Iron and immunity

The effects of zinc deficiency on homeostasis of twelve minerals and trace elements in the serum, feces, urine and liver of rats

Background

Zinc deficiency can change the concentrations of minerals and trace elements in the body. However, previous studies still had many limitations.

Objective

To reveal the effects of zinc deficiency on homeostasis of 16 minerals and trace elements.

Methods

Forty-five rats were divided randomly into three groups: normal zinc diet (30 mg/kg), low zinc diet (10 mg/kg), and pair-fed diet(30 mg/kg). The concentrations of 16 minerals and trace elements in serum, feces, urine, and liver were measured by inductively coupled plasma mass spectrometry. The excretion of 16 elements in urine and feces were calculated and compared.

Results

Zinc-deficient rats exhibited significant changes in up to 12 minerals and trace elements. The low zinc diet induced decreased excretion of zinc and concentrations of zinc in serum, feces, urine, and liver. Zinc deficiency increased feces concentrations of Mg, Cu, Se, K, Ag, Fe and Mn; decreased the concentrations of Mg, Cu, Se, K in liver and urine, and a diminished amount of Ag was observed in serum. Decreased urinary concentrations of Zn Ca, Mg, Cu, Se, K, Na, As and Cr, suggested that zinc-deficient rats increased the 9 elements’ renal reabsorption. Decreased concentrations of Ca in liver, urine, and feces, decreased excretion in urine and feces and increased serum total Ca suggested that zinc deficiency increased the redistribution of Ca in serum or other tissues. Zinc deficiency increased excretion of Cu, Se, Fe; and decreased the excretion of other 8 elements except for Ag.

Conclusions

Zinc deficiency changed the excretion, reabsorption and redistribution of 12 minerals and trace elements in rats. Our findings are the first to show that zinc deficiency alters the concentrations of Ag, Cr, and As.

Graphical abstract

Supplementary information

Supplementary information accompanies this paper at 10.1186/s12986-019-0395-y.

Identifying molecular targets of lifestyle modifications in colon cancer prevention

One in four deaths in the United States is cancer-related, and colorectal cancer (CRC) is the second leading cause of cancer-associated deaths. Screening strategies are utilized but have not reduced disease incidence or mortality. In this regard, there is an interest in cancer preventive strategies focusing on lifestyle intervention, where specific etiologic factors involved in cancer initiation, promotion, and progression could be targeted. For example, exposure to dietary carcinogens, such as nitrosamines and polycyclic aromatic hydrocarbons influences colon carcinogenesis. Furthermore, dietary deficiencies could alter sensitivity to genetic damage and influence carcinogen metabolism contributing to CRC. High alcohol consumption increases the risk of mutations including the fact that acetaldehyde, an ethanol metabolite, is classified as a group 1 carcinogen. Tobacco smoke exposure is also a risk factor for cancer development; approximately 20% of CRCs are associated with smoking. Additionally, obese patients have a higher risk of cancer development, which is further supported by the fact that physical activity decreases CRC risk by 55%. Similarly, chronic inflammatory conditions also increase the risk of CRC development. Moreover, the circadian clock alters digestion and regulates other biochemical, physiological, and behavioral processes that could influence CRC. Taken together, colon carcinogenesis involves a number of etiological factors, and therefore, to create effective preventive strategies, molecular targets need to be identified and beleaguered prior to disease progression. With this in mind, the following is a comprehensive review identifying downstream target proteins of the above lifestyle risk factors, which are modulated during colon carcinogenesis and could be targeted for CRC prevention by novel agents including phytochemicals.

Dietary restraint in relation to nutrient intake, physical activity and iron status in adolescent females

AIM

To investigate the prevalence of dietary restraint in a female adolescent population, and to examine the nutritional consequences of dietary restraint and its implications for iron status.

METHODS

A total of 64 adolescent females, aged 14-15 years, were recruited from two all-girl schools in central London. Nutrient intake, body weight, physical activity and iron status were measured. Findings were compared between three groups of subjects classified by dietary restraint.

RESULTS

Adolescents with a higher BMI percentile were more likely to be highly restrained. Scores on the dietary restraint psychometric measures were comparable with other UK studies in this age group. Energy intake was inversely related to dietary restraint (mean energy intake (SE) for each restraint group were: low 8.99 MJ (0.48), medium 7.98 MJ (0.22) and high 7.35 MJ (0.39) P < 0.05); however, a corresponding relationship between dietary restraint and reduced micronutrient intakes was not found. Highly restrained eaters obtained more of their energy intake from bread, fruit and cheese and less from meat, meat products and confectionery. Levels of physical activity were not significantly different between the dietary restraint groups. There was a poor relationship between reported energy intake and estimated energy expenditure. Haematological parameters of iron status were similar across the restraint groups.

CONCLUSIONS

Dietary restraint was exercised by the consumption of a "healthy eating diet". Dieting was not related to a lower iron status; however, the low dietary iron intake and poor iron status of the whole sample is of concern.

Iron-deficiency anaemia and physical performance in adolescent girls from different ethnic backgrounds

One hundred and fourteen 11-14-year-old schoolgirls from Wembley, Middlesex, were assessed for Fe status (haemoglobin (Hb), packed cell volume and mean corpuscular Hb concentration, height, weight, eating habits, and ethnic origin, and undertook a step test to assess physical performance. Overall, 20% of girls had Hb less than 120 g/l, ranging from 11% in White girls to 22-25% in girls of Asian origin. Prevalence of low Hb was 20% in vegetarians, higher in White vegetarians compared with non-vegetarians (23 v. 4%), but lower in the Indian vegetarians compared with non-vegetarians (17 v. 32%). Low Hb was present in 25% of girls who had tried to lose weight in the previous year, and was more common in girls from manual social class backgrounds than non-manual (24 v. 10%). At the start of the step test the twenty-three girls with low Hb had heart rates similar to those with normal Hb, but heart rates in the low Hb group were significantly elevated immediately after the step test, and still significantly elevated 1 min later. The present results confirm the findings of a previous study in White girls, and suggest that physical performance may be compromised at mild levels of anaemia.

The immune response in iron-deficient young children: effect of iron supplementation on cell-mediated immunity

The effects of iron deficiency on immunity remain controversial. This study was designed to assess the impact of iron supplementation on the immune status, in 81 children aged 6 months-3 years, at high risk for iron deficiency, using a longitudinal double blind randomised and placebo-controlled study. Lymphocytes of iron-deficient children produced less interleukin-2 in vitro. Iron supplementation for 2 months increased mean corpuscular volume, serum ferritin and serum transferrin, but had no effect on the parameters of T-cell mediated immunity. The lower interleukin-2 levels in iron-deficient suggest that cell-mediated immunity may be impaired in iron deficiency.

The effects of stress, Escherichia coli, dietary ethylenediaminetetraacetic acid, and their interaction on tissue trace elements in chicks

The present study determined effects of Escherichia coli infection, crowding stress, and EDTA supplementation on Cu, Fe, and Zn levels in the serum, liver, bursa of Fabricius, and spleen of chickens. Organ weights as a percentage of BW were affected by treatments prior to and after infection. Liver and spleen weights as a percentage of BW increased with infection but bursa weight decreased. One week of stress increased hepatic Cu, but 3 wk of EDTA ingestion increased serum Cu and serum, hepatic, bursal, and splenic Fe. These elemental changes resulting from EDTA may have predisposed the chicks to a higher mortality rate from E. coli compared with controls. Peak mortality occurred 2 days after infection, coincident with an increased serum Cu, decreased serum and bursal Fe and Zn, and increased hepatic and splenic Zn. At 7 days postinfection, recovering chicks experienced decreased hepatic Fe, elevated hepatic Zn, decreased bursal Cu, Fe, and Zn, and increased splenic Cu, Fe, and Zn. The current study demonstrates the interactive effects of EDTA, stress, and E. coli infection on serum and organ trace element concentration.

Trace element deficiencies in cattle

Deficiency of cobalt, copper, iron, iodine, manganese, selenium, or zinc can cause a reduction in production. Reduced production occurs most commonly when a deficiency corresponds to the phases of growth, reproduction, or lactation. Because of environmental, nutrient, disease, genetic, and drug interactions, deficiencies of single or multiple elements can occur even when the levels recommended by the National Research Council for these nutrients are being fed. Additionally, random supplementation of trace elements above National Research Council recommendations is not justified because of the negative interaction among nutrients and potential toxicosis. Evaluation of trace element status can be difficult because many disease states will alter blood analytes used to evaluate nutrient adequacy. Proper dietary and animal evaluation, as well as response to supplementation, are necessary before diagnosing a trace element deficiency.

Iron and immunity

Review of animal and human studies concerning the impact of iron deficiency on immune function in vivo indicates that in many instances there is no firm consensus of opinion as to the relationship between iron status and immunity. One major problem with almost all human studies is that other micro- and macronutrient deficiencies are inadequately controlled for and thus it is often unclear as to whether reported abnormalities of immune function can be attributed specifically to iron deficiency. Even when abnormalities of immune function have been detected it is often uncertain as to the biological and clinical relevance that these may have for the host. Within these restraints the available studies suggest that iron deficiency may at least contribute to impaired T lymphocyte function as judged by DTH responses in skin and impaired mitogen-induced proliferation. As in protein energy malnutrition, humoral immunity is largely spared in humans, the balance of evidence suggesting that immunoglobulin production and function is normal, as are serum concentrations of complement. The only other abnormality of non-specific immunity which has been reported consistently to be abnormal is that of reduced bactericidal activity of polymorphonuclear leucocytes. The clinical relevance of these abnormalities remains to be established. There is, however, no evidence to suggest that individuals with iron deficiency suffer the devastating infective complications of the well defined immunodeficiency syndromes either congenital or acquired. It seems likely therefore that despite the fundamental importance of iron in maintaining the integrity of immune function, humans can tolerate the extremes of deficiency and excess and survive in a relatively healthy state.

Body iron stores in patients subjected to surgery of the large bowel

Iron stores as estimated by serum ferritin concentration were studied in 40 patients subjected to colon surgery in reference to postoperative complications and restoration of iron stores, as well as to dietary and supplementary iron. The results showed that empty iron stores are common in patients subjected to colon surgery; 40 percent of the patients had a total loss before the operation. Preoperatively empty iron stores were associated (P less than .01) with an increased risk of postoperative complications that were not explained by other nutritional parameters. Surgery of the colon did not affect serum ferritin concentration or iron stores acutely or long-term. Intake of dietary iron was determined by food recording for seven days in all patients and was compared to 40 controls. The preoperative hemorrhagia and lower daily intake of dietary iron (8 +/- 3 mg) in the patients than in the controls (14 +/- 4 mg) may explain the empty iron stores. However, patients with normal iron stores also had low amounts of dietary iron (9 +/- 3 mg). In 12 patients with empty iron stores the effects of ferrous sulfate (80 mg Fe++) three times daily for six weeks were studied. The patients responded well to the therapy. It is concluded that preoperatively empty iron stores are common in patients subjected to colon surgery, and that this raises the risk of postoperative complications. Colon operations are not followed by acute or long-term changes in serum ferritin concentration or iron stores. The restoration of iron is achieved by oral iron therapy.