the science of taste
by Carrie Ruxton PhD, RD Freelance Dietitian
Dr Carrie Ruxton is a freelance dietitian who writes regularly for academic and media publications. A contributor to TV and radio, Carrie works on a wide range of projects relating to product development, claims, PR and research. Her specialist areas are child nutrition, obesity and functional foods.
www.nutrition-communications.com
Understanding the science of taste
The impact of taste and other sensory factors on compliance with oral nutritional supplements
Figure 1: Factors affecting nutritional intake12
Malnutrition is a serious condition that, if left untreated, can have an adverse effect on recovery, physical health, cognitive function and indeed, psycho- logical health (1-5). In addition to these effects (listed in Table 1), the medical and social consequences of malnutri- tion can have considerable economic implications. In 2007, it was estimated that public expenditure on disease- related malnutrition in the UK was in excess of £13 billion per annum (6). This is due to the impact of malnutrition on complication rates, mortality, length of hospital stay and use of healthcare resources (6).
Malnutrition can result when a person is less able in the long-term to meet their daily nutritional require- ments. This could be due to increased energy expenditure, for example, as a result of disease processes or infec- tion; decreased energy and nutrient intake due to loss of appetite; difficulty in eating or reduced access to nutri- tious foods (summarised in Figure 1). For these reasons, those with certain medi- cal conditions, children and the elderly are particularly susceptible to the risk of malnutrition. A key aspect in the elderly is age-related impairment of taste and smell (7) which can reduce appetite and, thus, food intake (8).
Despite our understanding of the causes, consequences and manage-
ment strategies for addressing malnutri- tion, the condition remains a common problem in hospitals and care homes, affecting approxi- mately 10-40 percent of patients (5). Oral nutritional supple- ments (ONS) are rec- ognised as an effective strategy for managing malnutrition. ONS have been shown to improve nutritional intake; lessen weight loss and improve physical function, for example, walking distances or activi- ties of daily living; as well as reducing medical complications and mortality (5,9). However, the benefits of ONS can only be realised if patients take them as prescribed. Evidence from clinical trials indicates that compliance with ONS regimens is approximately 50-65 percent of the amount prescribed by healthcare professionals, although this differs between patient groups investi- gated (10,11).
Appearance Texture/ composition
Information & education provided
Patient motivation
Support/ care
Figure 1: Factors affecting nutritional intake (12)
The impact of taste and other sensory factors on compliance
One of the challenges facing com- pliance with ONS is patients’ sensory experiences when they consume the
Table 1: Potential consequences of malnutrition 1-5
Potential consequences of malnutrition
x Lack of energy x Weight loss x Loss of muscle power x Increased susceptibility to infection
x Anaemia
x Decreased bone density x Depression, anxiety
NHDmag.com June '10 - issue 55
x Anger, tension x Impaired cognitive function x Impaired cardiac function x Impaired respiratory function x Prolonged hospital stay
x Increased use of healthcare resources
drinks, particularly in relation to the taste, smell and mouth-feel (10,13). The sensation of taste occurs when taste buds in the tongue and throat con- vey information about the chemical composition of the food and drink to the brain. There are five taste sensa- tions that contribute to our evaluation of foods and beverages, which may prevent us eating potentially harm- ful substances. These sensations are sweet, umami, salt, sour and bitter (14). Sweetness permits the identification of energy-rich nutrients, umami allows the recognition of amino acids, salt ensures the proper dietary electrolyte balance and sour and bitter tastes warn against the intake of potentially noxious and/or poisonous chemicals (14).
The physical sensations that we de-
rive from food and drink play a primary role in what is preferred and, ultimately, consumed. A positive experience will most likely lead to increased accept- ability and consumption. A likeness for sweetness and dislike for bitterness are innate human traits at birth (15), while specific taste preferences and aver- sions develop later through attitudes, beliefs and experiences (16,17). In addition to taste, when considering patient acceptability of ONS, we must take into account other sensory factors
19
Taste/ flavour
Variety
Volume/ frequency
Preparation/ convenience
Access
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