Your immune system consists of a complex collection of cells, processes, and chemicals that constantly defends your body against invading pathogens, including viruses, toxins, and bacteria. (1, 2)
Keeping your immune system healthy year-round is key to preventing infection and disease. Making healthy lifestyle choices by consuming nutritious foods and getting enough sleep and exercise are the most important ways to strengthen your immune system.
In addition, research has shown that supplementing with certain vitamins, minerals, herbs, and other substances can improve immune response to help protect against illness.
And although, currently there is no research that supports the use of any supplement to protect us against COVID-19 specifically, this article provides information on well-researched supplements that can help bolster your immune system defenses in general.
Here are 11 Supplements to Help Boost Your Immune System
1. Vitamin D
Vitamin D is a fat soluble nutrient essential to the health and functioning of your immune system.
Vitamin D enhances the pathogen fighting effects of monocytes and macrophages (white blood cells that are important parts of your immune defense — and decreases inflammation) which helps promote immune response. (3)
Many people are deficient in this important vitamin, which may negatively affect immune function. In fact, low vitamin D levels are associated with an increased risk of upper respiratory tract infections, including influenza and allergic asthma. (4)
Some studies show that supplementing with vitamin D may improve immune response. In fact, recent research suggests that taking this vitamin may protect against respiratory tract infections.
In a 2019 review of randomized control studies in 11,321 people, supplementing with vitamin D significantly decreased the risk of respiratory infections in people deficient in this vitamin and lowered infection risk in those with adequate vitamin D levels. (5)
This suggests an overall protective effect.
Other studies note that vitamin D supplements may improve response to antiviral treatments in people with certain infections, including hepatitis C and HIV. (6, 7)
Depending on blood levels, anywhere between 1,000 and 4,000IU of supplemental vitamin D per day is sufficient for most people, though those with more serious deficiencies often require much higher doses. (8)
2. Zinc
Zinc is a mineral that’s commonly added to supplements and other healthcare products like lozenges that are meant to boost your immune system. This is because zinc is essential for immune system function.
Zinc is needed for immune cell development and communication and plays an important role in inflammatory response.
A deficiency in this nutrient significantly affects your immune system’s ability to function properly, resulting in an increased risk of infection and disease, including pneumonia. (9, 10)
Zinc deficiency affects around 2 billion people worldwide and is very common in older adults. In fact, up to 30 percent of older adults are considered deficient in this nutrient. (11)
Numerous studies reveal that zinc supplements may protect against respiratory tract infections like the common cold. (12, 13)
What’s more, supplementing with zinc may be beneficial for those who are already sick.
In a 2019 study in 64 hospitalized children with acute lower respiratory tract infections (ALRIs), taking 30mg of zinc per day decreased the total duration of infection and the duration of the hospital stay by an average of 2 days, compared with a placebo group. (14)
Supplemental zinc may also help reduce the duration of the common cold. (15)
Taking zinc long term is typically safe for healthy adults, as long as the daily dose is under the set upper limit of 40mg of elemental zinc.
Excessive doses may interfere with copper absorption, which could increase your infection risk.
3. Vitamin C
Vitamin C is perhaps the most popular supplement taken to protect against infection due to its important role in immune health.
This vitamin supports the function of various immune cells and enhances their ability to protect against infection. It’s also necessary for cellular death, which helps keep your immune system healthy by clearing out old cells and replacing them with new ones. (16, 17)
Vitamin C also functions as a powerful antioxidant, protecting against damage induced by oxidative stress, which occurs with the accumulation of reactive molecules known as free radicals.
Oxidative stress can negatively affect immune health and is linked to numerous diseases. (18)
Supplementing with vitamin C has been shown to reduce the duration and severity of upper respiratory tract infections, including the common cold. (19)
A large review of 29 studies in 11,306 people demonstrated that regularly supplementing with vitamin C at an average dose of 1 to 2 grams per day reduced the duration of colds by 8 percent in adults and 14 percent in children. (20)
Interestingly, the review also demonstrated that regularly taking vitamin C supplements reduced common cold occurrence in individuals under high physical stress, including marathon runners and soldiers, by up to 50 percent. (20, 21)
Additionally, high dose intravenous vitamin C treatment has been shown to significantly improve symptoms in people with severe infections, including sepsis and acute respiratory distress syndrome (ARDS) resulting from viral infections. (22, 23)
These results confirm that vitamin C supplements may significantly affect immune health, especially in those who don’t get enough of the vitamin through their diet.
The upper limit for vitamin C is 2,000mg. Supplemental daily doses typically range between 250mg and 1,000mg. (24)
4. Elderberry
Black elderberry, which has long been used to treat infections, is being researched for its effects on immune health.
In test-tube studies, elderberry extract demonstrates potent antibacterial and antiviral potential against bacterial pathogens responsible for upper respiratory tract infections and strains of influenza virus. (25, 26)
What’s more, it has been shown to enhance immune system response and may help shorten the duration and severity of colds, as well as reduce symptoms related to viral infections. (27, 28)
A review of 4 randomized control studies in 180 people found that elderberry supplements significantly reduced upper respiratory symptoms caused by viral infections. (29)
An older, 5-day study from 2004 demonstrated that people with the flu who supplemented with 1 tablespoon (15mL) of elderberry syrup 4 times a day experienced symptom relief 4 days earlier than those who didn’t take the syrup — and were also less reliant on medication. (30)
However, this study is outdated and was sponsored by the elderberry syrup manufacturer, which may have skewed results.
Elderberry supplements are most often sold in liquid or capsule form.
5. Medicinal mushrooms
Medicinal mushrooms have been used since ancient times to prevent and treat infection and disease. Many types of medicinal mushrooms have been studied for their immune-boosting potential.
Over 270 recognized species of medicinal mushrooms are known to have immune-enhancing properties. (31)
Cordyceps, lion’s mane, maitake, shitake, reishi, and turkey tail are all types that have been shown to benefit immune health. (32)
Some research demonstrates that supplementing with specific types of medicinal mushrooms may enhance immune health in several ways and reduce symptoms of certain conditions, including asthma and lung infections.
For example, a study in mice with tuberculosis, a serious bacterial disease, found that treatment with cordyceps significantly reduced bacterial load in the lungs, enhanced immune response, and reduced inflammation, compared with a placebo group. (33)
In a randomized, 8-week study in 79 adults, supplementing with 1.68 grams of cordyceps mycelium culture extract led to a significant 38 percent increase in the activity of natural killer (NK) cells, a type of white blood cell that protects against infection. (34)
Turkey tail is another medicinal mushroom that has powerful effects on immune health. Research in humans indicates that turkey tail may enhance immune response, especially in people with certain types of cancer. (35, 36)
Many other medicinal mushrooms have been studied for their beneficial effects on immune health as well. Medicinal mushroom products can be found in the form of tinctures, teas, and supplements. (37, 38, 39, 40)
Aside from the items listed above, there are other supplements that show promise to help improve immune response:
6. Astragalus: is an herb commonly used in Traditional Chinese Medicine (TCM). Animal research suggests that its extract may significantly improve immune-related responses. (41)
7. Selenium: is a mineral that’s essential for immune health. Animal research demonstrates that selenium supplements may enhance antiviral defense against influenza strains, including H1N1. (42, 43, 44)
8. Garlic: has powerful anti-inflammatory and antiviral properties. It has been shown to enhance immune health by stimulating protective white blood cells like NK cells and macrophages. However, human research is limited. (45, 46)
9. Andrographis: is herb contains andrographolide, a terpenoid compound found to have antiviral effects against respiratory disease-causing viruses, including enterovirus D68 and influenza A. (47, 48, 49)
10. B complex vitamins: including B12 and B6, are important for healthy immune response. Yet, many adults are deficient in them, which may negatively affect immune health. (50 , 51)
11. Curcumin: is the main active compound in turmeric. It has powerful anti-inflammatory properties, and animal studies indicate that it may help improve immune function. (52)
According to results from scientific research, the supplements listed above may offer immune-boosting properties.
However, keep in mind that many of these supplements’ potential effects on immune health have not been thoroughly tested in humans, highlighting the need for future studies.
Bottom line
Many supplements on the market may help improve immune health. Zinc, elderberry, and vitamins C and D are just some of the substances that have been researched for their immune-enhancing potential.
However, although these supplements may offer a small benefit for immune health, they should not and cannot be used as a replacement for a healthy lifestyle.
Maintaining a balanced diet, getting enough sleep, engaging in regular physical activity, and not smoking are some of the most important ways to help keep your immune system healthy and reduce your chances of infection and disease.
Moreover, remember that there is no scientific evidence to suggest that any of them can protect against COVID-19— even though some of them may have antiviral properties.
