Diet diversity and nutrient intake

Variety is espoused as a key to dietary adequacy, yet data from new shortcut dietary measures suggest that intakes of relatively few foods can accurately classify individuals according to nutrient intake. This study examines diet diversity, caloric intake, and nutrient density values as contributors to the level of selected nutrients in the diets of 1,747 white men and 1,898 white women, 18 to 34 years old, completing the 24-hour recall in NHANES II. Nutrient intake was directly related to both number of foods eaten and total calories consumed, as well as to nutrient density values. For fat, saturated fat, and potassium, higher caloric consumption alone may account for substantial differences in nutrient intakes between the lowest and highest quartiles. For cholesterol, calcium, and vitamin A, differences in dietary density were more important in explaining nutrient intake differences. Both caloric intake and nutrient density influence sodium intake from food sources. For some nutrients, an overall measure of diversity may be useful for estimating intakes. For others, nutrient-specific diversity indexes would likely be needed. Knowledge of specific foods in diets with high levels of nutrients could aid the construction of food frequency instruments.     

Dietary fat and the regulation of energy intake in human subjects

The role of dietary fat in the regulation of energy intake was assessed by manipulating a conventional diet and measuring spontaneous food consumption. Twenty-four women each consumed a sequence of three 2-wk dietary treatments in which 15-20%, 30-35%, or 45-50% of the energy was derived from fat. These diets consisted of foods that were similar in appearance and palatability but differed in the amount of high-fat ingredients used. Relative to their energy consumption on the medium-fat diet, the subjects spontaneously consumed an 11.3% deficit on the low-fat diet and a 15.4% surfeit on the high-fat diet (p less than 0.0001), resulting in significant changes in body weight (p less than 0.001). A small amount of caloric compensation did occur (p less than 0.02), which was greatest in the leanest subjects (p less than 0.03). These results suggest that habitual, unrestricted consumption of low-fat diets may be an effective approach to weight control.     

Effects of caloric manipulations on food intake in baboons

Food intake of seven adult male baboons (Papio cynocephalus anubis) was monitored during daily 22-h experimental sessions. Food was available under a two-component operant schedule. Following completion of the first "procurement component" response requirement, access to food, i.e. a meal, became available under the second "consumption component," during which each response produced a 1-g food pellet. After a 10-min interval in which no response occurred, the consumption component was terminated. The effects of caloric preloads on food intake were determined by giving each baboon a meal of preferred foods 45-60 min prior to the start of the daily session. Caloric preloads decreased food intake during the first 8 h of the session, but had no effect on intake during the entire session. The effects of acute deprivation on food intake were determined by terminating sessions after a baboon had consumed 20-80% of baseline intake, and by starting a session 4-12 h late. Deprivation did not increase subsequent food intake. The effects of the availability of an alternative source of calories on total daily intake were determined by providing access to a dextrose solution. Baboons decreased intake of solid food in accordance with the caloric intake from the dextrose solutions by decreasing the number of meals. Finally, the effects of providing a diet of higher caloric density on food intake were determined. Two of the four baboons tested in this procedure maintained baseline levels of daily caloric intake, while the other two baboons increased daily caloric intake. In summary, free-feeding baboons were relatively insensitive to acute changes in feeding conditions, but were sensitive to long-term changes in the caloric content of available foods.     

Long-term strict raw food diet is associated with favourable plasma beta-carotene and low plasma lycopene concentrations in Germans

Dietary carotenoids are associated with a reduced risk of chronic diseases. Raw food diets are predominantly plant-based diets that are practised with the intention of preventing chronic diseases by virtue of their high content of beneficial nutritive substances such as carotenoids. However, the benefit of a long-term adherence to these diets is controversial since little is known about their adequacy. Therefore, we investigated vitamin A and carotenoid status and related food sources in raw food diet adherents in Germany. Dietary vitamin A, carotenoid intake, plasma retinol and plasma carotenoids were determined in 198 (ninety-two male and 106 female) strict raw food diet adherents in a cross-sectional study. Raw food diet adherents consumed on average 95 weight% of their total food intake as raw food (approximately 1800 g/d), mainly fruits. Raw food diet adherents had an intake of 1301 retinol activity equivalents/d and 16.7 mg/d carotenoids. Plasma vitamin A status was normal in 82% of the subjects (> or = 1.05 micromol/l) and 63% had beta-carotene concentrations associated with chronic disease prevention (> or = 0.88 micromol/l). In 77% of subjects the lycopene status was below the reference values for average healthy populations (< 0.45 micromol/l). Fat contained in fruits, vegetables and nuts and oil consumption was a significant dietary determinant of plasma carotenoid concentrations (beta-carotene r 0.284; P < 0.05; lycopene r 0.168; P = 0.024). Long-term raw food diet adherents showed normal vitamin A status and achieve favourable plasma beta-carotene concentrations as recommended for chronic disease prevention, but showed low plasma lycopene levels. Plasma carotenoids in raw food adherents are predicted mainly by fat intake.     

Threonine imbalance, deficiency and neurologic dysfunction in the kitten

The effect of feeding threonine-imbalanced and threonine-deficient purified diets (containing L-amino acids as the only source of dietary nitrogen on food intake, weight gain and blood plasma amino acid pattern has been examined in growing kittens. The imbalance was created by adding 17.5% of amino acid mixture lacking threonine to a low amino acid basal diet comtaining 17.5% amino acid mixture including 0.4% threonine. A depression in food intake and weight gain occurred while feeding the imbalanced diet which was corrected by adding an additional 0.2% threonine to the imbalanced diet. There was no adaptation with time in the form of increased food intake or weight gain while feeding the imbalanced diet. Plasma threonine was consistently and similarly depressed (10 to 35% of normal) while feeding the basal, imbalanced and corrected diets and increased to normal when the standard diet with 1.4% threonine was fed. Plasma threonine and total amino acid concentrations of kittens fed the imbalanced diet did not differ from those observed in kittens fed the basal diet. Signs of neurologic dysfunction and/or lameness developed in 14 of the 17 kittens fed threonine-imbalanced or deficient diets, which resolved as dietary threonine was increased.     

Food intake of very obese persons: quantitative and qualitative aspects.

To document the caloric intake of very obese persons and investigate the food choices and dietary composition that maintain severe obesity, we studied the self-selected food intake required to maintain stable weight in two groups of very obese subjects: 11 inpatients with a mean weight 181% above desirable body weight and 35 outpatients with a mean weight 125% above desirable body weight. Qualitative and quantitative food intake were evaluated using records obtained on the hospital metabolic ward for the inpatients and using self-recorded food records for the outpatients. Absolute caloric intake in both groups was greater in proportion to the degree of obesity (deviation from desirable body weight); caloric intake per unit of lean body mass (kilocalories per gram urinary creatinine) was constant regardless of the degree of obesity and was essentially the same as that of normal nonobese persons. Food records indicated that the obese subjects maintained their high caloric intake by consuming mostly foods of high caloric density, with occasional binge eating. They largely avoided foods of low intrinsic energy density and modified-calorie foods, ie, foods with decreased fat, nonnutritive sweeteners, or fillers. By substituting foods of lower caloric density for usual food choices from the same food group, obese persons could decrease caloric intake by 20% and increase potential for notable weight loss.     

A cost constraint alone has adverse effects on food selection and nutrient density: an analysis of human diets by linear programming

Economic constraints may contribute to the unhealthy food choices observed among low socioeconomic groups in industrialized countries. The objective of the present study was to predict the food choices a rational individual would make to reduce his or her food budget, while retaining a diet as close as possible to the average population diet. Isoenergetic diets were modeled by linear programming. To ensure these diets were consistent with habitual food consumption patterns, departure from the average French diet was minimized and constraints that limited portion size and the amount of energy from food groups were introduced into the models. A cost constraint was introduced and progressively strengthened to assess the effect of cost on the selection of foods by the program. Strengthening the cost constraint reduced the proportion of energy contributed by fruits and vegetables, meat and dairy products and increased the proportion from cereals, sweets and added fats, a pattern similar to that observed among low socioeconomic groups. This decreased the nutritional quality of modeled diets, notably the lowest cost linear programming diets had lower vitamin C and beta-carotene densities than the mean French adult diet (i.e., <25% and 10% of the mean density, respectively). These results indicate that a simple cost constraint can decrease the nutrient densities of diets and influence food selection in ways that reproduce the food intake patterns observed among low socioeconomic groups. They suggest that economic measures will be needed to effectively improve the nutritional quality of diets consumed by these populations.     

Plasma triglyceride lowering by exercise despite increased food intake in patients with type IV hyperlipoproteinemia.

Exercise can lower fasting triglyceride levels (TG). This study was undertaken to determine whether the exercise-induced decrease in TG is the result of a negative caloric balance. Five subjects with primary type IV hyperlipoproteinemia were given diets comparable in composition to their usual diets. During one experimental period the subjects exercised while maintaining their usual caloric intakes. During another experimental period their caloric intake was increased to compensate for the exercise-induced increase in energy expenditure. The exercise, which consisted of 30 min of treadmill walking per day for 4 days, resulted in a progressive decrease in TG. The reduction in TG, which averaged 120 mg/100 ml, occurred regardless of whether or not the increase in caloric expenditure was compensated for by an increase in food intake. The decrease in TG was limited to the very low density lipoprotein fraction. No significant changes occurred in total plasma cholesterol concentration or in the distribution of cholesterol between the lipoprotein fractions. Fasting plasma glucagon concentration was constant for each individual and was unaffected by the exercise. The finding that exercise induces a decrease in TG despite increased food intake indicates that the TG lowering effect of exercise is not mediated by a negative caloric balance.     

Dietary fat dose dependently increases spontaneous caloric intake in rat

OBJECTIVE: To characterize the dose-response relationship between dietary fat to carbohydrate ratio and spontaneous caloric intake. RESEARCH METHODS AND PROCEDURES: Male Long-Evans rats consumed milk-based liquid diets that differed in fat content (17% to 60% of kilocalories) but had equivalent protein content and energy density. In Experiment 1, rats consumed one of the diets (n = 9/diet group) as the sole source of nutrition for 16 days. In Experiment 2, diets were offered as an option to nutritionally complete chow for 4 days followed by a 3-day chow-only washout in a randomized within-subjects design (n = 30). In Experiment 3, nine rats received isocaloric intragastric infusions of diet overnight, with chow available ad libitum. At least two no-infusion days separated the different diet infusions, which were given in random order. Food intake was measured daily RESULTS: Dietary fat dose dependently increased total daily kilocalories in each of the three paradigms. DISCUSSION: These data imply that the postingestive effects of carbohydrate and fat differentially engage the physiological substrates that regulate daily caloric intake. These findings reiterate the importance of investigating macronutrient-specific controls of feeding, rather than prematurely concluding that dietary attributes that covary with fat content (e.g., caloric density and palatability) drive the overeating associated with a high-fat diet.     

Calcium intake and bone mass development among Israeli adolescent girls.

OBJECTIVE: To determine the possible relationship between food and life style habits and bone health in adolescent Israeli females. METHODS: 2,000 adolescent Israeli Jewish and Arab high-school girls (mean age 14.5) completed a semi-quantitative food frequency questionnaire and a personal history questionnaire. 27 food components were calculated for each subject. Bone mineral content and density were determined for 112 subjects with calcium intake below 800 mg/day. RESULTS: Average calcium intake was found to be 1,260 mg/day, but 20% of all girls had a calcium intake below 800 mg/day. All low-energy diets were very low in calcium, as mean calcium intake per 1,000 calories was 411 128 grams. A large percentage of diets with less than 800 mg calcium were also deficient in phosphorus (95.2%), magnesium (84.8%). iron (90.5%) and zinc (100%). Due to differences in food sources. Jewish girls had more phosphorus in their diet, but less magnesium and iron compared to Arab girls. Calcium and zinc deficiencies in Jewish and Arab diets were similar. A negative correlation was found between body mass index (BMI) and age at menarche for all girls in the study. Bone mineral density (BMD) measured for girls with calcium intake below 800 mg/day distributed normally around the average when compared to age matched controls despite their low calcium intake. There was a strong positive correlation between BMD and bone mineral content (BMC) at all sites and body weights. CONCLUSIONS: Low calcium intake, other nutritional deficiencies and delayed menarche due to low-energy diet in the growing period and in adolescence may prevent the formation of healthy bones. There is no evidence of lower bone mass among the low calcium intake group in the study population at this stage. It remains to be documented if the window of opportunity for optimal bone accretion for this group will be missed in the future. possibly leading to increased risk of osteoporosis.     

Response of normal and diabetic rats to increasing dietary medium-chain triglyceride content

Replacing dietary long-chain triglycerides (LCT) with medium-chain triglycerides (MCT) has not previously been shown to produce reliable changes in caloric intake. However, diabetic rats are particularly sensitive to changes in the fat content of their diet, and thus were used for comparison to normal rats in the studies reported below. Rats were fed synthetic diets that contained either corn oil or MCT. Food intake and plasma metabolic fuels were measured as the fat content of the diet was increased from 5 to 15 to 25%. Both normal and diabetic MCT-fed rats adjusted their caloric intake more quickly than LCT-fed rats as the fat content of the diet was increased. The relative preference of MCT- and LCT-fed rats for high and low concentrations of dietary fat was assessed. It was found that both normal and diabetic LCT-fed rats preferred high dietary fat, whereas MCT-fed rats did not. In normal rats, plasma triglycerides and glycerol were decreased and plasma ketones increased by MCT feeding. In diabetic rats, the only effect of MCT feeding was to decrease plasma glycerol and triglycerides. The relative importance of hedonic and metabolic feedback to the rapid caloric regulation of MCT-fed rats is discussed.     

Diurnal feeding and drinking patterns of adult cats as affected by changes in the level of fat in the diet

A continuous on-line computerized monitoring system was used to measure food and water intake patterns of mature cats during consecutive low-fat (3 week) or high-fat (3 week) feeding. Cats consumed less of the high-fat than the low-fat diet such that their mean daily gross energy intake was the same for both diets. It was concluded that cats regulate their daily food intake on the basis of energy density. High-fat substitution caused a reduction in the quantity of food consumed in the dark cycle. There was no apparent change in either the light- or dark-cycle meal frequency, both the light- and dark-cycle average meal size were curtailed. Water intake did not vary significantly between low- and high-fat diets. There was no significant difference in number of drinking bouts or average bout volume for the low- and high-fat diets in both the light and dark cycles. Two diet-choice trials produced no clear preference for the low- or high-fat diet. It appears that the fat content, independent of flavor components or physical consistency, has little effect on dietary preference of the cat.     

Dietary compliance for pediatric burned patients

Physician diet orders written for pediatric burned patients frequently differ from the diets patients actually receive. At Shriners Burns Institute in Boston, such deviations from the diet order were generally not recognized for at least two days. In order to increase compliance with physician diet orders, changes in the nutritional support program were implemented which included physician diet orders containing specific macronutrient requirements in addition to the caloric goal, which was changed in response to recent research demonstrating that the previously used formula provided excessive calories; introduction of modular diets for parenteral and enteral feedings; institution of daily nutrition flow sheets; and a change of the time at which daily caloric intake records were calculated. In order to assess the benefits of the new measures, the average deviation from the caloric goal was calculated for patients who did not receive the new assessment tools (control group, N = 51), compared with those who did (study group, N = 50). Least squares regression analysis indicated a trend toward improved compliance and less deviation from the calculated caloric goal following implementation of the four measures.     

Energy density of foods affects energy intake across multiple levels of fat content in lean and obese women

BACKGROUND: The results of previous studies indicated that energy density, independent of fat content, influences energy intake. In most studies, however, both fat content and energy density were lower than in typical American diets. OBJECTIVE: We examined the influence of energy density on intake when fat content was above, below, or similar to the amount of fat typically consumed and when energy density was closer to that of American diets. DESIGN: Lean (n = 19) and obese (n = 17) women consumed all meals daily in our laboratory during 6 experimental sessions. The main entrées, consumed ad libitum, were formulated to vary in fat content (25%, 35%, and 45% of energy) and energy density (5.23 kJ/g, or low energy density, and 7.32 kJ/g, or high energy density) but to have similar palatability. RESULTS: Energy density influenced energy intake across all fat contents in both lean and obese women (P < 0.0001). Women consumed less energy in the low (7531 kJ) than in the high (9414 kJ) energy density condition. Despite this 20% lower energy intake, there were only small differences in hunger (7%) and fullness (5%). Women consumed a similar volume, but not weight, of food daily across conditions. Differences in intake by weight, but not volume, occurred because for some versions of manipulated foods, weight and volume were not directly proportional. CONCLUSIONS: Energy density affected energy intake across different fat contents and at levels of energy density comparable with those in typical diets. Furthermore, our findings suggest that cues related to the amount of food consumed have a greater influence on short-term intake than does the amount of energy consumed.     

The effects of variations in carbohydrate, protein, and fat content of the diet upon weight loss, blood values, and nutrient intake of adult obese women

The effects on weight reduction of three different 1,200-kcal diets followed for a 10-week period were examined in adult, sedentary, overweight women. Diet patterns contained 25%, 45%, or 75% carbohydrate, with variations in fat and protein. Parameters evaluated and compared for each diet were body composition, cholesterol, triglycerides, blood urea nitrogen (BUN), uric acid, percent body fat, and nutrient intake. Each diet group contained at least 11 women. Behavioral approaches were used to ensure that subjects complied with the caloric intake and the dietary pattern. No significant differences were found in the parameters except for BUN, which was significantly greater in the 25% carbohydrate group. Each 1,200-kcal diet contributed to weight loss. Selection of a weight reduction diet can be designed around preferred food patterns and nutrition needs of individuals rather than a proportion of the energy provided by carbohydrate in healthy adult women. Practitioners may use this research to demonstrate to clients that body weight can be lost while following a variety of nutritious diets.     

Contemporary diet and body weight of Navajo women receiving food assistance: an ethnographic and nutritional investigation

Preceded by 6 months of ethnographic research, a survey of 107 Navajo women, primarily food assistance participants, was conducted to describe and evaluate the contemporary Navajo diet. On the basis of results of 1-day dietary recalls, mean nutrient intakes were found to be below the RDA for calcium, phosphorus, iron, vitamin A, and energy. Sixty-three percent of the women in the sample were overweight or obese. The overall percentages of energy from fat, carbohydrate, and protein were closer to those recommended in the Dietary Goals than those in the current U.S. diet. The fat in the diet appeared to be primarily saturated, however, and fiber intake was lower than the U.S. average. Traditional foods were infrequently consumed. Women with higher incomes tended to have better diets. Commodity foods supplied by USDA's Food Distribution Program provided 43% of caloric intake and 37% to 57% of the intakes of all other nutrients except fat and vitamin C for the 72% of the sample participating in that program. It is concluded that the Food Distribution Program provides an important nutritional contribution to the contemporary Navajo diet.     

The effect of a pre-load experiment on subsequent food consumption. Caloric and macronutrient intake in the days following a pre-load manipulation

The current study was designed to test potential caloric and macronutrient counter-regulation or compensation amongst 76 participants who participated in a milkshake preload experiment. Participants completed food diaries for 2 days before and 2 days after participating in the pre-load experiment. It was hypothesized that dieters and restrained eaters might respond to the pre-load by compensating or counter-regulating food consumption during the rest of the day following the experiment, and on the 2 days post-experiment. Results indicated that there were no significant differences in caloric or macronutrient consumption between the experimental and control groups on the days after the experiment. There were also no interactions between restraint and dieting status and the experimental condition. However, there was a main effect of caloric intake across dieting status, with those dieting to lose weight showing lower caloric intake than those not dieting and those dieting to maintain weight. The results of this study suggests that disinhibitory food stimuli may be less powerful than once thought or relatively short acting, as long-term counter-regulation or compensation did not occur for most people. Overall, the current study provides additional insight into potential long term caloric counter-regulation or compensation in participants who participated in a preload experiment, but additional research is needed to better understand this phenomenon.     

Effects of dietary excesses of the branched-chain amino acids on growth, food intake and plasma amino acid concentrations of kittens

The effect of excesses of the branched-chain amino acids (BCAA), particularly leucine, on growth, food intake and plasma amino acid concentrations were investigated in kittens. Effects of excess leucine were tested in kittens fed five basal diets that varied in their nitrogen and amino acid contents. Compared to rats, kittens were much less sensitive to excesses of the BCAA. Addition of 10% leucine to basal diets that provided nitrogen just at or below the minimal requirement of kittens resulted in no change or increased growth and food intake of kittens when the isoleucine and valine concentrations in the basal diet were just at or slightly in excess of the kitten's minimal requirements for those amino acids. An adverse effect of leucine added to low nitrogen basal diets was observed only when isoleucine and valine were provided below the kitten's requirement (80% of requirement). When basal diets containing adequate nitrogen (24% amino acids) were tested, the addition of leucine (10%) resulted in an adverse effect when isoleucine and valine were provided at 80% of the kitten's requirement and in mild growth depressions when isoleucine and valine were provided at 1.1 times the requirement. Leucine-induced growth depression was alleviated by the addition of isoleucine and valine at 0.5%, indicating that excess leucine caused a BCAA antagonism or an amino acid imbalance. With the addition of leucine to the basal diets, there were consistent decreases in concentrations of alanine and tyrosine in plasma but no consistent depressions in the concentrations of isoleucine and valine.