Relation between dietary fiber consumption and fibrinogen and plasminogen activator inhibitor type 1: The National Heart, Lung, and Blood Institute Family Heart Study

Effects of a novel therapeutic diet on liver enzymes and coagulating factors in patients with non-alcoholic fatty liver disease: A parallel randomized trial

OBJECTIVE

There are several reports regarding the role of therapeutic diets for patients with non-alcoholic fatty liver disease (NAFLD). Therefore, the aim of this study was to determine the effects of a low-calorie, low-carbohydrate soy-containing diet on lipid profiles, liver enzymes, and coagulating factors in patients with NAFLD.

METHOD

This was a randomized parallel clinical trial involving 45 patients with NAFLD. The participants consumed three kinds of diets for 8 wk. Patients were randomly assigned to consume a low-calorie diet; a low-calorie, low-carbohydrate diet; or a low-calorie, low-carbohydrate soy-containing diet. Measurements were done according to the standard method.

RESULTS

Changes in weight were not significantly different in the three groups. The low-calorie, low-carbohydrate soy-containing diet could reduce alanine aminotransferase (-15.2 ± 12.1 versus -6.8 ± 4.6 in the low-calorie, low-carbohydrate diet, and -6.4 ± 4.4 IU/L in the low-calorie diet; P = 0.02) and serum fibrinogen levels (-49.1 ± 60.1 versus -12.9 ± 8.1 and -17.4 ± 8.4 g/L, respectively; P = 0.01). Reductions in aspartate aminotransferase were significantly higher in the low-calorie, low-carbohydrate soy-containing group. Changes in lipid profiles did not differ significantly between the groups. The soy-containing diet did reduce malondialdehyde more than the other diets (P = 0.01).

CONCLUSION

A low-calorie, low-carbohydrate soy-containing diet could have beneficial effects on liver enzymes, malondialdehyde, and serum fibrinogen levels in patients with NAFLD.

No association of dietary fiber intake with inflammation or arterial stiffness in youth with type 1 diabetes

AIM

To examine the association of dietary fiber intake with inflammation and arterial stiffness among youth with type 1 diabetes (T1D) in the US.

METHODS

Data are from youth ≥ 10 years old with clinically diagnosed T1D for ≥ 3 months and ≥ 1 positive diabetes autoantibody in the SEARCH for Diabetes in Youth Study. Fiber intake was assessed by food frequency questionnaire with measurement error (ME) accounted for by structural sub-models derived using additional 24-h dietary recall data in a calibration sample and the respective exposure-disease model covariates. Markers of inflammation, measured at baseline, included IL-6 (n=1405), CRP (n=1387), and fibrinogen (n=1340); markers of arterial stiffness, measured approximately 19 months post-baseline, were available in a subset of participants and included augmentation index (n=180), pulse wave velocity (n=184), and brachial distensibility (n=177).

RESULTS

Mean (SD) T1D duration was 47.9 (43.2) months; 12.5% of participants were obese. Mean (SD) ME-adjusted fiber intake was 15 (2.8) g/day. In multivariable analyses, fiber intake was not associated with inflammation or arterial stiffness.

CONCLUSION

Among youth with T1D, fiber intake does not meet recommendations and is not associated with measures of systemic inflammation or vascular stiffness. Further research is needed to evaluate whether fiber is associated with these outcomes in older individuals with T1D or among individuals with higher intakes than those observed in the present study.

A high intake of dietary fiber influences C-reactive protein and fibrinogen, but not glucose and lipid metabolism, in mildly hypercholesterolemic subjects

PURPOSE

The aim of the study was to investigate how a diet high in dietary fiber, with several fiber sources included, modulates glucose and lipid metabolism and the inflammatory response in humans.

METHODS

Subjects (n = 25) aged 58.6 (1.1) years (mean and SD) with a BMI of 26.6 (0.5) kg/m(2) and a total cholesterol (TC) of 5.8 (0.1) mmol/L (mean and SEM) were given a high fiber (HF) and low fiber (LF) diet, in a randomized controlled 5-week crossover intervention, separated by a 3-week washout. The HF diet consisted of oat bran, rye bran, and sugar beet fiber incorporated into test food products; one bread roll, one ready meal, and two beverages consumed daily. Equivalent food products, without added fibers, were provided in the LF diet.

RESULTS

Total dietary fiber intake was 48.0 g and 30.2 g per day for the HF and LF diet, respectively. Significant reduction in C-reactive protein (CRP) was observed between the diets (P = 0.017) and a significant reduction in fibrinogen within the HF diet (P = 0.044). There were no significant effects in other measured circulating cytokines or in glucose, insulin, and lipid levels.

CONCLUSIONS

Our study suggests that a 5-week high dietary fiber intake of oat bran, rye bran, and sugar beet fiber might reduce the low-grade inflammatory response measured as CRP which could, together with reduced fibrinogen, help to prevent the risk of cardiovascular disease.

Adolescent fiber consumption is associated with visceral fat and inflammatory markers

CONTEXT

The link between adolescent fiber consumption, inflammation, and body fat distribution has not been investigated.

OBJECTIVE

This study investigated associations of dietary fiber intake with inflammatory-related biomarkers and robust measures of total and central adiposity in a sample of 559 adolescents aged 14-18 yr (49% female, 45% Black).

METHODS

Fasting blood samples were measured for leptin, adiponectin, resistin, C-reactive protein, and fibrinogen. Diet was assessed with four to seven 24-h recalls, and physical activity was determined by accelerometry. Fat-free soft tissue mass and fat mass were measured by dual-energy x-ray absorptiometry. Visceral adipose tissue was assessed using magnetic resonance imaging.

RESULTS

Multiple linear regression, adjusting for age, race, Tanner stage, fat-free soft tissue mass, energy intake, and physical activity, revealed that dietary fiber intake was inversely associated with fat mass and serum leptin in males (all P < 0.03) but not in females. In both genders, dietary fiber intake was negatively associated with visceral adipose tissue, plasma C-reactive protein, and plasma fibrinogen and positively associated with plasma adiponectin (all P < 0.05). No relations were found between dietary fiber intake and plasma resistin in either males or females.

CONCLUSION

Our adolescent data suggest that greater consumption of dietary fiber is associated with lower visceral adiposity and multiple biomarkers implicated in inflammation.

A diet rich in oat bran improves blood lipids and hemostatic factors, and reduces apparent energy digestibility in young healthy volunteers

BACKGROUND/OBJECTIVES

Oat bran shows cholesterol-lowering properties, but its effects on other cardiovascular risk markers are less frequently investigated. This study examined the effects of oat bran on blood lipids, hemostatic factors and energy utilization.

SUBJECTS/METHODS

A double-blind, randomized crossover study in 24 adults (age 25.2±2.7 years; body mass index: 24.9±2.9 kg/m2), who completed two 2-week dietary intervention periods: low-fiber diet (control) or an oat bran (control +102 g oat bran/day) diet. Fasting blood samples were drawn before and after each period, and 3-day fecal samples were collected during the last week of each period.

RESULTS

Total cholesterol decreased by 14% during the oat bran period compared with 4% during the control period (P<0.001). Non-high-density lipoprotein (HDL) cholesterol decreased by 16% in the oat bran period compared with 3% in the control period (P<0.01), as did total triacylglycerol (21 vs 10%, P<0.05) and very-low-density lipoprotein triacylglycerol 33 vs 9%, P<0.01). Plasminogen activator inhibitor-1 (PAI-1) and factor VII (fVII) levels decreased more during consumption of oat bran compared with the control period (PAI-1: 30 vs 2.3%, P<0.01; fVII: 15 vs 7.6%, <0.001). Fecal volume and dry matter were greater when consuming the oat bran diet compared with the control (P<0.001), and energy excretion was increased by 37% (1014 vs 638 kJ/day, P<0.001); however, changes in body weight did not differ (oat bran:-0.3±0.5 kg; control: 0.0±0.7 kg).

CONCLUSIONS

Addition of oat bran (6 g soluble fiber/day) to a low-fiber diet lowered total and non-HDL cholesterol, as well as hemostatic factors, and may affect energy balance through reduced energy utilization.

The Dietary Approaches to Stop Hypertension eating plan affects C-reactive protein, coagulation abnormalities, and hepatic function tests among type 2 diabetic patients

Few studies exist regarding the effects of the Dietary Approaches to Stop Hypertension (DASH) diet on novel cardiovascular risk factors among type 2 diabetic patients. We evaluated the effects of the DASH eating pattern on C-reactive protein (CRP) level, coagulation abnormalities, and hepatic function tests in type 2 diabetic patients. In this randomized, crossover clinical trial, 31 type 2 diabetic patients consumed a control diet or the DASH diet for 8 wk. The DASH diet was rich in fruits, vegetables, whole grains, and low-fat dairy products and low in saturated fat, total fat, cholesterol, refined grains, and sweets, with a total of 2400 mg/d sodium. The control diet was a standard diet for diabetic patients. There was a 4-wk washout between the 2 trial phases. The main outcome measures were CRP level, coagulation indices, and hepatic function tests. The mean percent change for plasma CRP level was -26.9 ± 3.5% after the DASH diet period and -5.1 ± 3.8% after the control diet period (P = 0.02). Decreases in both alanine aminotransferase and aspartate aminotransferase levels were greater after consuming the DASH diet compared with the control diet (-14.8 ± 3.0% vs -6.6 ± 3.4%; P = 0.001; -29.4 ± 3.7% vs -5.9 ± 1.4%; P = 0.001, respectively). The decrease in the plasma fibrinogen level during the DASH diet period (-11.4 ± 3.6%) was greater than that during the control diet (0.5 ± 3.4%) (P = 0.03). Among diabetic patients, the DASH diet can play an important role in reducing inflammation, plasma levels of fibrinogen, and liver aminotransferases. Future longer term studies are recommended.

Cereal based diets modulate some markers of oxidative stress and inflammation in lean and obese Zucker rats

Background

The potential of cereals with high antioxidant capacity for reducing oxidative stress and inflammation in obesity is unknown. This study investigated the impact of wheat bran, barley or a control diet (α-cellulose) on the development of oxidative stress and inflammation in lean and obese Zucker rats.

Methods

Seven wk old, lean and obese male Zucker rats (n = 8/group) were fed diets that contained wheat bran, barley or α-cellulose (control). After 3 months on these diets, systolic blood pressure was measured and plasma was analysed for glucose, insulin, lipids, oxygen radical absorbance capacity (ORAC), malondialdehyde, glutathione peroxidase and adipokine concentration (leptin, adiponectin, interleukin (IL)-1β, IL-6, TNFα, plasminogen activator inhibitor (PAI)-1, monocyte chemotactic protein (MCP)-1). Adipokine secretion rates from visceral and subcutaneous adipose tissue explants were also determined.

Results

Obese rats had higher body weight, systolic blood pressure and fasting blood lipids, glucose, insulin, leptin and IL-1β in comparison to lean rats, and these measures were not reduced by consumption of wheat bran or barley based diets. Serum ORAC tended to be higher in obese rats fed wheat bran and barley in comparison to control (p = 0.06). Obese rats had higher plasma malondialdehyde (p < 0.01) and lower plasma glutathione peroxidase concentration (p < 0.01) but these levels were not affected by diet type. PAI-1 was elevated in the plasma of obese rats, and the wheat bran diet in comparison to the control group reduced PAI-1 to levels seen in the lean rats (p < 0.05). These changes in circulating PAI-1 levels could not be explained by PAI-1 secretion rates from visceral or subcutaneous adipose tissue.

Conclusions

A 3-month dietary intervention was sufficient for Zucker obese rats to develop oxidative stress and systemic inflammation. Cereal-based diets with moderate and high antioxidant capacity elicited modest improvements in indices of oxidative stress and inflammation.

Effects of dietary fibers on disturbances clustered in the metabolic syndrome

Because of its growing prevalence in Western countries, the metabolic syndrome, a common metabolic disorder that clusters a constellation of abnormalities, including central obesity, hypertension, dyslipidemia and insulin resistance, is emerging as one of the most important public health problems in the world, taking into account that it is a major risk factor mainly for type 2 diabetes and cardiovascular diseases, and also for many types of cancer. Although the pathogenesis of this syndrome is complex and not fully understood, obesity and insulin resistance, accompanied by an altered profile of number of hormones and cytokines produced by the adipose tissue, seem to be the main causative agents. A prime therapeutic approach to the prevention and treatment of this syndrome involves lifestyle changes. Among dietary modifications, dietary fiber intake could play an interesting role in the management of metabolic syndrome through different mechanisms related to its dietary sources, specific chemical structure and physical properties, or fermentability in the gut. According to all of these variables, the different types of dietary fibers have been reported to take part in the control of body weight, glucose and lipid homeostasis, insulin sensitivity and in the regulation of many inflammation markers involved in the pathogenesis of metabolic syndrome, and which are also considered to be among its features.

Whole-grain foods do not affect insulin sensitivity or markers of lipid peroxidation and inflammation in healthy, moderately overweight subjects

High intakes of whole grain foods are inversely related to the incidence of coronary heart diseases and type 2 diabetes, but the mechanisms remain unclear. Our study aimed to evaluate the effects of a diet rich in whole grains compared with a diet containing the same amount of refined grains on insulin sensitivity and markers of lipid peroxidation and inflammation. In a randomized crossover study, 22 women and 8 men (BMI 28 +/- 2) were given either whole-grain or refined-grain products (3 bread slices, 2 crisp bread slices, 1 portion muesli, and 1 portion pasta) to include in their habitual daily diet for two 6-wk periods. Peripheral insulin sensitivity was determined by euglycemic hyperinsulinemic clamp tests. 8-Iso-prostaglandin F(2alpha) (8-iso PGF(2alpha)), an F(2)-isoprostane, was measured in the urine as a marker of lipid peroxidation, and highly sensitive C-reactive protein and IL-6 were analyzed in plasma as markers of inflammation. Peripheral insulin sensitivity [mg glucose . kg body wt(-1) . min(-1) per unit plasma insulin (mU/L) x 100] did not improve when subjects consumed whole-grain products (6.8 +/- 3.0 at baseline and 6.5 +/- 2.7 after 6 wk) or refined products (6.4 +/- 2.9 and 6.9 +/- 3.2, respectively) and there were no differences between the 2 periods. Whole-grain consumption also did not affect 8-iso-PGF(2alpha) in urine, IL-6 and C-reactive protein in plasma, blood pressure, or serum lipid concentrations. In conclusion, substitution of whole grains (mainly based on milled wheat) for refined-grain products in the habitual daily diet of healthy moderately overweight adults for 6-wk did not affect insulin sensitivity or markers of lipid peroxidation and inflammation.

Sesamol regulates plasminogen activator gene expression in cultured endothelial cells: a potential effect on the fibrinolytic system

Sesamol is a component in the nutritional makeup of sesame that was identified as an antioxidant. In recent years, the importance of the plasminogen activator (PA) and its adjustment factor, plasminogen activator inhibitor-1 (PAI-1), in the prevention of atherosclerosis has gradually received recognition. The objective of this in vitro study was to demonstrate the effects of sesamol on PA and PAI-1. We also compared the effects of sesamol with two well-known antioxidants, vitamins C and E, by using human umbilical vein endothelial cells as an experimental model and by treating them with the above-mentioned three nutrients with doses up to 100 micromol/L. After 24 h, cells and cultural medium were collected for analysis. The concentrations of tissue PA (tPA), urokinase PA (uPA) and PAI-1 were measured by an enzymatic immunity method. Northern blot method was used to analyze the expression of mRNA of these three types of proteins. The results showed that sesamol increased the production of uPA and tPA significantly and also up-regulated the mRNA expressions of these proteins. On the other hand, vitamins C and E could induce tPA but not uPA. As for PAI-1, none of the nutrients induced any evident response. These findings suggest that the overall vascular fibrinolytic capacity may be enhanced by using sesamol to regulate PA gene expression.

Hemochromatosis and Iron Overload Screening (HEIRS) study design for an evaluation of 100,000 primary care-based adults

BACKGROUND

The HEIRS Study will evaluate the prevalence, genetic and environmental determinants, and potential clinical, personal, and societal impact of hemochromatosis and iron overload in a multiethnic, primary care-based sample of 100,000 adults over a 5-year period. Participants are recruited from 5 Field Centers. Laboratory testing and data management and analysis are performed in a Central Laboratory and Coordinating Center, respectively.

METHODS

Participants undergo testing for serum iron measures and common mutations of the hemochromatosis gene ( ) on chromosome 6p and answer questions on demographics, health, and genetic testing attitudes. Participants with elevated values of transferrin saturation and serum ferritin and/or C282Y homozygosity are invited to undergo a comprehensive clinical examination (CCE), as are frequency-matched control subjects. These examinations provide data on personal and family medical history, lifestyle characteristics, physical examination, genetic counseling, and assessment of ethical, legal, and social implications. Primary and secondary causes of iron overload will be distinguished by clinical criteria. Iron overload will be confirmed by quantification of iron stores. Recruiting family members of cases will permit DNA analysis for additional genetic factors that affect iron overload.

RESULTS

Of the first 50,520 screened, 51% are white, 24% are African American, 11% are Asian, 11% are Hispanic, and 3% are of other, mixed, or unidentified race; 63% are female and 37% are male.

CONCLUSIONS

Information from the HEIRS Study will inform policy regarding the feasibility, optimal approach, and potential individual and public health benefits and risks of primary care-based screening for iron overload and hemochromatosis.

The effect of fiber-rich carbohydrates on features of Syndrome X

There has been much debate among nutritionists and scientists regarding the optimal dietary approach for the treatment of the Insulin Resistance Syndrome, also called Syndrome X. This condition, which may affect as many as 47 million individuals in the United States, significantly increases risk of coronary heart disease and stroke. Major health organizations have historically recommended high-carbohydrate, low-fat (HCLF) diets to reduce chronic disease risk. However, there is evidence that a high intake of carbohydrates may adversely affect one or more of the abnormalities associated with this syndrome. Studies in this area have often had limitations. For example, some studies showing adverse effects of an HCLF diet have not taken into account the dietary fiber content of the diet. This article describes abnormalities often associated with Syndrome X, reviews the beneficial effects of fiber-rich carbohydrates, discusses the effect of fiber-rich carbohydrates on features of this syndrome, and concludes with applications of these findings for those involved in treating individuals with features of this disorder. This review indicates that an HCLF dietary pattern such as that used in the DASH trial, with a level of dietary fiber consistent with the recommendations of the American Dietetic Association (eg, 20-35g/day), containing from 3 to 10 g soluble fiber/day, may be beneficial for treating those with Syndrome X.

Plasminogen activator inhibitor-1 and relations to fatty acid composition in the diet and in serum cholesterol esters

High plasminogen activator inhibitor (PAI)-1 levels and poor dietary fat quality are potential risk factors for cardiovascular disease. The aim was to investigate the cross-sectional associations between PAI-1 activity and dietary nutrient intake, focusing on fat quality, in a population-based study of 871 men aged 70 years. The relationship between PAI-1 and the fatty acid composition in serum cholesterol esters (n=381 men) was also studied. The estimated total fat intake was positively associated with PAI-1 activity. The intake of both monounsaturated and polyunsaturated fatty acids was positively associated with PAI-1 activity, whereas the intake of saturated fatty acids was not. In serum cholesterol esters, higher proportions of palmitoleic and dihomo-gamma-linolenic acid, a lower proportion of linoleic acid, and reduced estimated Delta5-desaturase activity were associated with higher PAI-1 levels. These associations were confounded by factors representing the insulin resistance syndrome. PAI-1 activity was positively associated with gamma-linolenic and arachidonic acid, independent of potential confounders. In conclusion, this study demonstrates that dietary intake of unsaturated fatty acids is positively associated with PAI-1 activity, whereas intake of saturated fatty acids is not. The associations present between PAI-1 activity and the fatty acid proportions in serum cholesterol esters are partly influenced by metabolic syndrome-related factors.

Effects of diet, drugs, and genes on plasma fibrinogen levels

Plasma levels of fibrinogen have been identified as independent risk predictors of cardiovascular disease. This has greatly increased interest in the regulation of plasma fibrinogen levels. Many demographic and environmental factors are known to affect fibrinogen levels, such as diet, use of several drugs, age, smoking, body mass, gender, physical exercise, race, and season. Additionally, it is also known that genetic factors determine the fibrinogen levels, and also that they determine the response of fibrinogen levels to environmental factors. Estimates, based on twin studies, suggest that 30-50% of the plasma fibrinogen level is genetically determined. The effect of dietary components on plasma fibrinogen levels is modest. Several components have been identified as factors that influence fibrinogen levels. Among those are fish oil, other lipids, and fibers. Dietary components that were expected to have an effect on fibrinogen, but for which no association was observed are black and green tea. Several drugs are known to influence fibrinogen levels, the most studied of which are platelet aggregation inhibiting drugs, such as ticlopidine, and the lipid lowering fibric acid derivatives (fibrates). Both types of drugs decreased the plasma fibrinogen level by about 10%, and bezafibrate lowers fibrinogen even more in patients with diabetes. No clear effect was observed for the HMG-CoA reductase inhibitors (statins). In the Bezalip study, fibrinogen levels decreased in patients treated with bezafibrate, but this had no clear effect on the risk of cardiovascular disease. This suggests that several mechanisms influence the fibrinogen level and that these mechanisms may contribute differently to cardiovascular disease. Several variations in the fibrinogen genes have been described and especially variations in the promoter region of the fibrinogen beta-gene are interesting, because the synthesis of the fibrinogen B beta chain is considered to be the rate limiting step in the fibrinogen biosynthesis. In many studies the fibrinogen beta-gene polymorphisms (-455G/A, -148C/T, and BclI) are found to be associated with the plasma levels of fibrinogen. However, they are not associated with the risk of cardiovascular events, although in several studies an association with the severity and progression of atherosclerosis has been reported. It has also been observed frequently that the fibrinogen beta-gene promoter polymorphisms are associated with the response of fibrinogen levels to environmental factors, such as exercise and trauma. In conclusion, plasma fibrinogen levels are regulated by an interesting and complex interplay between environmental and genetic factors.

Dietary fiber and cardiovascular disease: experimental and epidemiologic advances

Recently reported experimental studies offer insight into the various mechanisms through which dietary fiber may reduce the risk of cardiovascular disease (CVD) in humans. Although most work has focused on traditional risk factors, studies have begun to explore less studied areas of risk such as fibrinolysis. Epidemiologic results have consistently demonstrated inverse associations between dietary fiber, particularly cereal fiber and whole grain foods, and the development of CVD morbidity and mortality. These associations have been observed in both men and women and are not accounted for by potential confounders such as other dietary and lifestyle factors; nor can they be fully explained by body habitus, antioxidants, and other nutrients found in fiber-rich foods. The evidence to date supports clear recommendations for a diet based on fiber-rich foods.

Effect of wheat bran on serum lipids: influence of particle size and wheat protein

OBJECTIVE

Wheat fiber appears to protect from cardiovascular disease despite its lack of consistent effect on serum lipids. We therefore wished to determine whether reported inconsistencies in the effect of wheat bran resulted from differences in particle size or its high gluten content.

METHODS

Two studies were conducted. In one-month metabolic diets, 24 hyperlipidemic subjects consumed breads providing an additional 19 g/d dietary fiber as medium or ultra-fine wheat bran and extra protein (10% of energy as wheat gluten). In two-week ad libitum diets, 24 predominantly normolipidemic subjects consumed breakfast cereals providing an additional 19 g/d of dietary fiber as coarse or a mixture of ultra-fine and coarse wheat bran with no change in gluten intake. Both studies followed a randomized crossover design with control periods when subjects ate low-fiber breads and cereals respectively with no added gluten. Fasting blood lipids were measured on day zero and at the end of each phase.

RESULTS

Wheat bran had no effect on total, LDL or HDL cholesterol irrespective of particle size or level of gluten in the diet. However, consumption of increased gluten in the metabolic study was associated with a 13+/-4% reduction in serum triglycerides (p = 0.005) which was not seen in the normal-gluten ad libitum study.

CONCLUSIONS

The protective effect of wheat fiber in cardiovascular disease cannot be explained by an effect of wheat bran in reducing serum cholesterol although in hyperlipidemic subjects displacement of carbohydrate by gluten on the high-fiber phases was associated with lower serum triglycerides.