Genetic and environmental influences on taste receptors in the prevention of obesity

During this study, subjects will be evaluated for their taste sensitivity to a number of prototypical taste stimuli including sucrose (sweet taste), citric acid (sour taste), sodium chloride (salty taste), caffeine (bitter taste), oleic acid (fatty acid taste) and monosodium glutamate (umami taste). Individuals who are hyper- or hypo- sensitive to any of these taste stimuli, as defined by a score greater than, or less than 2 standard deviations from the mean, will be asked to participate in the study, which will involve consumption of a standardised diet, the Dietary Approaches to Stop Hypertension (DASH) diet. Whilst this diet was developed to reduce sodium intake, it is accepted as a suitable diet for general health, due to the high levels of fruits and vegetables, as well as whole grains that comprise the diet, and limitations on sugars and fats. The DASH diet will be customized to each participant. For this, all participants will receive recipe cards for cooking DASH style meals and information on how much of each specific food or food group (vegetables, fruits etc) they will be required to consume. In general, the DASH diet recommends the following 1) 7-8 serves of whole grains (whole wheat breads, pasta, cereals etc), 2) 4-5 serves of vegetables (where 1 serve is equal to 1 cup of raw vegetables, or 1/2 cup cooked vegetables), 3) 4-5 serves of fruit (where 1 serve is equal to 1 medium fruit, 1/4 cup dried fruit or 1/2 cup canned fruit), 4) 2-3 serves of low-fat or fat free dairy (where 1 serve is equal to 200 g yoghurt or 200 mls milk), 5) 2-3 serves of oils and fats (where 1 serve is equal to 1 teaspoon of unsaturated oil, low-fat salad dressing, or mayonnaise) per day. To account for differences in body size and energy needs, all diets will be customized for each participant. Taste sensitivity as well as taste receptor gene expression will be measured prior to and following the diet intervention, which will run for four weeks. For this, all participants will complete 4 X 30 minute taste tests, two prior to the intervention, and two during week four of the intervention, as well as 2 x 30 minute testing sessions where tongue tissue will be collected, once prior to, and the other following the intervention. The DASH diet will be consumed by all participants for 4 weeks.