zinc Research Articles

Abstract 4883: Zinc and prostate cancer: a systematic review.

Abstract Background: Zinc is involved in many essential cellular functions. It has been shown that the prostate contains high concentrations of zinc, but zinc levels decrease in prostate cancer tissues. Although, experimental evidence implicates zinc in the pathogenesis of prostate cancer, epidemiological data are inconsistent. We conducted a systematic review of the literature to summarize the evidence regarding the association between zinc and prostate cancer. Methods: Relevant studies were identified by searching PubMed and the Cochrane Library databases through November 2012 and reviewing reference lists of retrieved articles. Inclusion criteria were original and peer-reviewed publications reporting the association between zinc intake or status and prostate cancer outcomes (diagnosis, progression). No reviews, editorials, or comments were included. Two investigators abstracted study information and evaluated quality independently using standardized forms. Results: Sixteen studies met inclusion criteria, including 3 cohorts, 2 nested case-control, 10 case-control, and 1 randomized clinical trial, with a total of 111,288 participants and 11,681 cases of prostate cancer. All studies measured the association between zinc levels and prostate cancer. In most studies, regardless of the study design or source of zinc, the highest dose of zinc was associated with a modest elevation of odds of prostate cancer. Four studies had decreased odds of prostate cancer for the highest dose of zinc but the confidence interval crossed one. There was evidence of a dose-response relationship and subgroup analysis revealed a protective effect of high zinc intake among advanced prostate cancer cases. Conclusions: Although the level of zinc in prostate cancer tissue is reduced, studies assessing the association of zinc intake and prostate cancer have yielded inconsistent results. We performed a systematic review to assess the role of zinc in prostate cancer. As a result of this systematic review, the evidence is still insufficient to recommend zinc supplementation for cancer patients in clinical practice. Citation Format: Abeer M. Mahmoud, Umaima Al-alem, Ebony Shah, Ken Batai, Firas Dabbous, Mohamed Ali, Rick Kittles. Zinc and prostate cancer: a systematic review. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4883. doi:10.1158/1538-7445.AM2013-4883

Intake of selected minerals and risk of premenstrual syndrome.

Iron, potassium, zinc, and other minerals might impact the development of premenstrual syndrome (PMS) through multiple mechanisms, but few studies have evaluated these relations. We conducted a case-control study nested within the prospective Nurses' Health Study II (1991-2001). Participants were free from PMS at baseline. After 10 years, 1,057 women were confirmed as PMS cases and 1,968 as controls. Mineral intake was assessed using food frequency questionnaires completed in 1991, 1995, and 1999. After adjustment for calcium intake and other factors, women in the highest quintile of nonheme iron intake had a relative risk of PMS of 0.64 (95% confidence interval (CI): 0.44, 0.92; P for trend = 0.04) compared with women in the lowest quintile. Women in the highest quintile of potassium intake had a relative risk of 1.46 (95% CI: 0.99, 2.15; P for trend = 0.04) compared with women in the lowest quintile. High intake of zinc from supplements was marginally associated with PMS (for intake of ≥25 mg/day vs. none, relative risk = 0.69, 95% CI: 0.46, 1.02; P for trend = 0.05). Intakes of sodium, magnesium, and manganese were unrelated to PMS risk. These findings suggest that dietary minerals may be useful in preventing PMS. Additional studies are needed to confirm these relations.

High Dose Zinc Supplementation Induces Hippocampal Zinc Deficiency and Memory Impairment with Inhibition of BDNF Signaling

Zinc ions highly concentrate in hippocampus and play a key role in modulating spatial learning and memory. At a time when dietary fortification and supplementation of zinc have increased the zinc consuming level especially in the youth, the toxicity of zinc overdose on brain function was underestimated. In the present study, weaning ICR mice were given water supplemented with 15 ppm Zn (low dose), 60 ppm Zn (high dose) or normal lab water for 3 months, the behavior and brain zinc homeostasis were tested. Mice fed high dose of zinc showed hippocampus-dependent memory impairment. Unexpectedly, zinc deficiency, but not zinc overload was observed in hippocampus, especially in the mossy fiber-CA3 pyramid synapse. The expression levels of learning and memory related receptors and synaptic proteins such as NMDA-NR2A, NR2B, AMPA-GluR1, PSD-93 and PSD-95 were significantly decreased in hippocampus, with significant loss of dendritic spines. In keeping with these findings, high dose intake of zinc resulted in decreased hippocampal BDNF level and TrkB neurotrophic signaling. At last, increasing the brain zinc level directly by brain zinc injection induced BDNF expression, which was reversed by zinc chelating in vivo. These results indicate that zinc plays an important role in hippocampus-dependent learning and memory and BDNF expression, high dose supplementation of zinc induces specific zinc deficiency in hippocampus, which further impair learning and memory due to decreased availability of synaptic zinc and BDNF deficit.

Dietary zinc intake is inversely associated with stunting among adolescent girls in Tanzania

Stunting is a highly prevalent public health problem in developing countries, particularly among populations exposed to food insecurity and chronic malnutrition. Empirical research has shown that early childhood malnutrition is a strong predictor of stunting. Zinc is essential to growth and development, deficiency in this micronutrient may further contribute to stunting in childhood and adolescence. This cross‐sectional study examined the associations between stunting and dietary intake of zinc among a sample of never‐married adolescent girls (n=296) living in Kilosa District, Tanzania. Dietary, anthropometric, physical activity, morbidity and demographic data were collected. The associations between stunting (determined as height by age less than 3rd percentile of WHO reference) and dietary intake of zinc were tested using logistic regression, adjusting for age, socioeconomic status, BMI, energy intake, physical activity and individual dietary diversity. The prevalence of stunting was 62.2%. Adolescent diets were generally deficient in zinc, with a mean intake of 3.4 mg/day compared to the RDA value of zinc intake as 8–9 mg/day for adolescent girls. Higher intake of zinc was found to be associated with lower risk of stunting (OR, 0.872; 95%CI, 0.763–0.998, p<0.05). These findings suggest that dietary intake of zinc may play a significant role in the chronic nutritional status of adolescent girls. Longitudinal studies examining these associations in developing countries settings are needed.Grant Funding Source : ASN

Alteration in T-Cell Cytokine Production by Vitamin A and Zinc Supplementation in Mice

Simultaneous zinc and vitamin A deficiency are common health problems in developing countries. The objective of this study was to assess effect of supplementation of high zinc or vitamin A on immune function. After three months of feeding with a zinc and vitamin A deficient diet, mice were assigned into four groups which, for additional two months, received a normal or high zinc along with vitamin A deficient diet and a normal or high vitamin A along with zinc deficient diet. Serum and intestinal mucosa immunoglobulin A (IgA) were determined and supernatants of splenocytes were used to assess interlukin (IL)-2, IL-5, IFN-γ. Mice maintained on zinc deficient diet with normal or high vitamin A resulted in significantly lower production of IFN-γ. Also, supplementation of high dose vitamin A augmented production of the cytokine as compared to normal intake of the vitamin. Supplementation of either normal or high zinc along with low vitamin A diet significantly led to higher production of IFN-γ as compared to those receiving zinc limited but adequate vitamin A. High intake of zinc along with vitamin A deficient diet significantly enhanced secretion of IL-2. Levels of serum and mucosal IgA and IL-5 were not be significantly modulated. Moreover, animals fed with high doses of zinc showed increased IL-2 production than those that had normal intake of zinc. Results indicated that zinc and vitamin A supplementation up-regulates production of T-cell cytokines, IFN-γ and IL-2.

Dietary zinc and prostate cancer survival in a Swedish cohort

Zinc is involved in many essential cellular functions, including DNA repair and immune system maintenance. Although experimental evidence supports a role for zinc in prostate carcinogenesis, epidemiologic data are inconsistent; no data on cancer-specific survival have been reported. Our objective was to determine whether dietary zinc assessed near the time of prostate cancer diagnosis is associated with improved disease-specific survival. This population-based cohort consists of 525 men aged <80 y from Örebro County, Sweden, with a diagnosis of prostate cancer made between 1989 and 1994. Study participants completed self-administered food-frequency questionnaires, and zinc intake was derived from nutrient databases. Cox proportional hazards regression was used to estimate multivariate hazard ratios (HRs) and 95% CIs for time to death from prostate cancer as well as death from all causes through February 2009 by quartile (Q) of dietary zinc intake. Models were also stratified by disease stage at diagnosis (localized or advanced). With a median follow-up of 6.4 y, 218 (42%) men died of prostate cancer and 257 (49%) died of other causes. High dietary zinc intake was associated with a reduced risk of prostate cancer-specific mortality (HR(Q4 vs Q1): 0.64; 95% CI: 0.44, 0.94; P for trend = 0.05) in the study population. The association was stronger in men with localized tumors (HR: 0.24; 95% CI: 0.09, 0.66; P for trend = 0.005). Zinc intake was not associated with mortality from other causes. These results suggest that high dietary intake of zinc is associated with lower prostate cancer-specific mortality after diagnosis, particularly in men with localized disease.

Bar-Coded Pyrosequencing of 16S rRNA Gene Amplicons Reveals Changes in Ileal Porcine Bacterial Communities Due to High Dietary Zinc Intake

Feeding high levels of zinc oxide to piglets significantly increased the relative abundance of ileal Weissella spp., Leuconostoc spp., and Streptococcus spp., reduced the occurrence of Sarcina spp. and Neisseria spp., and led to numerical increases of all Gram-negative facultative anaerobic genera. High dietary zinc oxide intake has a major impact on the porcine ileal bacterial composition.

The impact of high zinc intake on the copper status of dairy cows in New Zealand

AIM: To determine the effect of a high Zn intake on the concentration of Cu in the liver of dairy cows. METHODS: Sixty non-pregnant, non-lactating, mixed-age Friesian dairy cows were randomised into four groups: unsupplemented control; thrice weekly oral treatment with 350 mg Cu (equivalent to 150 mg Cu/day) as CuSO4.5H2O; a ZnO bolus releasing 6.628 g Zn/day given on Days 0 and 28; and oral treatment with Cu and ZnO boluses. The cows were fed baled silage for the duration of the study (56 days). On Days -12, 14, 28, 42 and 56 liver biopsies were collected for determination of concentrations of Cu, and blood samples for measurement of Cu and Zn in serum. RESULTS: Mean concentrations of Cu in the liver of unsupplemented control cows decreased from an initial 717 (SE 108.5) to 396 (SE 88.0) µmol/kg fresh tissue on Day 28, and then increased to 542 (SE 105.3) µmol/kg fresh tissue on Day 42, before decreasing to 434 (SE 81.6) µmol/kg fresh tissue on Day 56. Administration of ZnO resulted in no change in the concentration of Cu in liver compared with controls. Supplementing with 150 mg Cu/day significantly increased the concentration of Cu in liver, compared with controls, to 1,074 (SE 105.2) µmol/kg fresh tissue on Day 56. Treatment with ZnO significantly reduced concentrations of Cu in liver on Day 56, compared with Cu-supplemented cows, to 786 (SE 107.7) µmol/kg fresh tissue. The treatments had no effect on concentrations of Cu in serum. In cows given the ZnO, mean concentrations of Zn in serum increased from 17 (SE 0.6) on Day 0 to 30 (SE 1.7) µmol/L on Day 14, then decreased to 20 (SE 1.3) µmol/L on Day 28, increased to 40 (SE 2.9) µmol/L on Day 42, then decreased to 24 (1.16) µmol/L on Day 56. In cows given ZnO plus Cu, concentrations of Zn in serum were significantly greater than in cows only given ZnO on Day 41 (46 (SE 2.71) vs 35 (SE 3.23) µmol/L, respectively). Mean concentrations of Cu, Mo and Zn in the baled silage were 4.4, 0.5 and 21 mg/kg dry matter (DM), respectively. CONCLUSIONS: High Zn intakes used in the prevention of facial eczema in dairy cows had little effect on concentrations of Cu in liver when the Cu intake was low, but decreased the efficacy of a Cu supplement by about 50%. CLINICAL RELEVANCE: When using Zn as a prophylactic treatment for facial eczema the level of Cu supplementation should be adjusted, which may mean that in some situations it is recommended not to supplement cows with Cu.

Abstract 5747: Anti-inflammatory nutrients and prostate cancer survival in the Örebro Prostate Cancer Survivors Cohort

Abstract While many studies examine diet and prostate cancer (PCa) risk, few have assessed whether diet could influence prostate cancer-specific survival. Dietary factors that modulate the inflammatory response may alter clinical outcome, as chronic systemic inflammation may enhance PCa progression. As such, dietary zinc and fatty acids affecting the inflammatory response are promising targets for secondary prevention to impact survival after diagnosis. We studied intake of dietary zinc and fatty acids in relation to cancer survival within the Örebro Swedish Cohort, including 525 confirmed PCa cases living in Örebro County who were diagnosed from 1989 to 1991. At the time of diagnosis, dietary data was collected by food frequency questionnaire specific to the Swedish diet. Use of dietary supplements was negligible in this population, which was assembled before the introduction of PSA testing. We studied intake of zinc and fatty acids (quartiles) and time to death (all cause and PCa-specific through Februrary 2009) using Cox proportional hazards models adjusted for lifestyle and clinical factors. Analyses were also stratified by clinical stage at diagnosis (early: T0-T2/M0, and advanced: T3-T4/M0/M1). During follow-up, 218 men died from PCa and 257 from other causes. Zinc was not significantly associated with overall PCa-specific mortality, total mortality or in men diagnosed at an advanced stage. Yet among those diagnosed at an early stage, men with the highest zinc intake were 74% less likely to die of PCa (95% CI:0.10-0.68, ptrend=0.005) compared to lowest. High versus low intake of marine omega-3 docosahexaenoic acid (DHA) was associated with a reduced risk of PCa mortality overall (OR: 0.70, 95% CI: 0.47-1.03, ptrend=0.26), particularly among men diagnosed at an early stage (OR: 0.55, 95% CI: 0.23-1.58). DHA was not associated with death from other causes (OR: 1.07, 95% CI: 0.74-1.55, ptrend=0.68). The highest quartiles of saturated (HR: 1.15, 95% CI: 0.78-1.69), monounsaturated (HR: 1.18, 95% CI: 0.80-1.75) and polyunsaturated (HR: 0.90, 95% CI: 0.62-1.31) fatty acids were not associated with PCa survival. Our results suggest men diagnosed at early stage prostate cancer may be sensitive to dietary zinc levels, which may prolong disease-specific survival. Omega-3 DHA may also be beneficial against prostate cancer-specific mortality, with inflammation being a potential common mechanism. Further research is needed to confirm these findings. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5747.

The Effect of Zinc Status on Salty Taste Acuity, Salty Taste Preference, Sodium Intake and Blood Pressure in Korean Young Adults

High sodium intake is one of the risk factors for the development of hypertension. According to 2007 Korean National Health and Nutrition Examination Survey, sodium intake of Korean was three times higher than adequate intake (1.5 g/day) recommended by Korean Dietary Reference Intakes. High sodium intake is related to high threshold and preference of salty taste. And zinc status is known to affect taste acuity. The hypothesis of this study is that zinc status is associated with salty taste acuity, preference, sodium intake and blood pressure. The subjects included in this study were 50 men and 41 women aged 20-29 y who did not smoke and not take supplements or medications regularly. Dietary intake data for 3 days were collected by 24-h recall for 1 day and dietary record for 2-days. Salty taste acuity and preference were determined by sensory test. Fasting serum concentration of zinc, height, weight, body composition and blood pressure data were collected. Salt taste preference in high zinc intake group (≥ estimated average requirement, EAR; men-8.1 mg/day, women-7 mg/day) was higher than that in low zinc intake group (< EAR). Salty taste preference was inversely correlated with serum zinc concentration in people with low concentration of serum zinc (≦ 81μg/dL)(r = -0.3520, p < 0.05). Diastolic blood pressure was higher in high sodium intake group than in low sodium intake group (p < 0.05), positively correlated with salty taste preference (r = 0.3866, p < 0.05) in subjects with daily zinc intake below the EAR. We conclude that low zinc status may be related to high salty taste preference and high blood pressure in Korean young adults. (Korean J Nutr 2010; 43(2): 132 ~ 140)

Zinc: An Essential Trace Element for Parenteral Nutrition

Zinc is an essential trace element for human nutrition that is an integral part of many enzyme systems, including DNA polymerase complex. Zinc deficiency has been associated with stunting of growth and sexual immaturity. In children, deficiency causes a fatal condition called acrodermatitis enteropathica. The same syndrome has been observed in patients on total parenteral nutrition (TPN) who do not receive zinc. In TPN the requirements have been estimated by balance studies to be 3 mg/d in patients without gastrointestinal losses and a mean of 12 mg/d in patients with diarrhea and fistula losses.

Ready-to-Eat Cereal Breakfasts Are Associated with Improved Nutrient Intake and Dietary Adequacy but Not Body Mass Index in Black Adolescents

The goal of this study was to determine whether nutrient intake, dietary adequacy, and weight status were associated with type of breakfast consumption: skipping breakfast, consuming ready-to-eat cereal (RTEC) at breakfast, or consuming other types of foods at breakfast. Data from black adolescents 13 to 18 years of age (n = 988) participating in the 1999-2002 National Health and Nutrition Examination Survey were used in a secondary data analysis. Thirty-seven percent of black adolescents skipped breakfast, 19% consumed RTEC at breakfast, and 44% consumed other breakfasts. RTEC breakfast and other breakfast consumers had higher mean energy intakes than breakfast skippers (P ≤ .05). After adjusting for gender and energy intake, RTEC breakfast consumers had higher intakes of thiamin, riboflavin, niacin, folate, calcium, phosphorus, magnesium, iron, zinc, potassium, and vitamins A, B6, and B12 than breakfast skippers and other breakfast consumers (P ≤ .05). RTEC breakfast consumers had the highest mean adequacy ratio, followed by other breakfast consumers, then breakfast skippers (P ≤ .05). Those consuming RTEC at breakfast had lower mean body mass index (P ≤ .05) and waist circumference (P ≤ .05) than breakfast skippers; however, there was no difference between those consuming RTEC and other breakfasts. If confirmed in prospective studies, consuming a breakfast meal with RTEC may be a useful strategy to encourage in black adolescents as a way to improve nutrient intake and dietary adequacy without increasing weight.

Effects of Low, Adequate and High Dietary Zinc Intake on Metabolic Interactions between Zinc, Copper and Iron in Different Mongolian Gerbil Tissues

This study examined the influence of low, adequate and high dietary zinc intake on the growth and metabolic interactions between zinc, copper and iron in different Mongolian gerbil (Meriones unguiculatus) tissues. Animals were fed a basal diet (for 3 wk) containing a low-zinc level (8 mg/kg diet, LZ-group), adequate zinc level (25 mg/kg diet, AZ-group) and saturated zinc level (38 mg/kg diet, SZ-group). After comparing the body weight of gerbils, the present study demonstrated that the LZ-group (51.68 g ± 3.35) showed growth retardation, contrary to the AZ- and SZ-groups (58.03 g ± 2.18 and 62.35 g ± 2.04, respectively). Concentrations of zinc in the liver, kidneys and testes in the LZ-group (41.28, 19.58, 22.55 mg/kg, respectively) were significantly lower than in the AZ-group (57.27, 23.73, 28.79 mg/kg, respectively) and the SZ-group (73.06, 30.07, 34.52 mg/kg, respectively). Results also showed that copper and iron concentrations in the kidney, heart and liver were significantly higher in the LZ-group (Cu 11.45, 7.01, 7.95 mg/kg; Fe 116.19, 126.07, 299.47 mg/kg) than in the AZ-group (Cu 8.72, 5.6, 6.5 mg/kg; Fe 97.27, 97.27, 250.25 mg/kg) and the SZ-group (Cu 6.48, 4.15, 4.8 mg/kg; Fe 74.95, 77.95, 200.27 mg/kg). There was an increase of testis copper concentration in the LZ-group (4.9 mg/kg) compared to the AZ- and SZ-groups (3.99 and 3.05 mg/kg, respectively), and there was no significant difference in testis iron concentration between animals in different diet groups. These results showed that a low-zinc diet had negative effects on growth and the concentration of zinc in the kidneys, liver and testes. This also affected homeostasis of copper and iron by increasing its distribution in the kidneys, liver and heart tissue. However, in testes only copper concentration was increased.

Effects of Zinc on Hepatic Antioxidant Systems and the mRNA Expression Levels Assayed by cDNA Microarrays in Rats

Background: This study evaluated effects of zinc on the hepatic lipid peroxidation, antioxidant components and mRNA expression levels in rats. Methods: Three diets with different Zn levels including Zn adequacy (ZA; 34.50 mg/kg, control), Zn deficiency (ZD; 3.30 mg/kg), and Zn overdose (ZO; 345.45 mg/kg) were fed to rats for 6 weeks. The mRNA expression levels were analyzed by cDNA microarrays. Results: The body weight of rats fed the ZD diet was less (p < 0.01) than that of rats fed the ZA diet. Zn overdose elevated body weight, but the increase was not detected (p > 0.05) at week 6. Although copper and iron status in serum were declined (p < 0.01), those in liver were not affected (p > 0.05) by the high intake of zinc. The glutathione peroxidase (GPx) and glutathione (GSH) remained unchanged (p > 0.05) by zinc treatment. Rats fed the ZD diet showed reductions(p < 0.01) in the Cu-Zn superoxide dismutase (Cu-Zn SOD) and catalase (CAT) activity, and increases (p < 0.01) in the malondialdehyde and hydrogen peroxide (H₂O₂) contents. Rats fed the ZO diet particularly had higher Cu-Zn SOD (p < 0.01) activity. The mRNA expression levels of SOD were upregulated in the ZO group, and CAT was downregulated in the ZD group, while no changes in GPx mRNA levels were found after zinc treatment. Conclusion: The study suggested that zinc deficiency largely decreased body weight; zinc overdose, however, moderately stimulated growth in the early growing phase of rats. High dietary zinc did not compete with liver copper and iron status. Although Zn deficiency impaired antioxidant functions, zinc overdose hardly enhanced the antioxidant systems of animals.

Dietary Zinc and Prostate Cancer Risk: A Case-Control Study from Italy

ObjectivesZinc concentration is higher in the prostate than in most other tissues. Since information on the role of zinc on prostate carcinogenesis is controversial, we analysed the issue in a case-control study. MethodsBetween 1991 and 2002, we conducted a multicentre hospital-based case-control study on prostate cancer in Italy. Cases included 1294 men with incident, histologically confirmed prostate cancer. Controls included 1451 patients admitted to the same hospitals as cases for a wide spectrum of acute non-neoplastic, non–hormone-related diseases. Zinc intake was computed from a valid and reproducible food frequency questionnaire, with the use of an Italian food composition database. Odds ratios (OR) of dietary intake of zinc and the corresponding 95% confidence intervals (CI) were estimated by unconditional multiple logistic regression models, after allowance for several covariates, including total energy. ResultsCompared with the lowest quintile, the OR for the highest quintile was 1.56 (95% CI, 1.07–2.26), with a significant trend in risk (p=0.04). The trend in risk was significant for advanced cancers only, the OR being 2.02 (95% CI, 1.14–3.59) for prostate cancers with a high Gleason score. ConclusionsIn this large study we found a direct association between high zinc intake and prostate cancer risk, particularly for advanced cancers. Our findings allow one to exclude a favourable effect of zinc on prostate carcinogenesis.

Production of stable-isotope-labeled bovine heme and its use to measure heme-iron absorption in children

Background:The use of stable isotopes has provided valuable insights into iron absorption in humans, but the data have been limited to nonheme iron.Objective:Our objectives were to produce heme iron enriched in 58Fe and to use it to study the absorption of heme iron and the effect of iron and zinc intakes on heme-iron absorption in children.Design:Labeled bovine heme was produced in a bovine model. Forty-eight children were randomly assigned to consume identical meals containing 1 of 3 doses of labeled heme iron (2, 4, or 8 mg as hemoglobin) and 1 of 2 doses of inorganic zinc (1 or 9 mg); successful measurements of iron absorption, zinc absorption, or both were made in 40 of these subjects. We hypothesized that fractional heme-iron absorption would decrease as heme-iron intake increased and that higher zinc intakes would decrease heme-iron absorption.Results:58Fe heme was produced with an enrichment (mass/mass) of 9.5%. Fractional iron absorption in children was significantly affected by the intake of heme iron (P= 0.0013) and of zinc (P= 0.0375), but, contrary to expectations, heme-iron absorption was higher at higher zinc intakes. Absolute heme-iron absorption was higher in the group with higher zinc intakes, but only for those with the lowest heme-iron intake (2 mg; P= 0.0147). Although fractional zinc absorption decreased as zinc intake increased (P= 0.031), absolute zinc absorption continued to increase across the intake range studied (P= 0.018).Conclusions:Heme iron intrinsically labeled with 58Fe can be produced at sufficient enrichments for use in human studies. In children, heme iron and zinc absorption decrease as the dose of each mineral increases. Heme iron did not inhibit zinc absorption. At lower heme intakes, zinc intakes may increase heme-iron absorption.

Iron, zinc, and alcohol consumption and mortality from cardiovascular diseases: the Iowa Women’s Health Study

The relation between iron status and atherosclerosis has long been a topic of debate. We examined associations of cardiovascular disease (CVD) mortality with dietary intakes of iron (a possible prooxidant), zinc (a possible antioxidant), and alcohol (a disruptor of iron homeostasis). Postmenopausal women (n = 34 492) aged 55-69 y at baseline, who completed a food-frequency questionnaire, were followed for CVD mortality over 15 y. Among women who consumed >/=10 g alcohol/d, after adjustment for CVD risk factors in a model that contained dietary heme iron, nonheme iron, and zinc intakes, dietary heme iron showed a positive association, dietary nonheme iron showed a U-shaped association, and dietary zinc showed an inverse association with CVD mortality. For example, the relative risks (RRs) for categories of dietary heme iron were 1.0, 1.46, 1.52, 1.73, and 2.47 (P for trend = 0.04); corresponding RRs for dietary nonheme iron were 1.0, 0.93, 0.63, 0.83, and 1.20 (P for quadratic term = 0.02). The corresponding RRs for dietary zinc were 1.0, 0.61, 0.59, 0.57, and 0.37 (P for trend = 0.07). In an analysis restricted to those who consumed >/=30 g alcohol/d, the risk gradients strengthened. Our results suggest that a higher intake of heme iron might be harmful, whereas a higher intake of zinc might be beneficial in relation to CVD mortality in the presence of a trigger that can disturb iron homeostasis, such as alcohol consumption.

Heme iron, zinc and upper digestive tract cancer: The Iowa Women's Health Study

We examined associations among dietary heme iron as a possible pro-oxidant, dietary zinc as a possible antioxidant, and the incidence of upper digestive tract cancer; 34,708 postmenopausal women, aged 55-69 years at baseline who completed a food frequency questionnaire, were followed 16 years. There were 75 upper digestive tract cancer cases (52 gastric cancer and 23 esophageal cancer). When heme iron and zinc were mutually adjusted, in dose-response manners, heme iron intake was positively associated with the risk of upper digestive tract cancer, while zinc intake was inversely associated with risk. After adjusting for age, total energy intake, cigarette smoking and alcohol consumption, relative risks for quintiles of heme iron intake were 1.0, 1.53, 2.15, 3.05 and 2.83 (p for trend = 0.06) and corresponding relative risks for zinc intake were 1.0, 0.86, 0.42, 0.37 and 0.13 (p for trend < 0.01). Additional adjustment for body mass index, physical activity, hormone replacement therapy, multivitamin intake and intake of saturated fat, vitamin C, vitamin E and folate did not change the results. Higher intake of heme iron is associated with higher risk, while higher intake of zinc is associated with lower, risk of upper digestive tract cancer.

Prediagnostic toenail cadmium and zinc and subsequent prostate cancer risk.

Cadmium is a recognized human lung carcinogen that has also been positively associated with prostate cancer mainly in occupationally exposed men. The association between dietary and supplemental zinc intake and prostate cancer has not been consistent in epidemiologic studies. We evaluated the association between prediagnostic toenail cadmium and zinc concentrations and risk of prostate cancer in a cohort in which the primary route of exposure to cadmium and zinc is the diet. Included in the analysis were 115 prostate cancer cases and 227 age-matched controls nested in the prospective CLUE II study located in Washington County, MD. Participants provided toenail samples at baseline in 1989. Furnace atomic absorption and flame atomic absorption were used to determine toenail cadmium and zinc concentrations, respectively. Odds ratios (OR) and 95% confidence intervals (CI) were estimated from conditional logistic regression models. Median toenail cadmium and zinc concentrations did not statistically significantly differ between prostate cancer cases (cadmium, 45.9 ppb; zinc, 155.3 ppm) and controls (cadmium, 54.5 ppb; zinc, 164.0 ppm). Prostate cancer risk did not increase with increasing concentrations of cadmium (P trend = 0.9) and did not decrease with increasing concentrations of zinc (P trend = 0.2). For both metals, the ORs for the top four fifths were each below 1.0 when compared with the bottom fifth. Men who have high toenail cadmium concentrations in the range observed in this general population sample were not at an increased risk for prostate cancer. Although there was no evidence of a linear dose-response, these findings suggest that risk of prostate cancer may be slightly lower among men with moderate and higher zinc intake.

Zinc Absorption and Exchangeable Zinc Pool Sizes in Breast‐Fed Infants Fed Meat or Cereal as First Complementary Food

ABSTRACTBackgroundThe aims of this study were to compare the absorption efficiency of zinc from rice cereal and meat, with and without human milk, in 7‐month‐old breast‐fed infants and to compare the size of exchangeable zinc pools in the infants according to the assigned complementary food.MethodsFractional absorption of zinc was measured in male infants using extrinsic labeling with a stable isotope of zinc in a test meal of either pureed beef (n = 9) or iron‐fortified infant rice cereal (n = 9). The effect on fractional absorption of the addition of human milk to each complementary food was measured in each infant with a second oral zinc isotope. Fractional absorption was measured using fecal monitoring of isotope excretion, and exchangeable zinc pool size was calculated from isotopic enrichment in urine.ResultsFractional absorption of zinc did not statistically differ between the beef (0.41 ± 0.11) and cereal (0.36 ± 0.05) test meals, although the trend showed that beef had higher fractional absorption than cereal. The higher intake of zinc from the beef versus cereal test meal resulted in a 16‐fold greater amount of absorbed zinc (P = 0.0002). The addition of human milk caused significant decreases in fractional absorption of zinc (0.07 ± 0.02, P = 0.01) and absorbed zinc (0.04 ± 0.01 mg, P &lt; 0.0001). The size of the exchangeable zinc pool did not differ according to group but was strongly correlated with mean daily zinc intake (r = 0.72, P = 0.003).ConclusionsThese results confirm that meat as a complementary food for breast‐fed infants can provide a rich source of dietary zinc that is well absorbed. The significant positive correlation between zinc intake and exchangeable zinc pool size suggests that increasing zinc intake positively affects metabolically available zinc.