By 2025, there will be over 1.2 Billion people worldwide aged 60 and over due to the improvements in public health and medical care.
Aging is associated with changes in the hormonal, gastrointestinal (GI), cytokine and psychosocial systems of the body. These changes can be evidenced by the decrease in resting energy expenditure, basal metabolic rate, physical activity, taste and smell of the elderly. Current evidences suggested that sustaining a healthy diet/nutrition will help to decrease the risk of developing disease, maintain functional independence and life quality of the individual.
The Immune System
The immune system is the most important “protective” physiological system of all organisms. Aging represents the most complicate & complex biological phenomenon, involved a “chronic progressive increase in the Pro-inflammatory status”. With aging, there is a decline in many immune parameters when compared to young healthy subjects; ie. immunologically, aging is related to “exhaustion of reserves”!
“Inflamm-Aging” was first named by Franceschi et al. in 2000: The term is used to describe the “low-grade, chronic, systemic inflammation in Aging”, in the absence of overt infection (ie. “sterile” inflammation). The primary feature of “inflamm-Aging” is an increase in the body’s Pro-inflammatory status with advancing age, and by tipping the balance from anti-inflammation to pro-inflammation, this imbalance leads to pathological changes. This type of inflammatory response supports my previous proposal for the function of the immune system as “the Ministry of Janitorial Services” to help maintain a healthy body!
During aging, the body accumulates damage at the molecular, cellular and organ levels; therefore, one source of inflamm-Aging could come from the damaged/aged host cells & organelles. The accumulation of the self-debris is resulted from either an increase in production of damaged/aged cells or impaired elimination (eg. due to Immunosenescence). Aging of the immune system in the elderly makes them more susceptible to age-related diseases such as Alzheimer, Parkinson, Osteoporosis, Atherosclerosis, Cardiovascular, Insulin resistance, type 2 Diabetes and Cancer, in addition to the inability to respond effectively to vaccination. Fortunately, a physically active lifestyle has been demonstrated to provide long-term benefits to the elderly with regard to cardiovascular, cognitive and psychosocial domains by reducing the chronic inflammatory responses.
“Acute” inflammation represents a beneficial, transient immune response to harmful conditions (eg. invading pathogen or traumatic tissue injury). This type of response also facilitates the repair, turnover and adaptation of many tissues. In contrast, “Chronic” inflammation has many features of Acute inflammation, but the response is usually of low grade and persistent, resulting in tissue degeneration (eg. many aged tissues are in a chronically inflamed state – without signs of infection = Sterile inflammation/InflammAging). Obesity is a good example of the body manifestation that provides a rich resource of inflammatory reactions. Therefore, nutritional interventions (eg. healthy diet) aimed at controlling weight in addition to “anti-inflammatory intervention (eg. low dose aspirin, metformin) may be efficient in reducing inflammAging.
Studies in “Psychoneuroimmunology” have demonstrated that stress can influence health by upregulating the inflammatory genes in people who are subjected/exposed to stressful and lonely conditions. The opposite (ie. Downregulation of inflammatory genes) was reported in people who are happy and sociable. Research into alleviating the inflammaging response has demonstrated efficacy in the following approaches:
- Calorie Restriction: is considered as the Gold standard to counteract Aging (eg. by enhancing T cell-mediated immunity). Caution: this approach should be avoided in “frail” elderly, or those with high risk of infection.
- Resveratrol: exhibits inhibitory effect on Inflamm-Aging (eg. by suppressing the upregulation of IL-1B, IL-6).
- Metformin: inhibits the expression of genes coding for multiple inflammatory cytokines seen during cellular senescence and blocks the activity of NF-kB (a major pro-inflammatory pathway).
- Vitamin E: 200 mg/d - improves T cell mediated function (eg. by decreasing PGE2 production – a potent T cell suppressor).
- Zinc: is an essential trace element and is involved in the maintenance of many homeostatic mechanisms (including efficiency of the immune system). Its deficiency promotes systemic inflammation and plays an important role in the aging process (eg. in age-related chronic illnesses such as Atherosclerosis, Alzheimer, Parkinson, Immunosenescence and Cancer). Currently, the recommended intake of Zinc varies in different studies, among populations and also with gender and regions [eg. > 70 years of age: some studies recommended 11 mg of oral Zinc/day for male & 8 mg for female – while 40 mg is the maximum recommended]. Based on current evidences, health-promoting activity suggests that educating the elderly to eat a healthy diet with foods that contain the necessary Zn requirements is appropriate (eg. nuts, beans, chickpeas, avocados, meat, oyster).
Up to date, nutrition intervention is still considered as the practical, cost-effective approach to improve the immune function, vaccination efficiency & resistance to infections in the elderly. However, its impact remains controversial: favorably modulate immune functions, BUT not in clinical outcome [eg. Vitamin E intake may need to be 5 – 10 X above recommended level (RL) for optimal effect; while Zn above RL may be harmful due to its narrow range of safe doses]. Subsequently, the following factors must be taken into consideration: a) the optimal dose for a particular population; b) the nutritional & health status along with the genetic background of the targeted population; c) the selection of clinically relevant, reproducible & feasible end points for reliable assessments of the intervention efficacy.
In conclusion, the current formula for “healthy aging” must involve both a healthy diet and a physically active lifestyle! The challenge that still needs to be addressed is how to sustain/maintain the healthy lifestyle? The answer will be put forward in the next publication .