Mary Keith

B-Vitamin Deficiency in Hospitalized Patients with Heart Failure

The impact of heart failure and its treatment on specific nutrient requirements is unknown. Furthermore, depletion of water-soluble B vitamins that play key roles in the production of cellular energy in patients with heart failure can contribute to depletion of energy reserves observed in the failing heart. A cross-sectional study recently reported that approximately one third of hospitalized patients with heart failure had tissue levels suggestive of thiamin deficiency (vitamin B-1). Riboflavin (vitamin B-2) and pyridoxine (vitamin B-6) are similar to thiamin in that they are water-soluble, subject to renal excretion, have limited tissue storage, and are dependent on intake. Therefore, it was hypothesized that the status of these B vitamins may also be adversely affected by heart failure. As a result, the prevalence of patients at risk of vitamin B-2 (erythrocyte glutathione reductase activity coefficient > or = 1.2) and B-6 deficiency (plasma B-6 < or = 20 nmol/L) was determined in a cross-section of 100 patients hospitalized with heart failure between April 2001 and June 2002 as well as in a group of volunteers without heart failure. Twenty-seven percent of patients with heart failure had biochemical evidence of vitamin B-2 deficiency, while 38% had evidence of B-6 deficiency. These prevalence rates were significantly higher than those observed in the volunteers without heart failure (2% and 19%, respectively; P < or = 0.02). Use of common B-vitamin-containing supplements by patients with heart failure did not significantly reduce deficiency rates in comparison with those who did not use supplements (B-2 P=0.38 or B-6 P=0.18)). Finally, while 80% of patients with heart failure took diuretics, neither the dose nor the duration of furosemide use was related to the presence of either B-2 or B-6 deficiency. Given the physiologic importance of these vitamins, further investigations aimed at determining the effect of heart failure on specific nutrient requirements as well as the safety and efficacy of B-vitamin supplementation are warranted.

Nutrition support affects the distribution and organ uptake of cachectin/tumor necrosis factor in rats

BACKGROUND We have previously observed a potentiation of the metabolic response to cachectin/tumor necrosis factor (TNF) by total parenteral nutrition (TPN) but not in anorexic orally fed animals. We hypothesized that nutritional status might affect TNF clearance kinetics. METHODS We compared the clearance of a bolus of labeled TNF in TPN-fed animals given sufficient nutrients to grow called weight-gaining rats (WGR) with those given 50% of the WGR called weight-losing rats (WLR) and with orally fed rats (OFR). Data were analyzed using a two-compartment open system model and by linear systems analysis. RESULTS The data from both types of analysis indicator that although metabolic clearance was similar, WGR had a slower fractional TNF clearance rate (FCR) as well as a larger volume of distribution than WLR or OFR. Further analysis showed that an increased proportion of the total mass of TNF resided in a plasma-associated compartment in WGR compared with WLR and OFR. In addition, WGR had reduced uptake of labeled TNF by the kidney. CONCLUSION The data suggest that nutrition support influences either the distribution of TNF or the FCR, resulting in a greater retention in the plasma-associated compartment with intact absolute removal rates. This study has important implications concerning the type of nutrition support provided to the critically ill patient because our data suggest that clinical states with increased circulating TNF levels may be adversely affected by currently available nutritional practices.

Preoperative Carbohydrate Loading in Patients Undergoing Coronary Artery Bypass or Spinal Surgery

BACKGROUND: Surgical stress creates a state of insulin resistance which may contribute to the development of hyperglycemia and, subsequently, postoperative complications. Consumption of an oral carbohydrate supplement before surgery may improve insulin sensitivity and reduce hyperglycemia. In this trial, we investigated the effects of carbohydrate supplementation on insulin resistance in coronary artery bypass graft and spinal decompression and fusion surgical patients. METHODS: Twenty-six patients undergoing coronary artery bypass graft and 12 undergoing spine surgery were randomized to receive 800 mL of an oral carbohydrate supplement the evening before and 400 mL 2 hours before surgery (CHO) or to fasting per standard hospital protocol (FAST). Baseline and postoperative measurements of insulin sensitivity were assessed using the short insulin tolerance test and homeostasis model assessment (HOMA). Interleukin-6, C-reactive protein, and free fatty acid levels were determined at baseline, postoperatively, and 24, 48, and 72 hours after surgery. Adiponectin was measured at baseline. Subjective feelings of well-being were measured immediately before surgery, and intra- and postoperative outcomes were documented. RESULTS: Postoperative insulin sensitivity did not differ significantly between the FAST and CHO groups whether measured by the short insulin tolerance test (rate of disappearance of blood glucose: 0.29%/min vs 0.38%/min; 99% confidence interval [CI] for difference, −0.17 to 0.32, P = 0.41) or HOMA (insulin resistance at values >1: 2.3 vs 3.3; 99% CI for difference, −0.8 to 2.8, P = 0.14). Circulating blood glucose levels after surgery in the CHO group, 6.2 mmol/L, tended to be lower than the FAST group, 6.9 mmol/L (99% CI for difference, −1.7 to 0.25, P = 0.05) and postoperative &bgr;-cell function, measured by HOMA-&bgr; (impaired &bgr;-cell function at values <100%), tended to be higher in the CHO group, 87%, vs 47.5% in the FAST group (99% CI for difference, −9.4 to 88.4), but these differences were not significant. Adiponectin levels were not different between groups at baseline, and levels of free fatty acid, interleukin-6 and C-reactive protein were not affected by treatment. CONCLUSIONS: Preoperative carbohydrate loading did not improve postoperative insulin sensitivity. However, the observed postoperative blood glucose levels and &bgr;-cell function as well as secondary outcomes warrant further study to reevaluate traditional fasting practices in surgical patients.

The Role of B Vitamins in the Management of Heart Failure

Heart failure (HF) is the leading cause of morbidity and mortality in industrialized countries, creating a significant burden on both the healthcare system and quality of life. Research efforts continue to explore new pharmaceutical or surgically based approaches to HF management, but the role of nutrition as an adjunct therapy has been largely ignored. Elderly age, anorexia, malabsorption, premature satiety, and disease severity are among the factors identified as contributing to reduced nutrient intakes in patients with HF. These factors suggest that patients with HF are at increased risk of multiple-nutrient deficiencies, including B vitamins. B vitamins may be of particular therapeutic interest because of their key roles as cofactors in energy-producing pathways. Recently, impaired stores of high-energy compounds have been linked with myocardial dysfunction and prognosis in patients with HF. Therefore, deficiencies of B vitamins might contribute to reduced energy stores and disease progression. This review summarizes the existing literature both with respect to the prevalence of B vitamin deficiency as well as evidence from supplementation trials in patients with HF. The findings suggest that most of the literature in this area has focused on thiamin deficiency in patients with HF, whereas other B vitamins remain largely unstudied. Although few sporadic trials suggest a role for B vitamins in the management of HF, none are conclusive. Therefore, there is a need for larger, more robust trials to assist in defining the B vitamin requirements as well as the impact of supplementation on both morbidity and mortality in patients with HF.

A modified portfolio diet complements medical management to reduce cardiovascular risk factors in diabetic patients with coronary artery disease.

BACKGROUND & AIMS Secondary prevention can improve outcomes in high risk patients. This study investigated the magnitude of cardiovascular risk reduction associated with consumption of a modified portfolio diet in parallel with medical management. DESIGN 30 patients with type II diabetes, 6 weeks post bypass surgery received dietary counseling on a Modified Portfolio Diet (MPD) (low fat, 8 g/1000 kcal viscous fibres, 17 g/1000 kcal soy protein and 22 g/1000 kcal almonds). Lipid profiles, endothelial function and markers of glycemic control, oxidative stress and inflammation were measured at baseline and following two and four weeks of intervention. Seven patients with no diet therapy served as time controls. RESULTS Consumption of the MPD resulted in a 19% relative reduction in LDL (1.9 ± 0.8 vs 1.6 ± 0.6 mmol/L, p < 0.001) with no change in HDL cholesterol. Homocysteine levels dropped significantly (10.1 ± 2.7 vs 7.9 ± 4 μmol/L, p = 0.006) over the study period. Flow mediated dilatation increased significantly in treated patients (3.8 ± 3.8% to 6.5 ± 3.6%, p = 0.004) while remaining constant in controls (p = 0.6). Endothelial progenitor cells numbers (CD34+, CD 133+ and UEA-1+) increased significantly following MPD consumption (p < 0.02) with no difference in migratory capacity. In contrast, time controls showed no significant changes. CONCLUSION Dietary intervention in medically managed, high risk patients resulted in important reductions in risk factors. Clinical Trials registry number NCT00462436.

Evaluation of Taste Sensitivity in Patients Undergoing Coronary Artery Bypass Graft Surgery

Patients report changes in their perception of food tastes following cardiac surgery. This study was designed to explore changes in taste sensitivity following coronary artery bypass graft (CABG) surgery. Detection and recognition thresholds for sweet (sucrose), salty (sodium chloride), sour (citric acid), and bitter (quinine hydrochloride) were determined using the multiple forced-choice ascending concentration series method at baseline (presurgical), discharge, 5 weeks, and 16 weeks post-CABG. Demographic and gastrointestinal data were also obtained. Mixed-model analyses for repeated measures were performed using the baseline scores as reference. Thirty-three patients (mean age=61.8+/-8 years), consented to participate in the study between January 2003 and January 2006, with 13 completing all visits. Detection and recognition thresholds for sweet were significantly lower at discharge compared with baseline (1.7+/-1.2 vs 2.43+/-1.4 and 5.1+/-1.8 vs 5.5+/-1.3, respectively; P<0.05). This difference remained significant 4 months after surgery. Detection and recognition thresholds for salt also declined with time, with significant differences at 4 months post-surgery (2.3+/-2.0 vs 1.8+/-1.5; P<0.001 and 5.3+/-1.3 vs 4.2+/-2.2; P<0.05, respectively). The same trends were noted for the detection of sour and the recognition of bitter. Patients undergoing CABG demonstrated stable or improved taste sensitivity during the recovery period. Further studies aimed at clarifying the relationships between the biological state, taste sensitivity, reported taste changes, and food intake will help to clarify the clinical impact of taste changes and subsequently to guide clinical nutrition care.

Reflections on Perceived Preparedness of Dietetic Internship Graduates Following Entry into Practice

PURPOSE To report on the perceived level of preparedness of dietetic internship (DI) graduates for entrance into practice as dietitians. METHODS Graduates of an Ontario based, nonintegrated DI program from 2007-2011 who were at least 1 year postgraduation were surveyed to determine their level of perceived preparedness for practice using an electronic, content validated, self-administered questionnaire. RESULTS Of 38 eligible graduates, 23 (61%) responded. Seventy-five percent of respondents were working as clinical dietitians, and 30% were working as community dietitians. Eighty-five percent of graduates reported feeling well or very well prepared for practice. Clinical and professional practice tasks were scored highest in terms of preparedness (ratings above 4.5/5) and research-related tasks such as using the research literature (4.1/5), making evidence-based decisions (4.2/5), and engaging in practice-based research (4.1/5) scored lower. Training gaps identified by 32% of respondents included community nutrition and management skill training. CONCLUSIONS Overall, results indicate that this DI program provides a positive training experience that prepares its graduates for entrance into practice as dietitians. Qualitative comments identifying gaps and improvements have guided changes to the curriculum including strengthening community-based placements. Post-graduate surveys represent an important tool in assuring that training programs evolve to meet the needs of students entering the workforce.

Myocardial Metabolism and Improved OutcomesAfter High Risk Heart Surgery

The healthy heart relies primarily upon the oxidation of fatty acids for energy, with the remaining coming from the oxidation of glucose and lactate. Changes in energy requirements are met by altering the balance of fuels depending upon the hormonal milieu as well as upon the availability of oxygen and substrates. The use of carbohydrates for fuel is metabolically more efficient and may improve the coupling between glycolysis and pyruvate oxidation. Therefore, promoting a shift in metabolic fuel substrate use during times of reduced oxygen availability may represent a cardioprotective strategy. Subsequently, there has been interest in pharmacologic strategies such insulin or drugs like ranolazine and dichloroacetate that stimulate carbohydrate oxidation either by enhancing oxidation at the pyruvate dehydrogenase complex or by limiting fatty acid oxidation. There is evidence that nutrients may also be able to stimulate carbohydrate oxidation. Previous studies by our group suggest that a combination of nutrients (carnitine, coenzyme Q10, and taurine) may work together, resulting in pleiotropic cardioprotective effects. Our current studies are investigating the potential of nutrients as both a preventative and adjunctive treatment before and after an ischemic event. These investigations will determine the role of nutritional supplementation in the care of patients with ischemic injury.

Prevalence of thiamin deficiency in hospitalized patients with congestive heart failure

OBJECTIVES The purpose of this study was to determine the prevalence of thiamin deficiency (TD) in a cross section of hospitalized congestive heart failure (CHF) patients and to investigate factors that contribute to its development. BACKGROUND Thiamin deficiency manifests as symptoms of CHF and, therefore, may worsen existing heart failure. Congestive heart failure patients may be at increased risk for TD as a result of diuretic-induced urine thiamin excretion, disease severity, malnutrition, and advanced age. METHODS Erythrocyte thiamin pyrophosphate concentrations, using high-performance liquid chromatography, were measured in 100 CHF patients and compared to 50 control subjects. Variables including diuretics (type and dose), left ventricle dysfunction, New York Heart Association functional classification, creatinine clearance, thiamin intake (diet and supplements), malnutrition, appetite ratings, and age were related to TD using univariate statistics and multiple logistic regression analysis. RESULTS Thiamin deficiency was more prevalent in CHF patients (33%) compared to control subjects (12%) (p = 0.007). Thiamin deficiency was related to urine thiamin loss (p = 0.03), non-use of thiamin-containing supplements (p = 0.06), and preserved renal function (p = 0.05). Increased urinary thiamin loss (mug/g creatinine) was found to be the only significant positive predictor of thiamin status on multiple logistic regression analysis (p = 0.03). CONCLUSIONS One-third of hospitalized CHF patients were TD. In contrast to previous studies, increased urinary losses of thiamin were predictive of improved thiamin status. Thiamin supplementation may be protective against TD in the clinical setting. Future studies are warranted to determine if thiamin supplementation improves thiamin status and disease severity in CHF patients.

Impaired recovery of hind limb muscle perfusion following ischemic injury in rodents receiving B vitamin supplementation

Background: B vitamin deficiency has been previously reported to be prevalent in patients with heart failure. However, clinical trials investigating the potential of B vitamin supplementation have failed to show benefit and have suggested some evidence of harm. Negative findings have been hypothesized to be the result of an anti-angiogenic effect associated with B vitamin supplementation. Objective: The current study aimed to determine the impact of vitamin B6 supplementation alone or in combination with folate and B12 on the angiogenic response in a rodent model of hind limb ischemia. Methods: Rats were divided randomly into three groups and fed one of three diets: control diet (CON), high B6 diet (HB6) or high B6+folate+B12 diet (TV). Following five weeks of diet therapy, ischemia was surgically induced in the hind limb. Changes in perfusion and markers of the angiogenic response were studied at either 5 (early) or 10 (late) weeks. Result: Circulating EPCs were reduced in HB6 animals, a finding that reached significance for the TV animals. Quantitative polymerase chain reaction analysis revealed a decline in VEGF and eNOS expression in HB6 and TV groups at week 10. Contrast enhanced ultrasound of the hind limb revealed a significant reduction in perfusion in HB6 and TV animals in comparison to CON at 10 weeks. B vitamin supplementation had no impact on EPC apoptosis or differentiation. Conclusion: Taken together, these results support a negative impact of B vitamin supplementation on the recovery of perfusion following ischemic injury which may be the result of a down-regulation of chemotactic gene expression, leading to lowered EPC recruitment from the bone marrow to the site of ischemic injury. Correspondence to: Mary Keith, Niagara North Family Health Team, 145 Carlton Street Unit #7, St. Catharines, Ontario, Canada; E-mail: mkeith@ niagaranorthfht.ca