Nutritional Requirements of the Elderly

Key Points

• Aging results in a reduction in caloric requirement. Caloric restriction (CR) is a proven intervention in the prevention of chronic diseases and promoting healthy aging. Caloric intake should be kept between 1.30 to 1.52 times the REE.
• Protein requirement increases with age to preserve the decreasing muscle mass, and partly due to ‘Anabolic Resistance (AR)’. The suggested minimum protein intake for aging healthy adults is 1.4g/kg/day irrespective of gender.
• Due to aging-related metabolic changes, fat intake should be limited. Saturated fat intake should be reduced and more MUFA’s and omega-3 should be included. Complex carbohydrates consumption should be encouraged.
• Aging adversely affects Vitamin D and calcium metabolism. The suggested dosing for Vitamin D and calcium are 800-1000IU and up to 1000mg respectively.

Introduction

As per population census 2011 data, there are approximately 104 million elder people (aged ≥60 yrs) in India and according to a report by HelpAge India and UNPF, this number will rise to 173 million by 2026.

In general, the increase in age is accompanied by progressing frailty, increased risk of falls and fractures, independence loss, metabolic diseases including type 2 diabetes, and reduced quality of life. Hence, as the number of the senior population increases in our country, it becomes more and more important to devise strategies to counteract these age-related health issues and improve their quality of life.

In this article, we will be discussing the effect of aging on different aspects of nutrition and the right intake for promoting healthy aging.

Energy Requirement

In general, aging appears to be associated with a reduction in energy requirement as a consequence of (i) Reduction in metabolic rate and (ii) Reduction in physical activity [1]. Caloric restriction (CR) is known to be the most effective and easily duplicable intervention for augmenting lifespan, preventing chronic diseases, and promoting healthy aging. CR helps in the prevention and treatment of obesity, which itself is an important contributing factor for numerous diseases such as cancer [2], type-II diabetes, etc. Caloric restriction not only appears to prevent diseases but also extends lifetime survival [3], promotes ‘anti-aging’ features, improves blood lipid profile [4], alters the level of several hormones, improves cognitive functions [5], etc. Thus, CR seems to be beneficial for the aging population.

Previous work has reported a decrease of 2-4% per decade in REE between 30-80 years of age. Data from several studies suggest that caloric intake of 1.30 to 1.52 times the REE is the most optimal for the aging population [6]. There is not sufficient data available to infer the existence of any gender-based difference.

Protein Requirement

RDA guidelines provide the basis for setting up guidelines for nutrient intake in the elderly population to prevent deficiency or excess of a certain nutrient. The guidelines for protein intake are established using nitrogen balance. Current Indian RDA guidelines (ICMR) set protein intake at 60gms/day for all adult males and 55gms/day for non-lactating and pregnant adult females. However, several shortcomings of nitrogen balance methods have been identified. 

Moreover, RDA is the ‘minimum’ daily average intake of the specific nutrient needed to prevent deficiency in 95% of the healthy population, but it may not foster optimal health or ensure the senior population from the loss of skeletal muscle mass [7,8]. Recently, Indicator Amino Acid Oxidation (IAAO), developed by the Institute of Medicine, has gained attention as a substitute for nitrogen balance for determining protein requirements. IAAO trials suggest that most people require and/or will be benefitted from an average daily intake above RDA. 

Protein requirement in the elderly population is found to be significantly higher than young population. This could be explained by the difference in the metabolism of protein and amino acids between younger and older individuals. For example, a study suggests that muscle protein anabolism is dulled in the elder population in comparison with the young population due to diminished response of muscle protein synthesis [9]. This phenomenon is termed ‘Anabolic Resistance (AR)’.

Factors like reduced digestion and absorption of food and post-prandial- amino-acid uptake and delivery can be responsible for it. Hence, studies suggest a minimum daily protein requirement to be 1.0-1.2 g per kg for normal healthy adults [10] and 1.4 g per kg for healthy elder adults [11,12]. There is no sufficient data available to infer the existence of any gender-based difference. In addition, uniform distribution of total ingested protein throughout the day was found to be beneficial [18].

Other Nutrient Requirements

There is no accounted data supporting the specific distribution of energy intake between fat and carbohydrates. However, it is known that aging is linked with several metabolic alterations. Studies show that elderly subjects oxidize less fat during the resting state in comparison to young people [13- 17]. However, during exercise, they utilize more glucose for energy [15]. 

Several factors such as reduced energy requirement, increased protein requirement, and reduced fat oxidation rates indicate that the fat intake should be reduced in the elderly, however, that remains to be studied. In addition, a high association between intake of saturated and trans-fat and the rate of cognitive decline was found [19,20]. Constant intake of ω-3 and MUFAs were established to diminish the risk of a cognitive drop in visual memory [21-23]. 

Once the desirable proportion of fat and proteins are set, carbohydrates can be used to meet 100% of the energy requirement. Consumption of complex carbohydrates should be encouraged since they are generally rich in micronutrients and high in dietary fibers. Higher intake of fibers is found to be associated with improved cognitive functions, blood lipid, intestine function, glucose tolerance, and decreased risk of all-cause dementia [24-27]. 

Aging also affects the Vitamin D and calcium metabolism in the following manner [28]

1. Reduction in Vitamin D production from the skin.
2. Reduction in Vitamin D metabolism.
3. Decreased calcium absorption (since Vitamin D regulates calcium absorption).

This together can result in Vitamin D and calcium deficiency in the aging population and can have severe implications such as

1. Increased risk of falls and fractures.
2. Negative calcium balance.
3. Secondary hyperparathyroidism.
4. Increased bone loss and osteoporosis.
5. Increased susceptibility to infections/ decreased immunity.

Hence, it is required to maintain optimal Vitamin D and calcium intake during aging. Sun exposure, supplements, and certain fortified foods are the main sources of vitamin D. Vitamin D3 supplementation is also highly recommended. The suggested daily dosage is 800-1000IU. The daily dosing of Vitamin D3 is better than bolus (weekly/monthly etc) dosing. The optimal intake of calcium is still unclear. Along with Vitamin D3, daily supplementation of calcium up to 1000 mg has shown to be beneficial. A combination of Vitamin D3 and calcium supplementation can reduce the chances of fracture by 30%.

Conclusion

In summary, there is enough evidence to conclude that nutritional interventions can mitigate the risk of sarcopenia & osteoporosis, improve the quality of life and promote healthy aging in adults.

Caloric restriction is a potent tool to augment lifespan and prevent numerous chronic conditions in aging adults. Along with that, several studies have shown the need and benefit of higher protein intake in elder individuals due to a phenomenon known as “anabolic resistance” and to prevent the loss of lean body mass. 

The present data indicate that consumption of saturated & trans- fats should be minimized and ω-3, MUFAs & fiber intake should be encouraged. Also, there are age-related changes in Vitamin-D and calcium metabolism which increases the demand for Vitamin D and calcium to prevent their deficiencies and to foster optimal bone health.

Author:

Aditya Mahajan

Assessment Division,

Institute of Nutrition and Fitness Sciences (INFS)

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