Samantha J. Caton

Repetition counts: repeated exposure increases intake of a novel vegetable in UK pre-school children compared to flavour-flavour and flavour-nutrient learning

Children are not consuming sufficient amounts of fruits and vegetables in their habitual diet. Methods derived from associative learning theories could be effective at promoting vegetable intake in pre-school children. The objective of the present study was to compare the effectiveness of different learning strategies in promoting the intake of a novel vegetable. Children aged between 9 and 38 months were recruited from UK nurseries. The children (n 72) were randomly assigned to one of three conditions (repeated exposure, flavour-flavour learning or flavour-nutrient learning). Each child was offered ten exposures to their respective version of a novel vegetable (artichoke). Pre- and post-intervention measures of artichoke purée and carrot purée (control vegetable) intake were taken. At pre-intervention, carrot intake was significantly higher than artichoke intake (P<0·05). Intake of both vegetables increased over time (P<0·001); however, when changes in intake were investigated, artichoke intake increased significantly more than carrot intake (P<0·001). Artichoke intake increased to the same extent in all three conditions, and this effect was persistent up to 5 weeks post-intervention. Five exposures were sufficient to increase intake compared to the first exposure (P<0·001). Repeated exposure to three variants of a novel vegetable was sufficient to increase intake of this vegetable, regardless of the addition of a familiar taste or energy. Repetition is therefore a critical factor for promoting novel vegetable intake in pre-school children.

Dose-dependent effects of alcohol on appetite and food intake.

To examine the potential dose-response effect of alcohol on appetite and food intake, 12 males attended the laboratory on three occasions. On each occasion, they were given a standard breakfast, then lunch 3 h later, and dinner, 4 h after that. Thirty minutes before lunch, Ss received 330 ml of no-alcohol lager (263 kJ: no-alcohol condition), the same amount of lager spiked with 1 unit (1 UA: 8 g ethyl alcohol, 498.2 kJ) or 4 units of alcohol (4 UA: 32 g ethyl alcohol, 1203.8 kJ). Visual analogue scale (VAS) ratings of appetite and mood were recorded before and after preloads and lunch, then hourly across the day. Intake at lunch (excluding energy from the preload) was significantly higher following 4 UA (5786+/-991 kJ) compared to 1 UA (4928+/-1245 kJ). Participants consumed more high-fat salty food items at lunch following 4 UA compared to the other preloads. Hunger was rated higher following 4 UA across the day in comparison to the other preloads, but fullness ratings failed to reflect any difference by condition. Energy intake at dinner was similar in all conditions and total energy intake across the day was significantly higher after 4 UA (14,615+/-1540 kJ) than after 1 UA (13,204+/-2156 kJ). In conclusion, above a certain threshold, alcohol appears to stimulate appetite in part, due to elevated levels of subjective hunger. When this occurs, energy intake is not reduced at subsequent meals. Thus, alcohol may contribute to positive energy balance via its additive effects to total energy intake and by short-term appetite stimulation.

Learning to Eat Vegetables in Early Life: The Role of Timing, Age and Individual Eating Traits

Vegetable intake is generally low among children, who appear to be especially fussy during the pre-school years. Repeated exposure is known to enhance intake of a novel vegetable in early life but individual differences in response to familiarisation have emerged from recent studies. In order to understand the factors which predict different responses to repeated exposure, data from the same experiment conducted in three groups of children from three countries (n = 332) aged 4–38 m (18.9±9.9 m) were combined and modelled. During the intervention period each child was given between 5 and 10 exposures to a novel vegetable (artichoke puree) in one of three versions (basic, sweet or added energy). Intake of basic artichoke puree was measured both before and after the exposure period. Overall, younger children consumed more artichoke than older children. Four distinct patterns of eating behaviour during the exposure period were defined. Most children were “learners” (40%) who increased intake over time. 21% consumed more than 75% of what was offered each time and were labelled “plate-clearers”. 16% were considered “non-eaters” eating less than 10 g by the 5th exposure and the remainder were classified as “others” (23%) since their pattern was highly variable. Age was a significant predictor of eating pattern, with older pre-school children more likely to be non-eaters. Plate-clearers had higher enjoyment of food and lower satiety responsiveness than non-eaters who scored highest on food fussiness. Children in the added energy condition showed the smallest change in intake over time, compared to those in the basic or sweetened artichoke condition. Clearly whilst repeated exposure familiarises children with a novel food, alternative strategies that focus on encouraging initial tastes of the target food might be needed for the fussier and older pre-school children.

Vegetables by stealth. An exploratory study investigating the introduction of vegetables in the weaning period

Few studies have examined in detail weaning practices and how mothers introduce vegetables into the diets of their infants. The current exploratory study set out to use both qualitative and quantitative methods to investigate approaches to nutrition in the weaning period and in early infancy with a particular focus on vegetables. 75 mothers of infants aged 24-72 weeks filled out a postal questionnaire regarding infant feeding during the weaning period. Mothers completed the infant feeding questionnaire (IFQ) and a food frequency questionnaire (FFQ) to measure familial fruit and vegetable intake. Mothers introduced solid food to their infants at around 20 weeks of age and those who breast-fed their infants tended to introduce solid foods later compared to formula feeding mothers (21 wks versus 17.8 wks, p<0.05). Infants were offered around 3 different types of vegetable during the first 4 weeks of weaning. 13 mothers then took part in a follow-up in-depth interview. Mothers reported that they relied upon advice from family and friends and their interpretation of cues from their infants indicating the readiness for food, rather than relying on official guidelines. Mothers demonstrated high concern about the nutrient quality of their childs diet and perceived vegetables to be an integral part of the diet. A number of strategies for promoting vegetable intake were identified by mothers, offering vegetables by stealth was one of the most commonly identified strategies.

A highly sensitive immunofluorometric assay for the measurement of aldosterone in small sample volumes: validation in mouse serum

Data on the involvement of aldosterone in the regulation of the renin-angiotensin-aldosterone system (RAAS) in rodents are still scarce, partly due to the high sample volumes needed by commercially available assays and to the very low aldosterone concentrations present. We have developed a highly sensitive and non-isotopic immunoassay, requiring a volume of only 50 microl serum for a duplicate measurement, employing a highly specific monoclonal antibody against aldosterone. The assay was validated in human and mouse samples and exhibited a linear working range from 10 to 1000 pg/ml. Values obtained after a chromatographic purification step correlated significantly to the dichloromethane extraction ordinarily used. Basal aldosterone values were measured in 75 mouse hybrids and found within the linear range (173+/-21 pg/ml), with no significant difference between males and females. Additionally, we show an increase in serum aldosterone in mice from 3 to 11 weeks of age. Mice of the same genetic background were treated with dexamethasone intraperitoneally (n=7), resulting in significantly decreased concentrations (35+/-3 vs 114+/-33 pg/ml in controls; P<0.001). In contrast, adrenocorticotropic hormone resulted in significantly increased serum aldosterone (603+/-119 pg/ml; n=7; P<0.001), as did the physiological stimulation of the RAAS by a high K(+)/low Na(+) diet (1369+/-703 vs 172+/-36 pg/ml). In conclusion, we have developed and validated an extremely sensitive assay for determination of aldosterone concentrations from very small serum samples, which could be especially useful in pharmacological intervention studies in rodent models.

The root of the problem: increasing root vegetable intake in preschool children by repeated exposure and flavour flavour learning.

Childrens vegetable consumption falls below current recommendations, highlighting the need to identify strategies that can successfully promote intake. The current study aimed to investigate the effectiveness of flavour-flavour learning as one such strategy for increasing vegetable intake in preschool children. Children (N = 29) aged 15 to 56 months were recruited through participating nurseries. Each received a minimum of six and maximium eight exposures to a root vegetable puree with added apple puree (flavour-flavour learning) alternating with six to eight exposures to another with nothing added (repeated exposure). A third puree acted as a control. Pre- and post-intervention intake measures of the three purees with nothing added were taken to assess change in intake. Follow-up measures took place 1 month (n = 28) and 6 months (n = 10) post-intervention. Intake increased significantly from pre- to post-intervention for all purees (~36 g), with no effect of condition. Magnitude of change was smaller in the control condition. Analysis of follow-up data showed that intake remained significantly higher than baseline 1 month (p < 0.001) and 6 months (p < 0.001) post-intervention for all conditions. Children under 24 months ate consistently more across the intervention than the older children (≥24 m) with no differences found in response to condition. This study confirms previous observations that repeated exposure increases intake of a novel vegetable in young children. Results also suggest that mere exposure (to the food, the experimenters, the procedure) can generalise to other, similar vegetables but the addition of a familiar flavour confers no added advantage above mere exposure.

Eating a rainbow. Introducing vegetables in the first years of life in 3 European countries.

Low vegetable consumption in children is a concern in many EU countries, fewer than one fifth of children in Europe consume the WHO recommended amounts. Systematic studies demonstrate that experience with a variety of vegetables early in childhood can promote later consumption as early dietary habits often track into adulthood. This study examined pre-school childrens experience with vegetables across three European countries in order to assess cultural differences, effects of age and culinary practices. Mothers of pre-school children (N=234) in the UK (N=71), Denmark (N=93) and France (N=70) completed a survey assessing parental and infant familiarity, frequency of offering and liking for 56 vegetables as well as preparation techniques for these vegetables. Analyses revealed that although children aged 25-36 months had been introduced to the greatest number of vegetables, children aged 6-12 months were offered vegetables more frequently and had a higher reported liking for these vegetables. UK childrens liking was related to frequency of maternal intake and frequency of offering. Denmark had introduced the greatest number of vegetables and offered vegetables more frequently than both the UK and France. Choice of preparation methods differed between countries while choice of seasonings was similar. Results suggest increasing variety and frequency of vegetable offering between 6 and 12 months, when children are most receptive, may promote vegetable consumption in children.

Acute effects of an alcoholic drink on food intake: aperitif versus co-ingestion.

To compare the effects on appetite and energy intake (EI) within a meal and across 4 days of drinking wine either before (aperitif) or with (co-ingestion) a meal, 11 men attended the laboratory on three occasions. On each occasion participants were given breakfast in the laboratory then 3 h later returned for a two course (garlic bread, pizza) lunch, then recorded food intake for the remainder of the day and the next 3 days. In the control condition, participants ate lunch ad libitum; in the aperitif condition 375 ml of red wine was consumed 20 min before lunch; and in the co-ingestion condition 125 ml of red wine was consumed with the starter and 250 ml of red wine was consumed with the main course. Subjective ratings of appetite and mood were administered before and after the meal. EI at lunch was greater when wine was consumed (p<0.01) (aperitif: 6436+/-435 kJ; co-ingestion: 6254+/-417 kJ) compared to control (5125+/-262 kJ). In particular, intake of the starter was enhanced by wine consumption. Having wine as an aperitif significantly influenced subjective ratings of light headedness and fatigue. These results suggest that the effects of wine on appetite are immediate, and stimulate food intake early in the meal. Total EI during the test days was significantly higher than during subsequent days revealing a tendency to overeat in the laboratory, exacerbated by drinking wine before or with lunch. However, lean healthy men adjusted total EI on the days following the laboratory in all conditions.

Low‐carbohydrate High‐fat Diets: Regulation of Energy Balance and Body Weight Regain in Rats

The aim of the current investigations was to examine the effects of a low‐carbohydrate high‐fat diet (LC‐HFD) on body weight, body composition, growth hormone (GH), IGF‐I, and body weight regain after stopping the dietary intervention and returning the diet back to standard laboratory chow (CH). In study one, both adolescent and mature male Wistar rats were maintained on either an isocaloric LC‐HFD or CH for 16 days before having their diet switched. In study two, mature rats were maintained on either LC‐HFD or CH for 16 days to determine the effects of the LC‐HFD on fat pad weight. LC‐HFD leads to body weight loss in mature rats (P < 0.01) and lack of body weight gain in adolescent rats (P < 0.01). Despite less body weight, increased body fat was observed in rats maintained on LC‐HFD (P < 0.05). Leptin concentrations were higher (P < 0.05), and IGF‐I (P < 0.01) concentrations were reduced in the LC‐HFD rats. When the diet was returned to CH following LC‐HFD, body weight regain was above and beyond that which was lost (P < 0.01). The LC‐HFD resulted in increased body fat and had a negative effect upon both GH and IGF‐I concentrations, which might have implications for the accretion and maintenance of lean body mass (LBM), normal growth rate and overall metabolic health. Moreover, when the LC‐HFD ceases and a high‐carbohydrate diet follows, more body weight is regained as compared to when the LC‐HFD is consumed, in the absence of increased energy intake.

Low-carbohydrate high-fat diets in combination with daily exercise in rats: effects on body weight regulation, body composition and exercise capacity.

BACKGROUND The aim of the current investigation was to examine the effects of consuming a low-carbohydrate high-fat diet (LC-HFD) in combination with daily exercise on body weight, body composition, endocrine control of the energy balance system and exercise capacity in adolescent and mature rats. METHOD Adolescent (n=23) and mature rats (n=16) were maintained on either a standard chow diet (CH) or a LC-HFD for a period of ten days prior to daily exercise training for 21 days in forced running wheel system. At the end of the 21 day training sessions all rats took part in an exercise performance test where time to exhaustion was measured. RESULTS Rats maintained on the LC-HFD demonstrated a significant lack of body weight gain (p<0.05) compared to CH maintained rats, despite equicaloric intake and performing identical amounts of daily exercise. Body composition was significantly altered in the LC-HFD rats (p<0.05) with increased body fat (p<0.01). Leptin concentrations were higher (p<0.05) and IGF-I concentrations were lower (p<0.01) in the LC-HFD fed rats. Exercise performance was not diminished in the LC-HFD group despite the higher fat mass. Both groups irrespective of age performed equally as well in the time to exhaustion test (p>0.05). CONCLUSION Maintenance on the LC-HFD in combination with forced daily exercise did not impact exercise capacity (total distance and meters per minute). Additionally consumption of an extreme LC-HFD in combination with daily exercise resulted in significantly less body weight gain but increased fat mass. When combined with daily exercise this diet clearly had a negative impact on body composition, but did not affect exercise capacity.