PLMI Blog

A growing body of research shows the pivotal role nutrition plays in modulating immune function and promoting healthy aging (1-3). Mounting findings further highlight connections between aging of the immune system and diet, most notably the consumption of processed foods (4). This is an important connection, as immune system dysregulation is associated with the development of chronic and age-related diseases, as well as with reductions in health and lifespan (5-6).

Hallmarks of Immunity: Immunonutrition & Immunosenescence

The immune system is strongly interconnected with other systems of the body, having widespread implications for health. Immunonutrition highlights the relationship between nutrition and the gut microbiome in mediating appropriate immune system functions and responses (7). Immunosenescence refers to the gradual decline of the immune system with age, often associated with a persistent low-grade pro-inflammatory state (8-9).

Age-related immune changes lead to increased susceptibility to illness, reduced healing capabilities, and disruptions in overall systemic balance, increasing the risk of developing chronic disease. Adequate nutrition, in conjunction with lifestyle factors, is integral for modulating and restoring immune dysfunction and dysregulation (3). While a range of foods, including refined carbohydrates, added sugars, and food additives, can be detrimental to health, one category is incredibly harmful to the human body: highly processed foods.

Ultra-Processed-Foods Unveiled

The consumption of highly processed foods has increased substantially with advances in technology and agriculture. Ultra-processed foods (UPFs), recognized by their lengthy ingredient lists and ready-to-eat convenience, have been implicated to be significant contributors to immune system dysregulation and aging (4). The extent to which these foods have been modified –  including coloring, artificial sweeteners, preservatives, acidity regulators, and emulsifiers – contributes to these heightened effects.

UPFs include pre-packaged meals and snacks, as well as sugary beverages and processed meats. These foods are heavily stripped of essential nutrients, including vitamins, minerals, and enzymes – all of which are vital for modulating immune system health. UPFs are also high in chemical additives, unhealthy fats, and sodium. Additionally, they are low in quality protein, anti-inflammatory fats, antioxidants, prebiotics, probiotics, and micronutrients – including Vitamin C, D, A, B12, Zinc, and Selenium – which are essential for robust immune function (10).

The Impact of Altered Foods on Systemic Health & Immunity

Increased consumption of ultra-processed foods (UPFs) has been shown to impede systemic health through altered immune responses and excessive inflammation. These foods disrupt the immune system’s natural defense mechanisms, impairing the body’s ability to respond efficiently to pathogens and other threats (1).

Over time, UPFs can induce systemic inflammation, oxidative stress, and gut microbiome imbalance (dysbiosis), leading to an increased risk of autoimmune, gastrointestinal, and metabolic conditions. UPF intake has been linked to heightened pro-inflammatory responses and increased levels of inflammatory biomarkers, such as C-reactive protein (CRP) and interleukin-6 (IL-6) (10). Gut dysbiosis and oxidative stress in the system from UPF consumption further impede immune health.

Altered Immune Functions & Dysregulated Responses

Regular consumption of highly processed foods can overstimulate the immune system due to their antigenic properties, triggering increased immune and inflammatory responses. UPFs contain many substances that the immune system does not recognize, thereby flagging them as foreign and potential threats, initiating an activated immune response by the adaptive immune system. This arm of the immune system creates an imprint of the UPF (invader), mounting a targeted inflammatory response of acquired antibodies that strengthens over time.

This response is exacerbated by the extent of the food processing and further compounded by other forms of stress endured by the body, including emotional, psychological, and physical. Over time, this heightened immune response can lead to persistent, low-grade inflammation, disrupting normal immune function and healthy tissue, and contributing to systemic imbalance (10-11).

This persistent inflammatory state disrupts systemic homeostasis by altering crosstalk between immune and metabolic responses (10). Such disruptions manifest as alterations in immune cell function, leading to the accumulation of senescent immune cells (12). In fact, chronic inflammation is a hallmark of age-related disease (13).

Ultra-processed foods have been correlated with autoimmune conditions. A central feature of these conditions is T (Treg) cell dysfunction. These cells have essential anti-inflammatory roles in modulating adaptive immune system function (14-15). Research highlights that dietary factors influence Treg development by altering gut microbiota composition and the production of microbial metabolites, further underscoring the profound impact diet has on immune regulation (16).

Alterations in the Microbiome & Immune System

The diversity of the microbiome is critical for modulating immune function and response, in addition to maintaining the integrity of the intestinal barrier and governing inflammation. Consumption of ultra-processed foods significantly impedes microbial balance, as UPFs undergo extensive modifications from their original form, thereby impeding these processes (15). Mounting research findings demonstrate that high consumption of UPFs is associated with reduced gut microbiome diversity (17).

A 2024 review revealed that UPF intake altered microbial composition, reducing beneficial microbiota while promoting growth of pathogenic bacteria (18). Certain food additives, such as the synthetic emulsifier carboxymethylcellulose (CMC), further exacerbate this imbalance by decreasing short-chain fatty acid (SCFA) levels, which are vital for GI integrity and immune regulation (19). CMC consumption has been shown to reduce microbiota quality and diversity, including reductions in Faecalibacterium prausnitzii and Ruminococcus sp, which are important for modulating immune health and synthesis of beneficial metabolites, as evidenced in a 2021 RCT (20).

Disruptions to microbiome diversity and functions significantly impede GI, systemic, and immune health, as 80% of the immune system resides in the gastrointestinal tract (21). The gut microbiome also regulates the balance of the body’s systems. Increased UPF consumption has further been associated with an increased risk of GI disorders, such as irritable bowel syndrome (IBS), underscoring the effects diet has in modulating GI and immune health (22). In contrast, a pilot study published in the Journal of Obesity and Metabolic Syndrome demonstrated that limiting intake of UPFs led to positive changes in gut microbiota composition (23).

Impeded Metabolic Health: Meta-Inflammation and Inflammaging

A growing body of research demonstrates a correlation between ultra-processed food consumption and non-communicable diseases (4). The consumption of UPFs has been shown to increase susceptibility to diabetes, obesity, cancer, and cardiovascular disease, all of which are linked to inflammation and metabolic dysfunction.

A 2021 systematic review and meta-analysis, including 43 observational studies with nearly 900,000 participants, echoed these findings, revealing that UPF consumption is significantly connected with increased risks of obesity, metabolic syndrome, and depression in adults, as well as wheezing in adolescents. This comprehensive study also found that UPFs are associated with higher all-cause mortality, cardiometabolic disease, cancer, and irritable bowel syndrome (IBS) (24). Further research highlights the connection between processed foods, oxidative stress, and impeded immune response, in addition to altered metabolic health (25).

Meta-inflammation (low-grade, chronic inflammation) has been strongly correlated with UPF consumption, disrupting the balance between immune and metabolic responses, fueling a vicious cycle of inflammation, and wreaking havoc on various body systems (10). This persistent inflammation triggers immune cell infiltration and cytokine secretion, altering lipid metabolism and increasing the risk of chronic disease.

Meta-inflammation can also result in inflammaging, the accumulation of senescent cells, further contributing to oxidative stress, metabolic dysregulation, acceleration of the aging process, and driving the onset and progression of age-related disease. These vicious cycles of inflammation further activate the senescence-associated secretory phenotype (SASP), accelerating tissue aging and also impeding the body’s ability to clear out damaged cells, further contributing to increased risk of chronic disease and compromised immune function.

Restoring Immunity: Lifestyle & Nutrition

Lifestyle factors, in conjunction with nutrition, are pivotal for governing immune system health. Quality sleep and rest, regular exercise, and mitigating stress are all imperative for optimal immune function. In fact, immunity and sleep have been shown to have a bidirectional relationship (26). Furthermore, sunlight exposure, social connections, intermittent fasting, forest bathing, and meditation have been shown to have beneficial effects on immune function by supporting circadian rhythm balance, reducing stress, and promoting autophagy (27-31).

Immunonutrition emphasizes the importance of nourishing the body with foods that reduce cellular aging and rejuvenate the immune system. A balanced, whole-food, nutrient-dense, anti-inflammatory diet, rich in a variety of fruits and vegetables, is essential for optimal immune function.

A 2022 randomized controlled trial published in Genome Medicine demonstrated that adopting a Mediterranean diet with an abundance of plants induced favorable changes in gut microbiome composition and cardiometabolic markers of health, as indicated by 16S rRNA sequencing (32). A meta-analysis of 2,300 participants across 17 clinical trials found that adherence to the Mediterranean diet was associated with lower levels of inflammatory biomarkers, such as CRP and interleukin-6 (IL-6) (10). This way of eating supports high-quality protein, minimally processed carbohydrates, and healthy fats while having optimal amounts of fiber, antioxidants, and phytonutrients, helping to mitigate inflammation and oxidative stress. Furthermore, this nutrient-dense way of eating provides the body with the raw materials necessary to modulate immune function.

Fermented foods, including kimchi, kefir, and sauerkraut, along with probiotics and prebiotics including yogurt, garlic, onions, and asparagus, can help restore a diversified gut microbiome, having a critical role in immune health. Ensuring sufficient intakes of Vitamin A (carrots, sweet potatoes), Vitamin D (wild-caught salmon), Vitamin C (oranges, strawberries), Vitamin B 12 (grass-fed beef, organ meats), Zinc (oysters, shiitake mushrooms), and Selenium (brazil nuts) are also integral to immune regulation and functioning. Limiting processed foods, refined carbohydrates, and added sugars is crucial to reducing immune dysfunction and the risk of associated metabolic and systemic health conditions (33).

Optimizing Healthspan & Lifespan

While lifespan has steadily increased over the years, healthspan – the number of years lived in optimal health – has not kept pace. Dysregulated immune functioning is associated with chronic disease and contributes to a reduced healthspan and lifespan.

The increasing prevalence of ultra-processed foods raises significant concerns regarding the effects they have on altering systemic health and the impact socioeconomic factors have in influencing their consumption. A shift towards whole, natural, nutrient-dense foods and lifestyle practices that support immune health can help to mitigate the effects of immune aging and improve systemic health while extending lifespan and healthspan.

Join us for this free webinar, Immunonutrition for Healthspan: Nutritional Targets to Rejuvenate Immunity and Slow Cell Aging, on December 10th from 5 to 7 pm PST with experts Stephan van Vliet, PhD, Mary Purdy, MS, RDN, Austin Perlmutter, MD, and Jeff Bland, PhD as they delve further into the compelling interrelationship between immunonutrition and aging

References

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