Diet And Lifestyle Considerations
The goal of caloric restriction is to reduce total caloric intake while maintaining optimal nutrition. This may be best accomplished by eating a diet primarily composed of low-calorie, nutrient-dense foods such as vegetables, fruits, legumes, nuts and seeds, and whole grains; limiting intake of animal products; and avoiding calorie-dense, nutrient-poor foods (Rizza 2014). Caloric restriction in animals has been shown to prolong lifespan and delay aging, and to confer a more youthful profile of T cells (Ahmed 2009; Fernandes 1997; Michan 2014).
In humans, long-term caloric restriction results in metabolic changes that reduce the risk of a number of age-related diseases including type 2 diabetes, cardiovascular disease, and cancer (Steven 2015; Rizza 2014; Bales 2013; Lefevre 2009; Meyer 2006; Fontana 2004; Stein 2012). In a clinical study, six months of caloric restriction significantly improved the ability of T cells to reproduce in response to foreign antigens (Ahmed 2009).
Studies in animal models have demonstrated that caloric restriction can improve multiple aspects of immune activity, particularly T-cell function (Jolly 2004; Messaoudi 2006; Nikolich-Zugich 2005). In a study in mice, caloric restriction was shown to maintain youthful function of the thymus gland and reduce immune senescence during aging. Compared with mice fed freely, calorie-restricted mice had greater proliferation and diversity of T cells (Yang 2009).
Further reading about the benefits of reducing caloric intake is available in Life Extension’s Caloric Restriction protocol.
The Mediterranean diet is a dietary pattern based on foods and drinks traditionally consumed by people in the region surrounding the Mediterranean Sea (Oldways 2016). The Mediterranean diet has been shown to protect against several age- and inflammation-related conditions including diabetes, atherosclerosis, obesity, cancers, and neurodegenerative diseases. The Mediterranean diet is primarily characterized by inclusion of olive oil, fruits, vegetables, legumes, whole grains, nuts, and seeds; with moderate amounts of fish, poultry, cheese, yogurt, and eggs; limited inclusion of red meat, cured meat products, and foods rich in refined sugars; and low-to-moderate alcohol intake, usually in the form of red wine consumed with meals (Casas 2014; Estruch 2010).
In a 2014 review of 17 clinical trials, greater adherence to a Mediterranean dietary pattern was associated with significantly reduced levels of interleukin (IL)-6 and high-sensitivity C-reactive protein, two important markers of inflammation (Schwingshackl 2014; Coventry 2009; Ershler 2000; US Department of Health and Human Services 2015).
Regular moderate-intensity exercise can strengthen resistance to infection and improve immune system function. Single bouts of moderate-intensity exercise have even been used to improve response to vaccines. On the other hand, prolonged high-intensity exercise temporarily suppresses immune function and increases vulnerability to infection (Simpson 2015; Gleeson 2013; Zheng 2015).
Several human studies have indicated that moderate exercise may combat immune senescence (de Araujo 2013; Simpson 2011; Simpson 2010; Spielmann 2011; Woods 2009). In a study in sedentary older adults, participants randomized to 10 months of moderate cardiovascular exercise exhibited improvements in antibody responses to influenza vaccine compared with elderly individuals who only engaged in flexibility and balance exercises (Woods 2009).
In a study in elderly women, two years of regular physical activity increased production of IL-2—an important regulator of immune response that ordinarily decreases with age (Drela 2004). A 2011 study demonstrated that aerobic fitness is associated with reduced accumulation of senescent T cells (Spielmann 2011).
Chronic stress causes dysregulation of innate and adaptive immune responses by promoting persistent systemic inflammation and suppressing immune cells (Morey 2015; Dhabhar 2014). When sustained stress diminishes immune function, it can allow latent viruses such as cytomegalovirus to escape immune system control. Frequent reactivation of latent viruses can then further strain the immune system (Morey 2015). Chronic stress, and the accompanying chronic elevation of the stress-induced adrenal hormone, cortisol, appear to contribute to immune senescence (Bosch 2009; Bauer 2015). In fact, the ratio of cortisol to another adrenal hormone, dehydroepiandrosterone (DHEA), may be an important determinant of immune senescence (Bauer 2008).
In studies on patients with early-stage breast cancer, stress management interventions have been shown to improve cellular immune function and reverse pro-inflammatory gene expression in circulating immune cells (Antoni 2012; McGregor 2004). Stress management training in patients with rheumatoid arthritis resulted in decreased levels of stress-induced IL-8—an inflammatory cytokine (de Brouwer 2013). See Life Extension’s Stress Management protocol for more detailed information.
Lack of sleep can weaken immune function and increase susceptibility to respiratory infections, including the common cold, and chronic lack of sleep may be associated with an increased risk of death (Prather 2015; Ibarra-Coronado 2015; Wilder-Smith 2013; Aldabal 2011). Sleep deprivation is associated with elevated cortisol levels, as well as higher daytime levels of inflammatory cytokines including IL-1, IL-6, and tumor necrosis factor-alpha (Aldabal 2011; Hirotsu 2015). A study in individuals aged 61‒86 found even a single night of partial sleep deprivation induced patterns of gene activation associated with biological aging (Carroll 2016).
The adverse effects of poor sleep include functional changes in regulatory T cells and other cells of the adaptive immune system, as well as reduced numbers of NK cells and T and B cells (Zuppa 2015; Bollinger 2009).
Reduced sleep has been shown to alter the balance between antibody-mediated and cell-mediated immunity (Ganz 2012). In one study, participants allowed regular sleep the night after vaccines had markedly superior long-term antibody responses compared with those who stayed awake that night. Another study showed sleep-deprived individuals had a significantly lower antibody response 10 days after immunization than those who had normal sleep (Lange 2003; Spiegel 2002). See Life Extension’s Insomnia protocol for more detailed information.