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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 mg/ml), rose slightly in the evening (to 16.6 ± 1.7mg/ml) and gradually increased during the night. During diet B, plasma larginine showed a peak after each meal (approximately 23 mg/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.

Abstract 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 (S f ) >400 and S f 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.

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.

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.

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. J Am Diet Assoc. 1996; 96:570-573.

benefit for meeting nutrient requirements up to a certain level of variety in food groups beyond which the meeting of nutrient requirements was not improved. In exploring issues of dietary quality and variety in a French population, Drewnowski et al (5) found that dietary variety scores correlated inversely with a dietary quality index, indicating that a good diet may be achieved at the expense of variety. In their study, dietary quality was largely based on total fat and saturated fat intakes. When they applied a dietary diversity score based on the number of food groups consumed per day, they found that low diversity scores were associated with low energy intakes. When Drewnowski et al examined dietary variety based on numbers of foods eaten, not classified within food groups, they found no increase in energy intake with increasing variety. In fact, they found improved dietary quality scores with increased variety. However, unlike the current study, the ranges of total energy intake were within 300 kcal (1.2 MJ) (6).

Recently, there has been increasing interest toward the liberalization of sucrose in the diets of individuals with non-insulin-dependent diabetes mellitus (NIDDM). However, there is evidence from several well-controlled prospective studies demonstrating that the consumption of moderate amounts of sucrose may result in hyperglycemia, hyperinsulinemia, hypertriglyceridemia, hypercholesterolemia, and reduced high-density lipoprotein cholesterol concentrations. The fact that not all studies demonstrate these deleterious effects does not negate the positive data. The magnitude of the deleterious effects will probably vary with individual patients, baseline status, and amount of sucrose. Because these metabolic abnormalities are most disturbed in diabetes and are associated with increased risk of coronary artery disease, it would seem reasonable to continue to advise patients with NIDDM to limit sucrose consumption, at least until available data would allow us to predict in which individuals and at what level of sucrose consumption these adverse metabolic effects would not be present.

Plasma glucose and insulin responses to both a 75-g oral glucose challenge and to conventional meals were determined in eight patients with hypertension and compared with values of a control population. The results indicated that patients with hypertension had significantly higher than normal plasma glucose and insulin concentrations in both situations. Furthermore, when dietary carbohydrate was increased by 16% of total calories (with a reciprocal reduction in dietary fat), the hyperglycemia and hyperinsulinemia present in patients with hypertension were accentuated. Since low fat-high carbohydrate diets are usually recommended for patients with hypertension, these data suggest that abnormalities of glucose and insulin metabolism associated with hypertension would be increased if patients with high blood pressure followed conventional dietary advice. Since hyperglycemia and hyperinsulinemia have been shown to be associated with an increased risk of developing coronary artery disease, it may be appropriate to reevaluate the clinical utility of low fat-high carbohydrate diets in the treatment of hypertension.