O f all the changes that occur with aging, one of the most under-recognized is the body's reduced ability to absorb nutrients. As we grow older, our bodies become less efficient at secreting the digestive enzymes that are necessary for the absorption of essential vitamins. Because of this absorption problem, I advise my older patients to follow the nutritious and heart-healthy Mediterranean diet -- rich in fresh greens (such as chard, kale and spinach), fresh fruit, whole grains, nuts, seeds, beans, healthful oils (olive, for example) and lean protein, such as turkey and fish. For more on the Mediterranean diet, visit the Web site of the American Heart Association, www.americanheart.org.

But it's not always easy to stick to a nutritious eating plan. What's more, many older adults suffer conditions that interfere with appetite -- for example, dry mouth, nausea or constipation caused by common medications, such as pain relievers and hypertension drugs. Dentures and waning senses of smell and taste also can prevent a person from eating healthful meals. In my opinion, all people over age 50 should consider taking certain supplements -- in addition to a daily multivitamin -- to compensate for nutrients that might be lacking in their diets. My favorite "healthy aging" supplements (all available at health-food stores...

Vitamin B-12 -- 800 micrograms (mcg) to 1,000 mcg daily, in sublingual (dissolved under the tongue) form. It helps with poor memory, a lack of energy, depression and neuralgia (nerve pain).

Vitamin A -- 10,000 international units (IU) daily. It helps promote health of the eyes and skin and general immunity. If you also take a multivitamin containing vitamin A, do not exceed 10,000 IU daily unless recommended by your doctor.

Vitamin E -- 400 IU daily. It protects nerve and muscle cells, reduces leg cramps and helps prevent heart disease.*

*If you take a blood-thinning drug, such as coumandin (Warfarin), check with your doctor before taking vitamin E supplements.

Vitamin D -- 1,000 IU daily. Recent research shows that many older adults are deficient in vitamin D, a nutrient that is essential for calcium absorption and osteoporosis prevention and may protect against certain malignancies, including cancers of the breast and colon.

Essential fatty acids, in the form of fish oil, containing 1,800 mg daily of combined eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Fish oil acts as a natural antidepressant for patients of all ages and improves brain function.

Digestive enzymes. Typically derived from papaya or pineapple, digestive enzyme supplements promote digestion -- and, in turn, the absorption of nutrients from foods and other supplements. Follow the manufacturer’s directions for dosages. If you have a gastrointestinal disease, such as an ulcer or diverticulitis, consult your physician before taking plant enzymes, which can irritate an inflamed gastrointestinal tract.