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Part I Introduction to Nutrition Care in Older Adults

BOX 1.2 Changes in Intestinal Absorption of Nutrients with Aging

Reduced absorption: ●

carbohydrate

● protein ●

●

triglycerides folate

● vitamin B-12 ● vitamin D calcium

●

No change in absorption: ●

thiamin ● riboflavin ● niacin

● vitamin K zinc

●

● magnesium iron

●

Increased absorption: ●

cholesterol

● vitamin A ● vitamin C

Source: Morley JE. The aging gut: physiology. Clin Geriatr Med. 2007;23:757–767. Reprinted with permission from Elsevier.

contributors to a lack of desire to eat (8). Medications that impair appetite are commonly prescribed for older adults and are frequently the cause of poor food intake and poor nutritional status (19).

Medications may increase nutrient requirements by reducing nutrient absorption (ie, isoniazid, hydrala- zine, stanol/sterol esters) or increasing nutrient metab- olism (ie, antiepileptic agents). Medications that act centrally by reducing appetite include catecholaminer- gics, dopaminergics, serotonergics, and endorphin modulators such as naloxone. Drugs that inhibit gastric emptying and bulking agents may act peripherally to reduce food intake. Other drugs commonly prescribed for older adults that are associated with anorexia/poor food intake include antibiotics, digoxin, potassium sup- plements, iron supplements, and anti-inflammatory drugs (20). (See Box 1.3.) The monitoring of oral intake and weight should be a part of the routine evalu- ation due to potential drug-nutrient interactions causing changes in appetite and thus food intake. In addition to alterations in gastrointestinal func- tion and physiology, age-related changes in almost every body system may alter nutritional requirements and contribute to poor health outcomes (22). Table 1.2

summarizes the impact of the aging processes on organ systems (see page 8).

Skin

The use of topical retinoids to improve aging skin has become common practice. Clinical features of aging skin include increased skin fragility, poor wound healing, and an increased propensity to form decubitus ulcers. Topical retinoids increase the dermal matrix, thus helping skin to withstand breakdown and ulcer formation (23). However, the use of topical retinoic acid and tazarotene, both approved to treat photoaging, is of concern in older adult populations because of possible irritation at application sites. The application of all-trans-retinol to aging skin improves fine wrinkles possibly through the induction of glycosaminoglycans, which facilitates water retention, and/or increased collagen synthesis; this may be a more promising approach to improving aging skin since it seems to cause noticeably less skin irritation (24). The effect of oral intake of retinoids on aging skin has not been evaluated.

Vision/Eyes Visual acuity begins to diminish more rapidly after age 70. Near vision begins to blur noticeably for virtually everyone. The lens gradually loses its elasticity, and the eye grows less able to accommodate and focus on closer objects. Aging affects the lenses and increases the older adult’s risk for cataracts, glaucoma, and macular degeneration. More than half of all Americans age 65 and older have cataracts.

Age-related macular degeneration (AMD), the most common cause of blindness in the older adult population worldwide, is defined as a chronic, progres- sive disorder characterized by changes within the macula reflective of the aging process (25). The Age- Related Eye Disease Study 2 (AREDS2) indicated that a dietary supplement of vitamin C, vitamin E, lutein, and zeaxanthin, along with zinc, decreased the risk of macular degeneration advancing in those at high risk for developing late-stage (wet) macular degeneration by at least 25% (26). There was no apparent impact for those with minimal macular degeneration or those who did not have signs of macular degeneration. Table 1.3 (see page 8) addresses recommended levels of supplementation.

Folic acid and vitamins B-6 and B-12 have been shown to be beneficial to women. Additionally, lutein- and zeaxanthin-rich greens and yellow, orange, and other fruits and vegetables may decrease the risk for macular degeneration (26). Vitamin supplements do not cure macular degenera- tion, nor will they restore vision that is already lost.