Diet tips to help support a healthy immune system

What’s the immune system? It’s the body's built-in defense system, which works constantly to protect people from bacteria, viruses and other microbes that are constantly invading from outside. What’s one of the top ways to keep the immune system strong? Eating a healthy diet. Here’s what to know. 

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How the immune system works

The immune system is a complex system of cells, tissues and organs that work together to fight off infections and certain diseases. It’s responsible for detecting and fighting off germs that make a person sick. The immune system also works to heal the body from an infection or injury, and it even helps fight off certain diseases like cancer.

Infections occur when germs such as bacteria, viruses, fungi, or parasites multiply in the body, triggering illnesses like the common cold or the flu. The immune system works by noticing the difference between these unhealthy cells and a person’s normal cells. Unhealthy cells can be caused by infections or other things like a sunburn or cancer.

There are two major parts of the immune system: the innate immune system and the adaptive immune system. The innate immune system, which includes the skin, acts as a protective barrier against any germ, even if the body has never encountered the germ before. The adaptive immune system learns to recognize certain organisms and helps fight them off when the body encounter them again. This is how vaccines work.

When the immune system isn't working properly, this increases the risk of infection. People can also get sick when the immune system is overactive (which can cause allergic diseases or severe allergic reactions) or when the immune system turns against itself and starts attacking healthy tissues (which can cause autoimmune disease).

Parts of the immune system

How does the body detect bad cells? It requires good partnership from the key players that make up the immune system:

• The skin is a person’s first line of defense against germs that can hurt them. It acts as a barrier, keeping germs out of the body.
• White blood cells are the warriors responsible for attacking harmful germs. There are five main categories of white blood cells, and they have different jobs, including killing germs, producing antibodies, cleaning up damaged cells and communicating with other white blood cells. White blood cells communicate with each other using special chemical messengers called cytokines, which are also an important part of the immune system.
• Antibodies are proteins that circulate in the bloodstream, identifying and helping to eliminate harmful substances.
• The lymphatic system includes organs and tissues like the tonsils, appendix and spleen, as well as the bone marrow and lymph nodes. It is responsible for moving lymph, a fluid that carries immune cells, through the body. The bone marrow is where white blood cells are made.
• The mucosa is the sticky membrane that lines the gut, as well as the respiratory and reproductive systems. It is the body's largest protective barrier against germs trying to enter the body.

How diet may impact the immune system

Eating a well-rounded diet can help support the immune system. Nutrition plays an important role in supporting a person’s total health, including how their body fights infection. Eating processed foods with poor nutritional value or not eating enough healthy foods could hurt the immune system. This may make people more prone to getting infections and certain diseases.

Nutrients to help support the immune system

Healthy foods fuel the cells that respond to threats in the body. There are several key vitamins and minerals that may help strengthen the immune system. Eating a balanced diet rich in fruits and vegetables and low on processed foods can help keep the immune system working at its best.

Vitamin A

Vitamin A is important for keeping the immune system healthy, and it’s essential to cell development. It’s also important for keeping the skin and linings of the intestines their healthiest. Some foods that contain vitamin A include:

• Apricots, mangos and cantaloupe
• Beef liver
• Broccoli
• Certain dairy products such as whole milk
• Eggs
• Green, leafy vegetables such as spinach, kale and romaine lettuce
• Orange vegetables such as carrots, pumpkin and sweet potatoes
• Salmon 

Vitamin C

Vitamin C helps heal wounds and maintain healthy skin. As an antioxidant, it can also help protect against cell damage. Some foods that contain vitamin C include:

• Bell peppers
• Broccoli and kale
• Brussel sprouts
• Citrus fruits
• Potatoes
• Strawberries, papaya and cantaloupe
• Tomatoes 

Vitamin D

Vitamin D helps the body build strong bones by helping to absorb calcium. It also helps the immune system function normally, which could help prevent infection and certain autoimmune diseases. People can get vitamin D by absorbing sunlight through the skin or by eating certain foods like:

• Beef liver
• Certain mushrooms if grown under certain conditions
• Egg yolks
• Fatty fish like salmon and tuna
• Fortified dairy products, including cow's milk and fortified milk alternatives such as soy, almond and oat milk 

Vitamin E

Vitamin E is an antioxidant that is also involved with immune function. Foods that contain vitamin E include:

• Broccoli
• Leafy greens such as spinach
• Nuts and seeds such as sunflower seeds, almonds, peanuts and hazelnuts
• Vegetable oils such as sunflower, corn or soybean
• Wheat germ

Iron

Iron is essential for helping blood cells deliver oxygen all over the body. Foods that contain iron include:

• Beans and lentils
• Beef, lamb, chicken and turkey
• Broccoli and green peas
• Dark chocolate and raisins
• Fortified grains and breakfast cereal
• Sardines, tuna and oysters
• Tofu

Zinc

Zinc, another antioxidant, helps with wound healing and cell growth. Foods that provide sources of zinc include:

• Beef, pork and turkey
• Greek yogurt
• Lentils
• Oysters, shrimp and crab
• Pumpkin seeds

Aside from Vitamin D, the body can’t make these other essential vitamins and minerals on its own. Most people get their essential vitamins and minerals through food. If someone’s deficient in a vitamin or mineral, either due to lifestyle or health conditions, they may need to take a supplement. Deciding whether to take a supplement and how much to take is something that should be determined by a health care provider.

Key takeaways

The immune system is designed to keep people healthy. It includes an interconnected network of organs, tissues and cells that work together to combat germs. The good news? Eating a healthy diet is one of the ways to support the immune system. Experts say most vitamins and minerals that are needed to support a healthier immune system can be found in food. However, some people are missing some key nutrients due to their diets or medical conditions. If this is the case, a person should talk to a health care provider about their options. Always talk to a health care provider before starting or stopping any vitamin or supplement.