MICRONUTRIENT DEFICIENCIES AMONG OLDER PERSONS
By Melanie Berg, MS, RD, and Gordon L. Jensen, MD, PhD
Although we often consider overt micronutrient deficiency to be rare in developed countries, deficiencies of certain vitamins/minerals are actually fairly common among older persons. These deficiencies are associated with the physiological changes of aging as well as disease processes that afflict the aged. One of the major changes that occurs with aging is decreased energy requirements associated with loss of lean body mass (sarcopenia) as well as decreased physical activity. To some degree, most organ system functions are adversely impacted by aging.
Growing numbers of both institutionalized and homebound elderly are at particularly high risk for micronutrient deficiencies.Other factors that increase risk for micronutrient deficiencies include depression, dementia, poor dentition, substance abuse, polypharmacy, functional limitation, and social isolation. Underlying morbidities and functional impairments may limit the ability of the elderly person to purchase, prepare, digest, and/or absorb food. The absorption and metabolism of certain vitamins/minerals may also be affected by medication usage, as well as by smoking and alcohol consumption.
Although it is expected that energy needs would be less in the elderly, it has been previously suggested that micronutrient needs would be unchanged. The 1989 Recommended Dietary Allowances (RDAs) were based almost entirely on extrapolations from studies conducted in young, healthy adults. They did not include further age-related recommendations beyond age 51 years because there was no research information for older adults available at that time. The health and physiological features of those under 51 years can differ from those aged 51 to 70 years, and can be quite different from those over 70 years.5 The most recent recommendations from the Food and Nutrition Board, Institute of Medicine (1997-2000), provides specific recommendations for these older age groups.
Some of the more prevalent vitamin deficiencies among older persons include deficiencies of vitamins D, C, B12, B6, and folate.
Vitamin D deficiency is quite prevalent in specific elderly populations. The risk for deficiency can be due both to inadequate intake and to decreased exposure to the sun. Inadequate intake is common because many older persons avoid fortified dairy foods because of gastrointestinal intolerance. Nursing home residents and homebound elderly often have inadequate exposure to sunlight.9 Those living in colder environments, such as New England, also have reduced sunlight exposure. One study found that 54% of homebound elderly and 38% of nursing home residents had serum levels of 25-hydroxy vitamin D below the normal level (<25 nmol/L).10 The Adequate Intake (AI) level for vitamin D from the new Dietary Reference Intakes (DRIs) is 10 mcg daily for men and women aged 51 to 70 years and 15 mcg daily for men and women over age 70. Supplementation of vitamin D should be considered in both homebound and institutionalized elderly populations.
Lower serum levels of vitamin C have been observed in elderly populations, especially those who live in nursing homes.11 Elderly people who smoke or are under metabolic stress may have increased needs of vitamin C; adequate intakes of foods rich in vitamin C should be encouraged. The RDAs for vitamin C are 90 mg daily and 75 mg daily, respectively, for men and women aged 51 years and older.
Decreased B12 absorption in the elderly can be caused by decreased gastric acid production associated with atrophic gastritis, since the protein-bound vitamin cannot be dissociated in order to bind to intrinsic factor. The decreased acid production may also precipitate bacterial overgrowth in the stomach and small intestine. Bacterial overgrowth can be associated with the consumption of vitamin B12 by the bacteria, further limiting its bioavailability. Both conditions are associated with decreased absorption of B12 and can lead to pernicious anemia. Inadequate intake of red meats, which are often poorly tolerated by elderly individuals, may also contribute to B12 deficiency. Macrocytic anemia or neurological symptoms may not manifest themselves until advanced deficiency is present. Screening of serum levels is suggested. One such study in patients > 60 years old and living at home revealed low levels of B12 (<148 pmol/L) in 51.1% of male subjects and 30.9% of female subjects.4 Replacement of B12 may be given orally or by injection. The RDA for B12 is 2.4 mcg per day for both men and women aged 51 years and older.
A need for increased B6 intake in the elderly may also be caused by atrophic gastritis, which interferes with its absorption. Deficiencies of this vitamin are also seen with alcohol abuse and liver dysfunction. The RDA for B6 is currently 1.7 mg daily for men and 1.5 mg daily for women 51 years of age and older. The Boston Nutritional Status Survey indicated B6 intakes below two thirds of the 1989 RDA in 27% of subjects.3 (At that time, the RDA was 2 mg daily for males and 1.6 mg daily for females.) Research has suggested improvement in immune indices with adequate B6 intake.
No specific age-related impact on folate requirements in the elderly has been detected, although alcohol use is a risk for deficiency. And several medications, including antacids, diuretics, phenytoin, sulfasalazine, and anti-inflammatory agents, affect both absorption and utilization of folate.3,12,13 The current (1999) RDA for folate for men and women aged 51 years and older is 400 mcg daily. The Boston Nutritional Status Survey revealed the dietary folate intakes of 75% of elderly men and 90% of elderly women to be below the recommended allowance.5 In 1996, the Food and Drug Administration mandated that all enriched flour, rice, pasta, cornmeal, and other grain products contain 140 mcg of folic acid per 100 g.14 Dietary intake is often inadequate in the elderly population; thus, the intake of fortified breads and cereals as well as folate-rich foods should be encouraged.
Deficiencies of B6, B12, and folate are risk factors for elevated serum levels of homocysteine. Homocysteine is now recognized as an independent risk factor for coronary artery disease, vascular disease, and stroke, as well as depression and certain neurological deficits, such as Alzheimer's disease and dementia. Homocysteine levels serve as disease risk markers, and adequate intakes of vitamins B6, B12 and folate should be encouraged.
More than 50% of older persons take nutritional supplements, most commonly a multivitamin with minerals. Unless specifically queried by a health/nutrition practitioner, this information will often be overlooked. The possibility of toxicity related to the ingestion of unsafe levels of nutrients, especially fat-soluble vitamins, must also be considered.
In conclusion, because of the prevalence of vitamin deficiencies in older persons, and risks of excessive supplementation, a comprehensive nutritional assessment should always include, but not be limited to, questions regarding diet, use of supplements, dentition, underlying morbidities, social conditions, functional and mental limitations, and medication use.
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