4. Discussion
muscle mass, satiety, Spice
VIRUS, LOSS OF APPETITE
A major objective of this study was to investigate whether protein intake at a single meal could meet or exceed the recommended per meal protein intake for community-dwelling older persons to maintain muscle mass and function. An additional aim was to determine whether the addition of culinary spices could improve liking of high-quality protein foods, potentially increasing their consumption to help meet this protein intake target. A daily protein intake of 1.2–2 g protein/kg body weight/d is recommended to preserve muscle mass and prevent loss of function in older adults [In this study, we observed protein intakes for the M meal of > 30 g/meal that met the 25–30 g total protein intake per meal and the 0.4 g/kg body weight/meal targets for roughly two-thirds of participants. In contrast, participants served the V meal consumed a mean of only 20 g of protein, and only one in five met the 0.4 g/kg body weight/meal target. These findings are not surprising given that the protein density of the M meal was nearly three times greater (0.167 g protein/g M entrée vs. 0.062 g protein/g V entrée). Even with the addition of soy protein powder to the V entrée, it was not possible to match the greater protein density of the M entrée. Participants served the V entrée would have had to consume substantially greater volumes in order to achieve the protein intake target, although the portions served were large enough to accomplish this. In the present study, participants fed the V meal actually ate 25% more energy than those fed the M meal, but it was still insufficient to meet the protein intake target. Both treatment groups ate to the same level of satiety (Surprisingly, the addition of culinary spices to either the M or V entrée did not increase consumption beyond that observed with addition of salt and pepper alone. Spice addition significantly improved liking scores for the V entrée, and meal and flavor intensity scores were greater for both M and V entrees and for the overall V meal. Food liking is often correlated with consumption [In the case of the M entrée, it is possible that the base recipe, with the flavors of chicken, mayonnaise, yogurt, celery and pepper, was sufficiently pleasant to a make further increase in liking less probable. Absolute liking scores for the NS version of the M entrée averaged 7.2–7.4, which is typical for foods that are well liked [Furthermore, 24 to 32% of our participants reported having weaker smell and flavor sensitivity than when they were 30–35 years old, while 32% reported average or below average smell acuity at present. These numbers are consistent with other studies of age-related changes in sensory acuity. Rawal and colleagues [Declining sensory acuity has been suggested to be one factor affecting the loss of appetite, reduced food intake and reduced food liking among older adults [Previous COVID-19 status (having the virus more than 6 months prior to study) did not affect the consumption of either the M or V meals. Although sensory losses from COVID-19 are reportedly restored within a few months [Variety-seeking behavior among individuals is one factor that may affect the selection and intake of foods [This study is encouraging in that it shows it is possible to achieve the proposed protein intake target of 0.4 g protein/kg body weight/meal for older individuals, at least for meat-based entrees. This was accomplished with ingredients that are readily available, affordable (canned chicken breast, etc.) and easily prepared at home. It also points to the challenges of achieving the same high level of protein intake when plant-based protein sources are used. While achieving adequate protein intakes from plant-based diets is possible for younger individuals whose total food and energy intakes are higher than for older adults, the lower protein per kcal density of plant proteins makes it much more difficult for older adults whose protein requirements are greater [Despite the lack of effect of culinary spices on increasing total protein intake in the present study, these substances have bioactive properties beyond their ability to enhance the flavor of foods. Culinary spices such as oregano, rosemary, cumin, parsley and dill used in the present study are rich in polyphenolic compounds [Study strengths and limitations: Strengths of this study include a relatively large sample size for a randomized and standardized meal test, objective measures of intake and subjective measures of liking, flavor intensity, appetite and subjective sensory acuity. Test foods were selected that were familiar and could easily be prepared at home from readily available and affordable ingredients. The test food formulations also eliminated potential problems related to chewing and swallowing, which are issues more common among older individuals. In effect, the food forms served were optimized for promoting easy consumption, providing a reasonable benchmark for testing the feasibility of achieving the higher protein intake target for older individuals. A significant limitation of this study is that it tested only one meal occasion, lunch, and further studies would be needed to determine whether total daily protein intake could be sustainably increased to meet the 1.2 g protein/kg body weight/day target for older individuals. We did not collect information about the dietary intake of participants either before or after the test lunch, so we could not estimate total daily protein intake. Finally, the particular choice of foods and spices tested is a limitation given the much wider variety of foods consumed as part of a normal diet.