High-dose oral vitamin C partially replenishes vitamin C levels in patients with Type 2 diabetes and low vitamin C levels but does not improve endothelial dysfunction or insulin resistance

Chen, Hui; Karne, Rajaram J.; Hall, G. E.; Campia, Umberto; Panza, Julio A.; Cannon, Richard O.; Wang, Yaohui; Katz, Arie; Levine, Mark; Quon, Michael J.

doi:10.1152/ajpheart.00768.2005

Cited by 159 publications

(116 citation statements)

References 86 publications

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“…Importantly, there was no improvement in forearm vascular responses to the endothelium-independent vasodilator sodium nitroprusside, which suggests that the beneficial effects of fruit and vegetable intake are related to protective effects on the endothelium 156 . The data from this study are in contrast to forearm plethysmography studies that assessed the effect of ascorbic acid on forearm vascular responses and suggest that a balanced, pragmatic approach that considers whole food and dietary patterns may be the best means of improving the overall vascular phenotype of patients with hypertension 156,[178][179][180] . Increased fruit and vegetable consumption may also make patients more likely to adopt other favourable dietary modifications, such as reduced salt and fat consumption.…”

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confidence: 59%

Drug Treatment of Hypertension: Focus on Vascular Health

Cameron

Lang

Touyz

2016

Drugs

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Hypertension, the most common preventable risk factor for cardiovascular disease and death, is a growing health burden. Serious cardiovascular complications result from target organ damage including cerebrovascular disease, heart failure, ischaemic heart disease and renal failure. While many systems contribute to blood pressure elevation, the vascular system is particularly important, because vascular dysfunction is a cause and consequence of hypertension. Hypertension is characterised by a vascular phenotype of endothelial dysfunction, arterial remodelling, vascular inflammation and increased stiffness. Antihypertensive drugs that influence vascular changes associated with high blood pressure have greater efficacy for reducing cardiovascular risk than drugs that reduce blood pressure but have little or no effect on the adverse vascular phenotype. Angiotensin converting enzyme Key Points• Hypertension is characterized by a vascular phenotype of endothelial dysfunction and structural remodeling.• Anti-hypertensive drugs that target the vascular changes associated with hypertension appear to be most efficacious• New anti-hypertensive drugs should promote vascular health as well as reducing blood pressure 3

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mentioning

confidence: 59%

Drug Treatment of Hypertension: Focus on Vascular Health

Cameron

Lang

Touyz

2016

Drugs

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“…Therefore, we were unable to address whether the low serum levels and the coexistence of DM was a cause of the disease or the consequence, while the studies by Harding et al (20) show the evident causal relationship of vitamin C in the development of DM. However, it is controversial whether a high oral dose of vitamin C is beneficial in persons with DM (41)(42)(43)(44)(45) or preventing DM (46). Besides the protective effect of a high dose, it may be necessary to study whether low or deficient status of vitamin C leads or accelerates the development of DM.…”

Section: Discussionmentioning

confidence: 99%

Vitamin C Nutriture in Newly Diagnosed Diabetes

Shim

Paik

Shin

et al. 2010

J Nutr Sci Vitaminol

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SummaryThis study was performed to investigate the relationship between serum Lascorbic acid, vitamin C intake, and diabetes in a nested case-control study. A cross-sectional survey of diet and health was conducted in 2,048 adults with an age of 30 y or older in Yonchon County, Korea. An oral glucose tolerance test was administered to all participants. One hundred cases of newly diagnosed diabetes were identified. Two healthy controls for each case matched with age, gender, drinking status, and smoking status were selected among the survey participants. L -Ascorbic acid levels were analyzed in fasting serum samples and one 24-h dietary recall was performed. Dietary vitamin C intake of persons with diabetes was 50.1 Ϯ 47.6 mg/d and that of controls was 55.1 Ϯ 41.1 mg/d. People with diabetes (22.3 Ϯ 16.8 mol/L) have lower serum ascorbic acid levels than their controls (26.3 Ϯ 17.0 mol/L) and the difference was significant by paired t -test ( p Ͻ 0.01). The association between diabetes and serum ascorbic acid level was still significant in non-smokers (24.2 Ϯ 17.8 mol/L for the diabetes group and 29.5 Ϯ 16.7 mol/L for the control group, p Ͻ 0.01) but not in smokers (19.4 Ϯ 15.7 mol/L for the diabetes group and 21.2 Ϯ 16.0 mol/L for the control group). Our results suggest that diabetes and smoking interactively affect serum ascorbic acid levels. Since this population had poor nutritional status of vitamin C, further investigation of association between serum ascorbic acid level and diabetes and smoking by the level of vitamin C consumption is warranted.

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“…Vitamin C at higher doses than those used to compound BH 4 has been demonstrated in some studies to have a mild antihypertensive effect 26 and to improve endothelial function, although this remains a subject of controversy. [27][28][29][30] To overcome this possibility, we made baseline measurements after a 2-week run-in period with vitamin C alone in Study 2 and found no change in BP. However, a synergistic effect of vitamin C with BH 4 cannot be excluded.…”

Section: Study Limitationsmentioning

confidence: 99%

Tetrahydrobiopterin: a novel antihypertensive therapy

et al. 2008

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Tetrahydrobiopterin (BH 4 ) is a cofactor for the nitric oxide (NO) synthase enzymes, such that its insufficiency results in uncoupling of the enzyme, leading to release of superoxide rather than NO in disease states, including hypertension. We hypothesized that oral BH 4 will reduce arterial blood pressure (BP) and improve endothelial function in hypertensive subjects. Oral BH 4 was given to subjects with poorly controlled hypertension (BP 4135/85 mm Hg) and weekly measurements of BP and endothelial function made. In Study 1, 5 or 10 mg kg À1 day À1 of BH 4 (n ¼ 8) was administered orally for 8 weeks, and in Study 2, 200 and 400 mg of BH 4 (n ¼ 16) was given in divided doses for 4 weeks. Study 1: significant reductions in systolic (P ¼ 0.005) and mean BP (P ¼ 0.01) were observed with both doses of BH 4 . Systolic BP was 15 ± 15 mm Hg (P ¼ 0.04) lower after 5 weeks and persisted for the 8-week study period. Study 2: subjects given 400 mg BH 4 had decreased systolic (P ¼ 0.03) and mean BP (P ¼ 0.04), with a peak decline of 16±19 mm Hg (P ¼ 0.04) at 3 weeks. BP returned to baseline 4 weeks after discontinuation. Significant improvement in endothelial function was observed in Study 1 subjects and those receiving 400 mg BH 4 . There was no significant change in subjects given the 200 mg dose. This pilot investigation indicates that oral BH 4 at a daily dose of 400 mg or higher has a significant and sustained antihypertensive effect in subjects with poorly controlled hypertension, an effect that is associated with improved endothelial NO bioavailability.

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High-dose oral vitamin C partially replenishes vitamin C levels in patients with Type 2 diabetes and low vitamin C levels but does not improve endothelial dysfunction or insulin resistance

Cited by 159 publications

References 86 publications

Drug Treatment of Hypertension: Focus on Vascular Health

Drug Treatment of Hypertension: Focus on Vascular Health

Vitamin C Nutriture in Newly Diagnosed Diabetes

Tetrahydrobiopterin: a novel antihypertensive therapy

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