Aging and nutrition % of elderly people in Canadian population is increasing more than for other age groups within the elderly age group there is great variability in terms health, metabolism, physical abilities... Life expectancy: average number of years people live in a given population proper nutrition can increase Life span: maximum number of years people can live Why do people age? Many questions a multi-factorial process What mechanisms influence the rates of aging? Are there genetic programs that limit life span? What is contribution of age-accumulated damage to molecules and tissues?...oxidative damage What is the relative contribution of genetics vs. environmental factors? research on centenarians (or healthy over-90 s) are there some common genetic traits? essential life span (ELS) represents idea that maintenance and repair systems (MRS) of the body assure reproductive fitness genes to next generation MRS deteriorate after ELS, and genetic factors influence the rates and extents of such deterioration Oxidative stress and damage Oxidative stress increases with one or more of the following: decreased intake of dietary antioxidants decreased levels or activities of endogenous antioxidants increased production of/exposure to pro-oxidants decreased repair of damage Scanning force microscopy: Repair enzyme scanning DNA for oxidative damage Oxidants.ROS (reactive oxygen species): superoxide radical, hydroxy radical, hydrogen peroxide.other reactive chemical species Excessive levels of several minerals such as iron and copper can promote oxidation Oxidative damage can affect functions of all classes of biomolecules 1
oxidative stress and antioxidants overviews Normal energy metabolism (oxygen) Reactive oxygen species & other oxidating agents Moderated by antioxidants: Dietary: vitamins & other phytochemicals Endogenous: glutath., GST & other enzymes, Tf & other carrier proteins Molecular and cellular damage to body Moderated by repair systems Aging and Disease Some sources of pro-oxidants: -incomplete reduction of oxygen (energy metabolism).. -killing of microbes (immunity) -cytochrome P450 (detoxification) -excessive tissue levels of iron (or other redox-active metals such as copper) -exposure to radiation, smoke, Increased exposure to pro-oxidants is likely to -increase aging-related dysfunctions -increases risk of major diseases such as cancer and CVD H 2 O 2 CAT GSP Peroxides Free Radicals Vit. E, other antiox Stabilized 2
SOD = superoxide dismutase (Cu, Zn, Mn) GSP = glutathione peroxidase (Se) GSH = glutathione reduced (GssG,oxidized) CAT = catalase (Fe) GST = glutathione transferase ROH = organic alcohol Aging & function of body systems relation to nutrition (prevention/management) Muscles: decreased lean body mass (sarcopenia: aging-associated loss of skeletal muscle) mobility may be affected why does sarcopenia occur? several associated factors, e.g., lack of physical activity Senses: decreased sense of taste/smell.e.g., associated with zinc deficiency, cancer treatments, medications, etc less pleasure from food.increase flavour/spices impaired physiological responses to food impaired ability to avoid spoiled foods/toxin Mouth: xerostomia (dry mouth), tooth loss may lower food intake avoidance of certain foods decreased saliva production/secretion affects chewing, swallowing (dysphagia), and increases risk of tooth decay, oral infections 3
GI tract: decreased lactase, gastritis, decreased absorption of nutrients avoidance of dairy products other souces of calcium, protein? lower absorption of calcium, vitamin B12, B6 increased risk of constipation Kidneys: function may decrease by up to 50% between age 30 & 80 especially with diabetes high protein intake (esp. amino acid supplements) may stress the limited kidney function can also increase risk of dehydration Nervous system: deterioration decreased neurotransmit. production, increased oxidative damage (nervous system esp. sensitive to ox. stress) poor appetite, memory, attention dysphagia is more common in elderly Immune system: compromised especially with nutrient deficiencies increased risk of infections, malignancies Cardiovascular: increased hypertension, decreased vascular elasticity Endocrine: decreased glucose tolerance.decreased insulin secretion capacity, increased resistance to insulin action Nutritional requirements for elderly usually lower energy requirements lower BMR (and, often, less physical activity) deficiency: if caloric intake too low, may lead to nutrient deficiencies typical decreased intake recommendations (relative to preelderly adults): 300-600 kcal/d (females-males) protein requirements: currently no change in recommendations for most elderly, but some differing opinions if too low: decreased muscle mass and bone density, poor disease outcome, increased sarcopenia risk? consider kidney function in cases of high intake (esp. if diabetic) 4
Calcium Carbonate crystals higher requirement for calcium about 20% increase for men over 70 and women over 50 reasons: increased bone loss, lower intake & absorption, cf. vit. D higher or altered requirements for some vitamins some reasons: lower intake, absorption, altered metabolism vitamin D: ~25% increase for those over 70 vitamin B6: ~15-25 increase (women-men) for ages 51+ Vitamin B12: greater proportion of intake from supplements/fortified foods containing crystalline forms of B12 higher fluid requirements due to decreases in thirst response (increased thirst threshold) decreased water conservation (re-absorption) by kidneys risks for dehydration include: being unable to drink without assistance; use of medications such as diuretics; high protein intake; ketosis maintain sufficient fat intake provides essential fatty acids, source of energy, omega-3 may help lower inflammation and CVD risk; helps avoid deficiency of fat-soluble vitamins Nutritional care of the elderly-summary of some major points Safe foods pasteurized, cooked Nutrient dense foods including those fortified with B12 Appropriate consistency dependent on chewing/swallowing ability Appropriate substitutes or supplements.if some foods or food groups are being avoided, e.g., dairy Deal with other possible causes of undernutrition. depression, dementia, polypharmacy also physical activity, lower alcohol intake 5