Article at a Glance
- Certain supplements have shown an ability to boost the immune system, but make sure you understand the effective dosage if you want to supplement.
- There are five primary ways that science-backed supplements may help strengthen your immune system, but lifestyle (diet, sleep, exercise, stress) is even more critical.
- Explore the top 10 science-backed immune-boosting supplements and understand their effective doses.
- The best way to supplement for a healthy and resilient immune system is not with pills, but rather a new alternative.
The immune system is on everyone's mind today. My patients often ask me how to boost their immune system and if supplements really work.
My answer is that lifestyle is the best way to strengthen your immune system, which means eating healthy, sleeping well, exercising, and lowering stress. When it comes to immune support vitamins, minerals, herbs, or other nutrients, the answer depends on what you're taking. There are science-backed supplements that have been proven to boost the immune system in a few different ways, including:
- Nutrients that increase the number of white blood cells (a.k.a. immune cells) circulating in your system
- Nutrients that "activate" or increase the efficiency of white blood cells
- Nutrients that slow viral replication
- Nutrients that support the regulation of the immune system
However, the problem with most immune-boosting supplements sold today, even if they do include science-backed ingredients, is related to dosing. Often the effective dose of a nutrient (or combination of nutrients) cannot fit into a single capsule or tablet. So you would need to take a handful of these supplements to get the effective doses. Since supplement makers know people will not tolerate this, they settle for doses lower than what has been shown effective.
In this article, I start with immune system basics so you can understand how the immune system works. Then I review the top 10 immune-boosting supplements backed by science and cite the effective dosages if they are established. Finally, I explain why the best way to supplement for a strong and resilient immune system is not with pills but rather a new alternative.
Immune System 101
Your immune system is made of particular organs, cells, proteins, processes, and chemicals that defend your body constantly against infection from pathogens like bacteria, viruses, fungi, and other toxins. 
Two primary parts make up your immune system:
The innate immune system and the adaptive immune system.
The innate immune system is inherited – what you're born with. Your body naturally recognizes pathogens, and the cells of this innate immune system, called phagocytes, engulf the threatening invaders (like bacteria) and kill them.
The adaptive immune system is what you develop over time as you are exposed to pathogens, and your body produces proteins called antibodies to protect you from them. As soon as your body is exposed to the pathogen, cells called B lymphocytes create the antibodies. Once developed, the antibodies will stay in your system and likely protect you from future infections from the same pathogen. Immunizations work with this part of your immune system.
Top 10 Science-Backed Immune Boosting Supplements (and effective doses)
Here are the top 10 supplements scientifically proven to impact the immune system with immune-boosting potential and their effective dosages (if established) according to published studies.
Echinacea is a genus of flowering plants that contain medicinal compounds, including antioxidants (mostly from the plant's fruit and flowers), alkamides, caffeic acid, phenolic acids, rosmarinic acid, and polyacetylenes. Several of these phytochemicals may contain antiviral and antimicrobial properties, while others may support the immune system in different ways.
There are several types of Echinacea, and it's important to take the right kind. Studies show three types (Echinacea angustifolia, Echinacea pallida, and Echinacea purpurea) can be used as herbal remedies. However, most studies cite the Echinacea purpurea extract, which has been shown to support immune health by boosting white blood cell count and activating immune cells (macrophages, leukocytes, and natural killer cells).
Other studies show it has potent antiviral effects against specific respiratory viruses, such as coronaviruses (although Covid-19 has not been specifically studied), influenza, respiratory rhinoviruses, and syncytial virus.
While studies suggest Echinacea can reduce the severity and duration of the common cold  and offer overall immune-boosting benefits, none have demonstrated efficacy in treating specific diseases like COVID-19. But there is enough evidence for me to recommend my patients take a good quality Echinacea purpurea extract as a supplement to support overall immune strength.
There is no officially recognized effective dose for Echinacea. Some studies indicate 300-500 mg, three times daily, to be effective in supporting immunity. This dose would be equivalent to a range of 900 to 1500 mg daily; however, most supplements offer a 400 mg dose. I recommend my patients take between 400 mg (when combined with other immune boosters that work similarly) and 1200 mg of a high-quality Echinacea purpurea extract daily to feel confident in a positive impact on immunity.
Elderberry (Sambucus nigra), also known as Black Elderberry or Elder, is a flowering plant containing polyphenols, including anthocyanins and flavonoids with immune-boosting properties.
Studies show elderberry extract has potent antiviral and antibacterial properties that protect against bacterial pathogens known to cause upper respiratory infections, as well as strains of influenza virus, and H1N1.
It can reduce the duration and severity of colds (likely due to its ability to reduce swelling in mucus membranes) and help you fight against viral infections by blocking critical viral proteins that viruses need to enter and infect your cells. It also may help you fight against viruses by making it more difficult for infected cells to release the virus into other non-infected cells.
Research suggests bioflavonoids (like those found in Elderberry) increase your ability to absorb vitamin C (one of the most well-known vitamins for immune system health), as a further potential immune boost.
Most of the studies used a liquid form of the Elderberry extract. A soluble pill form of the powdered extract could work roughly the same, but it's hard to know if the powdered form you are getting inside a pill is soluble. For this reason, I recommend my patients use a liquid form (just like I recommend liquid vitamins) instead of a pill form.
There is no officially recognized effective dose for Elderberry extract. Studies have shown positive outcomes in a wide range of doses, from 125 mg daily to 1500 mg. I recommend my patients take 500 mg of a liquid-form Elderberry extract daily for an immune-boosting impact.
3. Vitamin C
Vitamin C is a popular supplement for supporting immune health, and for a good reason. It supports many cellular functions related to the immune system, including:
- Boosting the number of immune cells in the body, specifically phagocytes and lymphocytes
- Enhancing the ability of immune cells to protect against infection
- Supporting a process called apoptosis, which is programmed cellular death – a positive process that helps support your immune system by clearing out old damaged cells and replacing them with new healthy ones
- Protecting the body as an antioxidant that can strengthen your body's natural defenses
- Strengthening your first line of defense – your skin – where it functions as an antioxidant to help maintain this barrier against pathogens
Like Elderberry and Echinacea, vitamin C supplementation helps to reduce the severity and duration of the common cold and other upper respiratory tract infections.
As an essential vitamin, the recommended daily dose of Vitamin C is 90 mg per day. Daily doses in supplements are usually higher, in the range of 250 - 1,000 mg. Since it is a water-soluble vitamin, your body will flush out what it doesn't use, so you don't need to worry about overdosing. For immune-boosting impact, I recommend my patients take 1,000 mg daily, along with a diet high in vitamin C, plus bioflavonoids that may help the body absorb vitamin C. This recommendation is consistent with recent comments by Dr. Anthony Fauci of the National Institute of Allergy and Infectious Diseases, where he recommends about a gram (1,000 mg) per day.
4. Vitamin D
Vitamin D is a fat-soluble nutrient essential to a healthy immune system, helping control innate and adaptive immune responses. It enhances the pathogen-fighting activity of white blood cells known as monocytes and macrophages that are critical parts of your immune system defense.
Multiple studies have shown that lower levels of vitamin D are associated with increased infection. One study done in Israel shows that low blood levels of vitamin D are associated with an increased risk of contracting upper respiratory tract infections, including those from COVID‐19 and influenza.
Current research suggests that consuming 25–100 mcg (1,000–4,000 IU) of vitamin D per day is ideal for helping most people reach healthy blood levels. Since vitamin D inadequacy and deficiency are so common, I recommend 100 mcg of supplemental vitamin D3 (also known as cholecalciferol) daily. If possible, taking a form pre-dissolved in a healthy oil is best rather than dry vitamin D tablets.
Sometimes called the gatekeeper of immune function, Zinc supports the immune system in several ways:
- It helps the body produce and activate T-cells so it can respond stronger to pathogens.
- It helps the body produce and activate B-cells so the body can produce antibodies to fight infection.
- It supports immune cell communication.
- It helps to inhibit viral replication.
Several studies have shown Zinc taken at the start of infection can lead to a faster recovery from, and may even protect against, respiratory tract infections such as the common cold.
I recommend a zinc supplement either as part of a liquid multivitamin, or as a standalone supplement, or as part of an immune-boosting supplement. I advise at least 11 mg per day (100% of the daily value recommended by the FDA), and for immune boosting purposes, I recommend 20 mg.
6. Aronia berry extract
Aronia berry (also known as Chokeberry, or Aronia melanocarpa) is one of the richest sources of polyphenols, including flavonoids and anthocyanins, that have a potent antioxidant effect. These phytonutrients also likely strengthen and support your immune system, just like the polyphenols in Elderberry, dark cherry juice, and other polyphenol-rich fruits.
Studies have shown Aronia berry extract to exhibit antibacterial effects against potentially harmful bacteria, such as Bacillus Cereus and Escherichia coli.
Finally, animal studies on influenza indicate Aronia may have antiviral properties.
There is no officially recognized effective dose for Aronia berry extract. Studies have shown positive cholesterol-related benefits from as little as 300 mg. You can find Aronia extract sold commonly as a supplement between 400 mg and 1000 mg. I recommend my patients take the larger dose of 1,000 mg (1 gram) for immune-boosting purposes.
Beta-glucan is a type of soluble fiber found in the cell walls of algae, bacteria, yeasts, fungi, lichens, and plants. This natural prebiotic is strongly linked to lowering cholesterol, stimulating immune cell activity, regulating inflammation, promoting blood sugar management, and boosting a healthy microbiome. Perhaps best known for its ability to combat cardiovascular disease, beta-glucan has long been recommended by healthcare professionals as a dietary staple for individuals with high cholesterol. However, recently beta-glucan has garnered a lot of attention among healthcare professionals for its immune-modulating abilities, especially as we approach the cold and flu season amid the COVID-19 pandemic.  Touted for its ability to fight infection, it has also been the focus of several studies assessing its potential cancer-fighting properties. 
Familiar sources of beta-glucans include oats, bran, barley, wheat, whole grains, and certain types of mushrooms.  There are also many beta-glucan supplements on the market. Grain-derived beta-glucan is best known for lowering cholesterol, regulating blood sugar, decreasing inflammation, and supporting a healthy microbiome. Beta-glucan from fermented mushrooms, algae, yeast, and seaweed is more strongly associated with modulating immune cells and effectively stimulating immune response so the body can fight off infections. 
As a prebiotic, beta-glucan helps promote a healthy microbiome by feeding beneficial bacteria in the gut, weakening disease-causing bacteria, and modulating inflammation.  Because a healthy microbiome is strongly linked to the strength of the immune system, consumption of beta-glucan may boost your defense against infections and diseases.
Studies have shown that beta-glucan influences immune receptors critical in initiating immune cell activity, leading to the mobilization of Macrophages, Neutrophils, Basophils, T-cells, and Natural Killer Cells (NKCs), among others.   In fact, some studies even point toward its ability to protect against cancer-causing carcinogens, deploy cancer-fighting molecules to inhibit cancer growth, and reduce proliferation of cancerous tumors. 
For immune health, daily doses of beta-glucan ranging from as little as 120 mg (human equivalent dose) have been studied. I recommend my patients eat a diet high in beta-glucan and take at least 500 mg daily in supplemental form.
8. Citrus Pectin
Citrus pectin is a water-soluble fiber extracted from the peel and pulp of citrus fruits, and is commonly used in jellies, jams, and preserves. While our bodies cannot digest citrus pectin in its natural form, an enzymatically altered form of citrus pectin called, modified citrus pectin (MCP), can be absorbed by the body and is widely used for its immune enhancing benefits.
Clinical and preclinical studies have demonstrated multiple ways in which modified citrus pectin provides support for the immune system:  One study showed that MCP led to an increase in B-cells, T-cells, and NK-cells, all of which are lymphocytes and play an integral role in acquired, or adaptive, immunity. Lymphocytes kill off foreign invaders and destroy damaged cells that have been invaded by viruses or have become cancerous.  According to the study, not only was there an increase in the activation of lymphocytes due to MCP, but the functional activity level of NK-cells also increased, rendering them more effective. 
Additionally, MCP may be able to reduce metastasis of cancer by adhering to an inflammatory protein called galectin-3 and inhibiting its ability to function effectively. Finally, studies have shown that MCP may also increase gut immunity, which is important for overall immune function. As a prebiotic, modified citrus pectin promotes the growth of beneficial bacteria that are critical to gut and immune health, including bifidobacteria, lactobacilli, Faecalibacterium prausnitzii, Roseburia spp. and Eubacterium rectal.
While there are many supplements on the market that contain modified citrus pectin, there is no official recommended dose.
9. Vitamin E
Of all the different types of cells that make up the body, this essential, fat-soluble vitamin is mostly concentrated in immune cells. Vitamin E is a powerful antioxidant that helps the body fight off infection and enhance immunity. It helps regulate immune function by increasing the proliferation and activation of the immune supporting T-lymphocyte white blood cells as well as enhancing activity of NK cells. According to studies, vitamin E is an especially important nutrient for supporting immune response in older adults.
Vitamin E deficiency is uncommon but can reduce immune function, causing an increased risk of infectious disease. The recommended daily intake of vitamin E has been set by the NIH at 15 mg per day. I recommend between 10 and 15 mg of supplemental vitamin E per day.
10. Vitamin B6
Vitamin B6 is a versatile water-soluble vitamin involved in a wide variety of functions from supporting cellular metabolism to boosting immune function. B6 is required by enzymes for the synthesis of hemoglobin, which is a protein in our blood that carries oxygen. This is why a deficiency in B6 can lead to muscle weakness, fatigue, and shortness of breath. B6 also plays a critical role in cognitive function through biosynthesis of neurotransmitters, which are chemical messengers in the brain. Along with supporting enzymatic reactions and biochemical reactions vital to the metabolism of protein, fat, and carbohydrates.
One way vitamin B6 is critical to immune function is its involvement in the production of lymphocytes and the protein interleukin-2. This protein regulates white blood cells and activates the immune system. Studies have shown that deficiency in vitamin B6 can reduce the production of interleukin-2 and antibodies that are needed to fight infection, hindering immune response. 
Make sure you get enough by either taking supplements or from your diet. I recommend at least 3.4 mg of supplemental B6 per day.
The Supplement Brand I Recommend
To get the effective dose of each immune-boosting supplement above, you would have to take about 15 pills per day! Even then, you would not be getting the most soluble, bioavailable, liquid forms. The only way to get all of these nutrients in the effective dose and form is to take a convenient gel pack called Immune Super Boost by Healthycell. The MICROGEL delivery format is better than liquid form. MICROGEL™ is the next-generation nutrient delivery technology replacing tablets, capsules and powders. Formulated by world-leading nutritional scientists, this unique technology ensures maximum absorption into the body by releasing extremely small, soluble, ultra-bioavailable nutrient particles in the digestive tract.
According to published results from rigorous scientific research, the nutrient supplements listed in this article are the best supplements for immune system resiliency. However, although these immune support supplements may boost immune health, the impact of a healthy and safe lifestyle is greater. A balanced diet, good quality sleep, and physical activity, and refraining from smoking are a few ways to support your immune system. For more information on lifestyle tips and supplements to boost immune system health, read the article How to Strengthen Your Immune System. If you're a plant-based dieter interested in vegan sources read 8 Immune Boosting Supplements for Vegans.
It is also important to note that there's no scientific evidence that any of these immune-boosting supplements will protect you against COVID-19 — despite the fact that many of them have antiviral effects.
By incorporating these immune-strengthening lifestyle tips and immune-boosting supplements into our routines, and sharing them with our loved ones, we can help prevent illness and thrive.
To your health,
Dr. Vincent Giampapa, MD, FACS
Visiting Scholar, The Sinclair Lab
Harvard University, Boston, MA
Cell Aging Researcher & Author
Director, Cell Health Institute