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The Worst Foods And Beverages for Your Immune System

The food you put into your body has a profound effect on all aspects of your health – including your immune system. In fact, 80% of your body’s immune system is located in your gut. The Gut Associated Lymphoid Tissue (GALT) is a mass of lymphoid tissue that consists of immune cells responsible for regulating immunity and keeping your body strong. What you eat affects your gut microbiome and, ultimately, your overall immune system.

Doctors have recently become concerned with what is called “leaky gut syndrome.” This is where your gut lining has large cracks or holes in it. Partially digested food, bugs, and other toxins can penetrate your gut lining, causing inflammation and adverse changes in the gut flora. While sometimes leaky gut is a result of genetics, modern life and the food it entails are often key contributors. Excessive amounts of processed foods, high sugar foods, dysbiosis (imbalance between good and bad bacteria) and alcohol all contribute to leaky gut syndrome. 

If you are trying to adopt a healthier lifestyle, there are several foods and beverages you should cut back on – if not nix from your diet altogether. Below, we will go over some of the worst foods for your immune system and what you should stock your pantry with instead.

Artificially Ripened Fruits And Vegetables

A diet rich in fruits and vegetables is great for your overall health, which of course includes your immune system. You’d be hard-pressed to find a doctor or dietician who wouldn’t recommend packing in multiple servings of fruits and veggies each day for a longer, healthier life. However, when fruits and vegetables are treated with ripening agents to be harvested prematurely, they can actually do more harm than good for your immune system.

Fruits and veggies play an important role in keeping your gastrointestinal tract, which is home to more immune cells than any other area in the body. When produce is picked before it has a chance to ripen naturally, it is high in a substance called lectin, which naturally depletes as a plant ages.

immune system

Lectin can interfere with the microbial balance in your gut, leading to a weakened immune system. Plus, plants grown out of season are also frequently treated heavily with pesticides, which can also adversely affect your health.

Eat plenty of fruits and veggies, but make sure they were grown naturally. Stick to organically grown produce whenever possible. Shop in the organic section of your local supermarket or do some shopping at a local farmers market.

We hate to mention the nightshade family like tomatoes and eggplants for example, as they are some of our favourite foods to consume, but they do contain these lectins so be aware if they affect you in any way.

Foods High In Added Sugar

Sugar affects your immune system in both the short and long term. Evidence indicates consuming sugar decreases your cell’s ability to attack foreign bacteria directly after eating it, an effect that lasts for several hours. If you keep overindulging in the long run, not only is your immune system perpetually inhibited, you end up damaging your gut bacteria.

While an occasional candy bar or treat won’t adversely affect your health too much, make sure to indulge in moderation. Avoiding sugar is not just a matter of staying away from the obvious culprits like candy bars and cookies. Check labels frequently. Things like canned pasta sauce and supposedly healthy snacks like granola bars are often loaded in added sugar.

Sugar also feeds harmful bacteria which will imbalance your gut microbiome and further challenge your immune system.

If you have ever noticed fatigue, swallon glands or a scratchy throat from eating too many lollies or sweets then this is your immune system being overburdened and lowering its activity.

Heavily Processed Foods

Processed foods like frozen meals, potato chips, and deli meats tend to be high in sodium, artificial ingredients, and refined grains. All of these ingredients alter your metabolic response. If your diet includes a heavy amount of processed foods, this could weaken your immune system and leave you vulnerable to diseases.

In general, stay away from processed foods that are high in sodium and come with lengthy lists of artificial additives. Not all processed foods are bad for you. If you rely on the occasional quick meal for convenience, go for things like canned beans and fish, frozen fruits and veggies, whole grain cereals, and nut butters.  

However, keep in mind our earlier advice. Always check the label of premade foods for added sugar, as seemingly healthy processed food options may sneak in hefty amounts of sugar.

Refined Grains

From white bread to white pasta, refined grains can be filling but are ultimately not great for your body. A diet high in refined grains can cause myriad health issues from weight gain to insulin resistance.

Refined grains are also a major contributor to inflammation, which can wear down your immune system over time. Plus, white bread often contains additives that can harm your immune system.

Whole grain foods are always preferable to refined varieties. Go for brown rice over white rice with dinner and a whole wheat English muffin for breakfast to better nourish your immune system.

As always, read labels at the grocery store, as products labeled “whole wheat” are often less healthy than they appear. If “whole wheat flour” is not near the top of an ingredient list, find another product.  


The occasional glass of wine with dinner is probably okay, but excessive binge drinking overtime can damage your gut and immune system. Alcohol also has myriad other negative effects on your body, especially the liver, so binge drinking in general should be avoided.

In large quantities, alcohol can overwhelm your intestinal tract. This disrupts your delicate gut ecology and damages the trillions of microorganisms that regulate immunity.

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This can make you more susceptible to bacteria and viruses. Excessive drinking irritates your gut lining causing leaky gut syndrome, inflammation and malabsorption, depleting energy and leaving you feeling unwell overall. It can also make you more vulnerable to the average cold or flu. Those who regularly drink to excess are at a higher risk for developing more serious illnesses like fatty liver and even cancer.

If you are going to drink, stick to one to two drinks at a time and for special occasions only.

Foods For Your Immune System: The Bottom Line

A lot of modern food is hard on your immune system, which is why it is important to be proactive about your shopping and eating habits. A diet rich in fruits, vegetables, protein, plant-based protein, and some whole grains and legumes is key to a healthy immune system, but even seemingly nutritious products can be hiding harmful ingredients. 

Always read labels and stick to all-natural food. Your immune system and gut lining will thank you for it. 

If you're trying to improve your immune system, we can help. At Smart Cleanse, we have a 14 Day Detox Kit made from all-natural ingredients that boosts immunity, promotes weight loss, and improves overall health.