Vivien Wong from Reading University has shared this blog with us at Nutrition and Hydration Week.
I still remember after my grandma fell ill, it slowly became more and more difficult to arrange meals and help her to get enough nutrients. When we thought the foods were fine, she would find the meals were bland. Most of the time she would have a poor appetite and ate very little. We were really worried about her losing weight too quickly and becoming more prone to illness. Reduced taste sensitivity happens in healthy older adults too. My neighbor is well and very active in her 80’s. Sometimes we will have lunch together and I realise she would put a lot of salt in her food because she can’t taste the flavour. These seem to be common observations among the older population, whether they are healthy or frail.
Deteriorated taste perception is an age related physiological change. As we grow old, our taste sensitivity will reduce gradually. Some older adults may have endured the change and some may not even notice it. Many studies have found that taste thresholds of older adults are significantly higher than for younger adults ; so, for example, more salt is needed for food to taste salty. Many older adults have at least one or more chronic health conditions; their medications and illnesses can also contribute to the taste impairment .
Although their salt taste deteriorates, it is not reasonable for older adults to add more salt to their foods as this can increase the risk of hypertension and cardio-vascular disease . If older adults find their meals are lacking in flavor and unpalatable, it’s likely that their enjoyment of food, and their appetite, will reduce. Consequently, they may start to eat less and such decreased nutritional intake can contribute to malnutrition.
You may have heard about the basic five tastes: sweet, sour, bitter, salt and the fifth taste Umami being described as a “savoury” “meat -like” taste. The umami taste can be derived from an amino acid called glutamate, which was first isolated from Konbu (a type of Seaweed) by Dr. Ikeda in Japan 100 years ago, as well as from ribonucleotides .
Recent research suggested umami taste compounds naturally present in foods, such as glutamate and inosine monophosphate, can be used instead of salt to increase savoury taste and enhance savoury flavour perception [5,6]. Studies have shown that umami taste enhancement can be used to increase appetite and food consumption [2, 7, 8]. Umami taste stimuli can also increase salivary secretion, which may help to relieve the discomfort of oral dryness, a common health problem among older adults [9, 10]. Sasano et al. suggested the increased salivary flow can help in overcoming dysphagia and facilitate food swallowing .
Whereas some studies have shown no significant effect of taste enhancement on appetite, nor liking, of meals by healthy older adults  the review of numerous studies by Song et al. concluded that taste enhancement has a positive effect on frailer older adults’ food preference . Dermiki et al. found the natural umami taste enhanced meals, increased food preference among the older hospital patients .
The effect of umami taste enhancement in improving older adults’ food intake and nutritional status is debatable, because it is not a ‘one size fits all’ solution. Dependent older adults usually have health problems and more impaired taste perception. This may explain why we see umami taste enhancement to positively influence food liking of frailer older adults, while those with less taste impairment may find enhanced meals overpowering . More research is needed to understand how to apply umami taste enhancement appropriately to derive its maximum benefits for older adults and tailor for their different nutritional needs.
Nevertheless, if we can adopt taste enhancement into our cooking and add a twist of umami, this can boost the pleasant savoury flavour, whilst avoiding high salt levels in food. By doing so we can help to encourage our older adults to enjoy their food again and eat more.
Introducing novel foods that are mismatched with the older adults’ memories can lower their food acceptance and liking . However, many umami- rich nature ingredients are already well known.
If you enjoy having a roast dinner on Sunday or a spaghetti Bolognese for tea now and then, you are already having umami- rich meals. Tomato puree, Parmesan, Worchester sauce, roasted beef and mushrooms, these are all umami- rich foods [4, 5, 17]. Why not give it a try to taste a small sip of tomato puree? Can you feel the increased salivary secretion at the side of your mouth? That’s your natural reaction to the stimuli of umami taste compounds.
You may not have recognised umami taste before, but umami has been used in cooking throughout history and in different cultures. Garum is a fish sauce (fermented from mackerels) which was used as a seasoning back in Ancient Greek and Roman times. Anchovy paste and sauce is the modern version. Tomato and Parmesan are the foundation of Italian cuisine and loved throughout generations. In Asia, they also have a long history of using fermented products, such as Chinese soy sauce and Japanese miso, in their cuisine to increase the umami taste. 
The umami synergy of matching different umami combinations, between the umami tasting amino acid with ribonucleotides, is still applied in modern culinary to maximise the umami sensation. For example:
Spaghetti Bolognese = Tomato (246 mg glutamate/100g food) x Beef (70 mg inosinate/ 100g food)
Chicken Cesar salad =Parmesan (1680 mg glutamate/100g food) x Chicken (201mg inosinate/ 100g food)
So how about adding some shavings of Parmesan to taste enhance your spaghetti Bolognese next time and see if you can notice the flavour has differed?
Taste enhancement can be applied together with the other nutritional care strategies in a flexible system to help meet older adult’s individual needs, preferences and overcome their barriers to adequate nutrition. We ought to tackle the problem now to prevent older adults becoming malnourished. Are you worried that the older adults you are caring for are not getting adequate nutrition? Why not give taste enhancement a try?
[A taste enhancement recipe booklet is available to here]
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