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How to Support Immune Defense with Nutrition

Caitlin Beale, MS, RDN

The immune system is a complex network of cells and tissues that work together to protect your body. It is essential for keeping you healthy throughout your life.  

Nutrition, especially cellular nutrition, is one crucial factor that can influence the health of our immune cells. This blog post will discuss why nutrition, and especially micronutrients, are essential for maintaining a strong immune defense. 


Immune defense includes both innate and adaptive immune systems 

The two main branches of the immune system are the innate immune system and the adaptive immune system. The innate immune system is the first responder against potential threats and is activated immediately upon exposure to a pathogen. It's non-specific and consists of various cells and proteins that work together to destroy pathogens. Physical barriers like your skin and mucous membranes are an important part of the innate response, acting like a first line of defense for your immune system. 

The adaptive immune system is a more sophisticated immune response that takes a little longer to activate, but specifically targets and destroys pathogens it recognizes. It includes different white blood cells responsible for mounting an immune response. 

To keep our immune cells in both systems functioning at their best, we need to ensure we get the proper nutrients. 

Nutrition is essential for immune cell health 

A healthy immune system depends on various considerations, including age, genetics, and lifestyle. But one of the most important and modifiable factors is nutrition. The nutrients we consume can directly affect the health and function of our immune cells—think of nutrition as foundational for your immune system. If we are sick or under stress, we may need more support. 

Proper nutrition is needed to provide energy for cells to carry out their appropriate function. For example, if you have a fever, as your immune system fights the infection, it produces heat, which raises your body temperature.  Proteins, carbohydrates, and fats are needed to provide energy for immune cells to continue to do their job. 

Micronutrients (vitamins and minerals) found in food are key players in the health of the immune system. Some act as antioxidants to protect cells from damage, others help regulate the inflammatory response, and promote cell division and repair. A review article published in Nutrients concluded that certain micronutrients work synergistically to keep your immune cells healthy and functioning as they should. 

Nutrient deficiency or malnutrition can impair immune system function, but even suboptimal nutrition status can affect immune cell health. Suboptimal nutrition could mean that while you don't have a clear deficiency reported in lab work, marginally low levels of certain nutrients could still affect cellular function.

Micronutrients for immune support 

Nutrition is vital for both branches of the immune system to function properly, but these micronutrients appear to be especially important: 

Vitamin C 

Vitamin C is usually the first nutrient people think of for supporting the immune system. It's a water-soluble vitamin that is found in many fruits and vegetables. Vitamin C is essential for the health of various cells in the body, including immune cells. 

Vitamin C is an antioxidant that helps protect cells from free radical damage. Free radicals are unstable, reactive compounds, which can damage cells, including immune cells. They are generated by everyday activities like exercising, eating, and breathing, but can also be caused by exposure to toxins like cigarette smoke or pollution. 

Just like everything in the body, balance is critical. Having some free radicals is normal, but when the scales tip and free radicals outnumber antioxidant activity, it can lead to cellular damage. Vitamin C is important for maintaining the balance between free radicals and helps protect immune cells. 

Vitamin C supports the function of cells from both the innate and adaptive immune systems. A meta-analysis found that taking daily vitamin C supplements in addition to extra doses when you’re depleted may help your immune system get you back on track more quickly. Strenuous exercise, chronic stress, or certain health conditions can also increase how much vitamin C your body needs. 

While vitamin C is found in many foods, including citrus, bell pepper, and broccoli, supplementation is often helpful to make sure you get enough.

Vitamin D 

For a long time, most people were taught that the primary function of vitamin D was to facilitate calcium absorption for strong bones and teeth. However, it is now known that vitamin D is vital for more than just bones. 

Vitamin D is a fat-soluble vitamin produced by the body when ultraviolet radiation from the sun hits the skin. Vitamin D is needed for the health of many cells in the body, including immune cells.  

Some of your innate immune system cells, including dendrites and macrophages, can manufacture the active form of vitamin D, suggesting that vitamin D is important for the innate immune system to function correctly.  

Nearly every cell in the body has a vitamin D receptor, including your immune cells, so vitamin D could alter the expression and responsiveness of many cells in the immune system

Vitamin D also plays a role in autoimmunity, which means that it can help regulate your immune response from attacking your own body. Studies show that people with autoimmune conditions often have low vitamin D levels, but supplementation can help. 

Research also suggests an association between low vitamin D and greater immune health challenges, but adequate vitamin D is linked to the effective maintenance of respiratory health, according to a systematic review and meta-analysis in the British Medical Journal.  

An interesting study on pregnant women who took vitamin D found that their children had better immune responses later in life than those born to moms who didn't supplement.  

Even though we can get vitamin D from the sun, many people don't get enough because of sunscreen, season, skin color, or simply not spending enough time outside. Absorption can also decrease with age. Vitamin D isn't found naturally in many foods, aside from fortified foods or fatty fish, so supplementation is often necessary.  


Another essential nutrient for the immune system is zinc. Zinc wears many hats in the body related to the immune system.  

Zinc functions to support the physical barriers of your innate immune system (like skin and tissues), helping with wound healing and protein synthesis. It also has antioxidant activity and is vital for the function of many cells in the adaptive and innate immune systems. 

Several studies show that supplemental zinc at times you’re feeling depleted can activate your immune cells and strengthen your response. Zinc supplements can also help with oxidative stress in the body. 

Zinc is found in some foods—primarily oysters, beans, and meat. But similar to the other nutrients, supplementation may be necessary to ensure you're getting enough.

Keep your immune system strong all year long 

It may feel more obvious to focus on your immune system seasonally, but it's essential to keep your immune system strong all year long. 

Of course, there may be times when you need more of a particular nutrient but focusing on the long term and incorporating a variety of nutrient-dense foods and immune support supplements into your diet is an excellent way to keep your immune system functioning well every day, even as you age. 

What is immunosenescence? 

Several cellular changes occur with aging. We see it on the surface of our skin, and we feel it as a decrease in muscle mass and strength. But aging isn't just about the physical changes we see on the surface. 

As you age, your immune cells shift, and immune function can decrease. This is called immunosenescence. Immunosenescence is the age-related deterioration of the immune system, and affects both the quality and quantity of immune cells. 

Both the adaptive and innate immune cells are impacted by immunosenescence, which is why older adults are more susceptible to illness.But research shows that supporting immune cells with micronutrients, especially through targeted supplements, could help slow down the decline.  

Some research also suggests that older adults with optimal nutrition have less of a reduction in immune function. On the other hand, poor nutrition status is linked to impaired immune cells.  

Can you slow down age-related immune cell changes? 

If you haven't started to focus on your immune system yet, it's not too late. Research suggests that you can slow down some of the age-related declines in the immune cells with nutritional interventions.  

The micronutrients mentioned earlier (vitamin D, zinc, and vitamin C) are essential for optimal immune cell health. But another way to support healthy aging is by boosting nicotinamide adenine dinucleotide (NAD+) levels. 

NAD+ is a coenzyme that is essential for energy production in all cells. As we age, our NAD+ levels decline, leading to a decrease in mitochondrial function (organelles that make cellular energy). Without healthy mitochondria, energy production drops, affecting the health of the entire cell.  

Taking NAD+ directly doesn't seem to be the best way to increase levels. Instead, research suggests that taking a specific type of vitamin B3 called nicotinamide riboside (NR) can help to increase NAD+ levels. NR is a precursor to NAD+, meaning it helps increase the amount of NAD+ produced in cells.  

Combining micronutrient supplementation with interventions that support NAD+ levels could help keep your immune cells as strong as you age. 

Optimizing nutrition can support immune cells at any stage of life 

No matter where you are in life, it's never too late to start focusing on your immune system. We still don't know everything about immunosenescence, but it's clear that optimizing cellular health is one way to help keep your immune system strong. 

Eating a diet rich in the vitamins and minerals needed to support immune system health is a simple way to get started. Still, you may also want to consider supplements for additional support.  

Tru Niagen® Immune is a cellular health supplement that provides the nutrients needed for healthy immune cells. It's an easy way to support your overall health and well-being so you can continue to feel your best.  

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