While no single food can provide the magic cure for escaping illness, a healthy diet with the proper nutrients may help prime your body for fighting viruses and infections. Keep reading to find out which foods to pick up on your next trip to the grocery store and which to avoid to help promote a healthy immune system.
Your Immune System
The immune system is one of the leading functions supporting survival in animals (even fish), as it works to detect and guard against harmful germs and microbes while protecting the body’s cells. Aside from the brain, this system is arguably the most complicated aspect of the human body – many medical experts even spend their whole careers studying and treating immune system disorders. Because this system of organs, cells, and proteins is so intricate, it is important to understand the basics of how immunology works before diving into the different foods to boost your immune system.
Immune System Basics
To understand the immune system, we must first recognize the difference between adaptive and innate immunity. Your innate immune system is your body’s first line of defense, quickly detecting and taking on germs and foreign substances entering the body. According to the National Library of Medicine, the innate immune system consists of both protection offered by the skin and mucous membranes and protection offered by immune system cells and proteins. If you have ever gotten a small wound that healed on its’ own, you have your innate system to thank for detecting and destroying bacteria that has entered the skin on the spot within just a few hours!
When the innate system is not able to destroy these germs on its own, the adaptive system comes into play. As the adaptive system needs more time to identify the specific germ causing an infection, it is slower to respond and more accurate than the innate system. This system also has the unique ability to “remember” and recognize specific germs, which is why there are some sicknesses you can only get once in your lifetime. This is also why other sicknesses, such as the flu, which have multiple strains, can sneak into your system multiple times.
Factors That Affect the Immune System
Many components, such as your age, genetics, hygiene, lifestyle, stress, nutrient intake, and more, can affect your immune system for better or for worse. The impact of these factors may go unnoticed for long periods of time, but if you are feeling sick and run down more often than usual, it may be beneficial to investigate these aspects of your life and see if one or more of them may be affecting you more than previously thought. For example, have you been feeling more stressed than usual? Maybe you are stressed about relationships, job security, or even your physical health. A recent poll by the American Psychiatric Association found that “more than one in four (26%) reported they anticipated experiencing more stress at the start of 2023, up from one in five (20%) last year.” This extra stress can reduce your body’s number of natural killer cells necessary for fighting infectious diseases.
What is the Link Between Nutrition and Immunity?
As discussed, your immune system is complex and influenced by an abundance of different factors, not just nutrient intake. However, maintaining a balanced diet is an important factor that can prime the body to help fight off infection and disease. Sufficient nutrients are required for all your body’s cells to operate correctly, including your immune system. Nutrient intake can help the immune system in several ways, including but not limited to the following:
- Working as an antioxidant to promote healthy cells
- Supporting growth and activity of immune cells
- Producing antibodies
Nutrition that supports immune cells’ activities will help effectively respond to dangerous pathogens and reduce inflammation. On the contrary, undernutrition is presumed to have adverse effects on the immune system, with severity depending on the level of the deficiency as well as other outside factors. It is important to note that excessive intake of a nutrient can also be associated with negative immune responses. Therefore, it’s important to understand which foods to avoid and which to consume to better promote your body’s immune response.
Foods That Can Negatively Impact the Immune System
A diet that is low in nutrients and high in processed foods can impair immune functions over time, with the level of dysfunction depending on the number of nutrients that are missing. This is why it’s critical to understand how your diet may be affecting your immune system functions. Continue reading to learn which foods to avoid that may have a negative impact on your body’s defenses.
Added Sugar and Processed Foods
The FDA defines added sugar as “any sugars that are inserted during the processing of foods (such as sucrose or dextrose), foods packaged as sweeteners (such as table sugar), sugars from syrups and honey, and sugars from concentrated fruit or vegetable juices.” This does not include naturally occurring sugars that are found in fruits, vegetables, or milk. While having a sweet treat occasionally is ok (and sometimes needed), consuming no more than 50 grams of added sugar daily is the best practice. According to the National Library of Medicine, excessive sugar intake may be associated with increased susceptibility to autoimmune diseases and increased inflammation. A few foods high in added sugar to limit your intake include candy, fortified breakfast cereals, sweetened drinks such as soda, coffee, or tea, and desserts such as donuts, cakes, and cookies.
Did you know that many foods we eat daily are high in added sugars, unhealthy fats, and additives? Processed foods are any foods that have undergone procedures that alter the food from their natural state. Studies have shown that eating processed foods may weaken the immune system and increase the risk of chronic inflammatory and metabolic conditions. There are apps that exist to help guide you through your shopping, such as Yuka, which deciphers product labels and analyzes the health impacts of food products and cosmetics on the spot. While many foods in our grocery stores today (yes, even apples) have been processed, here are a few highly processed foods you can try to avoid:
- Packaged snacks such as cookies or chips
- Frozen meals such as pizza or TV dinners
- Reconstituted meat products such as hot dogs
- Sweetened breakfast cereals
- Packaged bread and buns
Alcohol and Caffeine Intake
If you’ve ever experienced a big music, cultural, or film festival, chances are you have also experienced the “festival flu.” If so, you are not alone! Approximately 32 million people attend at least one music festival in the U.S. each year, and many of them will end up sick after a week of crowds, drinking, and little sleep. Over the years, studies have shown that excessive alcohol consumption is linked to many adverse immune health effects, including but not limited to pneumonia, acute respiratory stress syndromes, sepsis, alcoholic liver disease, certain cancers, and slower recovery from infections and physical trauma. Alcohol’s combined effects on innate and adaptive immunity significantly weaken host defenses, making it harder for your body to react quickly against harmful germs. Here are a few examples of how alcohol affects different parts of the body:
- The Lungs: Alcohol intake damages immune cells and fine hairs that have the important job of clearing pathogens out of our airways. Lung damage caused by alcohol often goes unnoticed until a second, more serious insult, such as an infection, leads to lung disease.
- The Gut: Drinking alcohol can trigger inflammation in the gut and kill normally healthy gut microbiota that works to reduce the risk of infections and leading to disrupted gut health or a “leaky gut.”
- The Liver: As the body doesn’t have a way to store alcohol, the liver works to prioritize metabolization over other body functions, such as the immune system. Bacteria leaking from the gut also activates the innate immune system in the liver, triggering inflammation that may eventually lead to liver cirrhosis and liver cancer.
Going Overboard with Salt
While the human body requires small amounts of sodium to use muscles, send nerve impulses, and maintain the right balance of water and minerals, too much salt can negatively affect your body and immune system. A high-salt diet has been shown to decrease the ability of immune cells to cope with bacteria in human subjects who consumed an extra 6 grams of salt over their daily intake. According to the FDA, Americans eat about 3,400 mg of sodium per day, while adults should limit sodium intake to less than 2,300 mg per day or about 1 teaspoon of table salt. If you want to cut down on your salt intake, a few sneaky sodium bombs to try to avoid include deli meats, dried meats, flavor packets and condiments, canned soups, and processed cheese.
Common ingredients in Western dietary patterns consist of fast food, sugary drinks, over-refined sugars, saturated fats, and animal fats while lacking plant-based fibers, minerals, and vitamins. This regime, coupled with the comparatively inactive lifestyle commonly found in Western cultures, can trigger an inflammatory response, suggesting that the immune system either directly or indirectly reacts. For example, your immune system may misunderstand common American ingredients and additives as dangerous bacteria and trigger an immune attack, distracting your immune cells, which are therefore unprepared to attack when facing a real infection. Studies have shown that consuming a Western diet can even cause long-term changes that may contribute to health conditions where inflammation is thought to play a part, such as type 2 diabetes and arteriosclerosis. If you believe you may have fallen victim to the Western diet, it is important to take steps towards integrating the nutrients your body cells need to function properly and maintain healthy systems, which we will consider in the following paragraphs.
Foods That Promote a Healthy Immune System
The immune system’s energy needs for proper cell function can be obtained through a healthy diet, with some micronutrients even playing specific roles in maintaining a healthy immune system and/or reducing inflammation. For example, both Vitamin A and Zinc help regulate cell division and therefore are necessary for an effective immune system response.
Citrus Fruits and Green Veggies
Have you ever been told to drink orange juice when you’re sick? This is because citrus fruits contain Vitamin C, which is thought to help increase the production of white blood cells that are imperative for fighting off infections. While eating citrus fruits won’t cure your cold, it has immune-boosting properties that may help shorten it! Some citrus fruits to try including in your diet include oranges, lemons, limes, and grapefruit. A few more surprising foods you can obtain Vitamin C from include cantaloupe, parsley, kale, broccoli, and strawberries.
While there are many reasons why nutritionists tell you to eat your vegetables, one important reason is that eating a healthy diet consisting of a variety of veggies can boost your immune system. Vegetables such as red bell pepper, broccoli, and brussels sprouts are high in Vitamin C. In contrast, leafy greens such as kale, arugula, and spinach are high in Vitamin A, another important nutrient for immune function. Vitamin A is essential for your health, promoting cell growth, immune function, vision, and more. This vitamin is involved in producing certain cells that play a central role in fighting against disease. A deficiency in this nutrient can lead to increased inflammation, reducing the immune system’s ability to function and fight infectious diseases.
While Vitamin C and A are important nutrients involved in immune system functions, your body needs a wide variety of micronutrients that all play a role in the immune response. A great rule of thumb is to add color to your plate! Different colors of foods represent various nutrients, antioxidants, and phytochemicals that are necessary for protection and recovery from illness. Here are a few more micronutrients to include in your diet to boost your immune health:
- Vitamin E: This powerful antioxidant is involved in fighting off infections found in almonds, peanuts, hazelnuts, and sunflower seeds.
- Vitamin D: Also known as the sunshine vitamin, this nutrient supports the immune system and can be found in salmon, mackerel, tuna, and sardines.
- Zinc: Aiding in producing new immune cells, zinc can be found in animal foods, oysters, crab, baked beans, and yogurt.
- Iron: This supplement helps carry oxygen to cells and can be found in chicken, turkey, oysters, mussels, and red meat.
- Selenium: Playing an important role in infection prevention, selenium can be found in seafood, meat and liver, poultry, and cottage cheese.
Do you carry your emotional support water bottle with you everywhere you go? Turns out this is a great idea! Water accounts for 60% of an adult’s body weight, and hydrating throughout the day is necessary for staying healthy. The National Academy of Medicine suggests that men should drink about 13 cups of water daily, while women should drink about 9 cups, with one cup equaling 8 ounces. This guideline may vary from person to person based on body size and activity levels. Without adequate levels of water, our bodies cannot transport nutrients effectively to each organ, contributing to muscle tension, headaches, and digestive issues. Staying hydrated helps detoxify pathways and clear out foreign invaders.
In this blog, we have discussed the basics of how your immune system functions and how different nutrients can negatively and positively affect your health. How will you try to change your diet to help better your body’s natural defenses?