Energy extraction from nuts: walnuts, almonds and pistachios.

The bioaccessibility of fat has implications for satiety and postprandial lipidaemia. The prevailing view holds that the integrity of plant cell wall structure is the primary determinant of energy and nutrient extraction from plant cells as they pass through the gastrointestinal (GI) tract. However, comparisons across nuts (walnuts, almonds and pistachios) with varying physical properties do not support this view. In the present study, masticated samples of three nuts from healthy adults were exposed to a static model of gastric digestion followed by simulated intestinal digestion. Primary outcomes were particle size and lipid release at each phase of digestion. Walnuts produced a significantly larger particle size post-mastication compared with almonds. Under gastric and intestinal conditions, the particle size was larger for walnuts compared with pistachios and almonds (P < 0·05). However, the masticated and digesta particle sizes were not related to the integrity of cell walls or lipid release. The total lipid release was comparable between nuts after the in vitro intestinal phase (P > 0·05). Microstructural examination showed ruptured and fissured cell walls that would allow digestion of cellular contents, and this may be governed by internal cellular properties such as oil body state. Furthermore, the cell walls of walnuts tend to rupture rather than separate and as walnut tissue passes through the GI tract, lipids tend to coalesce reducing digestion efficiency.

Effects of fruit and vegetable, consumed in solid vs beverage forms, on acute and chronic appetitive responses in lean and obese adults.

BACKGROUND: The effects of fruits and vegetables in solid vs beverage forms on human appetite and food intake, acutely and chronically, are unclear. METHODS: This 21-week, randomized, crossover study assessed appetitive ratings following the inclusion of fruits and vegetables, in solid and beverage form, into the habitual diet of healthy lean (n=15) and overweight/obese (n=19) adults with low customary consumption. The primary acute outcomes were satiation (amount of challenge meal consumed), satiety (latency of subsequent eating event) and dietary compensation after a 400 kcal fruit preload. Ratings of appetite were also obtained before and after 8 weeks of required increased fruit and vegetable consumption (20% estimated energy requirement). RESULTS: Acutely, overweight/obese participants reported smaller reductions of hunger after consuming the fruit preload in beverage compared with solid form (preload × form × body mass index effects, P=0.03). Participants also consumed significantly less of a challenge meal (in both gram and energy) after the ingestion of the solid fruit preload (P<0.005). However, the subsequent meal latency was not significantly different between the solid and the beverage fruit preloads. Total daily energy intake was significantly higher when the obese participants consumed the beverage fruit preload compared with the solid (P<0.001). Daily energy intake was markedly, but not significantly, higher among the lean with the beverage vs solid food form. Hunger and fullness ratings remained stable when participants consumed fruits and vegetables in solid or beverage form for 8 weeks each. CONCLUSION: Acute post-ingestive appetitive responses were weaker following consumption of fruits in beverage vs solid food forms. Consumption of beverage or solid fruit and vegetable food loads for 8 weeks did not chronically alter appetitive responses.

Peanut digestion and energy balance.

OBJECTIVE: To explore the effects of peanut consumption on fecal energy excretion with a balanced, non-vegetarian diet. DESIGN: Four arm parallel group design (that is, whole peanut (P), peanut butter (PB), peanut oil (PO) or peanut flour (PF) consumption) with one crossover (control and intervention). SUBJECTS: In total 63 healthy men and women from Ghana, Brazil and USA (N=15-16 per group) with an average body mass index of 21.8 kg m(-2). MEASUREMENTS: Percent fat of fecal wet weight daily energy excretion during the control and the treatment periods. RESULTS: Compared to control, the percentage of fat in the feces increased significantly for the P group (5.22+/-0.29%) relative to the other three groups ((PO=3.07+/-0.36%, PB=3.11+/-0.31% (P=0.001), and PF=3.75+/-0.40% (P=0.019)). The same findings held for kJ g(-1) of feces excreted. During the P supplementation period, the energy excretion was 21.4+/-1.0 kJ g(-1) versus 18.7+/-1.0 kJ g(-1) for PO (P=0.034), 18.8+/-0.7 kJ g(-1) for PB (P=0.042) and 18.5+/-0.8 kJ g(-1) for PF (P=0.028). CONCLUSION: Fecal fat and energy loss is greater with consumption of whole peanuts compared to peanut butter, oil or flour. This may contribute to the less than predicted change of body weight observed with peanut consumption. There were no cultural differences.

Short-term dietary compensation in free-living adults.

Evidence suggests that compensatory behaviors operate in infants and pre-school children, such that the high variance characteristic of single eating occasions is much reduced over the day. However, the concept has not been fully explored in adults. The present within-subject, observational study investigated short-term dietary compensation patterns in fifty, weight-stable, normal weight (n=27), overweight (n=14), and obese (n=9) free-living adults (11 M, 39 F; age 30+/-11 y; BMI 26.3+/-5.9). Twenty four-hour diet recalls were obtained for 7 consecutive days, by the multi-pass technique. Each 24-h period was divided into 7 eating occasions. The coefficient of variation for energy intake was calculated for each adult, for each eating occasion, and over each 24-h period. Sub-group variability was assessed by BMI and frequency of consumption of sweetened energy-yielding beverages. The mean coefficient of variation for energy intake for the 7 eating occasions was 110.5%, compared to 28.9% for the day as a whole. Correlations between energy intakes at successive eating events were uniformly negative. No significant differences were noted in the sub-group analyses. Significantly greater variation in energy intake was noted for snacks compared to meals (P<0.0001). These data suggest that adults regulate energy intake over a 24-h period more closely than they do at individual eating occasions, similar to the pattern previously observed in children. Further studies of compensatory responses by larger sub-groups of individuals at risk for weight gain are warranted.

Effects of appetite, BMI, food form and flavor on mastication: almonds as a test food.

OBJECTIVES: To investigate the effects of appetitive sensations, body mass index (BMI) and physical/sensory properties of food (almonds) on masticatory indices and resultant pre-swallowing particle sizes. SUBJECTS/METHODS: Twelve lean (BMI=22.2+/-0.3) and 12 obese (BMI=34.3+/-0.6) adults. After collecting appetitive ratings, electromyographic recordings were used to assess participants' microstructure of eating for five almond products (raw, dry unsalted roasted, natural sliced, roasted salted and honey roasted) under fasted and satiated conditions. Duplicate samples were masticated to the point of deglutition and then were expectorated and size sorted. RESULTS: No statistically significant effects of BMI were detected for any of the mastication measures. Maximum and mean bite forces were greater under the fasted condition. Sliced almonds required lower bite force than did the other almond varieties. The pre-swallowing particle sizes were significantly greater for the sliced almonds than all other varieties. Both the number of chews and mastication time were negatively correlated with particle size. There were no significant effects of almond form or flavor on particle size. CONCLUSIONS: These results do not support differences in masticatory performance between lean and obese individuals, nor effects of sensory properties. Instead, the physical form of foods as well as an individuals' appetitive state may have a greater influence on masticatory behavior. The health implications of these observations warrant further investigation.

Gustation as a determinant of ingestion: methodological issues.

To better characterize the relationship between taste function and dietary intake, measures of taste sensitivity, perceived intensity and preference for sweet (sucrose) and bitter (urea) stimuli were assessed in 35 healthy adults using aqueous and food tastants. Observations were then correlated with the proportions of calories contributed by carbohydrate, protein, fat and foods characterized by subjects as predominantly sweet or bitter on 7-day diet records. No significant association was noted among single measures of taste function and any of the five intake parameters, although taste profiles comprised of multiple taste ratings accounted for approximately a third of the variance in sweet and bitter calorie consumption. Levels of nutrient intake could not be predicted at better than chance levels using taste responses. Taste function plays a subordinate role to other determinants of food and nutrient intake, although taste profiles may facilitate the prediction of preferred tastes of diets.

The taste for salt in humans.

Accumulating evidence indicates that the taste of salt is innately appealing to humans, although responses to salty foods are strongly influenced by environmental factors. Except in instances of severe, prolonged sodium depletion, a sodium-specific appetite has not been documented in humans. Limited data reveal no clear association between early exposure to salt and various hedonic responses to salt later in life, but recent exposure markedly alters a person's preferred salt content of foods. Restricting exposure for 8-12 wk can enhance the appeal of reduced-sodium foods in both normotensive and hypertensive individuals. Although the appeal of the taste of salt is one factor contributing to its intake, the extent to which such a hedonic shift promotes long-term adherence to a reduced-sodium diet has not been determined. There is little evidence supporting a relation between either taste sensitivity or hedonic responses to salt and blood pressure.

Oral fat exposure alters postprandial lipid metabolism in humans.

Accumulating evidence indicates that oronasal sensory stimulation influences nutrient metabolism. This work examined the effects of oral exposure to dietary fat on postprandial plasma triacylglycerol (triglyceride) concentrations. Fifteen (six male, nine female) healthy adults were exposed to each of four treatments presented in random order. After ingestion of a 50-g load of safflower oil in capsules (to preclude oral exposure to the fat), they masticated and expectorated 1) crackers with cream cheese, 2) crackers with nonfat cream cheese, 3) crackers alone, or 4) nothing. Blood samples were collected at baseline and 2, 4, and 6 h after load ingestion. Sensory discrimination tests were conducted with the cream cheese samples after these sessions. Oral exposure to the full-fat cream cheese led to a significantly greater area under the plasma triacylglycerol curve than did the other treatments (P < 0.05). The increment was attributable to both a significantly higher peak concentration and a more enduring elevation (P < 0.05). The oral stimuli were not ingested (so did not add to the load), subjects were not aware of the macronutrient composition of the cream cheese samples (thereby eliminating cognitive effects), and subjects could not distinguish between the cream cheese samples in sensory tests (minimizing a sensory influence). Consequently, these data suggest that there is a chemosensory or tactile mechanism in the oronasal region of humans for detecting some aspect of the chemical composition of dietary fat, or a component derived from or carried in fat, that elicits a change in postprandial lipid metabolism.

Fat preference and adherence to a reduced-fat diet.

The nature and mechanisms of altered food acceptability during adherence to a reduced-fat diet have not been characterized. These issues were assessed in healthy adults assigned to a reduced-fat diet excluding discretionary fat sources (n = 9), a similar diet permitting fat-modified products (n = 9) or no dietary modification (n = 9). Sensory responses to foods, body composition, and dietary intake were determined at baseline, monthly during 12 wk of diet adherence, and 12 followup wk. Marked and comparable reductions of fat intake were achieved in the experimental groups. Hedonic (ie, pleasantness) ratings for high-fat foods and preferred fat content of selected foods declined, but only in the group deprived of sensory exposure to fats. Thus, the frequency of sensory exposure to fats exerts a stronger influence on hedonic ratings of foods containing fat than total fat intake. The hedonic shift may promote long-term compliance with a reduced-fat diet.

Human dietary responses to covert manipulations of energy, fat, and carbohydrate in a midday meal.

Dietary responses to dilution or supplementation of the energy value and macronutrient content of foods are poorly characterized in humans. After a 1-wk baseline, 16 free-living, normal-weight adults were provided midday meals systematically varying in energy, fat, and carbohydrate contents for 5-d periods. Their compensatory free-feeding intake was monitored through diet records. In response to energy dilution by carbohydrate or fat, mean daily energy intake was 88% and 97% of baseline, respectively. Responses to the energy surfeit led to intakes 104% and 116% of baseline, respectively. However, the absolute magnitude of the carbohydrate supplement challenge was small. Adjustments of macronutrient-specific intake during the high-carbohydrate, low-carbohydrate, high-fat, and low-fat meal periods were 134%, 91%, 165%, and 95% of baseline, respectively. Although these group findings indicate that defense against covert dilution of the energy, fat, or carbohydrate contents of a meal is stronger than that to supplementation, individual responses were highly variable.

Daily caloric intake of normal-weight adults: response to changes in dietary energy density of a luncheon meal.

The extent and time course of caloric compensation for surreptitious dilutions and supplements to the energy value of the diet were examined in free-living normal-weight adults. Ten subjects were provided lunches containing approximately 66% more or less calories than their customary midday meal for 2-wk periods which were interposed between 1-wk baseline or recovery periods. Diet records were kept throughout the study. Total energy intakes did not differ among the three control periods (weeks 1, 4, and 7) or between any of these periods and when subjects were provided the low-calorie meal. Total energy intake was significantly higher relative to all other periods when subjects ingested the high-calorie meal. To the extent that compensation occurred, it was apparent immediately and did not appear to change over the 2-wk study periods. The results suggest that humans compensate more readily for decreases than for increases in caloric intake.

Dietary evaluation of patients with smell and/or taste disorders.

The impact of smell and taste disorders on dietary habits and nutritional status has received limited research attention. This paper reports findings obtained from questionnaires and diet records completed by 40 healthy subjects and 118 patients with chemosensory dysfunction. Chemosensory disorders were frequently associated with decreases in food acceptability. Although dietary responses to these dysfunctions varied greatly, patients with distorted or phantom smell and/or taste sensations tended to report weight loss whereas those with simple sensory loss were more likely to report weight gain. Indices derived from diet records did not indicate that either group of patients was at substantial nutritional risk, but food frequency responses and estimates of body mass index were consistent with patient reports of changes in dietary patterns and weight. In addition, marked weight change and aberrant dietary practices were noted in individual patients. Thus, there were indications that chemosensory dysfunction may be associated with nutritionally important dietary alterations.

Effects of combined hydrochlorothiazide and amiloride versus single drug on changes in salt taste and intake.

Hydrochlorothiazide stimulates salt intake without altering salivary or gustatory function. Amiloride reportedly reduces salivary sodium levels and salt taste. It was hypothesized that these unintended drug actions would be attenuated by concurrent use of these 2 diuretics. Normotensive adults (n = 23) were administered placebo for 2 weeks, active combination drug Moduretic for 4 weeks, and placebo again for 2 weeks in a double-blind protocol. Salivary flow, gustatory function and sodium intake were monitored at the end of each period, together with selected physiologic measures (i.e., plasma aldosterone, plasma renin activity, body composition, blood pressure and heart rate). No significant changes were observed for salivary flow, salt taste or sodium intake. These findings indicate that amiloride and hydrochlorothiazide used in combination can reduce drug effects that may compromise the efficacy of either drug when used alone.

Effects of hydrochlorothiazide and amiloride on salt taste and excretion (intake).

The effects of hydrochlorothiazide (HCTZ) and amiloride on salt excretion (intake) and taste were examined in 73 normotensive adults (aged 18 to 56) who were randomly assigned to receive 50 mg/day of HCTZ (n = 24), 5 mg twice daily of amiloride (n = 24) or placebo (n = 25) for 8 weeks. Two and three week placebo periods preceded and followed active treatment, respectively. Relative to baseline, significant increases in sodium excretion (intake) of 31%, 53% and 30% were observed in subjects receiving HCTZ after 2, 4 and 8 weeks of treatment, respectively. An identical follow-up study with 16 subjects replicated the sodium excretion (intake) findings, but failed to reveal the source of the extra dietary sodium. Doubling the dose of amiloride in 11 additional subjects led to higher aldosterone excretion relative to thiazide-treated subjects, but did not increase salt excretion (intake) over a four week period. Only amiloride-treated subjects displayed significant increases in salt taste sensitivity. The increased sodium intake in HCTZ-treated patients may partially offset the desired effects of therapy and exacerbate potassium wasting.

Cephalic-phase insulin in obese and normal-weight men: relation to postprandial insulin.

Cephalic-phase insulin release (CPIR) and its relation to postprandial insulin release were examined in 18 normal-weight and 15 obese men. When the insulin data were expressed as absolute differences from baseline values, obese subjects exhibited significantly greater CPIR than normal-weight subjects (normals, 8.7 +/- 2.1 microU/mL/10 min; obese, 13.4 +/- 4.3 microU/mL/10 min; P < .01). Obese subjects were then separated into groups depending on their fasting insulin levels. This showed that only those subjects with elevated fasting insulin levels exhibited greater CPIR than normal subjects, and suggested that previous reports of exaggerated CPIR in the obese are merely a reflection of a basal hypersecretion of insulin. However, when insulin values were expressed as percentages of baseline, no significant differences between normal-weight and obese subjects were found, although a trend toward an attenuated response was observed in the obese group as a whole (normals, 81.6 +/- 19.1 microU/mL/10 min; obese, 51.3 +/- 16.1 microU/mL/10 min). A significant correlation between cephalic-phase and postprandial insulin release was found in normal-weight subjects (r = .62, P < .05), but not in obese subjects (r = .02, P < .9).

Influences on acceptance of bitter foods and beverages.

Bitterness is generally viewed as an undesirable attribute of foods and beverages, yet segments of the population regularly ingest items with a prominent bitter taste. The influence of taste sensitivity, exposure, selected personality traits (i.e., neophobia, variety seeking, sensation seeking) and pharmacological reactivity on alcohol and caffeine consumption, two widely consumed bitter substances, was assessed in 20 healthy adults (10 male, 10 female). Self-reported alcohol use was positively correlated with measured ethanol taste detection threshold and pharmacological reactivity (self-reported behavioral effects). The latter accounted for 23% of the variance in alcohol intake. Caffeine intake was significantly associated with personality traits. Sensation seeking status and self-reported reactivity to caffeine accounted for 46% of the variance in caffeine intake. Pleasantness ratings for novel bitter and sour foods were unaffected by 10 exposures whereas increased ratings were given to sweet and salty items. Variation in the influence of these factors between individuals and across products may explain individual differences in the acceptability and use of foods and beverages containing alcohol, caffeine and other bitter compounds.

Learned food aversions: a family study.

This study aimed to establish the reliability of prevalence estimates and various reported features of food aversions in the general population, explore relationships between aversions and selected individual characteristics, especially a familial association, and to assess the dietary implications of aversions. One hundred families comprised of 416 6-76 y/o individuals completed a questionnaire eliciting health, demographic and dietary information. A history of aversions was reported by 37.5% of subjects and 26.3% had current aversions. The prevalence was comparable in males and females through age 20 when the female:male ratio increased to about 2:1. A stable and higher level of aversions was observed in subjects 11-40 y/o compared to those younger or older. The mean onset of first aversions was about 16 years, and the mean duration was approximately 11 years. High protein foods were the most common target. The majority of aversive foods were rated as familiar and previously pleasant. Correlations were noted between aversions and medication use, food allergy and, in adults, BMI. The principal new finding was a significant familial association for aversions.

Dietary compensation by humans for supplemental energy provided as ethanol or carbohydrate in fluids.

Dietary compensation for energy provided as ethanol is reportedly limited. Whether this is a function of the ethanol or other aspect of the medium in which it is ingested is not known. Eight male and eight female adults ingested 1.08 liters of beer (5.0% ethanol w/v, 1891kJ), light beer (2.9% ethanol w/v, 1197kJ), no-alcohol beer (0.1% ethanol w/v, 816kJ), cola (1749kJ) or carbonated water (0kJ) every 3-4 days with a midday meal. Diet records were kept the preceding day and day of beverage ingestion. Energy intake was significantly higher each day an energy-bearing beverage was consumed relative to its preceding day. A literature review revealed dietary compensation for modifications of energy intake via fluids is less precise than when solid foods are manipulated. These findings demonstrate dietary adjustment for energy derived from ethanol is imprecise, but also indicate energy from carbohydrate elicits little dietary response when ingested in a beverage.

The taste of fat elevates postprandial triacylglycerol.

To explore the contributions of taste and smell stimulation by dietary fat on the postprandial rise of serum triacylglycerol (TAG), 19 healthy, overnight-fasted adults received lipid loads (50 g safflower oil in capsules) followed by oral (i.e., taste and smell) or odor-only stimulation with cream cheese on crackers or no load with odor or no stimulation. In eight participants, lipid loading was followed by taste-only stimulation. Stimulation was provided (where applicable) at 3-min intervals for 60 min and 15-min intervals for an additional 60 min. Blood was drawn at stipulated times. Fat loading with oral stimulation led to serum TAG concentrations that were significantly elevated over baseline at 2, 4, and 6 h. Fat loading with odor stimulation led to a significant rise only at 4 h. No significant elevation was observed with either no-load treatment. Taste-only treatment led to a significantly higher TAG response than all other treatments except loading with oral stimulation. These data provide additional evidence supporting a taste component for human fat perception.

Ethanol perception and ingestion.

Ethanol is a common dietary constituent, but knowledge of its chemosensory properties and their relationship to its ingestion is limited. Twenty-five male and 25 female, light-regular ethanol consumers participated in five test sessions. Sessions involved determination of taste, olfactory and nasal irritation thresholds for ethanol, taste thresholds for tetralone, suprathreshold intensity and quality judgements, determination of phenylthiocarbamide (PTC) taster status, acute oral exposure effect of ethanol on ratings for sucrose, NaCl, citric acid and quinine hydrochloride and hedonic judgments of beers. Questionnaires on personality traits, diet and health were also completed and body composition determined. Diet histories were obtained on three random days. A randomized subset of sensory tests and questionnaires were administered each session. The rank order of ethanol thresholds was taste>nasal irritancy>olfaction and the predominant taste near threshold was bitter. Except for a lower taste threshold in females, no other effects of gender, PTC taster status, ethanol use or body composition were observed. Acute exposure to ethanol suppressed the bitterness of quinine, but enhanced its bitter aftertaste. Ethanol use was not associated with differences in dietary, sensory or textural characteristics. Thus, among light to regular ethanol consumers, no substantive association was observed between sensory responses to ethanol and diet.