What affects the dietary choices of older people?
There is very little difference between the nutrient needs of most older people and those of younger adults. But older people can be more at risk of malnutrition for many reasons, and this is especially true for the very oldest.
Physiological, psychological, physical, medical, lifestyle and social factors all play a part. In the elderly, malnutrition very often means undernutrition, or not getting enough energy and nutrients for the body’s needs. About 1 of 7 older people living in their regular community setting consume fewer than 1,000 calories a day, which is not enough for adequate nutrition. The proportion is much higher for elderly patients in hospital and long-term health care settings. However, the majority of factors associated with a risk of malnutrition in the elderly are responsive to treatment or to alterations of lifestyle.
Hormonal changes affect many aspects of body physiology with ageing. Our body composition changes as we age, resulting in a decrease in lean body mass and an increase in body fat. The senses of taste and smell become less acute, affecting the enjoyment of eating, and older people may respond less well to hunger regulatory hormones, making them feel less hungry.
Tooth loss and the wearing of dentures can also affect eating habits. The sensitivity of our skin to sunlight, and thus our ability to make vitamin D, reduces as we get older. Loss of muscle and joint stiffening lead to reduced mobility. Lower activity levels in the elderly mean less energy is required from the diet for physical work.
The digestive system itself is surprisingly resistant to ageing compared with other organ systems in the body. The stomach loses some elasticity so it cannot accommodate as much food as before, but its ability to secrete digestive juices is not affected much.
But changes in the growth of certain gut bacteria can occur with age, and this can affect the absorption of nutrients such as iron, vitamin B12 and calcium and can also lead to weight loss.
Older people may not be exposed to enough sunlight if they are housebound, live in long-term care facilities, or need to go into hospital for a long time. There may also be a reduction in the responsiveness of the small intestine to vitamin D, which also affects calcium absorption.
Physical and mental illnesses, especially depression, can affect mobility and activity, as well as appetite. Depression affects about 1 in 6 older people and can result from losing a loved one, reduced income, a worsening chronic illness, a gradual loss of independence, or social isolation. Acute illnesses put an increased burden on the body’s metabolism and can quickly lead to undernutrition in the elderly. A common side effect of antidepressant medications in the elderly is a loss of appetite. Recovery from surgery can also be prolonged in the elderly, also increasing the demands on the body’s nutritional needs.
In turn, malnutrition in the elderly can increase the impact of some of these risk factors. It is thought that undernutrition is an important factor affecting the immune system in older people, where a reduction of protein, energy and important minerals and vitamins can contribute to poor immune responses. This is an important area needing more research.
For most older people, following the ‘healthy eating’ message as described in the Eatwell Guide should provide a balanced and healthy diet. Getting sufficient energy in the diet, with an adequate amount of protein, eating nutrient dense foods that contain adequate amounts of calcium and vitamin D, and taking supplements of vitamin D during the autumn and winter months, should help keep muscles and bones healthy.
© University of Liverpool/The University of Sheffield/Newcastle University