Macronutrient requirements in old age

In order to determine the nutritional needs of the elderly, in addition to age, sex, level of physical activity, height and state of health, other factors associated with individual circumstances must be taken into account, which can be very different from one person to another, such as the number of chronic diseases they suffer from, the amount and type of drugs they take and the nutritional limitations of the different diets they follow, among many others.

All this causes great variability in the nutritional requirements of the elderly, so it is recommended that any dietary intervention should be carried out only by specialized health personnel, based on an adequate study of the specific situation of each individual and periodically evaluating the results to check tolerance to it.

Energy needs

Energy demands decrease with age, due to the significant modification of two of the three components of energy expenditure:

• Physical activity (PA) level.

• Resting metabolic expenditure or basal metabolic rate (BMR).

The level of physical activity (PA): depends on the type, duration and intensity of the physical activity performed. In general, it is the most important element in the modification of energy expenditure. With age, this factor is very depressed in some individuals, as a consequence of handicaps, disabilities or sedentary behaviors, so that a reduction in the levels of energy intake provided by the diet is required to prevent these from exceeding those required for the performance of daily physical activities and accumulating in the form of fat, increasing the risk of becoming overweight or obese.

It is estimated that two thirds of the total energy to be reduced during this stage of life is due to a decrease in the level of physical activity; therefore, if physical activity levels continue to be adequate, reductions in energy intake should not be high.

Resting metabolic expenditure or basal metabolic rate (BMR): represents the energy expended by a person at rest. It depends mainly on the amount of metabolically active body tissues. As muscle mass is more active than adipose tissue, body composition, age and sex determine the values of this parameter. As a consequence of the decrease in muscle mass in the elderly, resting metabolic expenditure is also reduced, making it necessary to reduce energy intake.

A widely used formula for calculating the resting metabolic rate (tmr) is the Harris-Benedict formula based on weight (p) in (kg) and height (t) in (cm):

• Men tmr = 66 + [13.7 x p (kg)] + [5 x t (cm)] - [6.8 x age (years)].

• Women tmr = 655 + [9.6 x p (kg)] + [1.8 x t (cm)] - [4.7 x age (years)].

The lower energy expenditure and the necessary decrease in energy intake that this causes, is the factor that most influences the nutritional status of the elderly; since it is very difficult to maintain an adequate supply of nutrients, with a lower caloric intake, in organisms whose absorption capacity has been reduced, being very high the chances of causing nutritional deficiencies, especially of micronutrients.

In order to reduce caloric intake and keep all nutritional demands covered, this reduction must be achieved through a correct choice of diet, including foods with high nutrient density. Moreover, experience has shown that in this population group, with a high prevalence of malnutrition, reduced intakes are more harmful than moderate overweight, so it is recommended to be conservative in dietary limitations, without reaching the risk of obesity.

It is currently considered that the energy needs of the elderly should be maintained in a range between 1.4 and 1.8 times the resting metabolic rate (RMR), depending on the level of physical activity performed. For people with an adequate level of physical activity, which would be the most advisable, the values closest to the maximum of the range (1.8 x (TMR)) should be used, while for those with moderate or low activity the values closest to the minimum of the range (1.4 x (TMR)) should be used.

The average energy needs, from the age of 60 onwards, are between 1600 and 1700 kilocalories per day, with an upper limit of around 2000 kilocalories per day for women; while for men they are between 2000 and 2100 kilocalories per day, with an upper limit of 2500 kilocalories per day. Diets providing less than 1500 kilocalories per day should not be planned, due to the high risk of malnutrition (protein-calorie and vitamin and mineral deficits) involved.

Protein requirements

Protein in the diet of the elderly can provide between 12% and 17% of the total energy consumed, taking into account that at this stage of life energy intake is usually low.

The protein demand of the elderly is conditioned by the following factors:

• The decrease in muscle mass conditions a lower availability of amino acids for protein synthesis.

• In the event of caloric intakes below the recommended levels, due to deficiencies in the diet of the necessary amounts of carbohydrates and fats, the body will use proteins to provide energy, limiting the use of proteins provided by the diet for the appropriate purposes.

• Weight loss and chronic diseases require increased intakes of this nutrient.

• Protein requirements for the healthy adult population range from 0.9 to 1.1 grams per kilogram of weight of the individual.

• In case of elderly people suffering from acute infections and surgical interventions, it is recommended to increase the intakes between 1.25 and 1.50 grams per kilogram of weight per day.

• Elderly people suffering from renal or hepatic diseases should avoid an excessive protein intake, since a renal overload could deteriorate the aged kidney.

Protein selection: When selecting proteins for the diet, we must take into account that not all of them contain all the essential amino acids in sufficient quantities to satisfy the body's requirements. Proteins of animal origin contain more essential amino acids than those of vegetable origin and in general have a higher nutritional value. There is a wide variety of foods of animal origin rich in protein, such as meat, fish, eggs and dairy products.

Some plant foods are also rich in protein, such as legumes and cereals. In order to obtain all the essential amino acids in proteins of vegetable origin, without including proteins of animal origin, two products of vegetable origin should be planned in the same meal, which complement each other, as for example in a plate of stew of beans and white rice.

To guarantee the quality of proteins in the diet of the elderly, it is recommended that about 60% of the protein intake of the diet should come from foods of animal origin, while the remaining 40% should come from foods of vegetable origin.

Carbohydrate requirements

Each gram of carbohydrate provides approximately 4 kilocalories to the body. It is recommended that carbohydrates constitute between 50% and 60% of the total energy consumed by the body. Ensuring that complex carbohydrates provide between 85% and 90% of the total energy provided by carbohydrates, while simple carbohydrates provide the remainder, between 10% and 15%.

Foods containing simple carbohydrates are:

• Table sugar and products containing it such as sweets, pastries, cakes, chocolates and soft drinks.

• The sugar in fruits and some vegetables.

• Lactose or milk sugar.

The foods that contain complex carbohydrates are:

• The integral cereals (bread, rice, integral pastas, corn and flours).

• The potatoes.

• The legumes.

• Some vegetables.

For an average daily intake of 2200 kilocalories, about 300 grams of foods rich in carbohydrates will be necessary, such as bread, cereals, pasta and rice, preferably wholemeal, in order to increase the intake of micronutrients and fiber. This group provides complex carbohydrates, which require a longer digestion, causing a greater feeling of fullness, and avoids uncontrolled food intake between meals "pitirreos" that favor overweight and obesity.

It is not advisable to consume foods rich in simple carbohydrates such as table sugar, sweets, pastries, cakes, pastries, chocolates and soft drinks; these foods are rich in calories but provide very few nutrients.

However, we should bear in mind that table sugar can be very useful to increase the palatability of some nutrient-rich foods such as milk, facilitating consumption especially in elderly people with poor appetite.

Likewise, it is not recommended to reduce the intakes of milk, fruits, vegetables and greens, although they contain simple sugars, because of the important minerals and vitamins they provide to the organism.

Lipid requirements

Each gram of fats (lipids) provides 9 kilocalories. It is recommended that fats in the diet of healthy elderly people provide between 25% and 30% of the total daily energy intake, although up to 35% is allowed when olive oil is consumed mainly.

Fat in the diet of the elderly plays an important role in providing energy and essential fatty acids and fat-soluble vitamins. It is also an excellent palatable element, which contributes to increase the consumption of less attractive foods, but rich in nutrients, helping to raise the quality of the diet.

To prevent fats from becoming a health risk factor, it is recommended that the intake be obtained from the different types of fats in the following proportions:

• About 15% to 20% monounsaturated fatty acids, mostly from olive oil.

• 7% to 8% of saturated fatty acids coming from foods such as whole milk, butter and fatty meats.

• 7% to 8% polyunsaturated fatty acids, which are found in oily fish, nuts and seed oils such as sunflower, corn and soybean. These fatty acids are crucial in the diet of older people because of their anti-inflammatory, antithrombotic, antiarrhythmic and vasodilatory properties.

The most important recommendation regarding fat content in the diet of people of any age is to consume less saturated fats (fatty meats, butter, coconut and palm oil) and less partially hydrogenated fats or trans fatty acids (margarin