While being a strong force in our body, our immune system is also very delicate in its balance and function.
Further research also shows us that as we age, our immune function weakens – making us more susceptible to illnesses caused by foreign invaders.
Perhaps the most groundbreaking discovery in nutrition science is the role certain foods play in bolstering stronger immune function.
In the following article, I’ll show you clinical evidence behind the top 6 nutrients we should consume more of to optimize our immunity.
6 Nutrients For Enhancing Immune Function, According To Science
1.) Vitamin C
It is also a key nutrient for a strong and well-functioning immune.
Supports the production of interferons.
Interferons are produced when the presence of pathogens is detected. They facilitate the ability of cells to initiate protective cellular defenses*.
Enhances the function of phagocytes.
Phagocytes are a kind of white blood cell that surrounds pathogens and other dangerous particles. Once the intruders are captured, they are digested and neutralized enzymatically*.
Supports the cellular immune response.
There are two ways that the body can respond to a pathogen: antibody immunity and cellular immunity. The cell-mediated response refers to the activation of macrophages, natural killer cells, and antigen-specific T-lymphocytes that attack anything that is perceived as a foreign agent.
Enhances cytokine production by white blood cells.
Cytokines are communication proteins released from certain white blood cells and transmit information to other cells, thus promoting the immune response.
Inhibits the production of neuraminidase.
Some pathogenic viruses and bacteria create neuraminidase, an enzyme that keeps them from being trapped in the mucus, one of the natural lines of body defense. By inhibiting neuraminidase, vitamin C helps to optimize this defense mechanism of the body*.
Research indicates that vitamin C deficiency can lead to reduced resistance to certain pathogens, while a higher supply strengthens various parameters of the immune system.
High vitamin C foods include oranges (and other citrus fruits), guavas, bell peppers, kiwifruit, strawberries, papayas, broccoli, tomatoes, kale, and snow peas.
2.) Vitamin D
It is now clear that vitamin D has important roles in addition to its classic effects on calcium and bone homeostasis.
As the vitamin D receptor is expressed on immune cells (B cells, T cells and antigen presenting cells) researchers have uncovered several ways this micronutrient helps modulate the innate and adaptive immune responses.
Promotes immune responses.
This vitamin has both anti-inflammatory and immunoregulatory properties which make it crucial for the activation of immune system defenses*.
Activates antimicrobial defenses.
Vitamin D stimulates naturally occurring antimicrobial peptides, which protect the body by destroying invading microbes*. These antimicrobial peptides live in immune cells throughout the body, including cells lining the upper and lower respiratory tract. There, they are able to directly fight off viruses and bacteria that cause common immune and respiratory infections like colds and flu*.
Protects against respiratory-related illness.
In 2017, a large analysis of prospective clinical trials showed that taking vitamin D reduces the odds of developing a respiratory infection by approximately 42%*.
Increases immune cell function.
Vitamin D is known to enhance the function of immune cells, including T-cells and macrophages, that protect your body against pathogens*.
Vitamin D has important functions beyond those of calcium and bone homeostasis which include modulation of the innate and adaptive immune responses.
A deficiency in this nutrient may compromise immune response and increase your risk of infection and disease.
Your skin produces vitamin D when it’s exposed to sunlight. However, if you spend most of your time indoors or live at a high latitude, you’ll need to get this vitamin from your diet. Good dietary sources include fatty fish such as salmon or mackerel, egg yolk, butter, and liver.
It’s also essential for our immune system, as it affects how our cells respond to infections, and can help keep inflammation under control.
Inhibits viral replication.
A laboratory study in 2010 showed that zinc inhibited the activity and replication of SARS-CoV which caused an outbreak in 2002*.
Increases number and function of immune cells.
In a 2016 study, researchers found that zinc supplementation increased both the number and effectiveness of T-cells in the treatment group*. T-cells are at the core of adaptive immunity, the system that tailors the body’s immune response to specific pathogens.
Decreases duration of sickness.
A 2019 study showed that subjects with respiratory tract infections (ALRIs) who took 30 mg of zinc per day decreased the total duration of the infection and the duration of the hospital stay by an average of 2 days, compared with a placebo group*. Additional studies have also shown that supplemental zinc may also help reduce the duration of the common cold*.
Collectively, the data clearly demonstrates that immune integrity is tightly linked to zinc status.
However, zinc deficiency affects around 2 billion people worldwide and is very common in older adults. In fact, up to 30% of older adults are considered deficient in this nutrient*.
Studies suggest a deficiency in this nutrient causes a decrease in innate and adaptive immunity.
This significantly affects your immune system’s ability to function properly, resulting in an increased risk of infection and disease, including pneumonia*.
Because it is necessary for immune cell function and cell signaling, a deficiency can lead to a weakened immune response. However, zinc is an essential mineral which means that our body cannot make itself. This means we have to obtain it from our diet or supplements. Zinc-rich foods include oysters, beef, poultry, eggs, nuts, and seeds.
Flavonoids are considered as plant secondary metabolites that numerous pharmacological functions are attributed to including antioxidant, antibacterial, anti-angiogenic, anti-inflammatory, anti-allergic, and enzyme modulation.
The beneficial effects of flavonoids like quercetin come from their ability to function as antioxidants inside your body.
Free radicals are unstable molecules that may cause cellular damage when their levels become too high. Damage caused by free radicals has been linked to numerous chronic conditions, including immune suppression.
High levels of free radicals are known to lead to an increased inflammatory response which can impair the body’s ability to fight infections.
Enhances cytoprotective activity.
It is known to possess both mast cell stabilizing and gastrointestinal cytoprotective activity*. Cytoprotective agents stimulate mucus production and enhance blood flow throughout the lining of the gastrointestinal tract where approximately 80% of the body’s immune function occurs.
Expresses anti-pathogenic activity.
Under double-blind conditions, one study showed that quercetin supplementation alone resulted in a markedly lower incidence of URTI (upper respiratory tract infections)*. The literature is supportive of the anti-pathogenic capacities of quercetin.
In another study, the effects of quercetin were examined in a model of airway inflammation. Researchers observed mucus production in the lung to be inhibited by oral treatment, supporting optimal respiration*.
Research suggests that quercetin possesses anti-inflammatory and antioxidant capabilities which together promote immunological improvement within the body. Quercitrin can be found in a variety of foods and plants, including onions, apples, berries, grapes, tea, and tomatoes, as well as different seeds, nuts, flowers, barks, and leaves.
This dark purple fruit is a rich source of antioxidants known as anthocyanins, which are a unique type of flavonoid reputed by many researchers to be effective in treating the common cold, flu, constipation, hay fever, and sinus infections.
Fights harmful bacteria.
Elderberry has been found to inhibit the growth of bacteria like Helicobacter pylori and may improve symptoms of sinusitis and bronchitis*.
Increases white blood cells.
In a 2011 study, elderberry polyphenols were found to support immune defense by increasing the number of white blood cells*.
Reduces illness duration.
One study of 60 people with influenza found that those who took an elderberry supplement showed symptom improvement in two to four days, while the control group took seven to eight days to improve*. Furthermore, a study of 312 air travelers taking capsules containing elderberry extract found that those who got sick experienced a shorter duration of illness and less severe symptoms*.
Improves flu symptoms.
Another study of 64 people found that taking elderberry extract for two days resulted in significant improvement in flu symptoms, including fever, headache, muscle aches, and nasal congestion, after just 24 hours*.
Reasonable evidence supports the use of elderberry extract to reduce the length and severity of flu symptoms. Also, it may support heart health, improve antioxidant status, and have a variety of anti-inflammatory effects that also work to support immune function.
Ripe, cooked elderberry fruit is considered safe if consumed in moderation. The overconsumption of elderberries may cause diarrhea, stomach ache, and abdominal cramping due to their laxative effects. If elderberry is used for medicine, only ripe or dried berries should be used. The latter are available in many forms, including syrups, teas, capsules, gummies, tonics, and tinctures.
6.) Siberian Ginseng
Siberian ginseng is grown in Asia and Russia, and it is particularly high in compounds known as eleutherosides (hence its alias as “eleuthero”).
This adaptogenic (stress relieving) herb has been part of these cultures’ medicinal practices for centuries, and for good reason.
In particular, it’s been extensively reported to maintain homeostasis of the immune system and to enhance resistance to illness or microbial attacks through the regulation of the immune system.
Enhances immune cell production.
Research has shown that supplementing with eleuthero can increase immune cell production, specifically the antibody molecules immunoglobulins. It also works to maintain healthy T4 lymphocyte immune cell levels*.
Expresses antiviral activity.
In one study, this extract inhibited the productive replication of human rhinovirus (HRV), respiratory syncytial virus (RSV), and influenza A virus in cell cultures infected with these viruses, all of which belong to the RNA type viruses*.
Siberian ginseng supports your liver (the body’s primary detox organ) by assisting the processing and removal of toxins*.
A variety of studies suggest that ginseng, as a dietary supplement, plays a key role in illness prevention by modulating the immune function of the human body.
Although Siberian ginseng is available as a dried root to make tea, it has a notoriously strong, bitter taste. Most people prefer to take it in supplement form, or as an extract.