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International Journal for Vitamin and Nutrition Research, Nr. 1/2001

Zusammenfassungen / Summaries

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The Role of Folate, Antioxidant Vitamins and other Constituents in Fruit and
Vegetables in the Prevention of Cardiovascular Disease: The Epidemiological Evidence

Monika Eichholzer1, Jürg Lüthy2, Felix Gutzwiller1, Hannes B. Stähelin3

Summary

Evidence that fruit and vegetables may protect against coronary heart disease is accumulating. It is unclear which constituents of fruit and vegetables are responsible for this protective effect. Folate as a co-substrate in homocysteine metabolism may be important. An intake of about 400 mg folate equivalents/day seems to be required to achieve stable low homocysteine blood levels. Five of eight epidemiologic studies show significant inverse associations between folate and cardiovascular disease. These associations could be confounded by antioxidant vitamins and/or other substances. In trials examining an association between folate and cardiovascular disease such confounding must be excluded, before specific recommendations can be given. Observational studies suggest that vitamin C plays a role in the aetiology of cardiovascular disease, but there are no completed intervention trials of this vitamin alone. With regard to vitamin E two cohort studies point to cardiovascular benefits with the long-term use of supplements of at least 100 IU/day, but the results of controlled trials are inconclusive. There is some evidence from observational studies of an inverse association between b-carotene and cardiovascular disease, particularly in smokers. Intervention trials do not support this hypothesis, rather, they suggest a possible harmful effect of b-carotene supplements in smokers. Nevertheless, protective effects of b-carotene and vitamin E in different dosages, durations of administration, or different combinations, are still possible. The last paragraph of this review discusses limitations of the present and priorities of future research.

Key words

Folate, antioxidant vitamins, fruit, vegetables, cardiovascular disease

International Journal for Vitamin and Nutrition Research,
Band 71, 2001, Heft 1, © Verlag Hans Huber AG, Bern

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Vitamin E and the Prevention of Atherosclerosis

Denis Bron1 and Reto Asmis2

Summary

Successful strategy for the prevention of coronary heart disease (CHD) in particular of atherosclerosis, require a detailed understanding of the underlying mechanism. It is now being recognised that dietary antioxidants, in particular vitamin E, will play an important role in designing future strategies. Although more and more beneficial effects of vitamin E on atherosclerosis are being described, the biochemical and cell biological mechanism underlying these benefits are not yet fully understood, preventing the use of vitamin E as therapeutic agent. Recent new findings have shed new light on the physiological role of vitamin E and suggest that it has a much broader array of biological activities than originally expected. In addition to its well described role as an antioxidant, it is becoming evident that vitamin E also can modulate the immune system, suppress local and chronic inflammation, reduce blood coagulation and thrombus formation, and enhance cell function and survival. This review summarises new findings from in vitro studies and discusses their potential relevance in
human atherosclerosis.

Key words

Vitamin E, prevention, atherosclerosis, review, pathogenesis, cell, apoptosis, immunmodulation, hemostasis, macrophages

International Journal for Vitamin and Nutrition Research,
Band 71, 2001, Heft 1, © Verlag Hans Huber AG, Bern

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Are the Serum 25-Hydroxyvitamin D Concentrations in Winter Associated with Forearm Bone Mineral Density in Healthy Elderly Japanese Women?

Kazutoshi Nakamura, Mitsue Nashimoto and Masaharu Yamamoto

Summary

The objective of this study was to investigate whether the serum 25-hydroxyvitamin D (25[OH]D) concentrations in winter are associated with the BMD in elderly Japanese women. The subjects were 117 healthy elderly Japanese women. Serum 25(OH)D concentrations were determined by high-performance liquid chromatography. Forearm BMD in the non-dominant arm was measured by dual-energy X-ray absorptiometry (DXA) using a DTX-200 Osteometer. The mean age of the subjects was 66.1 (SD 6.5) years (range: 46­80). The average 25(OH)D concentration was 59.1 nmol/L (SD 16.1), and five of the subjects had low 25(OH)D concentrations (< 30 nmol/L). Forearm BMD decreased linearly with age (r2 = 0.275). There was no linear association between the serum 25(OH)D concentrations and the forearm BMD (p = 0.9483). Multiple regression analysis did not reveal any association between the two (p = 0.5318) when age (p < 0.0001, r2 = 0.271) and weight (p < 0.0001, r2 = 0.153) were taken into account. Our cross-sectional study failed to reveal any association between the serum 25(OH)D concentrations and the forearm BMD in elderly Japanese women, suggesting that 25(OH)D does not play an important role in the determination of BMD. A follow-up study should be conducted to confirm the results of our cross-sectional study.

Key words

Bone mineral density (BMD), elderly, 25-hydroxyvitamin D, Japanese, women

International Journal for Vitamin and Nutrition Research,
Band 71, 2001, Heft 1, © Verlag Hans Huber AG, Bern

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Supplementation of Rats with a Lutein Mixture Preserved with Vitamin E Reduces Tissue Phylloquinone and Menaquinone-4

Geraldine V. Mitchell, Kathleen K. Cook, Mamie Y. Jenkins and Erich Grundel

Summary

The modulation of tissue concentrations of vitamin K by a lutein supplement preserved with natural vitamin E was studied in Fischer 344 rats. Vitamin K is necessary for blood coagulation and may be essential for tissue and bone health. Weanling male rats were fed the AIN-93G diet (control) or modified AIN-93G diets containing 0.3, 0.6, 1.2, 2.4 and 4.8 g supplement/100 g diet for 8 weeks. The supplement contained 5% lutein, 0.22% zeaxanthin and 2.2% natural vitamin E as a preservative. Concentrations of trans-phylloquinone in the plasma (nmol/mmol triglycerides) and heart were significantly reduced (P < 0.05) in rats fed the supplement. The reductions in trans-phylloquinone in the heart ranged from ~20 to 60% of the control. Concentrations of phylloquinone in the liver were significantly lower in the rats fed the supplement at levels > 1.2 g/100 g diet than in the control rats. Ratios of cis/trans phylloquinone in liver and heart increased and concentrations of menaquinone-4 in heart decreased as the dietary level of the lutein supplement increased. The results suggest that the lutein supplement affected the absorption, tissue uptake and/or turnover rate of vitamin K. The presence of other components in the supplement confounded the interpretation of the biological effects of lutein alone on vitamin K metabolism.

Key words

Lutein, vitamin E, vitamin K, menaquinone, trans-phylloquinone, cis-phylloquinone, rats

International Journal for Vitamin and Nutrition Research,
Band 71, 2001, Heft 1, © Verlag Hans Huber AG, Bern

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Interactive Effect of Hesperidin and Vitamin E Supplements on Cholesterol Metabolism in High Cholesterol-Fed Rats

Yong Bok Park1, Kyung-Min Do, Song-Hae Bok2, Mi-Kyung Lee1, Tae-Sook Jeong2 and Myung-Sook Choi

Summary

Certain bioflavonoids are potent antioxidants and have pharmacologic effects similar to those of vitamin E. Accordingly, the interactive effect of hesperidin and vitamin E was studied with respect to cholesterol metabolism and the antioxidant status. Hesperidin supplement (0.1%, wt/wt) with comparable levels of vitamin E was provided with a high-cholesterol (1%, wt/wt) diet to rats for 5 weeks. The amount of vitamin E included in the hesperidin-free and hesperidin diets was either a low (low-E) or a normal (normal-E) level. The hesperidin supplement and different levels of dietary vitamin E did not significantly alter the concentrations of plasma triglycerides. However, the inclusion of hesperidin significantly lowered the concentration of plasma cholesterol in both the low-vitamin E group and the normal-vitamin E group compared to the hesperidin-free groups (p < 0.05). The hepatic triglyceride content was significantly lowered by the hesperidin supplement, as opposed to the plasma triglyceride content, regardless of the vitamin E level in the diet. The hepatic HMG-CoA reductase activity was significantly lowered by the hesperidin supplement with both the low-vitamin E and the normal-vitamin E compared to the hesperidin-free groups (p < 0.05). The hepatic HMG-CoA reductase activity was also significantly lowered with an increase in the dietary vitamin E within the hesperidin and hesperidin-free groups. The excretion of fecal neutral sterol and acidic sterols tended to be lower with the hesperidin supplement. Neither dietary hesperidin nor vitamin E significantly changed the hepatic antioxidant enzyme activity.
This data indicates that hesperidin lowers the concentration of plasma cholesterol and the hepatic triglyceride content regardless of the dietary vitamin E level. However, the concentration of plasma cholesterol in the hesperidin-free groups was dependent on the dietary vitamin E level. This information may contribute to understanding the interactive effect of hesperidin and vitamin E on cholesterol biosynthesis in high cholesterol-fed rats.

Key words

Hesperidin, vitamin E, HMG-CoA reductase, ACAT, fecal sterols, cholesterol metabolism, antioxidant enzymes

International Journal for Vitamin and Nutrition Research,
Band 71, 2001, Heft 1, © Verlag Hans Huber AG, Bern

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Supplementation with Vitamin E and/or Zinc does not Attenuate Atherosclerosis in Apolipoprotein E-deficient Mice fed a High-Fat, High-Cholesterol Diet

Antoni Paul, Lucía Calleja, Jorge Joven, Elisabet Vilella, Natàlia Ferré, Jordi Camps, Josefa Girona and Jesús Osada

Summary

Ever since oxidation has been known to be involved in atherogenesis, antioxidants have received considerable attention as potential antiatherogenic agents. The lipid-soluble vitamin E is the main antioxidant carried by lipoproteins. Zinc is a water-soluble trace element that acts as a cofactor of superoxide dismutase (SOD) and has an antioxidant role in several oxidative processes. To test the hypothesis that zinc could adjuvate the antioxidant activity of vitamin E and diminish atherogenesis, we explored how supplementing diet with vitamin E and/or zinc would affect an atherosclerosis-prone animal like Apo E-deficient mice. The increased plasma concentrations of both vitamin E and zinc showed that absorption was high. They had a significant hypolipidemic effect and the supplemented animals had 25% less plasma cholesterol and triglyceride than controls. The SOD activity was significantly higher in washed erythrocytes from mice supplemented with zinc. The plasma of supplemented animals was also significantly more resistant to oxidation. The size of lesions in the proximal aortic region did not differ among groups. Therefore, dietary supplementation resulted in the expected antioxidant effects but there was no substantial attenuation of atherosclerosis in this particular model.

Key words

Atherosclerosis, apolipoprotein-E, mice, oxidation, superoxide dismutase, vitamin E, zinc

International Journal for Vitamin and Nutrition Research,
Band 71, 2001, Heft 1, © Verlag Hans Huber AG, Bern

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Associations of age, smoking habits and diabetes with plasma vitamin C of elderly of the POLA study

Inès Birlouez-Aragon1, Cécile Delcourt2, Frédéric Tessier1, Laure Papoz2 and the POLA Study Group3

Summary

The objective of this study was to determine the associations of age and sex with plasma vitamin C (vit C) concentration taking into account smoking habits and the presence of age-related pathologies, such as diabetes. The POLA study is a population-based study on age-related eye diseases and their risk factors, and plasma Vitamin C evaluation is part of the biological parameters measured in the 1987 volunteer subjects living in Sète (South of France) and aged more than 60 years. Men had lower average plasma vit C levels than women (31.6 mM.L­1 versus 40.3 mM.L­1, p = 0.001). Plasma vit C was stable as a function of age in women but decreased in men (p = 0.02), enhancing the difference in vit C concentration between men and women with advancing age. Smoking more than 10 cigarettes a day was associated to a lower plasma vit C concentration in men (p = 0.001) but not in women, and diabetic subjects tended to have lower vit C concentrations, the difference being significant only in women (p = 0.003). We conclude that there is a clear influence of sex on plasma vit C. This difference may be due to dietary habits, or metabolism, but may also be due to different sensitivity of age, smoking and to some pathologies.

Key words

Plasma vitamin C, aging, sex, smoking, diabetes

International Journal for Vitamin and Nutrition Research,
Band 71, 2001, Heft 1, © Verlag Hans Huber AG, Bern

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Vitamin B-12-Deficiency Affects Immunoglobulin Production and Cytokine Levels in Mice

Ulala Funada1, Masahiro Wada1, Tetsunori Kawata2, Kazumi Mori2, Hiroko Tamai2, Tomoko Isshiki2, Junko Onoda2, Nobuo Tanaka3, Tadahiro Tadokoro1 and Akio Maekawa1

Summary

To clarify the role of B-12 in the immunological function, serum C3, IgM, IgG, IgE contents, splenocytes expression of CD4, CD8, and CD4 positive intracellular IFN-g and IL-4 were examined in B-12-deficient mice, and the effect of the administration of CH3-B-12 was also studied. Serum C3, IgM and IgG contents were lower in B-12-deficient mice than in the control mice. On the other hand, serum IgE content was sinificantly higher in B-12-deficient mice, and the value in CH3-B-12 administered mice, administered CH3-B-12 to B-12-deficient mice for 48 h before the end of feeding period, showed a tendency to recovery. CD4+CD8­ cells and CD4+CD8­/CD4­CD8+ ratio in splenocytes were significantly higher in B-12-deficient mice than in control mice. CD4+IFN-g+ cells was significantly lower in B-12-deficient mice than in control mice, and CD4+IL-4+ was significantly higher in B-12-deficient mice than in control mice. These results suggest that B-12-deficiency causes CD4+CD8­T cells shift from the T helper type 1 to the T helper type 2, which participate in the IgE production and elevates CD4+CD8­/CD4­CD8+ ratio. Thus, B-12 plays a role in maintaining the immune function in mice.

Key words

CD4, CD8, IgE, IgG, interferon-g, interleukin-4, B-12-deficient mice

International Journal for Vitamin and Nutrition Research,
Band 71, 2001, Heft 1, © Verlag Hans Huber AG, Bern

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Serum Free Carnitine and Total Triglycerid Levels in Children with Iron Deficiency Anemia

Fatos¸ Tanzer1, Selda Hzel2, Öge Çetinkaya3 and Ersin Sekreter4

Summary

Iron deficiency anemia and hyperlipidemia are common public health problems in Turkey. The connection between iron and lipid metabolisms has not been clarified yet. The aim of the study was to determine the effect of iron deficiency on carnitine and lipid metabolism.
Study group was consisted of 70 children (mean age 14.7 ± 1.3 months) suffering from iron deficiency anemia and 20 healthy children (mean age 13.7 ± 1.2 months) attended to outpatient clinics of Cumhuriyet University, Sivas were enrolled the study as the control group. Assessments of serum free carnitine concentrations, total triglyceride, total cholesterol and VLDL levels were made in both groups.
The mean serum free carnitine concentration was significantly lower than the control group (18.9 ± 0.43 nmol/ ml and 45.9 ± 1.47 nmol/ml respectively, t = 17.5 p < 0.01). Results of our study also indicated higher serum total triglyceride, total cholesterol and VLDL levels in iron deficient patients than the healthy controls. Regression analyses indicated a negative correlation between serum free carnitine and total triglyceride levels in iron deficient patients.
This study confirms that iron deficiency anemia may be linked to the endogenous carnitine synthesis in pediatric age group, and thus hyperlipidemia appears to be a risk factor for premature cardiovascular diseases.

Key words

Children, iron deficiency, anaemia, hyperlipidemia, carnitine

International Journal for Vitamin and Nutrition Research,
Band 71, 2001, Heft 1, © Verlag Hans Huber AG, Bern

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Effects of transient neonatal Hyperthyrotropinemia on Intellectual quotient and psychomotor performance

Fereidoun Azizi, Mohamed Afkhami, Aezam Sarshar, Mahtalat Nafarabadi

Summary

Transient neonatal hyperthyrotropinemia (TNH) occurs frequently in areas of iodine deficiency. To evaluate the effect of TNH in intellectual function and psychomotor performance, a historical cohohrt study was performed in 9 years old children with documented TNH at birth. 18 children with TNH who had been born in Mahdieh Hospital were studied at age 9 and compared to 19 matcheal children born at the same time, but having normal thyroid function at birth. Global intelligence (IQ) and psychomotor performance were evaluated with Raven and Bender-Gestalt tests, respectively. Total serum T4 and T3 by commercial RIA and TSH by IRMA. Urine was tested for iodine content by digestion method. Height and weight were similar in two groups at birth and at 9 years of age. Thyroid function tests were similar in the two groups except for TSH at birth which was higher in TNH than in control group (23.4 ± 8.3 vs 3.6 ± 1.0 mU/L, P < 0.001). Results of T4, T3, resine uptake, and urinary iodine at 9 years of age were not different between two groups. Mean IQ was 98 ± 11 and 106 ± 8 in TNH and normal children, respectively (P < 0.01). There was no significant difference between psychomotor performance in the two groups. There was no correlation between TSH at birth and IQ at 9 years of age. The present finding suggests that TNH can adversely affect longterm intellectual development.

Key words

Intelligence quotient, neonatal hyperthyrotropinemia, iodine deficiency, thyrotropin

International Journal for Vitamin and Nutrition Research,
Band 71, 2001, Heft 1, © Verlag Hans Huber AG, Bern

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Serum Leptin and Lipid Profiles in Thai Obese and Overweight Subjects

Rungsunn Tungtrongchitr1, Praneet Pongpaew1, Benjaluck Phonrat2,
Siriwan Tribunyatkul1, Duangkamol Viroonudomphol1, Venus Supawan1, Pornrutsami Jintaridhi1, Ariya Lertchavanakul3, Niyomsri Vudhivai1 and Frank Peter Schelp4

Summary

The weight, height, body mass index (BMI), waist/hip ratio, serum leptin and lipid profiles of 48 overweight (BMI > 25.00) Thai males and 166 overweight Thai females, compared with 26 males and 81 females in a control group (BMI = 18.5­24.9 kg/m2), were investigated. Subjects for the study were those persons who turned up regularly for physical check-ups at the out-patient department, general practice section of the Rajvithi Hospital, Bangkok. The study was conducted between March­October, 1998. Statistically significantly higher levels of serum leptin, cholesterol, LDL-C, LDL-C/HDL-C ratio and triglyceride were found in the overweight compared with the control subjects. The median serum leptin concentration in overweight subjects was 19.6 (2.0­60.0 ng/ml) compared with 9.0 (range 1.0­30.0 ng/ml) in the control subjects (p < 0.001). The median values of leptin serum concentrations in the overweight and obese males were significantly higher than those of the overweight and obese females. A total of 66.7% (32 out of 48) of the overweight and obese males had elevated leptin levels, while elevated leptin levels were found in 87.3% (145 out of 166) of the overweight and obese females. A total of 18.8% and 21.1% of the overweight and obese males and females respectively had cholesterol concentrations of > 6.48 mmol/l. However, the prevalence of low HDL-C (HDL-C < 0.91 mmol/l) was found to be 41.7% in the overweight and obese males and 4.2% in the overweight and obese females. Statistically significant associations were found between weight, height, BMI, waist, hip, waist/hip ratio, HDL-C, and serum leptin in both overweight male and female subjects. A negative correlation was found between serum leptin and LDL-C/HDL-C ratio in both the overweight and obese subjects.

Key words

Serum leptin, lipid profiles, obesity

International Journal for Vitamin and Nutrition Research,
Band 71, 2001, Heft 1, © Verlag Hans Huber AG, Bern

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Effect of Supplemental Methionine on Plasma Homocysteine Concentrations in Healthy Men: A Preliminary Study

Mary Ward1,4, Helene McNulty1, Joseph McPartlin3, J.J Strain1, Donald G. Weir3 and John M. Scott2

Summary

Hyperhomocysteinaemia is an established risk factor for vascular disease. The only source of homocysteine in humans is the amino acid methionine found in dietary protein. In an 8-week study, fasting plasma homocysteine concentrations were examined in a group of healthy male subjects (n = 6) under usual dietary conditions (weeks 1­4) and in response to weekly graded (25, 50 and 75mg/kg/d) supplementary methionine (weeks 5, 6, 7). Nutrient intakes, including methionine, were calculated from 4¥3 day food records. Under usual dietary conditions (mean methionine intake; 0.95 ± 0.51 mg/d) weekly mean plasma homocysteine concentrations for the group were not significantly different (ANOVA) from each other ranging from 6.82 ± 1.77 to 9.42 ± 2.73 mmol/l. Doubling (supplementing with 25 mg/kg/d; + 2.04 g/d) or quadrupling (50 mg/kg/d; + 4.08 g/d) methionine intakes did not result in a significant increase in plasma homocysteine (8.56 ± 3.68 mmol/l and 13.37 ± 5.09 mmol/l respectively). A significant increase, however, was achieved when diets were supplemented with methionine at the highest level of 75 mg/kg/d (+ 6.14 g/d) resulting in a mean plasma homocysteine concentration of 18.05 ± 11.8 mmol/l. Mean plasma homocysteine concentration returned to baseline (8.76 ± 3.42 mmol/l), 10 days post-supplementation. The results of this study indicate that an increased dietary methionine will only cause elevated fasting homocysteine concentrations if ingested at intakes equivalent to five times usual intake. Because it is very unlikely that such levels could be achieved through dietary means alone we conclude that plasma homocysteine is unlikely to be affected by longer-term changes in food methionine intake.

Key words

Human, supplementary methionine, chronic, intervention, homocysteine

International Journal for Vitamin and Nutrition Research,
Band 71, 2001, Heft 1, © Verlag Hans Huber AG, Bern

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Rapid Determination of Glutathione Peroxidase and Thioredoxin Reductase Activities Using a 96-well Microplate Format: Comparison to Standard Cuvette-based Assays

Allen D. Smith, Virginia C. Morris and Orville A. Levander

Summary

Gluthatione peroxidase and thioredoxin reductase are selenocysteine-containing enzymes that are constituents of the cellular antioxidant defense system. Conventional cuvette-based assays for glutathione peroxidase and thioredoxin reductase enzymes are laborious and time consuming. The ability to assay their activities rapidly in multiple samples would aid efforts focused on understanding the impact of these enzymes on the cellular antioxidant defense system. High throughput can be achieved with assays adapted to work in a clinical analyzer but require expensive equipment. Assays designed to work in a 96-well microplate reader provide an alternative methodology for high throughput with reduced instrumentation cost. However, due to differences in the light pathlength when using a 96-well format, the values obtained cannot be compared directly with those obtained using a 1-cm cuvette. Described here are assays for glutathione peroxidase and thioredoxin reductase modified to work in a 96-well format that incorporates light pathlength determinations into the assays. The values obtained using a high throughput 96-well format in conjunction with pathlength determinations are in agreement with those obtained using a standard 1-cm cuvette. While spectrophotometrically derived pathlengths are the most accurate, calculated pathlengths based on assay volume and well size can be used with only a small amount of error introduced. This method can also be applied to many other enzyme assays, thus allowing the rapid analysis of large numbers of samples without the need for expensive equipment.

Key words

Glutathione peroxidase, thioredoxin reductase, microplate, selenium, assay

International Journal for Vitamin and Nutrition Research,
Band 71, 2001, Heft 1, © Verlag Hans Huber AG, Bern