The impact of vitamins and/or mineral supplementation on blood pressure in type 2 diabetes.

OBJECTIVE: The present study designed to assess the effect of Mg+Zn, vitamin C+E, and combination of these micronutrients on blood pressure in type 2 diabetic patients. MATERIALS AND METHODS: In a randomized, double-blind, placebo controlled clinical trial, 69 type 2 diabetic patients were randomly divided into four groups, each group receiving one of the following daily supplement for three months; group M: 200 mg Mg and 30 mg Zn (n = 16), group V: 200 mg vitamin C and 150 mg vitamin E (n = 18), group MV: minerals plus vitamins (n = 17), group P: placebo (n = 18). Blood pressure was measured at the beginning and at the end of the trial. Treatment effects were analyzed by general linear modeling. RESULTS: Results indicate that after three months of supplementation levels of systolic, diastolic and mean blood pressure decreased significantly in the MV group by 8 mmHg (122 +/- 16 vs. 130 +/- 19 mmHg), 6 mmHg (77 +/- 9 vs. 83 +/- 11 mmHg), and 7 mmHg (92 +/- 9 vs. 99 +/- 13 mmHg), respectively (p < 0.05). Also combination of vitamin and mineral supplementation had significantly effects in increasing serum potassium (p < 0.05) and in decreasing serum malondialdehyde (p < 0.05). There was no significant change in the levels of these parameters in the other three groups. CONCLUSION: The results of the present study indicated that in type 2 diabetic patients a combination of vitamins and minerals, rather than vitamin C and E or Mg and Zn, might decrease blood pressure.

Lipid peroxidation and urinary excretion of vitamin E in rats submitted to an immunological inflammatory process.

Inflammation is a protective physiologic response, generally controlled by the organism at the injury site. Vitamin E is the most important antioxidant in the lipid phase present in nature and acts by interrupting the chain reaction produced by free radicals. The objective of this study was to evaluate the effect of inflammation on vitamin E levels and lipid peroxidation in rats. Forty Wistar rats (four groups of 10 rats each) were studied over a period of 15 days. Two substances inducing the inflammatory process were parenterally administered, anti-rat basement membrane serum (ABMG) and Freund's complete adjuvant (FAG). Lipid peroxidation levels in hepatic and renal tissue and in plasma and urine were analyzed and compared with the control (CG). Vitamin E was determined by HPLC and lipid peroxidation by quantification of thiobarbituric acid reactive substances (TBARS). ABMG produced more (p < 0.05) TBARS in renal and hepatic tissues (0.7 +/- 0.11 and 1.28 +/- 0.27 nmol/g protein, respectively) compared to CG (0.65 +/- 0.81 and 0.69 +/- 0.13 nmol/g protein). Analysis of TBARS in urine did not show statistically significant differences between the experimental groups and the control. Vitamin E levels in the hepatic tissue of ABMG and FAG (40.7 +/- 10.04 and 44.26 +/- 20.24 micrograms/g tissue) were higher than in CG (22.37 +/- 8.20 micrograms/g tissue) while in kidney tissue and plasma these values were lower (P < 0.05). Renal excretion was increased (P < 0.05) in the group that received anti-rat basement membrane serum (22.39 +/- 0.11 mmol/mL) compared to CG (0.56 +/- 0.056 mmol/mL). We conclude that the acute inflammatory process causes important alterations in the metabolism of vitamin E and lipid peroxidation leading to a significantly increased excretion of this vitamin in the urine.

Chromatographic techniques for the determination of putative dietary anticancer compounds in biological fluids.

Although a great number of papers demonstrate an association between high intake of fruits and vegetables and reduced risk of certain types of cancer, the epidemiological evidence is not conclusive. The identification and quantification of specific dietary anticancer compounds in plasma, urine and tissues is an important aspect of this research. We surveyed the recent literature for original papers which involved the use of separation techniques for the detection and quantification in biological fluids and tissues of putative anticancer compounds which are present in the diet. The compounds included in this review are flavonoids, phytoestrogens, carotenoids, retinoids, vitamin E and ascorbic acid. The review covers papers published in the last 3 years. For each class of compounds we discuss the sample preparation, chromatographic conditions, and validation of the methods used, in order to identify current trends in the bioanalysis of each class of these substances.

A novel 5'-carboxychroman metabolite of gamma-tocopherol secreted by HepG2 cells and excreted in human urine.

HepG2 cells were incubated with a medium containing fetal bovine serum enriched with RRR-gamma-tocopherol (gamma-TOH). After 48 h the medium was extracted and analyzed for gamma-TOH metabolites by gas chromatography-mass spectrometry. In addition to gamma-CEHC, the 3'-carboxychroman metabolite of gamma-TOH previously reported in human urine, these cells secreted a second substance whose extraction and mass spectral characteristics were consistent with those of the 5'-carboxychroman analog of gamma-CEHC, 2,7, 8-trimethyl-2-(delta-carboxymethylbutyl)-6-hydroxychroman. This is the first report of metabolism of gamma-TOH to carboxychroman metabolites in cell culture. Analysis of human urine samples revealed the consistent presence of the novel 5'-carboxychroman metabolite, along with that of gamma-CEHC. Oral supplementation with purified RRR-gamma-TOH resulted in elevated urinary concentrations of both metabolites, although the concentration of the 5'-gamma-carboxychroman metabolite was consistently and substantially less than that of gamma-CEHC. The presence of both metabolites is consistent with the involvement of an omega-oxidation-like process in the phytyl tail shortening of gamma-TOH to water soluble metabolites excreted in urine.

Urinary excretion and plasma vitamin E levels in patients with AIDS.

Individuals with acquired immunodeficiency virus (HIV) and patients with acquired immunodeficiency syndrome (AIDS) present a variety of pathologic alterations that influence their nutritional status during various stages of the disease. Previous studies have reported a reduction in plasma vitamin E levels in these patients associated with a higher production of free radicals. Individuals with infection, fever, or acute diarrhea excrete considerable amounts of vitamin A in urine. This observation raised the hypothesis that this may also be the case for vitamin E and that its urinary excretion may play a significant role in the reduction of plasma vitamin E levels. In the present investigation, 28 serologically positive HIV-1 (HIV group) divided into a group of 16 patients with AIDS (< 200/mm3 CD4+ T lymphocytes) were studied. The control group consisted of 11 healthy individuals. Urinary and plasma vitamin E levels were determined by high-performance liquid chromatography. Patients with AIDS presented reduced plasma vitamin E levels (15.25 +/- 12.19 mumol/L) compared with the HIV (26.40 +/- 17.01 mumol/L) and control (40.03 +/- 31.80 mumol/L) groups. On the other hand, urinary excretion was higher in the AIDS group (0.86 +/- 0.99 mumol/24 h) than in the HIV group (0.62 +/- 0.46 mumol/24 h) and considerably higher than in the control group (0.05 +/- 0.13 mumol/24 h). These results indicate elevated vitamin E excretion in the urine of both patients with AIDS and patients with HIV-1, levels is recommended for patients with HIV and patients with AIDS and, if necessary, the combination of existing medical therapy with vitamin supplementation to maintain the nutritional status related to vitamin E.