The immune system, often seen as the body’s first line of defense, begins to show signs of decline as early as the age of 35. A recent study underscores that even individuals who feel physically fit may experience a gradual deterioration in their immune function, making them more vulnerable to infections and chronic diseases. Dr. Chris Rhodes, a nutritional biochemist and longevity expert, highlights the natural slowdown in immune cell activity, which compromises the body’s ability to fight off pathogens, destroy cancerous cells, and repair wounds effectively. This decline, he explains, is exacerbated by the shrinking thymus gland, which produces crucial T-cells for immune response. Inflammation, a key factor in the aging process, is termed ‘inflammaging’ by experts, contributing to conditions such as cardiovascular disease and accelerated brain aging.
Dr. Pooja Gidwani, a board-certified internal medicine and obesity medicine specialist, points out that lifestyle choices—such as a diverse, nutrient-rich diet, sufficient sleep, and effective stress management—play pivotal roles in sustaining immune health. Additionally, moderate physical activity, avoiding excessive inflammation through exercise, and fostering social connections that boost the release of oxytocin are recommended to maintain long-term vitality and immune resilience. Gidwani emphasizes the importance of nutrient diversity, not just healthy eating, advocating for the inclusion of a variety of plants, proteins, and healthy fats daily. This approach nourishes the gut microbiome, which is crucial for training and regulating immune cells. She notes that since roughly 70% of immune tissue resides in the gut, microbial diversity directly predicts immune resilience.
Rhodes adds that diet plays an ‘enormous role’ in immune functionality and longevity, as the effects of certain foods can boost inflammation and lead to immune system stress. Over time, this can promote autoimmune disorders, contribute to disease progression, and decrease longevity. He advises focusing on a diet rich in antioxidants, polyphenols, and plant bioactives with anti-inflammatory effects, along with whole foods that avoid glucose and lipid spikes. Intermittent fasting is recommended to minimize the time the body spends in the ‘post-prandial state,’ harnessing powerful anti-inflammatory effects. Lack of sleep and chronic stress, Rhodes warns, can cause immune cells to be more worn out, less effective at disease prevention, and more prone to making mistakes. Elevated cortisol levels due to sleep deprivation or high stress lead to immune system activation, which is beneficial in the short term but accelerates immune cell aging over time. Chronic immune activation due to sleep deprivation and high stress will burn out immune cells faster, accelerating their aging.
Gidwani highlights sleep as the ultimate ‘immune modulator,’ noting that even one night of sleep deprivation can cut ‘natural-killer-cell activity’ by up to 70%. She recommends aiming for seven to eight hours of quality sleep nightly and maintaining a stable circadian rhythm. Finding ‘intentional’ ways to manage stress—such as journaling, meditating, and spending time outdoors—can also enhance immunity. While exercise strengthens the immune system by reducing stress hormones, decreasing chronic inflammation, and aiding immune cell mobility, Rhodes warns of its potential to be ‘pro-inflammatory.’ High-impact and intense-burst exercises like sprinting, HIIT training, or weightlifting are the most inflammatory, causing significant muscle and joint stress. In contrast, low-impact endurance activities like marathon running, hiking, swimming, or biking cause less inflammation, preserving immune system functionality in the long term. Gidwani suggests a blend of aerobic (cardio) exercise and strength training to optimize mitochondrial health. Consistent, moderate exercise improves mitochondrial function and lymphatic flow, enhancing immune surveillance without promoting inflammation.
Some supplements and newer interventions, according to Gidw, can help slow immune aging. She recommends core nutrients like vitamin D, magnesium, zinc, and omega-3s, along with NAD⁺ boosters, senolytic compounds, and specific peptides such as thymosin alpha-1 and BPC-157 for immune modulation and tissue repair. However, these supplements should complement, not replace, healthy lifestyle behaviors. Rhodes cautions that while certain vitamins and supplements are critical to immune function, their importance has often been overhyped. He states that while the immune system needs essential micronutrients, taking high doses generally offers no additional benefit beyond avoiding deficiencies. Instead, focusing on supplements with anti-inflammatory effects, like EGCG from green tea, omega-3 fatty acids, anthocyanins from berries, and biomimetics such as PE and OEA, is more effective. People should consult a healthcare provider before starting any new vitamin or supplement regimen. Research highlights oxytocin’s role in regulating stress responses and inflammation, with physical touch, laughter, and community fostering oxytocin release, thereby lowering cortisol and systemic inflammation.