Eating foods that boost your immune system can support heart and digestive health and may reduce your risk of certain illnesses or diseases.
The first step to improving your diet with immune-boosting foods is to understand exactly how your immune system works.
We also make specific supplement recommendations at the bottom of this page. But first let’s learn about the science behind your immune system, so you know which supplements and dietary changes are right for you.
Understanding Your Immune System
Your immune system is comprised of organs, tissues, special cells, and proteins, all of which protect your body from the bacteria and viruses you encounter daily.
It does so through a process known as the immune response.
Some of the most important cells involved in the immune response are white blood cells, also known as leukocytes.
They are found in many parts of the body, including bone marrow, lymph nodes, the spleen, and the thymus. White blood cells protect the body as they circulate through the blood vessels.
There are five major types of white blood cells:
The most abundant type of white blood cell. It is one of the first to travel to a site of infection. Neutrophils ingest microorganisms and release enzymes to kill them.
The two main types of lymphocytes are T lymphocytes, that kill tumor cells and control immune responses, and B lymphocytes which make antibodies.
Eosinophils is a cell containing granules that release enzymes during asthmatic episodes, infections, and allergic reactions.
Monocytes are also known as a macrophage and a type of phagocyte. This cell can surround and kill microorganisms, remove dead cells, ingest foreign material, and boost immune response.
Basophils contain granules that release enzymes during asthmatic episodes and allergic reactions.
When a foreign organism invades your body, the lymphocytes are activated and produce antibodies which attach themselves to specific invaders. Once the antibodies are made, they will remain in your body to prevent you from getting sick from the same pathogen.
T cells are then alerted to destroy the tagged invading organisms.
3 Types of Immunity
Humans have three forms of immunity:
An older evolutionary non-specific defense strategy that is activated immediately or shortly after a threat is detected. It includes physical barriers such as the skin, along with chemicals in the blood and immune system cells that attack foreign cells.
Also known as an antigen-specific immune response. This type of immunity develops throughout your life as you are exposed to different pathogens, and your body learns to fight them and remember them for subsequent encounters. You can also acquire adaptive immunity through vaccines.
This form of short-term immunity involves the transfer of ready-made antibodies. For example, antibodies in a mother’s breast milk will be passed on to her infant during breastfeeding.
These antibodies will give the child a temporary immunity to the same diseases to which she has been exposed. Passive immunity helps to protect infants through early childhood. Other examples of passive immunity include immunoglobulin therapy and transfer of maternal antibodies to the fetus during pregnancy.
This aromatic bulb has a number of health benefits, but one of the most widely researched is its effect on the immune system.
Garlic contains several compounds that can help your body fight germs. (Kyo et al., 2001) Several of these compounds can also boost the disease-fighting action of white blood cells. (West, 2016)
You should aim for 1-2 cloves per day - these need to be minced and allowed to sit for 10 minutes before swallowing right before food.
If you’re not a fan of the flavor of garlic, enterically-coated garlic supplements are available. They help you can reap the benefits of garlic — without the taste. The recommended dose is 600-1,200mg a day divided into two doses. (Patel, 2014)
Garlic is blood thinning — exercise caution if you take any other blood thinners such as warfarin or nattokinase.
The most healthful forms of yogurt contain natural probiotics such as Lactobacillus acidophilus, Lactobacillus bulgaricus, and Streptococcus thermophilus. You can also get a wider range of the probiotic spectrum by taking a daily supplement.
Yogurt has been shown to stimulate the immune system, although the mechanism is not entirely understood. (Meydani et al., 2000)
Fruits such as blueberries, raspberries, strawberries, and blackberries are all rich in antioxidants. These are compounds that destroy free radicals.
Although not too much is known about how free radicals affect human health, what is known is that they can damage cells, cause illness, and contribute to aging. (Villines, 2017)
Because berries contain antioxidants, they may help to boost the immune system and protect against infection. (Puertollano et al., 2011)
Regularly eating nutrient-dense shellfish such as oysters, clams, lobster, and crab may boost the immune system by helping white blood cells produce cytokines — the kind of proteins that help stave off viruses such as influenza.
Shellfish is also rich in zinc — a critical immune-supportive nutrient. In a 2000 study published in the American Journal of Clinical Nutrition, it was found that zinc deficiency in healthy elderly subjects was linked to a decrease in certain immune system functions. (Streit, 2019)
Aim for two servings a week to maximize your benefits.
Oats contain the fiber beta-glucan, which helps support a healthy heart and a healthy digestive system. Beta-glucan may be able to activate immune cells and may increase their effectiveness. (Kim et al., 2011)
However, due to the complexity of the immune system, researchers are not sure how this mechanism works. More studies are needed. You can still benefit from one to three servings of whole grains each day.
Green tea has long been touted for numerous health benefits, mainly because it is rich in a type of antioxidant known as catechins. These may be able to help boost the immune system by regulating T cells — a key factor in the development of autoimmunity. (Wu et al., 2012)
This application of green tea may also help people with autoimmune diseases because it has the potential to stop the immune system from attacking healthy cells.
Matcha green tea is a potent source of these catechins.
Kale is a leafy green. Like other cruciferous vegetables (such as spinach, cabbage, and Swiss chard) kale is considered to be an immune-boosting food because of its rich vitamin C content. It may also help the immune system because it is rich in fiber, which acts as a natural prebiotic. (Parnell et al., 2012)
This helps strengthen probiotic microflora and can support a healthy immune system. The optimal serving of kale is 1-2 cups per week. Any more than this could be harmful due to thallium content.
Curcumin is a substance found in the spice turmeric. Curcumin has been found to have multiple beneficial effects on many aspects of the immune system, not only T cells but also macrophages, dendritic cells, natural killer, cells, neutrophils, and B cells.
This means it has a significant positive effect on your immune system. (Jagetia et al., 2007)
Add it to your meals as often as you can, or take a daily turmeric supplement that contains 95% curcumin.
Many people are aware that it’s a good idea to load up on vitamin C when they’re not feeling well, but not so many realize that bell peppers are packed with this vitamin. Red, orange and yellow bell peppers can contain up to twice as much vitamin C as citrus fruits.
Many cells within the immune system, particularly T cells, need vitamin C to function properly. (Jagetia et al., 2007)
Sweet potatoes are another immune-boosting food. This vegetable is rich in beta-carotene, which converts into vitamin A. Vitamin A plays a vital role in enhancing the immune system. It helps with cellular immune responses and immune processes within the body’s fluids. (Huang et al., 2018)
Just one medium-sized orange sweet potato provides more than 100% of your daily recommended intake of vitamin A.
Unfortunately, many people don’t effectively convert beta-carotene to Vitamin A. In this situation, sources of preformed Vitamin A such as egg yolks and chicken liver are essential.
Not only is this mushroom a good plant protein source, but it is also rich in vitamins B, B12, C, D, and niacin. Eating shiitakes daily or taking a shiitake supplement could significantly benefit your immune system. (Science Daily, 2015)
Chaga mushrooms may help boost the immune system. This fungus is rich in antioxidants, which reduce inflammation and strengthen immune system function. Preliminary studies on animals suggest that chaga may help with cell-to-cell communication within the immune system. This, in turn, could help to fight infection. (Ko et al., 2011)
Reishi mushrooms support immune function because of their anti-inflammatory effect on white blood cells. (Cheng et al., 2010) They can also increase the activity of natural killer cells, which help fight infection in the body. (Gao et al., 2003)
Several compounds found in this mushroom enhance immune functions within the body’s cells and fluids. (Sheng et al., 2017) They may also reinforce the innate immune system by inducing the maturation of human dendritic cells. (Quach, 2019)
Eggs benefit your immune system in several ways. The yolks are rich in vitamins A and D, which are essential for a healthy immune system. A deficiency in these nutrients can depress your immune system and lead to immune disorders and respiratory infections.
Your immune cells have vitamin D receptors designed to regulate the immune response. (Prietl et al., 2013)
Just one egg contains around 41 IUs of vitamin D. Egg yolk is rich in selenium, which is an important mineral for the immune system because it helps to keep your immune system functioning at the optimum level. (Hoffman et al., 2008)
Kefir is a fermented milk drink made from a combination of bacteria and yeast fermentation. Many of Kefir’s health benefits are attributed to its probiotic content.
Because of this, Kefir helps to boost the immune system by modulating beneficial bacteria throughout the GI tract. Kefir helps to strengthen cytokine cells in the immune system. (Adiloglu et al., 2013)
Fatty fish such as mackerel, salmon, and herring, are rich in omega-3 fatty acids. Not only do omega 3s reduce inflammation, but in animal studies they also protect the lungs from respiratory infections. (Hinojosa et al., 2017)
For the maximum benefit, eat two to four 4-ounce servings of fatty fish per week.
There are several supplements you can take to boost your immune system.
The extracts from this flower include water-soluble polysaccharides and flavonoids. In a 2012 study published in Evidence-Based Complementary and Alternative Medicine, echinacea was shown to help prevent recurrent infections, reduce cold symptoms and to help prevent the common cold. (Jawad et al., 2012)
This is a great supplement to take through flu season.
Zinc is an essential mineral found in high concentrations in the muscles, red and white blood cells, eye, skin, liver, kidneys, and bones. Your body requires zinc for healing wounds, proper visual functions, digestive functions, as well as improving stress levels and metabolic processes.
Using these functions, this mineral also helps to maintain proper functioning of the immune system. (Rink et al., 2000)
Selenium is a trace mineral absorbed into the body from food. It may also be taken as a supplement.
Selenium is essential for many bodily functions, including blocking DNA damaging free radicals and protecting cells against toxins. In this way, it is also an immune system booster. (Kubala, 2017)
Vitamin B6 is a water-soluble vitamin, which means it cannot be stored in the body. This vitamin is responsible for making antibodies to fight diseases and is essential for a healthy immune system.
A deficiency in this vitamin can reduce your body’s production of white blood cells and T cells. (Qian et al., 2019)
Vitamin E is the term used for a number of fat-soluble compounds including alpha-tocopherol, which has antioxidant properties. Vitamin E is one of the most important vitamins for protecting the body’s cells against oxidative stress, a major cause of cellular damage.
It is also essential for the proper function of the immune cells. (Moriguchi et al, 2000)
Vitamin A is a group of compounds including retinal, retinol and beta-carotene. It helps to improve and regulate the immune system and prevent infections by increasing the production of white blood cells. (Huang et al., 2018)
Vitamin A should always be taken in a balanced amount with Vitamins D and K2.