Selenium and diabetes in the tropics

Selenium supranutrition: are the potential benefits of chemoprevention outweighed by the promotion of diabetes and insulin resistance?

Selenium was considered a toxin until 1957, when this mineral was shown to be essential in the prevention of necrotic liver damage in rats. The hypothesis of selenium chemoprevention is principally formulated by the observations that cancer incidence is inversely associated with selenium status. However, recent clinical and epidemiological studies demonstrate a role for some selenoproteins in exacerbating or promoting other disease states, specifically type 2 diabetes, although other data support a role of selenium in stimulating insulin sensitivity. Therefore, it is clear that our understanding in the role of selenium in glucose metabolism and chemoprevention is inadequate and incomplete. Research exploring the role of selenium in individual healthcare is of upmost importance and possibly will help explain how selenium is a double-edged sword in the pathologies of chronic diseases.

Oxidative stress and antioxidant capacity in patients with chronic pancreatitis with and without diabetes mellitus

AIM

To determine oxidant stress and antioxidant capacity in chronic pancreatitis (CP) patients with and without diabetes mellitus.

METHODS

This study is a secondary data analysis of our earlier study on 127 (male = 86) patients with CP, grouped as those with diabetes (case; n = 23) and those without diabetes (control). Markers of antioxidant status included vitamins A and E, total antioxidant capacity (TAC; measured as ferric-reducing ability of plasma [FRAP]), and total glutathione (T-GSH). Markers for oxidative stress included lipid peroxidation, measured as thiobarbituric acid reactive substances (TBARS) and serum superoxide dismutase (s-SOD).

RESULTS

Patients with diabetes were older (mean [SD] age 36.4 [9.7] vs. 29.3 [10.0] years; p = 0.032), had longer duration of CP [4 (0.3-21) vs. 3 (0.3-24) years; p = 0.07), and had a lower TAC (269.8 [92.4] vs. 355.5 [128.6] μmoles Fe(+2) liberated; p = 0.003) compared to those without diabetes. In multiple logistic regression analysis taking all exploratory variables, FRAP (<270 μmoles Fe(+2) liberated) was associated with diabetes independent of duration of CP, age of patients, and TBARS levels. However, oxidative stress levels were not different between diabetic and nondiabetic patients.

CONCLUSIONS

Diabetes was found to be associated with longer duration of CP and with low antioxidant capacity. Further studies will be needed to evaluate a causal association.

Selenium and preeclampsia: A global perspective

Preeclampsia is a complex multisystem disorder of pregnancy where oxidative stress plays an important aetiological role. The role of selenium in the synthesis of endogenous antioxidants is well documented, and a significant reduction in selenium has been reported in preeclamptic women. The objective of this study was to map global selenium status and preeclampsia incidence. This study identified peer reviewed journal articles reporting national preeclampsia incidence (%) and matched these with reported values of selenium intake and plasma/serum selenium concentrations (μg/L). Matched data were obtained for 45 regions, reporting 6456,570 births, spanning Europe, Asia, Australasia, Africa, North and South America. Increasing plasma selenium concentration was found to be correlated with a reduction in preeclampsia incidence (Pearson's r=-0.604, P<0.0001). Countries with a reported serum/plasma selenium level of ⩾95μg/L were considered selenium sufficient and a significant reduction in preeclampsia incidence for countries above this value (P=0.0007) was noted. Significant reductions in preeclampsia incidence were found to coincide with increases in plasma/serum selenium concentration in the New Zealand (P=0.0003) and Finland (0.0028) populations following Government intervention. This study supports the hypothesis that selenium supplementation may be beneficial in reducing oxidative stress in women at risk of preeclampsia.

Carotenoid deficiency in chronic pancreatitis: the effect of an increase in tomato consumption

BACKGROUND/OBJECTIVES

Carotenoids are potentially malabsorbed in patients with chronic pancreatitis (CP). The aims of this study were: (1) to determine the prevalence of low levels of each of the major carotenoids in subjects with CP; (2) to compare carotenoids in CP subjects with or without vascular disease and (3) to test the effect of an increase in dietary lycopene intake in patients with low plasma lycopene concentration.

SUBJECTS/METHODS

Simultaneous determination of carotenoids was done in 80 patients with CP and 20 healthy subjects, using high-performance liquid chromatography. Of the CP patients who had low lycopene concentration, 22 (<120 μg/l) had to consume daily 40 g tomato paste (approximately 24 mg lycopene).

RESULTS

Of these patients, 84.7% had at least one carotenoid deficiency and 27.5% had more than four carotenoid deficiencies. Low plasma concentrations in β-carotene and lycopene were correlated, in CP group, with a low body mass index (BMI), a low low-density lipoprotein (LDL) cholesterol concentration, alcohol consumption and current smoking status, whereas low plasma concentration in β-cryptoxanthine was correlated with a low BMI, a low LDL cholesterol concentration and alcohol consumption. Lycopene concentration was decreased in patients with vascular disease (171±197 vs 99±72 μg/l; P=0.02). After an intervention period of 8±2 months, lycopene concentration increased from 67.5±30 to 121.8±102 μg/l (P=0.025).

CONCLUSION

Carotenoid concentrations are dramatically decreased in CP, especially lycopene in CP patients with vascular disease. Despite malabsorption, it is possible to increase lycopene plasma concentration by increasing heated tomato consumption.

Selenium in global food systems

Food systems need to produce enough of the essential trace element Se to provide regular adult intakes of at least 40 μg/d to support the maximal expression of the Se enzymes, and perhaps as much as 300 μg/d to reduce risks of cancer. Deprivation of Se is associated with impairments in antioxidant protection, redox regulation and energy production as consequences of suboptimal expression of one or more of the Se-containing enzymes. These impairments may not cause deficiency signs in the classical sense, but instead contribute to health problems caused by physiological and environmental oxidative stresses and infections. At the same time, supranutritional intakes of Se, i.e. intakes greater than those required for selenocysteine enzyme expression, appear to reduce cancer risk. The lower, nutritional, level is greater than the typical intakes of many people in several parts of the world, and few populations have intakes approaching the latter, supranutritional, level. Accordingly, low Se status is likely to contribute to morbidity and mortality due to infectious as well as chronic diseases, and increasing Se intakes in all parts of the world can be expected to reduce cancer rates.

Diabetes mellitus worsens antioxidant status in patients with chronic pancreatitis

BACKGROUND

Patients with chronic pancreatitis (CP) are at high risk of antioxidant deficiencies. Furthermore, this disease can lead to diabetes mellitus (DM) that could exacerbate the severity of oxidative stress. Oxidative stress and the resulting LDL oxidation are a major cause of atherosclerosis.

OBJECTIVE

The objective of the study was to ascertain whether diabetes significantly modifies oxidative status in patients with CP.

DESIGN

CP patients with or without DM were compared with type 1 DM patients and healthy control subjects.

RESULTS

Two-way factorial analyses showed that a decrease in the plasma concentrations of vitamin A, vitamin E, and carotenoids accompanied both CP and DM, and CP was also associated with lower plasma concentrations of selenium and zinc, lower catalase activity, and higher plasma concentrations of copper. The lag phase of LDL oxidation was lower in CP patients with or without DM than in the control subjects, whereas there was no significant difference between type 1 DM patients and control subjects. Multivariate analysis showed that LDL vitamin E (R2 = 0.24, P < 0.0001) and fasting plasma glucose (R2 = 0.32, P < 0.0001) concentrations were the main determinants of the lag phase of LDL oxidation.

CONCLUSIONS

Antioxidant status is altered in CP patients, particularly in those who also have DM. In these patients, a vitamin E deficiency and an elevated plasma glucose concentration were associated with significantly higher LDL oxidizability.

[Tropical chronic pancreatitis in a young patient]

Tropical chronic pancreatitis is a form of idiopathic chronic pancreatitis that has not previously been described in Spain. Typically it is related to dietary factors and malnutrition, although genetic factors may also play a significant role in the development of the disease. We report a case of chronic tropical pancreatitis in a 27-year-old woman from the Dominican Republic domiciled in Spain since 1992. The patient was admitted to our hospital for acute pancreatitis that fulfilled the diagnostic criteria (clinical and radiological) for chronic tropical pancreatitis. This case has led us to review this uncommon entity. Because of the increasing number of immigrants from tropical countries, chronic tropical pancreatitis will probably need to be taken into account in the differential diagnosis of chronic pancreatitis in our patients.

Evidence that diabetes mellitus favors impaired metabolism of zinc, copper, and selenium in chronic pancreatitis

Diabetes mellitus, a common complication of chronic pancreatitis, can disturb the metabolism of zinc, copper, and selenium. We analyzed the effects of hyperglycemia, malabsorption, and dietary intake on these factors in 35 men with alcohol-induced chronic pancreatitis complicated by insulin-treated diabetes mellitus (CP-D), 12 men with chronic pancreatitis but no diabetes (nondiabetic CP), 25 men with type 1 diabetes mellitus (type 1 DM), and 20 control subjects. Diabetes due to chronic pancreatitis was associated with decreased plasma zinc and selenium concentrations and with increased urinary copper excretion. Of the chronic pancreatitis patients, 17% had low plasma zinc, and 41% of them had low plasma selenium. None of the type 1 diabetic patients had low plasma concentrations of zinc, but 12% of them had a low selenium concentration. Hyperglycemia, as assessed by fasting plasma glucose and by plasma HbAlc, was responsible for the increased zinc excretion and the decreased superoxide dismutase activity. The perturbations of the copper, selenium, and zinc metabolism were particularly pronounced in subjects with chronic pancreatitis plus diabetes mellitus. We have yet to determine whether the differences in trace-element status contribute to the clinical expression of the disease.

The antioxidant profiles of patients with recurrent acute and chronic pancreatitis

OBJECTIVE

It has been suggested that patients with chronic pancreatitis have antioxidant deficiencies. It is unclear whether these antioxidant deficiencies also occur in patients with recurrent acute pancreatitis and whether this condition represents an intermediate state between normality and chronic pancreatitis. The aim of this study was to determine the antioxidant profiles of patients with pancreatitis (recurrent acute and chronic) and to compare their profiles with a control population.

METHODS

The antioxidant profiles of patients with chronic pancreatitis (n = 27) and recurrent acute pancreatitis (n = 11) were determined and compared with the antioxidant profiles of control subjects (n = 19). The following parameters were measured in blood: trace elements (selenium, copper, zinc), vitamins A and E, and carotenoids (alpha-carotene, beta-carotene, xanthine, beta-cryptoxanthine, lycopene).

RESULTS

Patients with chronic pancreatitis had significantly lower plasma concentrations of selenium, vitamin A, vitamin E, beta-carotene, xanthine, beta-cryptoxanthine, and lycopene compared with both control subjects and patients with recurrent acute pancreatitis (p < 0.05). There were no significant differences between the antioxidant profiles of patients with chronic pancreatitis due to alcohol excess and patients with idiopathic chronic pancreatitis, or between the antioxidant profiles of patients with recurrent acute pancreatitis and control subjects.

CONCLUSIONS

Patients with chronic pancreatitis had evidence of multiple antioxidant deficiencies. The antioxidant profiles of patients with recurrent acute pancreatitis did not differ from those of control subjects, discounting the hypothesis that recurrent acute pancreatitis represents an intermediate state between normality and chronic pancreatitis.

Urinary selenium in healthy and diabetic Saudi Arabians

We examined Se in urine of 170 Saudi Arabian diabetics (19 insulin-dependent [type 1] and 151 insulin-independent [type 2]) and in an equal number of control subjects of the same origin by measuring the ratio of the concentration of this metal (C(Se)) to that of creatinine in urine (C(creat)) for each subject. The mean (and SEM) of C(Se) /C(creat) for the control subjects was 56 (2.9) mu mol/mol creat, whereas, the value for the diabetics combined or separated into type 1 and type 2 was 56.7 (3.2), 51.5 (6.3), and 57.4 (3.5) mu mol/mol creat, respectively. With the exception of type 2 diabetics who were treated with insulin in addition to oral hypoglycemic and diet (35 patients) (mean [SEM] = 43 (4.3) mu mol/mol creat), there was no significant difference in C(Se)/C(creat) between the diabetics and control subjects. Also, there was no significant correlation between C(Se)/C(creat) and age, sex, or weight of diabetics, whereas, the correlation with the degree of diabetic control was significant (p < 0.0136). Of all diabetes-associated disorders (cardiovascular diseases, neuropathy, ophthalmologic diseases, infections, and hepatic disease), only ophthalmologic diseases appears to cause a significant (p < 0.05) reduction in C(Se)/C(creat), but only among type 2 diabetics. Inasmuch as Se status is reflected by urinary Se, healthy Saudi Arabians appear to have Se status that is comparable or higher than those reported for other populations.

Micronutrient antioxidant status in black South Africans with chronic pancreatitis: opportunity for prophylaxis

Biochemical assessments of micronutrient antioxidant status were done in 14 consecutive black patients with calcific chronic pancreatitis and 15 controls at Soweto, near Johannesburg in southern Africa. The patients showed subnormal levels of vitamin C in plasma; selenium, beta-carotene and alpha-tocopherol in serum; and inorganic sulphate (as an index of long-term sulphur amino acid intake) in urine (P < 0.001 for each): furthermore, among the patients ascorbate constituted a lower fraction of vitamin C (P < 0.002), indicating heightened oxidation of the bioactive form. By comparing the results in Sowetan controls with reference ranges from Manchester, UK, the markedly lower vitamin C and, hence, ascorbate levels in the Sowetans was underlined (P < 0.001) and their selenium levels were also lower (P < 0.001), but beta-carotene, alpha-tocopherol and inorganic sulphate levels were comparable. The very low bioavailability of ascorbate among Sowetan controls is reminiscent of our previous finding in outwardly healthy people at Madras in southern India: in both these areas chronic pancreatitis is currently endemic, has a propensity to pancreatic calculi and runs a virulent course towards premature death from diabetes, malnutrition or pancreatic cancer. Considering that low ascorbate levels are a feature in patients with chronic pancreatitis who develop pancreatic calculi at Manchester and that antioxidant supplements ameliorate painful symptoms, we suggest that poor antioxidant intake may predispose underprivileged tropical communities to the disease. If so, there could be an opportunity for prophylaxis through a daily tablet containing vitamin C, perhaps along with selenium at Soweto and beta-carotene at Madras.

Micronutrient antioxidant status in tropical compared with temperate-zone chronic pancreatitis

Micronutrient antioxidants interact with glutathione in tissues to facilitate the disposal of reactive oxygen species and xenobiotic metabolites derived via cytochromes P450. Published evidence linking cytochrome P450I induction with chronic pancreatitis therefore led us to compare antioxidant status in patients at Manchester in the northwest of England and at Madras in the southeast of India. Serum studies in healthy volunteers showed that the biologic availabilities of selenium and alpha-tocopherol were equally high in the two zones but that the availabilities of beta-carotene and ascorbic acid were lower in the tropical area (p < 0.001), where the ratio of ascorbic acid to total vitamin C concentration in serum was substantially reduced (p < 0.001). The serum antioxidant profiles of the chronic pancreatitis groups reflected these indigenous differences: a decrement in selenium and alpha-tocopherol was evident in both zones, whereas beta-carotene and ascorbic acid values were subnormal only in the Manchester group. The concentration of inorganic sulphate in urine--an index of long-term intake of sulphur amino acids for synthesis of glutathione and other detoxifiers--was similar in controls and patients from Manchester, but levels were lower than in their Madras counterparts (p < 0.02, p < 0.01, respectively). The results suggest that culinary practices that erode the biologic availabilities of ascorbic acid and beta-carotene may predispose to pancreatic oxidative stress and thereby to the changes leading to chronic pancreatitis at an early age in south India. These findings have implications for treatment and prophylaxis.