Senior Health The 7 Worst Foods for Your Immune System 3/14/2025 | By Deborah Murphy Like a cape-clad superhero, your immune system constantly monitors villainous threats like viruses or bacteria and jumps into action when you come down with an illness. While no specific food or supplement can guarantee that you’ll never get sick, your overall diet can play an important role in supporting the work your immune system does to ward off unwanted infections. To give your immune system all the support it needs to keep you from getting sick, here are seven foods you should limit. Refined grains Since the majority of your immune cells are found within the lymphoid tissue lining the gut, it is important to limit refined carbohydrates, which generally are higher in sugar and stripped of the fiber that allows a healthy gut to thrive. Alcohol Alcohol also isn’t the best for your gut which plays a vital role in immunity. A 2021 review in Toxicology Reports noted that alcohol could affect the diversity of the healthy bacteria in your gut and contribute to a less functional gut barrier, meaning pathogens can sneak past it. Excess alcohol intake can also inhibit your adaptive immune system’s ability to create the antibodies you need to ward off foreign invaders like the flu virus. Alcohol can also keep you from getting good sleep, which is essential for the immune system to be in tip-top shape. Sugar-sweetened beverages We know that too much added sugar isn’t good for you. Excessive sugar intake, particularly through sugar-sweetened beverages, may negatively affect the body and contribute to a weakened immune system. High blood sugar levels can alter the gut’s permeability, contributing to chronic inflammation. Although inflammation is a normal step in the body’s innate immune response, chronic inflammation can leave your immune system too overworked to ward off new infections. Fried foods Fried foods are higher in advanced glycation end products (AGEs). These compounds naturally occur during cooking, especially at high temperatures like frying. Research, such as a 2020 article in Nutrients, has found that AGEs may be associated with a less optimal gut microbiome, increased inflammation, and a weaker intestinal barrier which can all affect your immune system. Red meat and processed meats Although red meat can have a place in a healthy diet, excessive intake of red meat and processed meats like bologna and hot dogs can be bad news for your immune system. When red meat is digested, gut bacteria create a substance called trimethylamine (TMA) that is then transformed into trimethylamine N-oxide (TMAO) by the liver. Caffeinated beverages Coffee and tea are high in antioxidants that can support a healthy immune system by reducing inflammation, but if caffeinated, they can interfere with quality sleep. Numerous research studies have linked sleep with immune function. Hence, if you enjoy caffeinated beverages, limit them to just a couple of cups daily and try to consume them at least 6 hours before bedtime. Salty foods A 2018 review in Hypertension linked high sodium intake to increased inflammation, changes in the gut microbiome, and changes in the body’s adaptive immunity. Most people generally eat a lot more salt than recommended. Consume foods high in sodium like fast food, salty snacks, processed meats, and canned goods less often to reduce your overall salt intake. EatingWell is a magazine and website devoted to healthy eating as a way of life. Online at www.eatingwell.com. ©2025 Dotdash Meredith. All rights reserved. Used with permission. Distributed by Tribune Content Agency, LLC. Keep on improving your diet and your immune system on Seniors Guide: 5 Superfoods to Support Your Immune System Read More Deborah Murphy