Unit
- Basal Metabolic Rate Declines: Aging reduces lean body mass and increases fat mass, lowering basal metabolic rate. Energy requirements drop by approximately 10-20% per decade after age 60. This change means older adults need fewer calories but cannot sacrifice nutrient density. Deficiency risks rise if caloric intake is reduced without careful nutrient selection. Eating plans must prioritize vitamins, minerals, and protein over empty calories.
- Body Composition Shifts: Sarcopenia; age-related muscle loss; begins around age 30 and accelerates after 60. Fat redistribution increases visceral adiposity even when weight is stable. These changes affect drug distribution, hydration status, and metabolic resilience. Sarcopenia is a strong predictor of frailty, falls, and hospitalization. Nutrition interventions must target muscle preservation through adequate protein and resistance training.
- Endocrine Alterations: Hormonal changes include reduced growth hormone, insulin-like growth factor, and sex steroids. Thyroid function often declines subtly, affecting metabolism. Insulin sensitivity may decrease, raising diabetes risk. Cortisol regulation can become dysregulated, impacting stress responses and appetite. These hormonal shifts interact with nutritional status, requiring careful monitoring of glucose control and bone health.
- Immune Function Compromise: Immunosenescence increases susceptibility to infections and impairs wound healing. Nutrient deficiencies; especially zinc, vitamin D, and vitamin C; further weaken immune responses. Inadequate protein intake impairs antibody production. Antioxidant-rich foods become more important. Nutrition plans should include immune-supporting nutrients while avoiding excessive supplementation that may cause harm.
- Renal and Hepatic Changes: Kidney function declines with age, reducing glomerular filtration rate by about 1% per year after 40. This affects clearance of water-soluble vitamins and some medication metabolites. Liver size and blood flow decrease, altering drug metabolism and nutrient processing. Protein recommendations may need adjustment in renal impairment. Hydration status requires frequent assessment due to reduced renal concentrating ability.
- Gastrointestinal Alterations: Gastric acid secretion often decreases, leading to reduced absorption of vitamin B12, calcium, iron, and folic acid. Motility slows, causing constipation and delayed gastric emptying. The gut microbiome composition changes, affecting inflammation and nutrient fermentation. Lactose intolerance may become more apparent. Fiber and fluid intake must be emphasized to support bowel regularity and microbiome health.
- Sensory and Oral Changes: Diminished taste and smell reduce appetite and food enjoyment. Dentition loss and dry mouth further limit food choices and chewing efficiency. These changes can lead to poor dietary variety and increased sodium use for flavor. Nutrition interventions should incorporate texture modifications, flavorful herbs, and soft protein sources. Regular oral health assessments are necessary for adequate intake.
- Hydration Regulation Impairment: Aging reduces thirst sensation and total body water percentage, making dehydration more common. Kidneys become less able to concentrate urine, increasing fluid loss. Medications like diuretics compound risk. Dehydration leads to confusion, falls, and urinary tract infections. Care plans must include scheduled fluid intake, monitoring for signs of deficiency, and offering appealing beverages throughout the day.
Regulatory Note
Regulation: The Dietary Guidelines for Americans provide foundational recommendations for older adults, emphasizing nutrient-dense food choices and limiting added sugars, saturated fats, and sodium. However, clinical judgment must supersede general guidelines for individuals with specific chronic conditions. Nutrition standards in long-term care facilities are additionally governed by state regulations and federal requirements under the Older Americans Act.
Source: Dietary Guidelines Advisory Committee; U.S. Department of Health and Human Services.
Terminology
- Sarcopenia
- Age-related loss of skeletal muscle mass and function, strongly linked to frailty and falls.
- Immunosenescence
- Gradual deterioration of the immune system associated with aging, increasing infection susceptibility.
- Presbyphagia
- Age-related changes in swallowing function that may lead to dysphagia and aspiration risk.
Quick Revision
- Aging reduces basal metabolic rate and alters body composition, requiring nutrient-dense, lower-calorie diets.
- Hormonal shifts and immune decline increase the need for protein, zinc, and vitamin D.
- Renal and hepatic changes affect drug and nutrient clearance, necessitating careful monitoring.
- Hydration, oral health, and sensory changes are critical factors in geriatric nutrition planning.