12 Immunity-Boosting Foods
Certain foods that contain various vitamins and minerals, amino acids, fatty acids, and plant compounds boost the immune system and help the body prevent and fight colds, flu, and other illnesses.1
Nutrients in citrus fruits, leafy greens, fatty fish, vegetables, and more promote a healthy gut microbiome, boost immune cell response, and fight harmful inflammation and oxidative stress.
This article looks at the best immunity-boosting foods and foods that may weaken the immune system.
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Citrus Fruits
Citrus fruits like grapefruits, oranges, tangerines, lemons, and limes are high in vitamin C, which helps boost white blood cells that fight infections. Vitamin C is also an antioxidant that fights free radicals that can prevent the immune system from working well.2
Citrus fruits also contain flavonoids (anti-inflammatory plant compounds) that help boost the immune system and disease recovery. Flavonoids in citrus fruits can help relieve coughs and promote digestive health.3
It's important to regularly consume foods high in vitamin C, especially if you are sick. The body can't make it on its own.4
Broccoli
Broccoli is considered one of the best foods for enhancing the immune system. This cruciferous vegetable is high in immunity-boosting vitamins C, E, and A and contains numerous plant compounds known for their antioxidant properties, including sulforaphane, a powerful anti-inflammatory. Consume broccoli raw, steamed, or lightly cooked to preserve its nutrients.4
Dark Chocolate
Dark chocolate is made from cocoa, which is high in polyphenols, plant compounds with antiviral and anti-inflammatory properties. A diet high in cocoa benefits the body’s immune system and gut microbiome and reduces inflammation.5
Berries
Strawberries, blueberries, and raspberries are high in vitamin C and other disease-fighting nutrients. Polyphenols, such as resveratrol, are found in berries and have antiviral and anti-inflammatory effects that also help enhance immune system function.6
Foods high in dietary fiber, such as fruits, vegetables, and whole grains, are rich in prebiotics and probiotics that help boost the immune system by promoting a healthy gut microbiome and its immunity-boosting metabolic functions.7 Dietary fiber enhances the gut microbiome’s production of metabolites, such as short-chain fatty acids, which increase immune cells’ functions. Studies also have shown that fiber reduces inflammation.8
Fatty Fish
Fatty fish are rich in omega-3 fatty acids, tryptophan (an amino acid), taurine, and polyamines. These compounds help strengthen and regulate the immune system and increase the number of beneficial bacteria in the gut microbiome.9
Bell Peppers
Bell peppers are high in powerful immunity-boosting vitamins C and A and beta carotene, which
converts to vitamin A in the body. Red bell peppers contain more vitamin C than most common citrus fruits.10 Bell peppers are also high in lycopene, a plant pigment with antioxidant and anti-inflammatory properties.11
What About Echinacea?
Echinacea is an herb that is widely touted as an immune booster. Research shows echinacea can have immunity-stimulating properties and shorten the duration and severity of illnesses like the common cold. However, there are no standards for echinacea preparations sold on the market, which has led to inconsistent data on their effectiveness.12
Tea
Green and black tea are rich in flavonoids and antioxidants that help boost the immune system. Green tea also contains epigallocatechin gallate, an antioxidant that improves immune system function, lowers the risk of some diseases, and reduces inflammation.13
Herbal teas are made from blends of various dried plant parts such as chamomile, ginger, cinnamon,
ginseng, and cloves. These ingredients have anti-inflammatory, antiviral, antibacterial, and antioxidant properties that can enhance the immune system.14
Garlic
Freshly crushed garlic has many sulfur‐containing compounds with antiviral properties, stimulating T-cells and lymphocytes that fight viruses and diseases. Components of garlic are also known to block inflammatory pathways in the body. Garlic consumption may help the body make and release nitric oxide, aiding in processes that protect against viral illness.4
Yogurt
Yogurt is made by fermenting milk with lactic acid bacteria. This makes yogurt a good source
of probiotics, which help the immune system function by increasing the growth of beneficial bacteria and hindering harmful bacteria in the digestive system to protect against disease.15
Eating plain, unsweetened yogurt is best because flavored yogurts and yogurt drinks are often high in sugar.10
Nuts and Seeds
Nuts and seeds are high in vitamin E, which supports antibody production and protects against oxidation.1 Almonds are known to be effective immune boosters because they contain a mix of fats and plant sterols that help the immune system function well and fight inflammation.16 Sunflower seeds also stand out for containing zinc and selenium, minerals with numerous disease-fighting properties.1
What About Elderberry?
Elderberry is a popular over-the-counter supplement marketed as beneficial for the immune system. Though there is evidence that elderberry can shorten the duration and severity of viral respiratory illnesses such as colds and flu, there is no solid evidence that taking elderberry
prevents disease.17
Spinach and Other Leafy Greens
Leafy greens like spinach, kale, and collard are high in vitamin C, one of the most important vitamins for immune system function.18 Leafy greens are also high in beta carotene, which converts to vitamin A, an anti-inflammatory vitamin that helps antibodies fight viruses.19
Turmeric
The active ingredient in turmeric is curcumin, which is a powerful anti-inflammatory, immunity-boosting, and antiviral agent.20 Curcumin helps boost immunity cells' functioning, while other turmeric compounds have anti-inflammatory properties.12
Foods to Avoid for a Healthy Immune System
Certain foods are known to harm the immune system and prevent it from working properly, especially when consumed in high quantities. Foods to avoid (or limit) for a healthy immune system include:
Sugary foods: High amounts of sugar can cause inflammation and keep the immune system’s cells from working properly.21
Alcohol: Alcoholic beverages can damage immune cells in the blood and digestive systems and
disrupt communication between immune system cells.22Fast food: These foods are highly processed and high in salt and saturated fats. Eating a high quantity of unhealthy fast food can damage the immune system and intestinal microbiome.23
Summary
Certain foods have proved helpful in supporting the immune system. Adding citrus fruits, leafy greens, dark chocolate, and other foods to your diet can be an important strategy for fighting colds, flu, and other diseases. These foods help support the immune system by boosting immune cells' activity, supporting the gut microbiome, and reducing inflammation. Sugary foods, fast food, and alcohol are known to be harmful to the immune system and should be avoided or only consumed in small quantities.