Biology Forums - Study Force

Discuss the physiological changes that occur with aging and how they affect nutrition status.

Older adulthood is a time in which growth is complete and our body systems begin to slow and degenerate. Although aging of our body tissues is inevitable, eating a nutritious diet and living a physically active lifestyle can help slow this process. Some of the physiological changes that occur with aging include:
•   decreased muscle mass and lean tissue
•   increased fat mass
•   decreased bone density
•   decreased immune function
•   impaired ability to absorb or metabolize various nutrients

These changes are partly within your control. For instance, some of the decrease seen in muscle mass, bone mass, and muscle strength is due to low physical activity levels. Older adults who regularly participate in strengthening exercises and aerobic-type activities have reduced risks for low bone mass and muscle atrophy and weakness, which in turn reduces their risk for falls and the fractures related to falls that commonly occur in this population.

These changes cause an increased need for a few nutrients, reduced need for a few other nutrients, however many nutrient needs remain the same as for young and middle-aged adults. The nutrient changes are as follows:

1.   Energy. The energy needs of older adults are lower than those of younger adults, because older people have lost muscle mass and lean tissue, have lower levels of thyroid hormones, and are less physically active.

2.   Vitamin D. The recommendation for vitamin D increases for older adults, because they have lower bone density, less ability to convert vitamin D from the sun to its active form in their skin, and reduced absorption of dietary calcium.

3.   Calcium. The AI for calcium is higher for older adults because they have lower bone density and reduced absorption of dietary calcium.

4.   Vitamins B6 and B12. There is a greater need for these vitamins among older people as they have lower levels of stomach acid, reduced absorption from the gastrointestinal tract, and a greater need to lower homocysteine levels and to optimize immune function.

5.   Dietary fibre. Older adults need slightly less dietary fibre because they eat less food. After age 50, 30 grams of fibre per day for men and 21 grams for women is assumed to be sufficient to reduce the risks for constipation and diverticular disease, maintain appropriate blood levels of glucose and lipids, and provide good sources of nutrient-dense, low-energy foods.


6.   Iron. A reduced need for iron with aging is primarily due to reduced muscle mass and lean tissue in both men and women. The RDA for men remains at 8 mg per day whereas the RDA for women is also set at 8 mg per day, a full 10 mg per day lower than the RDA for younger women.