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Vulnerability of drug-induced nutritional deficiencies is greatest in older adults, chronically ill persons, and anyone with marginal or inadequate nutrition intake. Older adults are more likely to be taking multiple drugs, both prescription and over the counter, than younger people. Among older Americans (60 and over), more than 76% used two or more prescription drugs and 37% used five or more as reported by the US Department of Health and Human Services. It is well documented that prescription drug use increases with age (1). Medications are prescribed to older adults to treat the multiple pathological processes associated with aging, as well as memory loss, confu- sion, and altered sleep patterns.

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Older adults compose 13% of the population but account for 24% of all prescription medicine use and 30% of all over-the-counter (OTC) drug use. Approx- imately 80% of older adults live with one or more chronic conditions and take at least one prescription drug each day (2). Many of these individuals take mul- tiple medicines at the same time. A recent survey of 17,000 Medicare beneficiaries found that 2 out of 5 older adults reported taking five or more prescription medicines (3). In another study, it was identified that 30% of 65-and-over adults take more than eight pre- scribed drugs each day. Older adults have more than 50% of all reported serious adverse drug events causing hospital admission; this reflects the pharmaco- dynamics changes in the distribution, metabolism, and elimination of drugs that place them at increased risk (2). “People taking 5 concurrent medicines have a 50% probability of at least one drug interaction; each addi- tional medicine adds an additional 12% increase in risk of drug interactions” (4). The number of possible drug- drug interactions rises sharply when five or more med- icines are taken concurrently. Thus, small increases in the number of medicines taken make large differences to the number of potential drug-nutrient or drug-drug interactions (5).

Implications of Drug- Nutrient Interaction and Pharmacology

Unfortunately, most illnesses in the older adult are managed with prescription drugs. Four of every five individuals older than 65 years are afflicted with chronic conditions such as heart disease, hypertension, arthritis, and diabetes; 35% have three or more of these problems (6). Those living in their own homes take three or more different drugs daily; in institutions, the quantity frequently increases to 10 or more different drugs per day. Because of this increase in usage, there is an increased likelihood of overprescribing practices, including inappropriate or excessive drug use, exces- sive dosage, and prolonged drug use. Consequently, drug interactions are more likely in this group because of this polypharmacy coupled with self-administered over-the-counter drugs and herbal remedies. Older adults may be on long-term drug therapy. They also have a higher risk of drug interactions because of physical changes related to aging such as the increase in the ratio of fat tissue to lean body mass, a decrease in liver mass and blood flow, and impair- ment of kidney function. Illness, cognitive or endo- crine dysfunction, and ingestion of restricted diets also increase this risk. Malnutrition and dehydration, both often seen in older adults, affect drug kinetics. Central nervous system side effects of drugs can interfere with the ability or desire to eat. “Drugs that cause drowsi- ness, dizziness, ataxia, confusion, headache, weakness, tremor, or peripheral neuropathy can lead to nutritional compromise,” particularly in older adults. Recognition of these problems as a drug side effect rather than a consequence of disease or aging is often overlooked even though many of these adverse outcomes can be predicted and avoided (7,8).

First published in 1991, then updated in 1997, 2003, and 2012, the Beers Criteria lists medications that can cause dangerous effects in the older adult (9). Many of the drugs can cause cardiac, gastrointestinal (GI), or urinary effects. It is important to note that the