Effects of the glycemic index of foods on serum concentrations of high-density lipoprotein cholesterol and triglycerides.

The role of carbohydrates in cardiovascular disease prevention has garnered increasing attention due to accumulating evidence showing deleterious effects of low-fat, high-carbohydrate diets on serum triglycerides and high-density lipoprotein (HDL) cholesterol. Researchers argue that classifying carbohydrates based on their capacity for increasing blood glucose (termed the glycemic index ) is a useful tool for elucidating the effects of carbohydrate-rich foods on glucose and lipid metabolism. Several epidemiologic reports show that lower dietary GI is associated with lower serum triglycerides and higher HDL cholesterol. Results from intervention studies show that substituting low-GI for high-GI foods in a low-fat, high- carbohydrate diet lowers serum triglycerides by 15% to 25%. The available evidence to date suggests that the glycemic index of foods will be an important factor in future dietary prevention research.

Short-term effects of a progestational contraceptive drug on food intake, resting energy expenditure, and body weight in young women.

BACKGROUND: Studies showed that hormonal fluctuations that occur over the human menstrual cycle affect energy intake and expenditure. However, little is known about the possible effects on body weight regulation that may arise when these cyclic changes are suppressed with hormonal contraceptives. OBJECTIVE: The aim of this study was to examine how a progestational contraceptive drug (depot medroxyprogesterone acetate) affects food intake, resting energy expenditure (REE), and body weight in young women. DESIGN: Twenty normal-weight women were tested in a single-blind, placebo-controlled experiment. Body weight, REE, and 3-d food intake (food provided) were measured in the follicular and luteal phases of 2 menstrual cycles before a single injection of depot medroxyprogesterone or saline solution was administered. Measurements were also taken 4 times after injection: in the luteal and follicular phases of 2 cycles in the placebo group and 2 wk apart (to mimic timing of the menstrual phases) in the drug group. RESULTS: Before injection, the phase of the menstrual cycle affected both energy intake and REE. The study participants consumed more energy (4.3%; P = 0.02) and expended more energy at rest (4.3%; P = 0.0002) in the luteal phase than in the follicular phase. Comparison of pre- and postinjection means showed that treatment with the contraceptive drug had no significant effects on energy intake, REE, or body weight. CONCLUSIONS: This study showed that, although phases of the menstrual cycle affected energy intake and REE, depot medroxyprogesterone acetate did not alter energy intake or expenditure or cause weight gain in young women.

Effects of dietary fat, nutrition labels, and repeated consumption on sensory-specific satiety.

This study investigated whether energy from fat, nutrition information, and/or repeated consumption of a palatable snack food affects the development of sensory-specific satiety (SSS). Participants (51 males and 44 females) ate an afternoon snack of potato chips in a laboratory for two 10-day (Monday-Friday) sessions in a repeated measures, cross-over design. In one 10-day session, participants were given regular, full-fat potato chips (22.2 kJ/g; 150 kcal/oz) and, in the other, they were given potato chips made with olestra (11.8 kJ/g; 80 kcal/oz), a non-absorbable fat replacer. Information about the fat and energy content of the chips was provided to half the participants, while the other half was not informed. In both sessions, participants were instructed to consume the potato chips ad libitum. Initial ratings of sensory properties of the two types of chips did not differ significantly. In SSS tests, participants rated sensory properties of the chips and four test foods (turkey, strawberry yogurt, cookie, and carrot) on days 1, 5, and 10 of the 10-day sessions. Following consumption, ratings of pleasantness of taste and texture and prospective consumption of both types of chips declined compared to the test foods. Further analyses showed that the development of SSS was not affected by the fat and energy content of the chips, the provision of nutrition information, or repeated consumption.

Effectiveness of a social influences smoking prevention program as a function of provider type, training method, and school risk.

OBJECTIVES: This study determined the effect of provider (nurse or teacher) and training method (workshop or self-preparation) on outcomes of a social influences smoking prevention program. METHODS: One hundred elementary schools were stratified by school risk score (high risk = high smoking rate among senior students) and assigned randomly to conditions: (1) teacher/self-preparation, (2) teacher/workshop, (3) nurse/self-preparation, (4) nurse/workshop, and (5) control. Intervention occurred in grades 6 to 8. Smoking status at the end of grade 8 was the primary endpoint variable. RESULTS: Intervention reduced grade 8 smoking rates in high-risk schools (smoking rates of 26.9% in control vs 16.0% in intervention schools) but not in low-risk schools. There were no significant differences in outcome as a function of training method and no significant differences in outcome between teacher-provided and nurse-provided interventions in high- and medium-risk schools. Although nurses achieved better outcomes than did teachers in low-risk schools, neither provider type achieved outcomes superior to the control condition in those schools. CONCLUSIONS: Workshop training did not affect outcomes. Teachers and nurses were equally effective providers. Results suggest that programming should target high-risk schools.

Comparative lipid and lipoprotein responses to solid-food diets and defined liquid-formula diets.

BACKGROUND: Liquid-formula diets (LFDs) are useful in metabolic studies of the cholesterolemic effects of dietary lipids because they can be formulated with accuracy, facilitating precise delivery of fatty acids of interest. However, because of differences in composition and nutrient delivery between LFDs and solid-food diets (SFDs), there is a need to determine differences in their effects. OBJECTIVE: Our objective was to compare lipid and lipoprotein responses to changes in total fat, saturated fatty acids (SFAs), and cholesterol in subjects consuming an SFD or LFD. DESIGN: Twenty-one healthy subjects consumed controlled diets representative of an average American diet [AAD; 37% of energy from fat (15% from SFAs), and <50 mg cholesterol/MJ] or a National Cholesterol Education Program (NCEP) Step II diet [26% fat (5% from SFAs) and <25 mg cholesterol/MJ]. Other nutrients were similar between diets. Diets were consumed for 23 d in a randomized, crossover design. RESULTS: For the AAD and NCEP Step II diet, there were no significant differences in lipids and apolipoproteins when the LFD or SFD versions were consumed. In contrast, consumption of the SFD was associated with significantly lower total cholesterol and triacylglycerols than was consumption of the corresponding AAD or Step II LFD (P < 0.05). Subjective ratings of satiety, hunger, and quality of life between diet forms did not differ significantly. CONCLUSIONS: Both LFDs and SFDs yield quantitatively similar cholesterolemic responses to changes in dietary fat, SFAs, and cholesterol. LFDs may offer advantages because they provide easily administered, complete, balanced nutrition without affecting satiety.

Energy density but not fat content of foods affected energy intake in lean and obese women.

BACKGROUND: Studies have shown that energy intake increases when both the fat content and energy density of the entire diet increases. When the fat content and energy density vary independently of one another, however, energy density, but not fat content, influences intake. OBJECTIVE: The present study examined whether energy intake in lean and obese women is affected when either the energy density or the fat content of a portion of the diet is manipulated and palatability is held constant. DESIGN: In a within-subjects design, 17 lean and 17 obese women consumed meals in the laboratory for four, 4-d test periods. In 3 of these test periods the energy density (4.4 and 6.7 kJ/g) or the fat content (16% and 36% of energy) of compulsory entrees representing 50% of each subject's usual energy intake was manipulated. Additional self-selected foods were consumed ad libitum at meals and as snacks. RESULTS: There were no systematic differences in palatability of the manipulated foods across conditions. Obese and lean participants responded similarly to the dietary manipulations. Intake of self-selected foods at meals was reduced significantly by 16% for both lean and obese subjects in the low- compared with the high-energy-density condition. The fat content of the compulsory foods had no significant effect on energy intake. Ratings of hunger did not differ between diets. CONCLUSION: These results indicate that when a portion of the diet was manipulated, the energy density, but not the fat content, of the foods affected total energy intake at meals in both lean and obese women.

Volume of food consumed affects satiety in men.

This study tested the hypothesis that the amount (weight or volume) of food consumed affects the satiating potency of a food, independent of its energy content. Normal-weight young men (n = 20) were tested in a within-subjects design. Subjects were served a milk-based drink or no drink (control), followed 30 min later by a self-selected lunch and > 4 h later by a self-selected dinner. Milk drinks were equal in energy content (2088 kJ, or 499 kcal) and had similar proportions of fat (30.3%), carbohydrate (54.7%), and protein (15%) across three volumes: 300, 450, and 600 mL. Ratings of palatability, sensory properties, and energy content of the drinks and of hunger completed before consumption of the preloads were not significantly different among conditions. The results showed that preload volume affected energy intake at lunch (P < or = 0.009) such that energy intake was less after the 600-mL preload than after the 300-mL preload. This effect was still present when energy intake at dinner was included (P < or = 0.022). At lunch, including energy from the preload, subjects overate relative to the control condition (4323 +/- 322 kJ) after the 300- (5263 +/- 321 kJ) and 450-mL (5011 +/- 300 kJ) preloads but not after the 600-mL (4703 +/- 353 kJ) preload. Thus, the best adjustment for the energy in the preloads was with the largest, least energy-dense drink. Consistent with the effects on intake, the volume of the drinks affected ratings of hunger and fullness. These results indicate that the volume consumed is an important determinant of satiety after milk drinks under these conditions.

Energy density of foods affects energy intake in normal-weight women.

This study examined the effect of energy density, independent of fat content and palatability, on food and energy intakes. With use of a within-subjects design, normal-weight women (n = 18) were provided with meals for 2 d during each of three test sessions. During lunch, dinner, and an evening snack, subjects were given free access to a main entree varying in energy density (low, medium, or high). The manipulated main entrees were similar in palatability to their counterparts across conditions. Low-energy compulsory (consumption required) side dishes accompanied each meal. Subjects also consumed a standard, compulsory breakfast. Results showed that subjects consumed a similar amount of food (by weight) across the three conditions of energy density. Thus, significantly more energy was consumed in the condition of high energy density (7532 +/- 363 kJ, or 1800 +/- 86 kcal) than in the medium- (6356 +/- 281 kJ, or 1519 +/- 67 kcal) and low- (5756 +/- 178 kJ, or 1376 +/- 43 kcal) energy-density conditions (P < 0.0001). There were no differences in hunger or fullness before meals, after meals, or over the 2 d across conditions. The results from this study indicate that energy density affects energy intake independent of macronutrient content or palatability, suggesting that the overconsumption of high-fat foods may be due to their high energy density rather than to their fat content.

Sensory properties of a nonabsorbable fat substitute did not affect regulation of energy intake.

Many reduced-fat foods retain the sensory properties of their high-fat counterparts through the use of fat substitutes. This study examined whether regulation of energy intake is affected when the nonabsorbable fat substitute olestra is used to uncouple the sensory properties of fat from fat absorption and metabolism. Cream of broccoli soups were developed in three versions: fat-free, fat-free+olestra (33.3 g olestra), and high-fat (33.3 g fat) (923900 and 2150 kJ per serving, respectively). The olestra soup had the nutrient composition of the fat-free soup but the sensory properties of the high-fat soup. Subjects were grouped by sex, body weight, and dietary restraint (total n = 67). Subjects had either no preload (control) or a soup preload (465 g) followed by a self-selection lunch. Intake was measured at lunch, dinner, snack, and breakfast. At lunch, the response to the soup preloads was not affected by sex, dietary restraint, or body weight. Energy intake (soup+lunch) was significantly greater in the high-fat than in the control condition (P < 0.05), but energy intake in the fat-free and olestra-soup conditions was not significantly different from that in the control condition (3570, 3352, 3464, and 4457 kJ in control, fat-free, olestra, and high-fat soup conditions, respectively). Thus, subjects compensated completely for the energy in the fat-free and olestra soups but not for the energy in the high-fat soup. No differences were found in the response to the two fat-free conditions, one with the fatty taste and one without. In this study the sensory properties of fat alone, ie, apart from the physiologic effects of fat, did not affect energy regulation.

Applicants to B.Sc.N., R.N., and R.P.N. nursing programs: differences and predictors.

We surveyed 205 applicants to three types of nursing programs (B.Sc.N., diploma-R.N., and diploma-R.N.A.) offered in Toronto, Ontario. Applicants were predominately white, unmarried women living within commuting distance of the institutions to which they applied. Applicants to practical nursing programs tended to be older than applicants to B.Sc.N. and diploma-R.N. programs, be married, have at least one dependant, come from blue-collar families, be out of school longer, and submit fewer applications. Applicants with dependants were 11 times more likely to choose R.P.N. over R.N. programs. Recency of graduation and high school average were predictive of choosing B.Sc.N. over R.N. programs. While this 1992 cohort had some appreciation for the challenges facing the nursing profession, most applicants still expected to secure full-time employment in acute care post-graduation. The data provide an important benchmark for comparing current and future cohorts of applicants with respect to socio-demographic characteristics and expectations of nursing as a career choice.

Effects of early rearing experience on feeding behavior in B6D2F2 mice.

This work investigated putative factors contributing to the hyperphagia previously observed in mice which had been overfed during the preweaning period by rearing in small litters. In the first study, B6D2F2 mice, reared in small (Sm = 4), medium (Md = 8) and large (Lg = 12) litters, were subjected to a series of diets adulterated with varying concentrations of sucrose octa-acetate (1, 2, 4, and 8%). All animals reduced their food intake in response to the dietary adulteration, with evidence of a dose-response effect, but this response did not differ as a function of litter size. The second study addressed the involvement of the opioid system in the feeding response through the administration of a series of doses of naloxone (0.1, 0.25, 0.5, 1.0, 2.5, and 5.0 mg/kg, or 5, 7.5 and 10.0 mg/kg). Although naloxone treatment did reduce food intake, there was not a clear dose-response relationship. Again, there was no interaction with litter size. These results do not support effects of early rearing on the feeding response to dietary adulteration or to the effects of naloxone administration.

The quantitative relationship between nutritional effects on preweaning growth and behavioral development in mice.

Our objective was to establish whether nutritional effects on the behavioral development of preweaning mouse pups were linearly related to effects on body and brain growth or whether there was a threshold effect, with behavior being affected only by nutritional extremes. We also used a standardized scale of development to compare the relative magnitude of such effects on morphological and behavioral measures. The level of nutrient availability was manipulated continuously by rearing the pups in litter sizes ranging from 3 to 12. On Day 32 post-conception, measures were taken of body weight, brain weight, thickness of the cerebellar external granular layer (EGL), and behavioral development. The relationship between litter size and body weight, brain weight, and behavioral development was best described by a linear regression model; no threshold effect was apparent. By comparing measures on animals from different litter sizes at the same age (32 days) to standard developmental curves over a wide range of ages, we found that for every additional pup in a litter, body growth was retarded by the equivalent of 1.28 days, brain weight by 0.44 day, and behavioral development by 0.07 day. Although the variation in nutrient availability provided by this range of litter sizes does result in a linear relationship between growth and behavioral development, there is nevertheless considerable sparing of function.