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Variety is the spice of life: Using food variety to improve nutritional intake in older adults

7th September, 2021

Variety is the spice of life: Using food variety to improve nutritional intake in older adults

Laura Wilkinson & Rochelle Embling

Why should I care about ‘food variety’?

The need to eat a variety of foods for the good of our health is an idea that is familiar to most of us. Indeed, eating a varied diet appears in dietary guidelines across the world. This is because different types of foods provide different nutrients that we need. For whole natural foods, there tends to be a relationship between differences in colour, texture, and taste, with differences in nutrient-content. This is the basis of the often-heard advice to ‘eat the rainbow’. However, when it comes to eating foods like sweets, ‘eating the rainbow’ may not be very helpful from a nutritional point of view.

When we think about the variety of foods that we eat, we also have to think about how much we are eating. This is because when we are presented with foods that vary in their sensory characteristics (e.g., colour, texture, and taste), we tend to eat more of them. This is known as ‘the variety effect’ and is very helpful when it comes to fruits and vegetables but unhelpful when it comes to indulgent foods like confectionary.

The variety effect exists because of an essential process that helps to signal when to bring an end to a meal and when to move onto dessert! This process is known as ‘sensory specific satiety’ and refers to a reduction in the desire to eat and pleasantness of a food as we eat it. By contrast, foods with a different colour, texture, and taste –  that we are not eating – remain desired and perceived as pleasant. This can be why we often find room for a ‘sweet’ dessert even after we are finished with our ‘savoury’ main meal.

What happens to our experience of food variety when we get older?

As we get older our experience of food changes, and this includes our experience of the process of sensory specific satiety. A key study by Rolls & McDermott (1991) compared the experience of sensory specific satiety across four age groups; teenagers, young adults, adults and older adults. They found that compared to the other age groups, older adults did not experience a reduction in desire to eat and pleasantness of the food that they were eating compared to other foods (that had not been eaten).

Rolls and McDermott explain that this is important because older adults may be less likely to stop consumption of the food that they are eating and switch to another food with different sensory characteristics. If we are less likely to switch foods, then we will consume less of a variety of foods, and this is particularly unhelpful when we consider the need to eat a variety of nutrient-dense foods at an appropriate volume.

How can we encourage food variety in older adults?

Despite the relative loss of sensory specific satiety – the underlying driver of the variety effect – it may still be possible to encourage the consumption of a variety of foods as we get older. Researchers Hollis and Henry (2007), gave older and younger adults a four course meal which contained either the same type of sandwich for each course or different sandwiches for each course. As expected, the older adults ate more than the younger adults when the same type of sandwich was presented for each course and the younger adults ate more than the older adults when sandwiches were varied across courses. However, overall, older adults still ate more when courses were varied compared to when courses were the same. Indeed, other studies by Professor Katherine Appleton (Bournemouth University) have shown that the addition of sauces and seasonings can increase the amount eaten in an older person’s meal.

 

Taken together, these findings suggest that despite a relative loss of sensory specific satiety as a driver of the consumption of food variety, more will be consumed overall if variety is presented as a part of a meal anyway (rather than when food is monotonous). One possibility is that more of a conscious effort must be made to include variety in a meal for an older person because that natural driver to switch foods is absent or reduced.

What can I do?

Making a conscious effort to include food variety in meals – whether you are cooking for yourself as an older person or cooking for other older adults – can be a way to simply increase the amount an older person is eating. Going a step further, it may be a way to actively improve nutrition when applied to nutrient-dense foods. This approach may be especially helpful when it comes to eating enough protein, which is important for the prevention of health issues such as sarcopenia (loss of skeletal muscle) and, more generally, healthy ageing.

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