Five Foods That Wreak Havoc on Your Immune System

4 min read

woman choosing vegetables over doughnuts

Viruses. Bacteria. Parasites. Fungi.

These are just four things waiting to attack your body. And if your immune system is compromised, they can do real damage to you.

Our immune system is essential to our survival. Keep it strong and — chances are  — you’ll live a long, healthy life. Let it weaken and your future could be riddled with sickness.

To help you keep your immune system strong, here are five things you can cut down on today that will give your immune system an immediate boost:

  1. Salt — According to the CDC, 70% of salt consumption by Americans consume doesn't come from the salt shaker, but from processed foods. And a March 2020 study by the University of Bonn published in the journal Science Translational Medicine found that “human volunteers who consumed an additional six grams of salt per day showed pronounced immune deficiencies.” (Six grams (6,000 milligrams) is the equivalent amount of salt in about two fast-food meals.) Professor Dr. Christian Kurts from the University of Bonn says that “We have now been able to prove for the first time that excessive salt intake also significantly weakens an important arm of the immune system.”

    So how much salt do you need? The American Heart Association recommends no more than 2,300 mg a day, but they suggest that a better target for adults is no more than 1,500 mg per day. According to the CDC, the average American adult consumes about 3,440 mg per day. The World Health Association says that 5,000 mg is the maximum amount of salt you should consume each day.

  2. Sugar — A 2015 study by Case Western Reserve University concluded: “It appears that high blood sugar unleashes destructive molecules that interfere with the body's natural infection-control defenses.” Too much sugar has also been linked to weight gain and the increased risk of heart disease and other dangerous health conditions.

    That said, it’s important to understand the two fundamental sugar distinctions: natural sugar, and refined sugar. Natural sugar is the sugar that comes in fruit. When you eat a piece of fruit you also consume fiber, antioxidants, vitamins, minerals, phytonutrients — all things that improve your health. Natural sugar is the good type of sugar. At least 83 research studies found that a diet high in fruits and vegetables improves immune function.

    The other type of sugar is refined sugar, which is typically extracted from sugar cane and sugar beets. This processed sugar, which is added to many foods and beverages, lacks fiber and all the nutrients that natural sugar contains, which means it provides no health benefits. And because refined sugar has no fiber to slow its absorption, it enters the bloodstream rapidly, which may cause a blood sugar high. In response, the body releases insulin to remove the sugar, which results in you wanting more sugar. Refined sugar is the one that studies have shown suppresses immune function (not to mention contributes to inflammation, disease, weight gain and obesity).

    How much sugar should you have each day? The American Heart Association recommends that men consume no more than 36 grams (nine teaspoons) per day; and women should have no more than 25 grams (6 teaspoons) per day. According to the website, the average American consumes 17 teaspoons per day (about 71 grams).

  3. Fat — Excess body fat weakens your immune system. According to an information posted on the Nestle Nutrition Institute website, APC Microbiome Ireland scientists based at University College Cork have shown that a high fat "western diet" reduces the efficiency of the immune system. The article states that “increased human consumption of a westernized diet has been linked to the dramatic rise in conditions such as obesity and type 2 diabetes, and research has demonstrated the direct effects of dietary fats upon both the immune system and the gut microbiota.”

    The news gets worse. In 2019, Iowa State researchers found that “less muscle and more body fat may affect how flexible our thinking gets when we become older, and changes in the immune system could be responsible.” Yet another reason to make sure you keep your immune system strong!

  4. Processed foods — Not all “processed foods” are bad for you. There are two main classes of processed foods: mechanically processed and chemically processed. Mechanically processed foods have been cut, ground, sliced and so on but retain their natural vitamins and minerals and have no chemicals added. Examples of mechanically processed foods are roasted nuts and pre-cut or chopped fruits or veggies.

    Chemically processed foods have refined ingredients and artificial substances added to them. If you reduce your reliance on ultra-processed foods, you will also cut down on how much sugar, sodium and fat you consume. Study after study links high consumption of ultra-processed foods and increased risk of type 2 diabetes, celiac disease, cancer and multiple sclerosis.

    The following are some ultra-processed foods you should consume with extreme moderation: processed meats, deli meats, frozen dinners, instant foods, microwave popcorn, chips, crackers, candy, pastries, baked goods, bread, pasta, breakfast cereal, granola, granola bars, energy bars, store-bought ice cream, chicken nuggets, fruit snacks and gummies made with refined sugar, sauces, condiments and plant-based alternatives to animal products, like vegan cheese, veggie burgers, or meat substitutes made from processed soy.

  5. Sugary drinks — American poet and philosopher Henry David Thoreau once wrote that “Water is the only drink of a wise man.” Thoreau, who died in 1862, most likely said this as a warning against consuming drinks containing alcohol, as Coca-Cola wasn’t invented until 1886.  But, today, it serves as brilliant advice to avoid the health dangers associated with sugary drinks, especially when you consider that a can of Coca-Cola contains 39 grams of sugar — more than the daily recommended amount for an adult male! And it’s not just traditional soda you should avoid: Fruit juice, hot cocoa, sweetened iced tea, energy drinks, sweetened yogurt drinks and specialty coffees can push you over your daily recommended sugar intake level.

Since 70% to 80% of our immune cells live in our gastrointestinal tract (the organ system that takes in food, digests it to extract and absorb nutrients, and expels the remaining waste), it makes sense that what we eat plays a key role in keeping our immune system healthy. Avoiding many of the foods you love to eat may be easier when you learn that nurturing your immune system will simultaneously help keep your weight under control and make you healthier overall.

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