the science of taste
that contribute to the experience of taste in humans (see Table 2). The first of these factors is flavour, which directly relates to the smell or aroma of the food. Humans have sensory cells in their noses which are activated when food is chewed and molecules within the foods are released (18). Flavour also incorpo- rates the tactile sensation of the food as it is being eaten, sometimes referred to as mouth-feel. Next is the percep- tion of palatability, which often relates to habitual food intake and expecta- tions. Depending upon their experience, people expect certain foods to be served at a particular temperature and to have a particular colour, shape and sound (12,16). For example, people may dislike the idea of drinking blue milk, but enjoy the sound of frying bacon. The final factor to consider is accept- ability which incorporates the environ- ment in which people are served the food; cultural influences; memories of pleasant or unpleasant experiences with food; genetic links as this determines how many taste buds we have; age and personal condition such as current mood and health status (12,16). For ex- ample, if a person is depressed or upset they may be less inclined to eat or drink. These additional sensory factors all play an important role in whether or not a patient likes an ONS and, ultimately, whether they find it acceptable. One study reported that only 43 percent of hospitalised patients showed good compliance (defined as at least 80 percent of prescribed intake) with nutritional supplements with flavour, taste, texture and also predictability of the supplements contributing to non- adherence (10). When patients need to use ONS drinks over long periods, the issue of sensory pleasure is paramount. Despite medical recommendations and a prescription for use, patients are unlikely to continue taking something that they dislike, especially if they do not fully understand the justifications for its use. Patients may also develop taste fatigue, i.e. a taste-driven loss of desire to ingest a particular food, again
Sweet Sour Salty Bitter Umami
Flavour
Aroma
leading to a reduction in compliance. Providing supplements which offer a variety of flavours can help to minimise taste fatigue (19).
Overcoming poor compliance
Healthcare professionals have an important role in helping patients and carers to understand why nutritional supplements have been prescribed and the value and benefits of contin- ued use. The National Institute for Health and Clinical Excellence (NICE) recom- mends setting goals for all patients receiving nutritional support (5). Identify- ing clear, short- and long-term goals, combined with support and follow-up, can help patients to get the best from their treatment. ONS are now formulated in a va- riety of flavours aimed at increasing patient choice, with the expectation that improvements in sensory experi- ence will aid compliance. Research and development of new ONS formulations are focusing more on sensory characteristics of drinks and improvement of compliance. New studies are expected to emerge later this year. In the meantime, health professionals can improve compli- ance with ONS by: • establishing taste preferences and ensuring that the patient can choose from a variety of flavours (and styles);
• ensuring that the ONS is within reach of the patient and that the patient is positioned comfortably for eating and drinking;
• educating patients and their carers on the need for ONS and when and how to take them;
• offering ONS between mealtimes, or providing recipe ideas;
• making the patient’s eating environ- ment as pleasant as possible, i.e. surroundings and social atmosphere;
• serving ONS in an appealing and appropriate manner , for example pouring a drink into a glass rather than serving in the packaging and ensuring the feed is chilled;
Table 2: How humans experience food (12)
Basic taste senses
‘Mouth-feel’ -
texture/thickness
Chemical senses
Palatability
Temperature Colour Shape Sound
• helping the patient to maintain good oral hygiene (which will en- courage appetite and increase the enjoyment of the ONS).
Resources For more information on malnutrition and malnutrition initiatives please visit:
http://www.espen.org/index.php http://www.bapen.org.uk http://www.rcn.org.uk/newsevents/campaigns/nutritionnow http://www.european-nutrition.org/ http://www.nice.org.uk/nicemedia/pdf/cg032fullguideline.pdf
The fee for this article was paid for by Abbott Nutrition. The views expressed are the author’s own.
References 1 Bourre JM. Effects of nutrients (in food) on the structure and function of the nervous system: update on dietary re- quirements for brain. Part 2 : macronutrients. J Nutr Health Aging 2006;10:386-99 2 Arora NS, Rochester DF. Respiratory muscle strength and maximal voluntary ventilation in undernourished patients. Am Rev Respir Dis 1982;126:5-8 3 Windsor JA, Hill GL. Risk factors for postoperative pneu- monia. The importance of protein depletion. Ann Surg 1988;208:209-14 4 Stanga Z, Field J, Iff S, Stucki A, Lobo D N, Allison SP. The effect of nutritional management on the mood of malnourished patients. Clin Nutr 2007;26:379-82 5 British Association for Parenteral and Enteral Nutrition. Nutrition screening survey in the UK in 2007. Available from:
http://www.nice.org.uk/nicemedia/pdf/cg032fullguide- line.pdf. Accessed February 25, 2010 6 Elia M. Combating Malnutrition: Recommendations for Action. Report From The Advisory Group On Malnutrition, Led By BAPEN 2009 7 Murphy C, Schubert CR, Cruickshanks KJ, Klein BE, Klein R, Nondahl DM. Prevalence of olfactory impairment in older adults. JAMA 2002;288:2307-12 8 Schiffman SS. Intensification of sensory properties of foods for the elderly. J Nutr 2000;130:927S-30S 9 Stratton R, Elia M. A review of reviews: A new look at the evidence for oral nutritional supplements in clinical practice. Clinical Nutrition Supplements 2007;2:5–23 10 Lad H, Gott M, Gariballa S. Elderly patients compliance and elderly patients and health professional's, views, and attitudes towards prescribed sip-feed supplements. J Nutr Health Aging 2005;9:310-4 11 McColl J, Potter J, Reilly J, Roberts M. Can prescription of sip-feed supplements increase energy intake in hospita- lised older people with medical problems? British Journal of Nutrition 2003;90: 425-429 12 Nieuwenhuizen WF, et al. Older adults and patients in need of nutritional support: Review of current treatment options and factors influencing nutritional intake. Clinical Nutrition 2009; doi:10.1016/
j.clnu 2009.09.003 13 Darmon P, Karsegard V, Nardo P, Dupertuis Y, Pichard C. Oral nutritional supplements and taste preferences: 545 days of clinical testing in malnourished in-patients. Clinical Nutrition 2008 ;27(9) 660-665 14 Konstantinidis I. The taste peripheral system. B-ENT 2009; 5(13):115-21 15 Ganchrow J, Steiner J, Daher M. Neonatal facial expressions in response to different qualities and intensities of gustatory stimuli. Infant Behavior and Development 1983;6(4):473-484 16 Clarke J. Taste and flavour: their importance in food choice and acceptance. Proceedings of the Nutrition Society 1998;57:639-43 17 Beauchamp GK, Mennella JA. Early flavor learning and its impact on later feeding behavior. J Pediatr Gastroen- terol Nutr 2009; 48 Suppl 1:S25-30 18 Araujo IET de. Taste-olfactory convergence and the representation of the pleasantness of flavour in the human brain. European Journal of Neuroscience 2003; 18(7): 2059-2068 19 Ravasco P. Aspects of taste and compliance in pa- tients with cancer. European Journal of Oncology Nursing 2005; 9:S84-S91
Acceptability
Environment Culture Memory Genetics Age
Personal condition –
mood/health
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NHDmag.com June '10 - issue 55
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