The Effect of Consumption of Sumac in Vegetable Soup on Appetite and Food Intake Among Older Adults (Aged Over 65 Years) and Young Adults (Aged 18-35 Years)

Rhus coriaria Linn, also known as Sumac, is a spice that is widely used in Turkish, Iranian and Middle Eastern foods. In these regions, the fruit of sumac is used for seasoning or flavouring, as an appetizer and for souring food. This spice has also been used in herbal folk medicine to relieve certain conditions including bowel disorders, anorexia and indigestion. In addition, many studies have shown that sumac contains a high level of antioxidant activity and polyphenol content that may benefit certain diseases such as cancer and diabetes.

Taste and smell perception may play a vital role in food preference, nutrient intake and appetite; however, both ageing and disease can have a negative impact on these senses. It has been suggested that by 2025 the older adult population (i.e. those aged 60years and over) worldwide will rapidly increase and reach 1.12 billion. One of the major physiological changes in this age group is the loss or reduction in sensory perception including smell and taste. These changes as a result of ageing and medication increase the risk of poor health by reducing the enjoyment of food followed by decreasing food and nutrient intake.

It is possible, therefore, that all these factors together may lessen the enjoyment of food, leading to malnutrition and disease complications. In light of the above, the aim of this study was to assess the level of the appetite and food intake among young adults in comparison with free living older adults following the consumption of sumac. This was achieved by assessing the amount of food intake during a lunch course and the impact on food intake for the subsequent 12 hours.

This study assessed the use of sumac at 1% dose (0.37g) of total volume of a vegetable soup (150g), in two forms: 1) added to finished cooked soup 2) added to the soup from the beginning of the cooking process, in addition to consumption of the same soup without added sumac as the control soup. The study comprised of 20 young adults (18-35 years old) and 20 free living older adults aged >65 years. Each participant in these groups attended the Oxford Brookes Centre for Nutrition and Health (OxBCNH) for three sessions and each session lasted up to one hour.