Vitamin, mineral absorption may change, leading to changing dietary requirements. Fat distribution patterns change, so skinfold thickness becomes a less accurate measure of total body fat. In the young fat is mostly subcutaneous. In the elderly it is mostly intra-abdominal and intramuscular. Special nutritional problems are associated with aging.
Physical limitations can affect nutrition by affecting ease of obtaining and preparing foods.
Transportation, financial problems can limit food choices. Drugs may interact with foods favorably or unfavorably. This is true for all ages. But the elderly typically take more drugs, so are more at risk.