Weight Loss Sale

Abstracts

ABSTRACTS FOR THE VITAMIN C CONTROVERSY

41. Vitamin C Supplement Intake and Progression of Carotid Atherosclerosis. the Los Angeles Atherosclerosis Study

American Heart Association meeting presentation March 2000
James H Dwyer, Lisa M. Nicholson,, Anne Shircore, Ping Sun, Keck Sch of Medicine of the Univ of Southern CA, Los Angelos, CA; C Noel Bairey Merz, Cedars-Sinai Med Ctr, Los Angeles,CA, Kathleen M Dwyer, Keck Sch of Medicine of the Univ of Southern CA;. Los Angeles, CA

Several clinical studies have found that vitamin C supplements (CS) acutely improve vasodilation and blood flow after hyperemia. However, evidence concerning long-term effects of chronic CS intake on mortality and cardiovascular disease is inconsistent. Method. The relation between CS intake during the previous year and progress or arterial wall thickening was investigated in a cohort of 373 employees from a large utility company. Participants were aged 40-60 years and free of symptomatic cardiovascular disease at entry. Wall thickness was measured at baseline and 18-month follow-up as far wall intima-media thickness (IMT) of the left and right common carotid arteries using high resolution B-mode ultrasound. Regular intake of CS and other supplements over the previous year was measured with a questionnaire at baseline, while intake of vitamin C from food (CF) was determined from three 24-hr recalls. Results. The validity of self-reported CS intake at baseline was supported by plasma ascorbate. Plasma ascorbate levels increased across tertiles of CS intake: 0.61±0.02 mg/dL±SEM (non-users), 0.63±0.06 (20-190 mg/day), 0.75±0.05 (192-479), 0.89±0.05 (480-3355). In regression analysis, the logarithm of CS intake was a significant positive predictor of IMT progression in age-sex adjusted (p=0.001) and cardiovascular risk factor adjusted (p=0.005) models. Further adjustment for intake of vitamin E and multiple vitamin supplements did not reduce the strength of this association. The association was observed in both women (p=0.01) and men (p=0.03), and was dose dependent. IMT progression increased by 1.2, 2.1 and 2.7-fold across tertiles of CS intake, relative to nonusers of CS. This adverse association was stronger in baseline current smokers than in non-smokers, but the interaction was not significant in a covariate-adjusted model (p=0.09). In contrast, CF showed a small inverse relation with IMT progression. Conclusion. Regular use of vitamin C supplements may promote early atherosclerosis. Population use of these supplements for primary prevention of cardiovascular disease should await the outcome of randomized trials.



42. Dietary antioxidants and carotid artery wall thickness. The ARIC Study.
Atherosclerosis Risk in Communities Study.

Circulation 1995 Oct 15;92(8):2142-50
Kritchevsky SB, Shimakawa T, Tell GS, Dennis B, Carpenter M, Eckfeldt JH,
Peacher-Ryan H, Heiss G
Department of Preventive Medicine, University of Tennessee, Memphis 38163, USA.

BACKGROUND: Evidence that dietary antioxidants may prevent atherosclerotic
disease is growing. The relationship between the intake of dietary and
supplemental vitamin C, alpha-tocopherol, and provitamin A carotenoids and average carotid artery wall thickness was studied in 6318 female and 4989 male participants 45 to 64 years old int he Atherosclerosis Risk in Communities Study. METHODS AND RESULTS: Intake was assessed by use of a 66-item semiquantitative food-frequency questionnaire. Carotid artery intima-media wall thickness was measured as an indicator of atherosclerosis at multiple sites with B-mode ultrasound. Among men and women > 55 years old who had not recently begun a special diet, there was a significant inverse relationship between vitamin C intake and average artery wall thickness adjusted for age, body mass index, fasting serum glucose, systolic and diastolic blood pressures, HDL and LDL cholesterol, total caloric intake, cigarette use, race, and education (test for linear trend across quintiles of intake, P = .019 for women and P = .035 for men). An inverse relationship was also seen between wall thickness and alpha-tocopherol intake but was significant only in women (test for linear trend, P = .033 for women and P = .13 for men). There was a significant inverse association between carotene intake and wall thickness in older men (test for linear trend, P = .015), but the association weakened after adjustment for potential confounders. No significant relationships were seen in participants < 55 years old. CONCLUSIONS: These data provide limited support for the hypothesis that dietary vitamin C and alpha-tocopherol may protect against atherosclerotic disease, especially in individuals > 55 years old.



43. Body iron stores and the risk of carotid atherosclerosis: prospective results from the Bruneck study.

Circulation 1997 Nov 18;96(10):3300-7
Kiechl S, Willeit J, Egger G, Poewe W, Oberhollenzer F
Department of Neurology, Innsbruck University Clinic, Austria.

BACKGROUND: Fe2+ released from tissue iron stores may accelerate lipid peroxidation by virtue of its pro-oxidant properties and thus promote early atherogenesis. METHODS AND RESULTS: The present prospective survey addresses the potential association between serum ferritin concentrations and the 5-year progression of carotid atherosclerosis as assessed by ultrasonographic follow-up evaluations. The study population comprises a random sample of 826 men and women 40 to 79 years old. Serum ferritin was one of the strongest risk predictors of overall progression of atherosclerosis. The main part of this association appeared to act through modification of the atherogenic potential of LDL cholesterol (OR [95% CI] for a 1-SD unit increase in ferritin at LDL levels of 2.5, 3.6, and 4.9 mmol/L: 1.55 [1.30 to 1.85], 1.77 [1.40 to 2.24], and 2.05 [1.50 to 2.80]; P=.0012 for effect modification). Changes in iron stores during the follow-up period modified atherosclerosis risk, in that a lowering was beneficial and further iron accumulation exerted unfavorable effects. All these findings applied equally to incident atherosclerosis and the extension of preexisting atherosclerotic lesions. The significance of prominent iron stores in the development of carotid stenosis was clearly less pronounced. Finally, ferritin and LDL cholesterol showed a synergistic association with incident cardiovascular disease and death (n=59). CONCLUSIONS: The present study provided strong epidemiological evidence for a role of iron stores in early atherogenesis and suggests promotion of lipid peroxidation as the main underlying pathomechanism. This hypothesis could in part explain the sex difference in atherosclerotic vascular disease.


44. Increased systemic oxidative stress after elective endarterectomy: relation to vascular healing and remodeling.

Arterioscler Thromb Vasc Biol 1999 Nov;19(11):2659-65
Mezzetti A, Guglielmi MD, Pierdomenico SD, Costantini F, Cipollone F, De Cesare D, Bucciarelli T, Ucchino S, Chiarelli F, Cuccurullo F, Romano F
Centro per lo Studio dell'Ipertensione Arteriosa delle Dislipidemie e dell'Aterosclerosi, University "Gabriele D'Annunzio", Chieti, Italy. mezzetti@unich.it

It has been reported that systemic and local redox state may have an important role in the functional and organic changes characterizing the process of vascular response to injury. Carotid endarterectomy to remove atherosclerotic plaque is followed by a long lasting healing and remodeling process that can be carefully followed over time with noninvasive ultrasonography. Plasma vitamin C concentration and native LDL (n-LDL) content in lipid peroxides, vitamin E, beta-carotene, and lycopene as well as LDL susceptibility to peroxidation were assessed in 45 patients undergoing elective endarterectomy for internal carotid stenosis, at baseline, 24 hours, 3 and 15 days, and 1 month after surgery. Serial duplex scans were performed in all patients postoperatively and 3, 6, and 12 months. The changes in far wall thickness (FW) and % renarrowing from postoperatively to 12 months were used as remodeling indices. Plasma antioxidant vitamins and lag-phase showed a sharp and significant decrease during the first 24-hours after surgery remaining unchanged until the third day, whereas, an opposite trend was evidenced for n-LDL content in lipid peroxides and serum ceruloplasmin. After the third day all the parameters returned progressively to baseline within one month from endarterectomy. Interestingly, the n-LDL lipid peroxide content, the serum ceruloplasmin and the plasma vitamin C concentration, measured at 24 and 3 days from surgery, were significantly associated to the change in % renarrowing from postoperatively to 12 months. The higher the LDL content in lipid peroxides, the higher the serum level of ceruloplasmin, the lower the plasma content in vitamin C and the higher the % of vessel renarrowing. In conclusion, carotid endarterectomy with atherosclerotic plaque removal is associated with an acute and prolonged increase in systemic oxidative stress that influences vascular healing and late luminal loss.


45. Effect of coenzyme Q10 on experimental atherosclerosis and chemical composition and quality of atheroma in rabbits.

Atherosclerosis 1999 Feb;148(2):275-82
Singh RB, Shinde SN, Chopra RK, Niaz MA, Thakur AS, Onouchi Z
Centre of Nutrition, Medical Hospital and Research Centre, Moradabad, India.

The effects of the administration of coenzyme Q10 (3 mg/kg per day) (group A, n=10) and placebo (aluminum hydroxide, 3 mg/kg per day) (group B, n=10) were compared over 24 weeks in a randomized, single-blind, controlled trial. There were two groups of rabbits receiving a trans fatty acid (TFA)-rich diet (5-8 g/day) for 36 weeks. Oxidized rabbit chow with vitamin C plus ferric chloride was administered for 4 weeks in all rabbits. Intervention with coenzyme Q10 after feeding of TFA-rich diet was associated with a significant decline in thiobarbituric acid reactive substances (TBARS), diene conjugates and malondialdehyde, and an increase in plasma levels of vitamin E in the coenzyme Q group compared to placebo group. These changes, which were indicators of a decrease in oxidative damage, were independent of lipid lowering. The aortic and coronary artery plaque sizes, coronary atherosclerosis index, aortic and coronary atherosclerosis scores were significantly lower in the coenzyme Q group than placebo group. Aortic and coronary plaque frequencies, as well as frequencies of ulceration, thrombosis or hemorrhage, and cracks and fissures, were also significantly lower in the coenzyme Q group, indicating a better quality of atheroma compared to those in the control group. Aortic cholesterol, triglycerides and sudanophilia were significantly lower and vitamin E significantly higher in the coenzyme Q group in comparison to the placebo group indicating that coenzyme Q10 can have beneficial effect on the chemical composition of atheroma. The findings suggest that antioxidant therapy with coenzyme Q10 may be used as an adjunct to lipid lowering for additional beneficial effects related to chemical composition and quality of atheroma independent of hypolipidemic agents.


46. The antiatherosclerotic effect of Allium sativum.

Atherosclerosis 1999 May;144(1):237-49
Koscielny J, Klussendorf D, Latza R, Schmitt R, Radtke H, Siegel G, Kiesewetter H
Institute for Transfusion Medicine and Immunohematology, University Clinic Charite of the Humboldt University, Berlin, Germany.

In a randomized, double-blind, placebo-controlled clinical trial, the plaque volumes in both carotid and femoral arteries of 152 probationers were determined by B-mode ultrasound. Continuous intake of high-dose garlic powder dragees reduced significantly the increase in arteriosclerotic plaque volume by 5-18% or even effected a slight regression within the observational period of 48 months. Also the age-dependent representation of the plaque volume shows an increase between 50 and 80 years that is diminished under garlic treatment by 6-13% related to 4 years. It seems even more important that with garlic application the plaque volume in the whole collective remained practically constant within the age-span of 50-80 years. These results substantiated that not only a preventive but possibly also a curative role in arteriosclerosis therapy (plaque regression) may be ascribed to garlic remedies.


47. Homocyst(e)ine: an important risk factor for atherosclerotic vascular disease.

Curr Opin Lipidol 1997 Feb;8(1):28-34
Duell PB, Malinow MR
Department of Medicine, Oregon Health Sciences University, Portland 97201-3098, USA.
duellb@ohsu.edu

Homocysteine is an intermediate compound formed during metabolism of methionine. The results of many recent studies have indicated that elevated plasma levels of homocyst(e)ine are associated with increased risk of coronary atherosclerosis, cerebrovascular disease, peripheral vascular disease, and thrombosis. The plasma level of homocyst(e)ine is dependent on genetically regulated levels of essential enzymes and the intake of folic acid, vitamin B6 (pyridoxine), and vitamin B12 (cobalamin). Impaired renal function, increased age, and pharmacologic agents (e.g. nitrous oxide, methotrexate) can contribute to increased levels of homocyst(e)ine. Plausible mechanisms by which homocyst(e)ine might contribute to atherogenesis include promotion of platelet activation and enhanced coagulability, increased smooth muscle cell proliferation, cytotoxicity, induction of endothelial dysfunction, and stimulation of LDL oxidation. Levels of homocysteine can be reduced with pharmacologic doses of folic acid, pyridoxine, vitamin B12, or betaine, but further research is required to determine the efficacy of this intervention in reducing morbidity and mortality associated with atherosclerotic vascular disease.



48. Plasma homocyst(e)ine and arterial occlusive diseases: a mini-review.

Clin Chem 1995 Jan;41(1):173-6
Malinow MR
Oregon Regional Primate Research Center, Beaverton 97006.

Homocysteine (HCY), which is derived from the intracellular metabolism of methionine, is exported into plasma, where it circulates mostly in oxidized forms (i.e., homocystine and cysteine-HCY disulfide) and mainly bound to proteins. Concentrations of total HCY, or homocyst(e)ine [H(e)], are increased in 15-40% of patients with coronary, cerebral, or peripheral arterial diseases.
Such association of H(e) with arterial occlusive diseases has been documented in retrospective, cross-sectional, and prospective studies. Concentrations of H(e) are also increased in subjects having thickened carotid arteries, as determined by ultrasonography, and who are asymptomatic for atherosclerosis. Statistical analyses of data from several series of patients demonstrate that H(e) concentrations are associated with coronary artery disease, independently from most other risk factors for atherosclerosis. The increased concentrations of H(e) are readily corrected by folic acid, occasionally supplemented with pyridoxine, vitamin B12, choline, or betaine. Whether these supplements affect the evolution of atherosclerotic disease needs to be established by prospective, placebo-controlled clinical trials.


49. Betaine in wine: answer to the French paradox?

Med Hypotheses 1999 Nov;53(5):383-5
Mar MH, Zeisel SH
Department of Nutrition, School of Public Health, School of Medicine, University
of North Carolina, Chapel Hill 27599-7400, USA.

In France, a diet high in saturated fat and cholesterol is associated with low coronary artery disease mortality and it may be that drinking wine is protective against ischemic heart disease. Recent studies suggest that high plasma homocysteine concentrations are an independent risk factor for coronary, cerebral and peripheral arterial occlusive diseases. One of several routes for metabolism of homocysteine involves methylation using betaine as the methyl donor. Betaine is often added to less expensive wine when beet sugar is used to increase alcohol content. We found that many commercial wines contain betaine; an average glass of wine contains approximately 3 mg betaine. This small amount is less than the dose used to lower homocysteine in patients with genetic forms of hyperhomocysteinemia, but we do not know whether humans with modest elevations of homocysteine would be influenced by this dose.



50. Betaine:homocysteine methyltransferase--a new assay for the liver enzyme and its absence from human skin fibroblasts and peripheral blood lymphocytes.

Clin Chim Acta 1991 Dec 31;204(1-3):239-49
Wang JA, Dudman NP, Lynch J, Wilcken DE
Department of Cardiovascular Medicine, Prince Henry Hospital, University of New South Wales, Sydney, Australia.

Chronic elevation of plasma homocysteine is associated with increased atherogenesis and thrombosis, and can be lowered by betaine (N,N,N-trimethylglycine) treatment which is thought to stimulate activity of the enzyme betaine:homocysteine methyltransferase. We have developed a new assay for this enzyme, in which the products of the enzyme-catalysed reaction between betaine and homocysteine are oxidised by performic acid before being separated and quantified by amino acid analysis. This assay confirmed that human liver contains abundant betaine:homocysteine methyltransferase (33.4 nmol/h/mg protein at 37 degrees C, pH 7.4). Chicken and lamb livers also contain the enzyme, with respective activities of 50.4 and 6.2 nmol/h/mg protein. However, phytohaemagglutinin-stimulated human peripheral blood lymphocytes and cultured human skin fibroblasts contained no detectable betaine:homocysteine methyltransferase (less than 1.4 nmol/h/mg protein), even after cells were pre-cultured in media designed to stimulate production of the enzyme. The results emphasize the importance of the liver in mediating the lowering of elevated circulating homocysteine by betaine.