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How To Improve Your Immune System, Pre/Post Illness

Updated: Jun 1, 2020

“No matter how much it gets abused, the body can restore balance.

The first step is to stop interfering with nature.”

Deepak Chopra

© AlexRaths / Getty Images / iStock

What Is Our Immune System...Really?

The overall function of the immune system is to prevent or limit infection and provide protective responses against foreign pathogens. These are primarily microbes (germs) that cause organisms such as bacteria, viruses, parasites, and fungi. Because the human body provides an ideal environment for many microbes, they try to break in. It is the immune system’s job to keep them out or seek out and destroy them. The immune system is amazingly complex. It can recognize and remember millions of different enemies, and it can produce secretions and cells to match up with and wipe out each one of them.

There are 2 main parts of the immune system:

  • The innate immune system. You are born with this.

  • The adaptive immune system. You develop this when your body is exposed to microbes or chemicals released by microbes.

The innate immune system is inherited. It is active from the moment you are born. When this system recognizes an invader, it goes into action right away. The cells of this immune system surround and cover the invader. The invader is killed inside the immune system by cells called phagocytes.

The acquired immune system, with help from the innate system, makes cells (antibodies) to protect your body from a specific invader. These antibodies are developed by cells called B lymphocytes after the body has been exposed to the invader. The antibodies stay in your body. It can take several days for antibodies to form. But after the first exposure, the immune system will recognize the invader and defend against it. Immunizations instruct your immune system to make antibodies to protect you from harmful diseases.

The cells of both parts of the immune system are made in different organs of the body, including:

  • Adenoids: Two glands located at the back of the nasal passage.

  • Bone marrow: The soft, spongy tissue found in bone cavities.

  • Lymph nodes: Small organs shaped like beans, which are located all over the body and connect via the lymphatic vessels.

  • Lymphatic vessels: A network of channels all over the body that carries lymphocytes to the lymphoid organs and bloodstream.

  • Peyer's patches: Lymphoid tissue in the small intestine.

  • Spleen: A fist-sized organ located in the belly (abdominal) cavity.

  • Thymus: Two lobes that join in front of the windpipe (trachea) behind the breastbone.

  • Tonsils: Two oval masses in the back of the throat.


Some types of white blood cells, called phagocytes chew up invading organisms. Others, called lymphocytes, help the body remember the invaders and destroy them.

The two kinds of lymphocytes are B lymphocytes and T lymphocytes. Lymphocytes start out in the bone marrow and either stay there and mature into B cells, or go to the thymus gland to mature into T cells. B lymphocytes are like the body's military intelligence system, they find their targets and send defenses to lock onto them. T cells are like the soldiers, they destroy the invaders that the intelligence system finds.

Keeping The Immune System Healthy

This task....can be a balancing act. Stress, sleep deprivation, poor hygiene and nutrition along with a sedintary lifestyle can contribute to a depleted immune system. Try to manage stress (see my May post about stress for more details), try to get at least 7-8 hours of sleep per night and wash your vegetables and your hands often to reduce the spread of germs. Get 30 minutes of moderate exercise, 5 days a week to keep your blood circulating throughout your body.

The following nutrients play a role in the immune system and can be found in a variety of foods:

  • Beta Carotene is found in plant foods, such as sweet potatoes, spinach, carrots, mango, broccoli and tomatoes.

  • Vitamin C-rich foods include citrus fruits, berries, melons, tomatoes, bell peppers and broccoli. 

  • Vitamin D is found in fatty fish and eggs. Milk and 100% juices that are fortified with vitamin D also are sources of this important nutrient.

  • Zinc tends to be better absorbed from animal sources such as beef and seafood, but also is in vegetarian sources such as wheat germ, beans, nuts and tofu.

  • Probiotics are “good” bacteria that promote health. They can be found in cultured dairy products such as yogurt and in fermented foods such as kimchi.

  • Protein comes from both animal and plant-based sources, such as milk, yogurt, eggs, beef, chicken, seafood, nuts, seeds, beans and lentils.

If you suspect your diet is not providing you with all your micronutrient needs, for example, you don't like or have little access to fruits and vegetables — taking a daily multivitamin and mineral supplement may close those nutritional gaps and may provide additional health benefits. 

Can I Really BOOST My Immune System?

A word of caution: Many companies market megadoses of a single vitamin or vitamin packets that claim to boost your immune system. This practice is not recommended. More is not necessarily better. You don’t want to overload your system. The goal is balance. Stress management, quality sleep, good hygiene, moderate exercise and a healthy diet all help support your immunity and overall health.

Malnutrition And COVID-19

Common symptoms of COVID-19 can lead to problems with nutrient absorption and/or overall inadequate dietary intake. Patients recovering from COVID-19 infection who are discharged from the hospital may still be experiencing symptoms and may be malnourished and still have increased nutrient needs. It is crucial to maintain suffcient nutrient and hydration levels if you are continiuing to recover from COVID-19 sympoms at home.

Registered Dietitian Nutritionists (RDNs) can help patients recovering from COVID-19 by recommending increased intake of energy/protein. Here are some good practices below in an effort to decrease malnutrition while recovering from COVID-19. 

Disclaimer: Do not increase caloric intake unless you have consulted your Doctor and RDN prior to implementation. 

 ● High-calorie, high-protein meals and snacks can help prevent weight loss and maintain lean muscle mass. For example, RDNs can advise eating vegetables with cream, butter, margarine, cheese sauce, olive oil, or salad dressing to increase energy intake and choose foods high in protein, such as milk, eggs, cheese, meats, fish, poultry, nuts, and beans.

● Nutrient-dense foods and beverages including oral nutritional supplements are good  methods to increase calorie and protein intake if oral dietary intake is not adequate to meet needs (e.g., protein powders and meal replacement shakes and bars).

● For individuals having difficulty coordinating chewing and breathing, beverage supplements might be a better option to efficiently increase energy intake compared to solid foods.

● Micronutrient supplements can help compensate for inadequate oral intake to address deficiencies.

● Manage nausea, vomiting and shortness of breath by offering small, frequent meals and snacks.

● Focus on providing foods that require little handling, preparation, or effort to eat.

● Ensure adequate intake of fluids to stay hydrated throughout the day and evening. If the patient is suffering from vomiting and diarrhea, advise consumption of rehydration drinks.

Food Insecurities

Government agencies have developed flexibilities during this crisis to help individuals who use programs such as the Special Supplemental Nutrition Program for Women, Infants and Children (WIC) and the Supplemental Nutrition Assistance Program (SNAP). The U.S. Department of Agriculture (USDA) has also developed plans for children who participate in the National School Lunch and School Breakfast Programs so that they are able to have continued access to food during prolonged school closures.

Older adults and other individuals who are considered at increased risk for complications from COVID-19 should evaluate the foods they have at home. If you are at high-risk or are unable to get the items you need, consider contacting family or friends to assist. Meal delivery and grocery delivery services may be available as an alternative option.

We are all in this together and remember….Health starts from the inside out!

To discuss more detailed information regarding the topics within this blog, or to inquire about customized nutrition plans, please reach out to Cathleen Winter at

A Little About Me:

My name is Mary DeBlasio, and I live in Silver Spring, MD. I am currently a student studying Nutrition and Dietetics at the University of the District of Columbia. I am set to graduate with a Bachelor’s of Science in May of 2021. I am very interested in mindful eating, and foods that correlate with the seasons. My goal after graduation is to pursue a dietetic internship with a focus on clinical dietetics. I am interested in transplant, renal and gastrointestinal issues. All the information presented within this blog is backed by the credible sources cited below.


Coronavirus (COVID-19). (n.d.). Retrieved from

Ellis, E. (n.d.). How to Keep Your Immune System Healthy. Retrieved from

Handu D, Moloney L, Rozga M, Cheng F, Malnutrition Care during the

COVID-19 Pandemic: Considerations for Registered Dietitian Nutritionists Evidence Analysis Center, Journal of the Academy of Nutrition and Dietetics (2020), doi:

Lefranc, M.-P. (n.d.). IMGT, The International ImMunoGeneTics Information System®, Antibody Engineering, 27–50. doi: 10.1385/1-59259-666-5:27

Stanford Children's Health. (n.d.). Retrieved from

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