Insulin resistance, dietary cholesterol, and cholesterol concentration in postmenopausal women.

Questions remain concerning the effect of variations in cholesterol intake on plasma cholesterol concentration, as well as on the role of factors modulating the metabolic impact of this dietary intervention. To define the impact of wide variations in dietary cholesterol intake on plasma total and low-density lipoprotein (LDL) cholesterol concentrations, as well as testing the hypothesis that resistance to insulin-mediated glucose disposal would accentuate the increase in plasma total and LDL cholesterol concentrations in response to a given increment in dietary cholesterol intake, we performed a prospective, randomized study comparing diets varying in cholesterol content in 65 healthy, postmenopausal women, 31 defined as insulin-resistant and 34 as insulin-sensitive. The changes in total and LDL cholesterol in response to increments in dietary cholesterol of up to approximately 800 mg/day were modest in magnitude, without evidence of a statistically significant diet-induced increase in cholesterol concentration, or of any difference in the responses of insulin-resistant as compared with insulin-sensitive women. These results indicate that relatively large increments in dietary cholesterol intake had little effect on total or LDL cholesterol concentrations in healthy, postmenopausal women, irrespective of whether they were insulin-resistant or insulin-sensitive.

Enteral nutrition in the patient with diabetes mellitus.

Diabetes mellitus is a serious and fairly common metabolic disorder that affects carbohydrate, protein and fat metabolism. Indications for nutritional support are no different for patients with diabetes than in any other patient group. The setting may be recovery from surgery or trauma and transition to solid food is anticipated, or, as a result of permanent injury or stroke, enteral feeding may be the permanent manner of nutrition delivery. Attention must be given to the selection of a macronutrient intake that will optimize blood glucose and lipid control. It is vital that blood glucose concentration be carefully monitored and that over- and underfeeding be avoided.

The role of dietary fats in plant-based diets.

In the United States, the notion that low-fat, high-carbohydrate diets are essential for health has grown into an obsession, driven largely by an effort to reduce heart disease and, more recently, certain types of cancer. We know that saturated fatty acids are more closely associated with risk factors for heart disease than are unsaturated fatty acids. Many people believe that plant-based diets are healthy because they are low in fat. However, plant-based diets are not necessarily low-fat. In true plant-based diets, unsaturated fatty acids predominate, whereas saturated fatty acids come largely from animal sources such as dairy products and eggs. Plant-based diets include foods that contain fats, such as nuts and seeds and oils from grains and seeds. The fats in these foods are not associated with increased risk for heart disease. In addition, for people with insulin resistance, higher-fat diets protect against the heart disease risk factors of low HDL-cholesterol concentration, hypertriglyceridemia, hyperglycemia, and hyperinsulinemia. Because humans can synthesize fat from dietary carbohydrate, and because our adipose stores and circulating fatty acids reflect dietary intake, scientists understand the relations between the amounts and types of dietary fats and the types of fats found in body fat depots. Consuming dietary fats that are not associated with increased risk of disease can be a part of a healthful diet.

L-arginine and nitric oxide-related compounds in plasma: comparison of normal and arginine-free diets in a 24-h crossover study.

The amino acid L-arginine is the precursor of nitric oxide (NO), a powerful vasodilator with antiplatelet properties. The availability of L-arginine has been suggested to be a rate-limiting factor in the production of NO in conditions such as hypercholesterolemia. It was speculated that fluctuations in plasma concentrations of L-arginine during the day may be dependent upon dietary intake of the amino acid, or other variables, and might modify the elaboration of endogenous NO. Over a 24-h period, the plasma concentrations of L-arginine and NO-related compounds (NOx) were measured during an L-arginine and nitrate/nitrite-free diet (diet A) or a nitrate/nitrite-free diet with a fixed amount of L-arginine intake (3.8 g/d) (diet B) in eight healthy volunteers during a 2-day crossover study. Subjects were randomly selected to begin with diet A or diet B and consumed the other diet on the second day. During diet A, plasma L-arginine decreased significantly from 09.00 to 16.00 (21.4+/-2.0 to 11.9+/-1.1 microg/ml), rose slightly in the evening (to 16.6+/-1.7 microg/ml) and gradually increased during the night. During diet B, plasma L-arginine showed a peak after each meal (approximately 23 microg/ml). Plasma NOx concentrations measured by chemiluminescence did not show any circadian variation on either diet. Plasma L-arginine concentrations change during the day and are influenced by dietary intake. Importantly, plasma NOx do not seem to vary with this pattern in healthy individuals.

Experiencia clinica con formulas modificadas enterales para pacientes con diabetes / Enteral nutrition and diabetes cases

Las fórmulas estándar para alimentación por sonda pueden no ser adecuadas para las necesidades específicas de nutrición en muchos pacientes con deficiente tolerancia a la glucosa. En particular, las fórmulas entérales estándar causan con frecuencia aumentos potencialmente peligrosos en los niveles de glucosa sanguínea. La experiencia clínica y los estudios realizados hasta ahora muestran es ventajoso usar en estos pacientes fórmulas entérales diseña- das específicamente para la enfermedad. Las fórmulas especializadas con abundante fibra pueden mejorar el control de la glucemia, pero el aumento concomitante de la viscosidad puede limitar su utilidad en la alimentación por sonda. Glucerna, que es una fórmula especializada baja en hidratos de carbono y rica en ácidos grasos monoinsaturados, así como en fibra, permite el paso por sonda y ha demostrado que mejora el control de la glucemia y disminuye la posibilidad de complicaciones. Sin embargo, la determinación de la adecuada alimentación por sonda en pacientes con deficiente tolerancia a la glucosa no se limita a la elección de la fórmula, pues tales pacientes requieren monitoreo permanente de la glucosa sanguínea, valoración de la motilidad gástrica y evaluación del estado general de salud y del estado nutricional

Obesity as an epidemic: facing the challenge.

Obesity has reached what some scientists see as epidemic proportions. Clearly, a rethinking of the medical nutritional therapeutic approach is needed. Treatment programs must include a variety of health professionals to facilitate the lifestyle changes needed to treat this condition. There is a role in obesity management for registered dietitians, behaviorists, physicians, exercise physiologists, and geneticists. A chronic disease treatment model is being proposed. Are dietitians ready for the challenge?

Clinical experience with modified enteral formulas for patients with diabetes.

Standard tube-feeding formulas may not meet the specific nutritional needs of many patients with impaired glucose tolerance. In particular, standard enteral formulas often cause potentially dangerous increases in blood glucose levels. Clinical experience and studies to date have shown advantages of using disease-specific enteral formulas for these patients. Specialized formulas with increased fiber may improve glycemic control, although the concomitant increases in viscosity of these formulas may limit their usefulness for tube feeding. Glucerna, a specialized formula with low-carbohydrate, high-monounsaturated-fat content that has been enriched with a fiber source that permits tube feeding, has been shown to improve glycemic control and decrease the potential for complications. Appropriate tube feeding for patients with impaired glucose tolerance, however, extends beyond formula composition. Patients also require ongoing blood glucose monitoring, evaluation of gastric motility, and assessment of overall health and nutritional status.

Meals-on-wheels applicants are a population at risk for poor nutritional status.

OBJECTIVE: To identify older adults with poor nutritional status among the independent-living elderly applying for meals-on-wheels, and to compare how a self-assessment tool and more traditional criteria identify nutritional risk. DESIGN: Descriptive study. SUBJECTS/SETTING: Meals-on-wheels applicants (n = 230 between 60 and 90 years of age (mean age = 77.4 +/- 7 years) who were free from terminal illness. Nutrition assessment data were collected in the home of each participant. MAIN OUTCOME MEASURES: Risk assessment for poor nutritional status was determined using anthropometric, dietary, and laboratory data and with a Nutrition Screening Initiative (NSI) self-assessment tool-the "DETERMINE Your Nutritional Health" checklist. STATISTICAL ANALYSES: Differences were assessed using Student's t test for unpaired data. RESULTS: Seventy-four percent of study participants were found to be at risk for poor nutritional status according to the study criteria, and 98% were at risk for poor nutritional status according to the NSI self-assessment tool. CONCLUSIONS: The majority of the applicants for meals-on-wheels were at risk for poor nutritional status. Thus, many independent-living older adults may need additional nutrition assessment and intervention to remain independent and in good nutritional status.

Relation between dietary vitamin intake and resistance to insulin-mediated glucose disposal in healthy volunteers.

The relation between the self-reported intake of various dietary constituents and insulin-mediated glucose disposal was evaluated in 52 healthy volunteers. Insulin-mediated glucose uptake was independently associated with degree of obesity (inversely) and estimates of level of physical activity (directly). An independent relation between increased intake of vitamin A and insulin action was shown, ie, the greater the intake of vitamin A, the more effective was insulin in stimulating glucose disposal. However, there was no independent relation noted between insulin-mediated glucose disposal and estimates of the intake of carbohydrate, protein, amount or kind of fat, fiber, or vitamins C and E. Furthermore, the 20 individuals with estimates of vitamin A consumption > 10 000 IU/d had significantly lower plasma glucose (P < 0.01) and insulin (P < 0.05) responses to oral glucose, and insulin-mediated glucose disposal values that were higher (P < 0.005) than those of the 20 individuals whose estimated vitamin A intake was < 8000 IU/d. These results suggest that vitamin A intake, but not intakes of vitamin C and E, fiber, fat, or carbohydrate is associated with enhanced insulin-mediated glucose disposal.

Postprandial triglyceride and retinyl ester responses to oral fat: effects of fructose.

It has been shown that addition of fructose to an oral fat load results in higher postprandial concentrations of triglyceride. The present study, performed in 11 healthy volunteers, was initiated to see whether the effect of fructose on fat-induced lipemia also involved changes in postprandial concentrations of triglyceride-rich lipoproteins of intestinal origin. Vitamin A was used to label intestinal lipoproteins, and the retinyl palmitate concentrations were determined in plasma and in the Sf > 400 and Sf 20-400 lipoprotein fractions (Sf denotes the Svedberg flotation index). Addition of fructose (50 g) to a standard (40-g oral) fat load resulted in higher postprandial concentrations of triglyceride and retinyl palmitate in plasma and the Sf > 400 lipoprotein fraction (P < 0.001, analysis of variance), and the higher the fasting plasma triglyceride concentration, the greater the magnitude of the fructose effect (r = 0.83, P < 0.002). These data show that triglyceride-rich lipoproteins of intestinal origin play a role in the fructose-induced accentuation of postprandial lipemia.

Relation between insulin resistance, hyperinsulinemia, postheparin plasma lipoprotein lipase activity, and postprandial lipemia.

We examined the relation between insulin resistance, plasma glucose and insulin responses to meals, lipoprotein lipase (LPL) activity, and postprandial lipemia in a population of 37 healthy nondiabetic individuals. Plasma glucose and insulin concentrations were determined at frequent intervals from 8 AM through midnight (breakfast at 8 AM and lunch at noon); resistance to insulin-mediated glucose disposal was determined by measuring the steady-state plasma glucose (SSPG) concentration at the end of a 180-minute infusion of glucose, insulin, and somatostatin; LPL activity was quantified in postheparin plasma; and postprandial concentrations of triglyceride (TG)-rich lipoproteins were assessed by measuring the TG and retinyl palmitate content in plasma and the Svedberg flotation index (Sf) > 400 and Sf 20 to 400 lipoprotein fractions. Significant simple correlation coefficients were found between various estimates of postprandial lipemia and SSPG (r = .38 to .68), daylong insulin response (r = .37 to .58), daylong glucose response (r = .10 to .39), and LPL activity (r = -.08 to -.58). However, when multiple regression analysis was performed, only SSPG remained independently associated with both postprandial TG and retinyl palmitate concentrations. These data provide evidence that insulin resistance plays an important role in regulating the postprandial concentration of TG-rich lipoproteins, including those of intestinal origin.