Older adults need the same nutrients -- protein, carbohydrate, fat, vitamins, minerals and water -- as younger people, but in different amounts. Getting enough may be challenging if health problems limit food intake.

A few nutrients may require special attention: protein, calcium, vitamin D, vitamin C, iron, vitamin A, folic acid, vitamin B12, zinc and water. Eating enough fiber-rich foods aids digestion and helps to prevent constipation.

As people age, most use less energy, or calories, than they did in younger years. That's because the body uses energy at a slower rate, and many older adults live less active lifestyles.

Although calorie needs vary depending on activity level and age, many older adults need about 1,600 calories daily. Chosen carefully, those 1,600 calories can be nutrient-packed and can supply the minimum recommendations from the Food Guide Pyramid. The following daily servings add up to about 1,600 calories:

Older adults need at least five ounces, or two servings, of protein a day. However, for some elderly people, protein-rich foods such as meat or poultry may be hard to chew. In addition, some may not buy meat, poultry or fish because they can be more expensive than other foods. Below are some recommendations for protein consumption:

As adults age, calcium needs go up. To help maintain bone mass and reduce the risk of osteoporosis, calcium recommendations increase by 20 percent. Both men and women over age 50 should consume at least 1,200 milligrams calcium each day. Milk, cheese and yogurt are the best sources of calcium. In addition, dark green leafy vegetables, fish with edible bones, tofu made with calcium sulfate and calcium fortified fruit juices and cereal also have significant amounts of calcium.

Keep in mind that it's never too late to consume more calcium. At the same time, consume enough vitamin D and do some weight-bearing exercise, such as walking. Aim for a total of 30 minutes of physical activity each day to help keep bones dense.

Vitamin D and calcium go hand-in-hand. Vitamin D helps deposit calcium in bones and helps protect against bone disease by keeping them stronger. Vitamin D is known as the "sunshine vitamin" because the body makes it after sunlight, or ultraviolet light, hits the skin. Twenty to 30 minutes of sun exposure two to three times per week is adequate. However, for those who are housebound, vitamin D can be obtained from foods. Most milk is fortified with vitamin D, as are cereals. Check the Nutrition Facts panel to see if it has been added.

Iron deficiency is a common nutrition problem as we age and often leads to anemia and its symptoms: fatigue, weakness and poor health. Vitamin C helps the body absorb iron from plant sources. Consuming vitamin C with iron-rich foods will enhance the body's ability to absorb iron.

A few tips to avoid iron-deficiency:

Vitamin A, found in dark green leafy and yellow and orange vegetables, helps eyes adjust to dim light and protects skin and other body tissues.

Folate helps the body make red blood cells and can lead to anemia if intake is low. Good sources include leafy, green vegetables, fruits, beans, enriched grain products, wheat germ and some fortified cereals.

Vitamin B12 works with folate to make red blood cells. Too little vitamin B12 can also lead to anemia, and in some older adults, is linked to neurological problems. Meat, poultry, fish, eggs and dairy foods are all good sources.

Older adults need plenty of fluids: eight to 12 cups a day. Food provides some water, but drinking at least eight cups daily is advised. Water can come from all kinds of beverages, including juice, milk, soup, tea, coffee and soft drinks. Plain water is great, too. Remember that juice, milk and soup offer other nutrients as well.