While some foods can boost your immunity, others can weaken it.
The immune system constantly monitors malicious threats such as viruses or bacteria and responds to illness by springing into action. Keeping your immune system in shape may be your top priority after the COVID-19 pandemic.
Your diet plays an important role in supporting the work your immune system does to protect you from unwanted infections, although no specific food or supplement can guarantee that you won’t get sick.
You can support your immune system by eating a diet rich in fiber, healthy fats and essential nutrients, such as vitamins A, E, C, D, zinc and iron.
However, a diet lacking in these nutrients and high in added sugars and saturated fats could weaken your immune system. To give your immune system all the support it needs to keep you from getting sick, here are seven foods you should limit. [1].
Refined grains
Because most of your immune cells are found in the lymphoid tissue that lines your gut, you should limit refined carbs, which are high in sugar and lack fiber. According to a 2022 study published in Allergydietary fiber supports the immune system in many ways [2].
First, a healthy gut barrier is the primary defense mechanism against bacteria and viruses in your diet. Second, gut bacteria produce short-chain fatty acids (SCFAs) by fermenting the fibers in your food. These SCFAs help regulate the function of your immune cells so that they work effectively when introduced to a viral or bacterial threat.
Alcohol
Alcohol is also not the best for your gut which plays a vital role in immunity. A 2021 review in Toxicological reports noted that alcohol could affect the diversity of healthy bacteria in your gut and contribute to a less functional gut barrier, which means pathogens can sneak past [3].
Excessive alcohol consumption 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 prevent you from sleeping well, which is essential for the immune system to be in top form. If you like the occasional drink, do so in moderation — two standard drinks a day for men and one or less a day for women, according to the CDC. [4].
Sugary drinks
We know that too much added sugar is bad for you. Excess consumption of sugar, mainly through sugary drinks, can have a negative effect on the body and contribute to weakening the immune system.
According to a 2022 review in Human immunologyexcessive consumption of fructose (a type of sugar) changes the makeup of your gut microbiota, making it harder for beneficial strains of bacteria to thrive [5].
High blood sugar can also alter gut permeability, contributing to chronic inflammation. Although inflammation is a normal part of the body’s innate immune response, chronic inflammation can leave your immune system overworked to prevent further infections.
fried food
Fried foods are higher in advanced glycation end products (AGEs). These compounds occur naturally during cooking, especially at high temperatures such as frying.
Research, such as a 2020 article in Nutrientsdiscovered that AGEs may be associated with a less optimal gut microbiota, increased inflammation, and a weaker gut barrier, all of which can affect your immune system [6].
Red meat and charcuterie
While red meat may have its place in a healthy diet, eating too much 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) which is then converted into trimethylamine N-oxide (TMAO) by the liver.
Some TMAOs are nothing to worry about, but higher levels of TMAOs are often associated with an unhealthy community of gut bacteria, as noted in this 2019 review in Nutrients [7].
More TMAO-producing gut bacteria living in the gut are often linked to chronic inflammation, which could lead to an overworked immune system.
Caffeinated drinks
Coffee and tea are high in antioxidants that can support a healthy immune system by reducing inflammation, but if they contain caffeine, they can interfere with quality sleep.
A 2019 article by Physiological examinations notes that numerous research studies have linked sleep to immune function [8]. Therefore, if you like caffeinated beverages, limit them to a few cups a day 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 [9]. However, early clinical studies are small, so more research is needed to help us understand the relationship between salt intake and immunity.
However, most people usually eat a lot more salt than recommended. According to the FDA, Americans consume about 3400 mg of sodium per day. [10].
Still, the 2020-2025 Dietary Guidelines for Americans recommend adults limit their sodium intake to less than 2,300 mg per day or about one teaspoon of table salt. [11]. Eat sodium-rich foods like fast food, salty snacks, processed meats, and canned foods less often to lower your overall salt intake.
Healthy meals filled with nutrient-dense foods will support your immune system. Good immune function is also ensured by drinking plenty of fluids, getting enough sleep and reducing stress.
Consider limiting the foods on this list, but don’t worry too much about the occasional dessert, salty snack, or glass of wine if you’re wondering what foods can weaken it.
[1] https://www.eatingwell.com/article/8050179/worst-foods-for-immune-system/[2] https://onlinelibrary.wiley.com/doi/10.1111/all.15430
[3] https://www.sciencedirect.com/science/article/pii/S2214750021000469
[4] https://www.cdc.gov/alcohol/fact-sheets/moderate-drinking.htm
[5] https://www.binasss.sa.cr/jun22/39.pdf
[6] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7146186/
[7] https://www.mdpi.com/2072-6643/13/2/699
[8] https://journals.physiology.org/doi/full/10.1152/physrev.00010.2018
[9] https://www.ahajournals.org/doi/full/10.1161/HYPERTENSIONAHA.118.11128
[10] https://www.fda.gov/food/nutrition-education-resources-materials/sodium-your-diet
[11] https://www.dietaryguidelines.gov/sites/default/files/2020-12/Dietary_Guidelines_for_Americans_2020-2025.pdf