NUTRITION FOR OLD AGE
The ageing of the developed world's population and the big incidence of nutritional problems in the aged gives rise to an increasing interest on the part of society to learn more about the nutritional needs of this age group.
Dietary measures are unable to stop the natural process of ageing but they can improve the quality of life of our elders.
The nutritional needs of older individuals in an optimal state of health do not appear to differ much from those of adults. A varied, balanced and healthy diet provides all the energy our body needs. Nonetheless, ignorance about the basic principles of nutrition may be the cause (on the part of people and other groups) of multiple nutritional deficiencies: very restrictive diets due to the presence of added diseases, monotonous or unappealing served at institutions, use of miracle diets with the idea of rejuvenation, etc.
The nutritional status of elderly people may be altered by several reasons:
A. Energy requirements
The manifestations of aging are attributable to a cell loss and reduced metabolic function that translates into a loss of energy and state of health.
The basal metabolism of people decreases 3% each year between the ages of 20 and 80. Coupled with this, as a general rule, in elderly people the intensity of physical activity decreases. This all translates into a decrease of the daily general energy expenditure. Energy needs must be calculated taking into account adequate formulas for the level of energy required. Here is how to calculate energy needs:
- Harris-Benedict formulas
Males: Basal Energy Expenditure (BEE) = 66.5 + (13.74 x P) + (5.03 x T) - (6.75 x E)
Females: BEE = 655.1 + (9.56 x P) + (1.85 x T) - (4.68 x E)
- Formula employed by the WHO
Males > 60 years: BEE = 487 + (13.5 x P)
Females > 60 BEE: GEB = 596 + (10.5 x P)
B. Protein requirements
As the individual ages, muscle mass decreases and body fat increases.
Even though it would be logical to suppose that the reduction in muscle mass would cause a proportional decrease in protein replacement, it has been shown that the renovation of body proteins in an elderly subject does not significantly differ from that of a healthy adult, being established at 0.75 g/Kg weight7day.
C. Fat requirements
The interest in fats in nutrition is based on preventing atherosclerosis and on the benefits to maintain adequate cholesterol levels (LDL and HDL fractions).
The levels of cholesterol rise at the time of birth, reaching a peak at the age of 50-60 years to then start decreasing progressively with age.
In elderly individuals, it is advisable to reduce the consumption of saturated fats, as with the general population. However, the objectives to be achieved should not be too restrictive so that quality of life of the individual is not limited or reduced. Thus, an intake of fats of about 30-35% of the daily calorie consumption should be provided each day, maintaining an adequate provision of polyunsaturated fats of about 10% to ensure the intake of essential fatty acids and liposoluble vitamins with the diet.
D. Carbohydrate requirements
The diet of elderly people should contain 45-50% of carbohydrates. It should be rich in fiber to ensure good intestinal motility.
Except in cases where it is medically contraindicated (diabetes), it is not necessary to reduce the consumption of sugar in old people, as sugar can be a very useful and palatable source of energy.
E. Vitamins and minerals
The requirements for vitamins and minerals do not change in old people with respect to adults; however, calcium, iron and zinc fall into a different category:
Calcium
Calcium requirements in elderly people are important due to the problem of osteoporosis (1 out of 3 people over the age of 65 suffers from in today's society). Hormones, genetic factors and calcium intake are of fundamental importance.
It should be taken into account that calcium requirements are dictated by the content of phosphorus and protein in the diet. The increased intake of proteins in the diet tends to increase the loss of calcium in the urine.
Inadequate calcium contents may be the result of a deficient intake, a loss of calcium absorption due to inadequate levels of vitamin D (exposure to light and intake) or excessive loss caused by increased protein intake in the diet, favoured by the consumption of alcohol and caffeine.
Recommended daily allowances for calcium consumption suggest an intake of 1200 mg each day in males over the age of 50 and 1500 mg in postmenopausal women. This intake for both sexes should always be supplemented with a provision of vitamin D. Doses above 2500 mg per day are not recommended in any cases, since this may favour the formation of kidney stones.
Milk and milk products are the best sources of calcium in the diet.
Iron
En las personas de edad avanzada no es infrecuente la aparición de anemia; sin embargo la deficiencia de hierro no es siempre la causa, y muchas veces son debidas a alteraciones digestivas, sobre todo por alteración en la absorción de vitamina B12. Por eso, antes de utilizar suplementos de hierro es necesario investigar las posibles causas subyacentes.
En general, las necesidades de hierro en los ancianos son las mismas que en los adultos más jóvenes.
Zinc
Even though zinc absorption decreases with age, deficiency of this mineral is not common in people who follow a healthy balanced diet. Dietary recommendations for the elderly age group goes up to 15 mg/ day.
Vitamins
In Western societies, the group at highest risk for vitamin deficiency is the elderly age group. Deficient intake may cause functional, organic and clinical alterations.
Recommended daily allowances for vitamins are being currently revised, as a large proportion of elderly people present borderline levels of vitamins. The use of megadoses of vitamins is not indicated as prophylaxis, since elderly people run a greater risk of overdosing.
A varied and balanced diet covers mineral and vitamin requirements of most elderlies.
F. Water
The percentage of body water is greater in males and in females and tends to decrease with passing age. A 70 to 80 year-old male has less than 60% water and in a woman of the same the amount is below 50%. In some old people, the most important factor for weight loss is a reduced percentage of water due to changes in body composition (decreased muscle/lean mass and increased fat mass), which causes changes in temperature regulation with an increased tendency to dehydration. Any alteration in the water balance (relation between intake and output or loss of fluids) can be life threatening for the affected individual.
- It is critical to follow up water balance in elderly patients as they run a higher risk of dehydration. In the adult, 10% water loss from the body sets off evident disturbances and a water loss greater than 20% is usually fatal.
During ageing, several factors favour water imbalance:
Decreased water intake caused by:
- Increased elimination due to the ageing of the kidney itself or due to medication or diseases such as diabetes and respiratory insufficiency, among others.
Elderlies should be advised and encouraged to drink water as it were a medication. They should be instructed to drink 8 glasses of water each day (at least 2 litres of liquid). Water should be consumed preferably between meals so as to avoid dilution with gastric fluids and early satiation. Nonetheless, water can be taken during meals but not in excessive amounts. Sugar water should be avoided and the intake of alcoholic and caffeine and cola containing foods should be limited. When the intake of liquid is difficult, it can be delivered in the form of gelatinised water.