Lisa P. Newman

Oral sensitivity to oleic acid is associated with fat intake and body mass index

BACKGROUND & AIMS Taste sensitivity to fatty acids influences food ingestion and may regulate fat intake and body weight status. Fatty acids are detected via homologous receptors within the mouth and gastrointestinal (GI) tract, where attenuated sensitivity may be associated with greater fat intake and BMI. This study aimed to extend observations surrounding fatty acid taste, specifically the types of foods consumed and dietary behaviours that may be associated with fatty acid taste sensitivity. METHODS 51 subjects (41 female; BMI, 21.4 ± 0.46 kg/m², age, 20 ± 0.52 yrs, 10 male; BMI, 23.6 ± 1.4 kg/m², age, 22 ± 1 yrs) were screened for oral sensitivity to oleic acid (3.8 mM) using triplicate sensory evaluations, and classified as hypersensitive; (3/3 correct identifications), or hyposensitive, (<3/3). Fat-taste perception (using sensory-matched custards made with 0, 2, 6, 10% oil), recent diet (4-day diet record) and food habits and behaviours (food habits and behaviours questionnaire) were also established. RESULTS 75% (n = 38) of subjects were classified as hyposensitive to oleic acid and these subjects differed from those who were classified as hypersensitive. Hyposensitive subjects consumed significantly more energy, fat, saturated fat, fatty foods (butter, meat, dairy), had greater BMI and were less perceptive of small changes in the fat content of custard (all P < 0.05), compared to hypersensitive subjects. CONCLUSION An inability to perceive low concentrations of fatty acids in foods was associated with greater consumption of fatty foods, specifically butter, meat, dairy, and increasing BMI.

Functionality of Fatty Acid Chemoreception: A Potential Factor in the Development of Obesity?

Excess dietary fat consumption is recognized as a strong contributing factor in the development of overweight and obesity. Understanding why some individuals are better than others at regulating fat intake will become increasingly important and emerging associative evidence implicates attenuated fatty acid sensing in both the oral cavity and gastrointestinal (GI) tract in the development of obesity. Functional implications of impaired fatty acid chemoreception include diminished activation of the gustatory system, the cephalic response and satiety. This review will focus on knowledge from animal and human studies supporting the existence of oral fatty acid chemoreception including putative oral detection mechanisms, and how sensitivity to fatty acids is associated with fat consumption and fatty food preference.

Dietary fat restriction increases fat taste sensitivity in people with obesity

Individuals with obesity may be less sensitive to the taste of fat, and it is hypothesized that this is due to excess dietary fat intake. This study assessed the effect of a 6‐week low‐fat (LF) or portion control (PC) diet matched for weight loss on fat taste thresholds, fat perception, and preference in people with overweight/obesity.

Impaired oral fatty acid chemoreception is associated with acute excess energy consumption.

Excessive consumption of dietary fat is implicated with development of obesity. Impaired oral and gastrointestinal chemoreception to the breakdown products of dietary fat, fatty acids, may be associated with increased energy consumption. The objective of this study was to determine if impaired oral fatty acid chemoreception influences energy intake and perceived satiety. Subjects (n = 24) attended six laboratory sessions. Impaired fatty acid chemoreception was defined as subjects who could not identify >3.8 mM oleic acid (C18:1). Subjects participated in a blinded crossover study and consumed each of three high macronutrient breakfasts (high fat, high protein, high carbohydrate) and a balanced macronutrient breakfast on four separate days. Following breakfast, subjects were required to consume a buffet-style lunch until comfortably full. The amount consumed (MJ and g) was measured, as was perceived satiety prior to and following meals. Following the high fat breakfast, subjects with impaired fatty acid chemoreception (n = 10) consumed significantly more energy (2.1 ± 0.8 MJ) and grams (237.70 ± 46.37 g) of food at lunch compared to other subjects (P < 0.05). There were no significant differences in energy, grams of food consumed at lunch and perceived satiety, between subjects for the other breakfasts (P > 0.05). Impaired oral fatty acid chemoreception was associated with excess energy consumption following a high fat meal.

Effects of Salt and Fat Combinations on Taste Preference and Perception

Fat and salt are a common and attractive combination in food and overconsumption of either is associated with negative health outcomes. The major aim was to investigate contributions and interactions of salt and fat on taste pleasantness and perception. The minor aim was to investigate individual fat taste sensitivity (detection threshold of oleic acid [C18:1]) on pleasantness for fat. In a complete factorial design, 49 participants (18–54 years, 12 males) tasted tomato soups with 4 different fat concentrations (0–20%) and 5 different salt concentrations (0.04–2.0%). The preferred concentration and the discrimination ability for both fat and salt were determined by ranking tests. Results show that salt and fat affected pleasantness separately (P < 0.01), with salt having the strongest effect. Fat concentrations 0%, 5%, and 10% did not differ in pleasantness, whereas 20% was less pleasant (P < 0.05). There were no interactions for fat and salt on pleasantness or saltiness and fattiness intensity. Fat taste sensitive participants preferred lower fat concentrations than less sensitive participants (P = 0.008). In conclusion, the strong effect of salt on pleasantness in this study suggests that salt, rather than fat, play a major role in the attraction to savory fatty foods.

Salt Promotes Passive Overconsumption of Dietary Fat in Humans

BACKGROUND Excess fat consumption has been linked to the development of obesity. Fat and salt are a common and appetitive combination in food; however, the effect of either on food intake is unclear. Fat taste sensitivity has been negatively associated with dietary fat intake, but how fat taste sensitivity influences the intake of fat within a meal has, to our knowledge, not yet been investigated. OBJECTIVES Our objectives were, first, to investigate the effects of both fat and salt on ad libitum food intake and, second, to investigate the effects of fat taste sensitivity on satiation responses to fat and whether this was affected by salt. METHODS Forty-eight healthy adults [16 men and 32 women, aged 18-54 y, body mass index (kg/m(2)): 17.8-34.4] were recruited and their fat taste sensitivity was measured by determination of the detection threshold of oleic acid (18:1n-6). In a randomized 2 × 2 crossover design, participants attended 4 lunchtime sessions after a standardized breakfast. Meals consisted of elbow macaroni (56%) with sauce (44%); sauces were manipulated to be1) low-fat (0.02% fat, wt:wt)/low-salt (0.06% NaCl, wt:wt),2) low-fat/high-salt (0.5% NaCl, wt:wt),3) high-fat (34% fat, wt:/wt)/low-salt, or4) high-fat/high-salt. Ad libitum intake (primary outcome) and eating rate, pleasantness, and subjective ratings of hunger and fullness (secondary outcomes) were measured. RESULTS Salt increased food and energy intakes by 11%, independent of fat concentration (P= 0.022). There was no effect of fat on food intake (P= 0.6), but high-fat meals increased energy intake by 60% (P< 0.001). A sex × fat interaction was found (P= 0.006), with women consuming 15% less by weight of the high-fat meals than the low-fat meals. Fat taste sensitivity was negatively associated with the intake of high-fat meals but only in the presence of low salt (fat taste × salt interaction on delta intake of high-fat - low-fat meals;P= 0.012). CONCLUSIONS The results suggest that salt promotes passive overconsumption of energy in adults and that salt may override fat-mediated satiation in individuals who are sensitive to the taste of fat. This trial was registered at the Australian New Zealand Clinical Trials Registry (www.anzctr.org.au) as ACTRN12615000048583.

The influence of a high-fat meal on fat taste thresholds

A high-fat diet for four weeks has been shown to attenuate fat taste sensitivity in healthy weight individuals. However, there is minimal evidence as to whether a single high-fat meal immediately prior to fat taste threshold testing has an effect on thresholds. Therefore, the aim of the study was to determine the effect of a high-fat meal immediately prior to detection threshold testing for oleic acid (C18:1). Thirty-two participants (15 males, 17 females, aged 39.1 ± 3.1 years, Body Mass Index 23.1 ± 0.7 kg/m(2)) attended three laboratory sessions. In each session, participants were randomly assigned to one of three different types of breakfast: a high-fat (60% energy from fat), or low-fat (20% energy from fat) or macronutrient balanced (33% energy from fat) frittata. Fat taste thresholds were evaluated using ascending forced choice triangle tests on two occasions each day; once one-hour post breakfast and then one-hour post the completion of the first threshold test. There was no effect of breakfast type on fat taste detection thresholds for the first testing session of each day (P = 0.288), or the second testing session of each day (P = 0.754). There was also no effect of breakfast within each day (day 1: P = 0.198, day 2: P = 0.199, day 3: P = 0.125). There was no effect of macronutrient composition on the ability of participants to rank the level of fat in food (P = 0.345), or preference for the level of fat in food (P = 0.187-0.868). This study provides preliminary evidence that the composition of the meal consumed by a participant immediately prior to testing does not affect fat taste thresholds.

ATTENUATED ORAL FATTY ACID SENSITIVITY IS ASSOCIATED WITH ACUTE EXCESS ENERGY INTAKE

Abstract of paper that presented at 20th International Congress of Nutrition, Granada, September 2013.Background and Objectives: Indonesia is one of the countries facing nutrition transition with an increased proportion of the middle-class population. Few studies explored young child feeding practice amongst middle class families in developing countries. This study aims to assess child feeding practices and their associations with child nutritional status in urban area of Indonesia. Methods: The study was designed as a mixed-method study in an urban middle-class community, comprising of a qualitative study amongst 26 families of young children and a case-control study involving 288 (109 cases and 179 controls) children aged 12-36 months. Cases were mild to moderately underweight children, while controls were normal weight children. The data collection methods consisted of in-depth interview for the qualitative phase and anthropometry measurements, structured interviews pertaining to child feeding practices and 24-hours recall for the quantitative phase. Results: The qualitative study suggested that mothers appeared to have positive attitude and were familiar with many brands of toddler formula milk. Mothers reported challenges in encouraging their children to eat and relied on formula milk to increase child’s food intake.The results of the case-control study showed that only 10.4% children received six-month exclusive breastfeeding and there was a significantly higher proportion of control than case children who were offered formula milk within their first month of life. Almost all children (91.7%, CI = 87.7 – 94.5) had low dietary diversity (consumed 1-3 food groups) in the last 24 hours. Formula milk was the largest contributor to child’s energy intake amongst the control children. Conclusions: The low dietary diversity warn potential problems for the health of Indonesian children. A large government strategy on complementary feeding practices including controlling the marketing activities of formula milk need to be enhanced.