Effect of Vitamin K on Vascular Health and Physical Function in Older People with Vascular Disease--A Randomised Controlled Trial

BACKGROUND AND AIMS

Vitamin K insufficiency is common and linked to an increased risk of cardiovascular disease and osteoporotic fractures. The aim of this study was to examine whether daily supplementation with oral vitamin K could improve vascular health and physical function in older people with established vascular disease.

METHODS AND RESULTS

A double blind, randomised, placebo-controlled trial. Participants aged ≤ 70 years with a history of vascular disease were randomised to receive 6 months of daily oral 100mcg vitamin K2 (MK7 subtype) or matching placebo with outcomes measured at 0, 3 and 6 months. The primary outcome was between-group difference in endothelial function assessed using flow-mediated dilatation of the brachial artery at 6 months. Secondary outcomes included carotid-radial pulse wave velocity, augmentation index, blood pressure, carotid intima-media thickness, C-reactive protein, B-type natriuretic peptide, cholesterol and desphospho-uncarboxylated matrix Gla protein levels. Handgrip strength and the Short Physical Performance Battery assessed physical function, while postural sway was measured using a 3-dimensional force platform.

RESULTS

80 participants were randomised, mean age 77 (SD 5) years; 44/80 were male. Vitamin K levels rose in the intervention arm compared to placebo (+48 pg/ml vs -6 pg/ml, p=0.03) at 6 months. Desphospho-uncarboxylated Matrix Gla protein levels fell in the intervention group compared to placebo at 6 months (-130 [SD 117] pmol/L vs +13 [SD 180] pmol/L, p<0.001). No change was seen in endothelial function (between group difference -0.3% [95%CI -1.3 to 0.8], p=0.62). A modest, non-significant improvement in pulse wave velocity was seen in the vitamin K group (-0.8m/s [95%CI -1.8 to 0.3], p=0.15) while all other vascular and physical function outcomes unchanged.

CONCLUSIONS

Six months of vitamin K2 supplementation did not improve markers of vascular health or physical function in older patients with vascular disease.

Modification of high saturated fat diet with n-3 polyunsaturated fat improves glucose intolerance and vascular dysfunction

AIMS

The ability of dietary enrichment with monounsaturated fatty acid (MUFA), n-3 or n-6 polyunsaturated fatty acids (PUFAs) to reverse glucose intolerance and vascular dysfunction resulting from excessive dietary saturated fatty acids is not resolved. We hypothesized that partial replacement of dietary saturated fats with n-3 PUFA-enriched menhaden oil (MO) would provide greater improvement in glucose tolerance and vascular function compared to n-6 enriched safflower oil (SO) or MUFA-enriched olive oil (OO).

METHODS

We fed mice a high saturated fat diet (HF) (60% kcal from lard) for 12 weeks before substituting half the lard with MO, SO or OO for an additional 4 weeks. At the end of 4 weeks, we assessed glucose tolerance, insulin signalling and reactivity of isolated pressurized gracilis arteries.

RESULTS

After 12 weeks of saturated fat diet, body weights were elevated and glucose tolerance was abnormal compared to mice on control diet (13% kcal lard). Diet substituted with MO restored basal glucose levels, glucose tolerance and indices of insulin signalling (phosphorylated Akt) to normal, whereas restoration was limited for SO and OO substitutions. Although dilation to acetylcholine was reduced in arteries from mice on HF, OO and SO diets compared to normal diet, dilation to acetylcholine was fully restored and constriction to phenylephrine was reduced in MO-fed mice compared to normal.

CONCLUSION

We conclude that short-term enrichment of an ongoing high fat diet with n-3 PUFA rich MO, but not MUFA rich OO or n-6 PUFA rich SO, reverses glucose tolerance, insulin signalling and vascular dysfunction.

The effects of dietary and nutrient interventions on arterial stiffness: a systematic review

BACKGROUND

Although dietary and nutrient interventions have been extensively studied as a means of improving arterial stiffness, to our knowledge no systematic analysis of the data has been conducted.

OBJECTIVE

The aim of the current study was to systematically review the human clinical trial data and qualitatively examine the efficacy of dietary and nutrient interventions in the treatment of arterial stiffness.

DESIGN

We systematically searched multiple databases until July 2010 for relevant randomized controlled human clinical trials of common dietary and nutrient interventions in the treatment of arterial stiffness. Located studies were subject to strict inclusion criteria and objectively assessed for scientific quality.

RESULTS

Of the 75 relevant studies located, we considered 38 studies to be appropriate for review. Results revealed support for intakes of omega-3 (n-3) fish oils (Cohen's d = 0.21-0.81) and soy isoflavones (Cohen's d = 0.35-0.39) in the treatment of arterial stiffness. There was limited but consistent evidence to suggest that salt restriction (Cohen's d = 0.28-0.37) as well as consumption of fermented-milk products (Cohen's d = 0.15-0.33) that contain bioactive peptides improved arterial stiffness. The evidentiary support for intakes of vitamins, micronutrients, and herbal medicines was insufficient. Limited but consistent evidence suggested that caffeine intake acutely increased arterial stiffness (Cohen's d = 0.34-0.51).

CONCLUSIONS

Current evidence from several small studies suggests that omega-3 and soy isoflavone supplementation provides an effective means of reducing arterial stiffness. There was little research that explored intakes of herbal medicines or micronutrients in the treatment of arterial stiffness, and this remains an area of potential research.

Morinda citrifolia fruit reduces stress-induced impairment of cognitive function accompanied by vasculature improvement in mice

The purpose of this study was to investigate effects of Morinda citrifolia fruit juice, which is locally called Noni, on stress-induced impairment of cognitive function. Male ICR mice were divided into four groups: Control (C mice), Restraint stress (RS mice), Restraint+Noni (Noni mice), and Restraint+vitamin E (VE mice). The RS, Noni, and VE mice were subjected to 8h of chronic restraint stress (CRS) 6days a week for 6weeks. During this period, the Noni and VE mice were given a diet supplemented with either Noni or vitamin E, respectively. At Week 5, the mice were subjected to the Morris water maze (MWM) test to measure cognitive function. At Week 7, mouse brains were isolated for immunohistochemical analysis with BrdU or CD31 antibody to assess the proliferation of new cells and blood vessel density in the dentate gyrus of the hippocampus. The time taken to reach the platform in the MWM test was shorter in the Noni mice than in the RS mice on Day 16. Malondialdehyde (MDA ) level of the Noni mice was significantly higher than that of the C mice; however no difference was found in MDA levels between the VE and C mice. Blood vessel area was significantly lower in the R and VE mice than in the C mice; no difference was found between the C and Noni mice. These findings suggest that the administration of Noni fruit juice protects brains from stress-induced impairment of cognitive function and that this protective effect may be related to improvement in stress-induced decreases in blood vessel density in the hippocampal dentate gyrus.

Endothelial dysfunction in obesity: etiological role in atherosclerosis

PURPOSE OF REVIEW

To review studies of vascular endothelial dysfunction in obesity, discuss potential mechanisms of disease, and address the therapeutic effects of weight loss interventions on arterial health.

RECENT FINDINGS

Endothelial dysfunction represents the earliest abnormality in the development of vascular disease, and is pathophysiologically linked to subsequent atherosclerosis progression and cardiovascular disease events. Obesity is closely associated with a number of established cardiovascular risk factors, including diabetes mellitus, insulin resistance, dyslipidemia, and hypertension that are cumulatively damaging to the endothelium. In addition, there is now a growing recognition of non-traditional risk factors as potential modulators of the endothelial phenotype in obesity, including fat tissue production of proatherogenic adipokines, oxidative stress, and chronic inflammation. Clinical studies have demonstrated that even modest weight loss reverses endothelial dysfunction, and the restoration of arterial homeostasis could potentially reduce cardiovascular risk.

SUMMARY

Obesity is associated with altered arterial homeostasis and endothelial dysfunction. Mechanisms of disease are related to a complex interplay of metabolic and inflammatory factors that coordinately improve along with arterial function in response to weight loss interventions.

Chronic abdominal pain associated with intermittent compression of the celiac artery

Recurrent abdominal pain (RAP), surely one of the most frequent causes of medical intervention, is frequently present in many gastrointestinal disease. Usually no structural and/or biochemical alterations can be demonstrated. This condition is, therefore, considered to be due to functional disorders such as irritable bowel syndrome (IBS) or functional dyspepsia. Previous observations suggest the presence of a rare alteration of celiac vessels among the possible causes of RAP. This pathological condition was known as Dunbar syndrome. We report 2 cases of chronic abdominal pain. The former reported weight loss and the latter anemia with iron deficiency. It is remarkable that patients with initial diagnosis of IBS can be affected by celiac disease (CD), which is the cause of their abdominal pain. Our patients were tested for CD; the former was negative and IBS was diagnosed, the latter was positive and a gluten free diet was prescribed. The presence of an epigastric bruit, accentuated during expiration, suggested a possible vascular alteration known as tripod celiac artery compression syndrome. Duplex Doppler sonography suggests the diagnosis of celiac arterial constriction due the diaphragmatic ligament. These cases show that tripod celiac artery compression syndrome might be a cause of RAP and that it may be evaluated and investigated when the clinical examination discloses an abdominal systolic bruit.

Soy protein diet improves endothelial dysfunction in renal transplant patients

BACKGROUND

Since it has been demonstrated that soy diet can improve endothelial function, in the present study we evaluated the effect of dietary substitution of 25 g of animal proteins with soy proteins on endothelial dysfunction in renal transplant patients.

METHODS

In 20 renal transplant patients (55 +/- 11 years, serum creatinine 1.7 +/- 0.6 mg/dl), brachial artery flow mediated dilation (FMD) and endothelium-independent vasodilation (sublingual nitroglycerine, 25 microg) were measured at baseline, after 5 weeks of a soy diet and finally after 5 weeks of soy wash-out. Changes in plasma lipids, markers of oxidative stress (lipid peroxides, LOOH) and inflammation (C-reactive protein), isoflavones (genistein and daidzein), asymmetric dimethyl arginine (ADMA) and L-arginine were also evaluated.

RESULTS

At baseline, patients showed a significantly lower FMD as compared with age-matched healthy subjects (3.2 +/- 1.8 vs 6.3 +/- 1.9, respectively; P < 0.001), while response to nitroglycerine was similar. After soy diet, actual protein intake was not changed, cholesterol and lipid peroxides were significantly reduced, and isoflavones were detectable in plasma. Soy diet was associated with a significant improvement in FMD (4.4 +/- 2.0; P = 0.003 vs baseline), while response to nitroglycerine was unchanged. Improvement in FMD was related to L-arginine/ADMA ratio changes, but no significant relation was found to changes in cholesterol, lipid peroxides or genistein and daidzein plasma concentrations. After 5 weeks of soy diet discontinuation, FMD (3.3 +/- 1.7%) returned to baseline values and isoflavones were no longer detectable in plasma.

CONCLUSIONS

A soy protein diet for 5 weeks improves endothelial function in renal transplant patients. This effect seems to be strictly dependent on soy intake as it disappears after soy withdrawal and is mediated by an increase in the L-arginine/ADMA ratio, independently of change in lipid profile, oxidative stress or isoflavones.

RELATIONSHIP BETWEEN ARTERIAL STIFFNESS AND GLUCOSE METABOLISM IN WOMEN WITH METABOLIC SYNDROME

1. Cardiovascular risk factors associated with the metabolic syndrome affect vascular functions adversely. The aim of the present study was to assess the relationship between parameters of glucose homeostasis and arterial stiffness in women with characteristics of the metabolic syndrome. 2. Twenty post-menopausal women participated in a cross-sectional study in which systemic arterial compliance (SAC) and plasma glucose, lipids and glycosylated haemoglobin (HbA1c) were measured while subjects were maintained on a diet high in fibre, raised in protein and reduced in saturated fat. 3. Regression analysis suggested that mean ( +/-SD) fasting glucose of 5.9 +/- 1.7 mmol/L, glucose levels 2 h after a 75 g glucose load of 6.8 +/- 3.6 mmol/L, systolic blood pressure of 131 +/- 12 mmHg and HbA1c of 5.3 +/- 1.7% predicted SAC negatively. The following correlations were obtained between SAC and: (i) fasting glucose: R = -0.49, P = 0.028; (ii) 2 h glucose level post-glucose load: R = -0.42, P = 0.064; (iii) HbA1c: R = -0.42, P = 0.056; and (iv) systolic blood pressure: R = -0.55, P = 0.012. 4. Relationships between SAC and fasting glucose and systolic blood pressure were significantly independent of each other. There was no evidence of relationships between SAC and any plasma lipid parameter (other than a trend in relation to plasma triglyceride), bodyweight or waist circumference. 5. In conclusion, in post-menopausal women with metabolic syndrome, fasting plasma glucose and systolic blood pressure, and possibly HbA1c and the 2 h glucose post-glucose load, predicted increased arterial stiffness.

Glycine rectifies vascular dysfunction induced by dietary protein imbalance during pregnancy

Protein restriction in rat pregnancy programmes the development of elevated systolic blood pressure and vascular dysfunction in the offspring. A recent study has shown that hypertension is reversed by maternal glycine supplementation. Whether this protective effect is exerted directly on the embryo and fetus, or indirectly via effects on the mother, is unknown although we have previously shown abnormalities in the maternal vasculature. We tested the hypothesis that dietary glycine repletion would reverse endothelial dysfunction in protein-restricted pregnant rat dams using wire myography. Impaired acetylcholine- (P < 0.01) and isoprenaline-induced (P < 0.05) vasodilatation in isolated mesenteric arteries (MA) from protein-restricted pregnant dams was accompanied by reduced vascular nitric oxide (NO) release (P < 0.05). Dietary glycine supplementation reversed vascular dysfunction in MA (P < 0.05) and improved NO release thus potentially protecting the maternal circulation. The impaired NO release in the MA of low protein diet dams was not accompanied by reduced eNOS mRNA expression, suggesting that eNOS activity was altered. Protein restriction did not alter the vascular function of a conduit artery, the thoracic aorta. These results provide evidence that adequate provision of glycine, a conditionally essential amino acid in pregnancy, may play a role in the vascular adaptations to pregnancy, protecting the fetus from abnormal programming of the cardiovascular system.

Improvement of vascular dysfunction and blood lipids of insulin-resistant rats by a marine oil-based phytosterol compound

The syndrome that is characterized by obesity, insulin resistance, and hyperlipidemia is increasingly prevalent in all prosperous societies. It is now recognized as a major contributor to cardiovascular disease. Vascular dysfunction in the form of hypercontractility and impaired nitric oxide-mediated relaxation is a significant component of cardiovascular disease, predisposing to ischemic events. The JCR:LA-cp strain of rats exhibits all major aspects of the obesity/insulin resistance syndrome, including vascular dysfunction and ischemic lesions of the heart. Dietary lipid intake may have a marked effect on plasma lipid levels and, potentially, on vascular disease. We have investigated the effects of a novel preparation, ONC101 (a phytosterol esterified with fish oil), on plasma lipids and vascular function in the insulin-resistant JCR:LA-cp rat. Treatment of obese male rats with ONC101 from 8 to 12 wk of age resulted in no change in plasma lipid concentrations at 0.5 g/kg body weight. At the higher dose of 2.6 g/kg, plasma TG fell 50% (1.26 vs. 2.59 mmol/L, P < 0.002) and cholesterol esters were significantly reduced (1.34 vs. 1.61 mmol/L, P < 0.002). Food intake and body weights were unaffected by ONC101 treatment. At the low dose of 86 mg/kg, the hypercontractility of aortic rings in response to phenylephrine was normalized and the relaxant response to acetylcholine was significantly improved. The results indicate that ONC101 at high doses has significant hypolipidemic effects and, at very low doses, has beneficial effects on endothelial and vascular smooth muscle cell function.

The effects of dietary restriction on age-related changes in rat serum prostaglandins

This study investigated whether or not dietary restriction (DR), consisting of 60% of the daily caloric allowance of ad libitum fed (AL) rats, has a modulating effect on prostaglandins (PGs), thromboxane (TXA), and lipids in the serum of rats. Results showed that DR rats had consistently, 30-40% lower overall lipid peroxide levels than AL rats. On the other hand, the age-related increases in arachidonic acid contents observed in AL rats were significantly suppressed by DR during aging; while unsaturated/saturated fatty acid ratios remained consistently higher (15-50%) in DR rats than in AL rats. Serum PGE2 and PGF2 levels in DR rats were maintained at consistently higher levels (30-65% and 40-90%, respectively) than in AL rat serum. PGI2 levels (as measured by 6-keto PGF2) in serum of DR rats were also consistently higher (40-50%) than those of AL rats, while TXA2 levels sustained lower levels (15-20%) than those of AL rats, showing a significantly higher (27-38%) PGI2/TXA2 ratios in DR than in AL rats. Thus, our study clearly indicated that DR effectively modulates prostaglandin levels by preventing age-related decreases in PGI2 levels and increases in TXA2 levels. These findings, with the other known beneficial actions of DR, strongly suggest vascular activity to be well-regulated in DR animals.

[Risk factors for arteriosclerosis and diet of surgical patients. 10 years of outpatient activity]

The follow-up of arteriopathic subjects who have already been hospitalized (abdominal-peripheral vascular district 79% of patient and supra-aortic branch district 21%) has been carried out for around 10 years using an out-patient regime at the Institute of General and Cardiovascular Surgery of Milan. During outpatient visit the main risk factors for arteriosclerosis are routinely checked and treated if required; among the various therapies for metabolic control particular emphasis is placed on diet since its influence on the metabolism is well known, above all in the long term. The efficacy of this treatment has been evaluated by evaluating blood chemical changes (total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, VLDL and glycemia) in a group of patients who followed the diet in comparison to a group which did not. The results obtained show that in dieting patients there was a statistically significant decrease in blood values for total cholesterol, LDL cholesterol, triglycerides and VLDL, together with a decrement, which failed to reach statistical significance, in glycemia and HDL cholesterol. In non-dieting patients it was found that all parameters increased but that this was only statistically significant for total cholesterol and HDL cholesterol. The control of risk factors for arteriosclerosis through diet therapy therefore appears to be satisfactory even for secondary prevention in surgical arteriopathic subjects. It is important to underline that these results were not obtained under conditions of clinical research but in the reality of day-to-day clinical and therapeutic activity whose efficacy is vitally important for scientific health.

Plasma lipid levels and platelet and neutrophil function in patients with vascular disease following fish oil and olive oil supplementation

This double-blind study was designed to examine and compare the effects of supplementing the existing diet with fish oil or olive oil on lipids and cell function in patients with peripheral vascular disease. Thirty-two patients with symptomatic and angiographically demonstrated peripheral vascular disease were screened, matched, and randomly allocated to take either 15 g/d fish oil or olive oil for 4 weeks. Fish oil reduced serum triglyceride levels by 26%, but increased total cholesterol levels due to a significant increase in both low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein-2 cholesterol (HDL2-C). There was a nonsignificant decrease in HDL3-C levels. Olive oil reduced total cholesterol levels, accountable to a significantly decrease in LDL-C levels. Serum thromboxane B2 (TXB2) levels remained unchanged following fish oil, but were significantly increased by olive oil. Urinary excretion of TXB2 and 6-keto-PGF1 alpha was unaffected by either oil supplement. Platelet aggregation, which was measured in platelet-rich plasma in response to two doses of collagen or platelet-activating factor (PAF), was significantly reduced after fish oil, but was increased by olive oil. Following fish oil, there was a significant increase in eicosapentaenoic acid (EPA, 20:5) and docosahexaenoic acid (DHA, 22:6) levels and a decrease in arachidonic acid content of platelet phospholipids. The platelet fatty acid composition after olive oil was unchanged. Fish oil decreased neutrophil leukotriene B4 (LTB4) generation following calcium ionophore stimulation by 33%, while leukotriene B5 levels increased significantly. Neutrophil PAF production and plasma lyso-PAF were unaffected by either oil.(ABSTRACT TRUNCATED AT 250 WORDS)

Reducing blood cholesterol levels in patients with peripheral vascular disease: dietitian or diet fact sheet?

A randomized trial was performed to test the hypothesis that, among patients with peripheral vascular disease, no difference is achieved in the magnitude of the reduction in blood cholesterol levels as a result of advice which is provided by a dietitian and that which is provided by a diet fact sheet. Fifty-nine patients were allocated at random either to a "dietitian" group (n = 31) or to a "diet fact sheet" group (n = 28). Dietary advice which was provided by a dietitian involved two personal interviews; the diet fact sheet was prepared by the NSW Department of Health. Twenty-two and 23 members of each group, respectively, returned for follow-up at three months. The mean cholesterol level fell by 8.5% among the "dietitian" group but only by 1.9% among the "diet fact sheet" group. The difference of 0.47 mmol/L in the total cholesterol level reduction between the two groups was statistically significant (P = 0.02; 95% confidence interval, -0.88 to -0.07 mmol/L). It appears that individual advice which is provided by a dietitian is more successful in leading to a reduction in blood cholesterol levels than is the administration of a diet fact sheet, even though this particular diet fact sheet appears to be excellent and is used widely. In view of the large numbers of patients and of persons in the population as a whole who would benefit from a reduction in blood cholesterol levels, and the expense of individual advice to be provided by a dietitian, explorations of cost-effective methods of providing dietary advice are needed.

Effects of two "lipid-lowering" diets on plasma lipid levels of patients with peripheral vascular disease

Fifty subjects with peripheral vascular disease were randomly assigned to either the American Heart Association Hyperlipidemia Diet C (AHA, N = 23) or a higher fiber, low fat diet based on the Pritikin maintenance diet (HFD, N = 27) and studied for a 12-month period. Diet counseling was provided, and the subjects were encouraged to exercise regularly, to decrease their consumption of salt, alcohol, and caffeine, and to restrict cigarettes as much as possible. Dietary intake data showed that energy distribution was approximately 49% and 64% carbohydrate, 20% and 22% protein, and 31% and 14% fat for the AHA and HFD groups, respectively. Cholesterol and dietary fiber intakes averaged 201 mg and 23 gm per day, respectively, for the AHA group and 108 mg and 43 gm per day, respectively, for the HFD group. Generally, both groups showed tendencies toward decreased serum triglycerides, cholesterol, and LDL cholesterol and increased HDL cholesterol. The HFD group achieved a significant decrease in serum cholesterol (at month 12) (p less than .01). The only significant between-group difference was in serum cholesterol at 4 months (p less than .01), with the lower value in the HFD group. There was a consistent negative correlation between dietary fiber and serum cholesterol levels (p less than .01). Average weight loss was 4.1 kg for the AHA group and 6 kg for the HFD group. We concluded that both dietary regimens, combined with exercise, can be of benefit to patients with peripheral vascular disease.

Beneficial effect of fish oil on blood viscosity in peripheral vascular disease

Reports suggest that the low incidence of ischaemic heart disease in Greenlandic Eskimos is related to the effect of a diet rich in eicosapentaenoic acid on platelet reactivity and plasma lipid concentrations. A double blind randomised investigation was therefore conducted of the effects on blood viscosity of dietary supplementation with an oil rich in this fatty acid (1.8 g/day, given as fish oil) and an eicosapentaenoic acid poor oil (as corn/olive oil) in patients with peripheral arterial disease. A statistically significant reduction in whole blood viscosity was observed at seven weeks in those patients receiving the eicosapentaenoic acid rich oil. No changes in plasma viscosity, haemoglobin concentration, packed cell volume, or platelet count were seen. A significant fall in plasma triglyceride concentration was also noted only in the patients receiving oil rich in eicosapentaenoic acid; plasma concentrations of cholesterol and high density lipoprotein cholesterol were unchanged. It is concluded that rheological changes that result from a diet rich in eicosapentaenoic acid may contribute to the suggested protective effects of such a diet against arterial disease and that such changes are of potential therapeutic importance in established arterial disease.

Effects of dietary manipulation on vascular status of patients with peripheral vascular disease

In a one-year, double-blind clinical trial, 45 patients with peripheral vascular disease (PVD) were randomly assigned to either the American Heart Association Hyperlipidemia Diet C (n = 20) or a low-fat, high-fiber, complex carbohydrate diet similar to the Pritikin Maintenance Diet (n = 25). Vascular status and blood lipid levels were monitored at 0, 2, 4, 6, and 12 months. Walking distance increased significantly in both groups, with no difference between groups. No vascular parameters changed significantly, suggesting that increased walking distance was due to improved metabolic capacity of the muscle. A trend toward lower blood lipid values was observed, with no significant differences within or between groups. We conclude that while patients with PVD benefit from a program of diet and exercise, there is no apparent advantage to the more difficult complex carbohydrate diet.