Recognizing Signs of Immune System Aging and Strategies to Combat It

Recent studies have revealed that your immune system may be aging faster than you think, even if you feel fit and healthy, potentially increasing your risk of infections and immune-related disorders.

“Immune aging, like all aging, means that our immune systems start to slow down, make more mistakes and be less effective at protecting us from infection as we get older,” explained Chris Rhodes, Ph.D., a nutritional biochemist and longevity expert who serves as CEO and co-founder of Mimio Health in San Francisco.

When the immune system ages, Rhodes notes that immune cells become less capable of performing vital functions such as fighting infections, destroying cancer cells, and healing wounds. The decline becomes particularly noticeable after age 35, when immune systems become progressively less able to adapt to new antigens, allergens, and inflammatory stimuli.

“Our thymus, the organ responsible for producing T-cells, gradually shrinks, meaning our immunity and ability to respond to new infections becomes more compromised with age,” Rhodes added.

Experts point to inflammation as a primary driver of declining immune function, a phenomenon many refer to as “inflammaging.” Dr. Pooja Gidwani, a double board-certified doctor of internal medicine and obesity medicine in Los Angeles, warns that “low-grade inflammation accelerates many age-related diseases, from cardiovascular disease to neurodegeneration.”

Signs that your immune system might be slowing down include increased frequency of infections or colds, slower wound healing, diminished recovery from exercise or injury, fatigue, joint stiffness, persistent aches and pains, recurrent viral flare-ups, and weaker vaccine response.

Most people begin experiencing measurable immune decline by their late 30s to early 40s. However, according to Dr. Gidwani, implementing specific lifestyle changes and boosting metabolic health can significantly delay this process.

“A youthful immune system isn’t about never getting sick — it’s about recovering quickly, regulating inflammation effectively, and preserving the energy and cognitive clarity that define long-term vitality,” she explained.

Health experts recommend five key strategies to slow down immune aging:

First, optimize nutrition diversity by incorporating a variety of plants, proteins, and healthy fats daily. “A wide variety of polyphenols, fibers and omega-3 fats nourishes the gut microbiome, which trains and regulates immune cells,” said Gidwani. With approximately 70% of immune tissue residing in the gut, microbial diversity directly predicts immune resilience.

Rhodes emphasizes that diet plays an “enormous role” in immune functionality and longevity. “The best way to keep your immune system youthful and happy is to focus on a diet rich in antioxidants, polyphenols and plant bioactives that have anti-inflammatory effects, as well as whole foods that avoid the glucose and lipid spikes that promote inflammation,” he advised.

Second, protect sleep quality and manage stress effectively. Sleep deprivation and chronic stress can cause immune cells to become worn out and less effective. “Increases in cortisol caused by lack of sleep or high stress levels will promote immune system activation, which can be beneficial in the short term to avoid infection, but will lead to accelerated immune cell aging and less effective functionality over time,” Rhodes warned.

Gidwani describes sleep as the ultimate “immune modulator,” noting that even one night of poor sleep can reduce natural killer cell activity by up to 70%. She recommends seven to eight hours of quality sleep nightly and maintaining a stable circadian rhythm. Finding intentional ways to manage stress—such as journaling, meditation, and spending time outdoors—can further support immune health.

Third, engage in regular exercise, which strengthens immunity by lowering stress hormones, reducing chronic inflammation, and helping immune cells circulate through the body. Rhodes cautions that while exercise is essential for promoting long-term health, certain types can be pro-inflammatory.

“High-impact and intense-burst exercise like sprinting, HIIT training or heavy weight lifting will be the most inflammatory,” he explained, while “low-impact endurance exercise, like marathon running, hiking, swimming or biking, will typically cause less inflammation over time, helping to keep the immune system functional and fresh.”

Fourth, consider appropriate supplements—but with caution. “Core nutrients like vitamin D, magnesium, zinc and omega-3s remain foundational,” said Gidwani, who also notes promising research on NAD⁺ boosters, senolytic compounds, and select peptides. However, both experts emphasize that supplements should complement, not replace, healthy lifestyle behaviors.

Finally, foster social connections. Research has shown that oxytocin, known as the “bonding” hormone, plays a crucial role in regulating stress responses and inflammation. “Physical touch, laughter and community raise oxytocin, lowering cortisol and systemic inflammation,” Gidwani explained.

By implementing these evidence-based strategies, individuals may be able to preserve immune function and resilience well into their later years, potentially reducing age-related health complications and enhancing overall quality of life.