In order for our immune system’s to perform their best, we must give them the support they need. Food can have a dramatic impact on our immune health, and several foods have reproducibly been shown to decrease our immune systems’ ability to fight off infections.

Research has long shown that nutrition plays an important role in our immune health. Our post last month highlighted many foods that have been shown to improve our immune function, helping us to ward off infections. Conversely, certain foods have consistently been shown to weaken a person’s immune response, making them more susceptible to infection and slowing down the healing process.

Foods that Weaken the Immune System

“Everything in moderation” is a common refrain you often hear when someone wants to justify eating something that they know is not healthy, but they want to eat it anyway. And many times, eating something on occasion – let’s say at a birthday party or other yearly celebration – that isn’t healthy but provides a great sense of pleasure or satisfaction – like a piece of cheesecake or bowl of ice cream – probably doesn’t do any long-term harm. However, there are certain foods (or food ingredients), that have consistently been shown to depress immune function. This effect may last for a few hours to a few days after consumption, no matter how often you eat them. Naturally, the more often you eat them, the greater the effect on the immune system, which can significantly decrease your body’s ability to fight off infection over time.

Here are the foods to avoid in order to optimize immune health:

Foods High in Sugar

Research has consistently shown that foods high in sugar – whether that is sucrose, glucose, high fructose corn syrup, organic cane sugar or beet sugar or any other source – consistently and reproducibly depresses immune function, and this effect can last from hours to days after consumption. Eat foods that are high in sugar (or simple carbohydrates) too often, and you will significantly increase your risk of infection.

Foods high in sugar or simple carbohydrates include:

  • Soda, fruit juices and energy drinks
  • Candy, chocolate and sweets
  • Cakes and cookies
  • Baked goods, including muffins, breads and pastries
  • Sugary breakfast cereals and bars
  • Sweetened and flavored dairy products, including ice cream, sweetened yogurt and chocolate milk

Alcoholic Beverages

Many alcoholic beverages present a particularly nasty combination of immune-suppressing ingredients because they are often loaded with sugar, increase consumption of unhealthy foods and displace healthier foods and drinks from the diet. Not only that, alcohol contains more calories (7 kcal/gram) than either carbohydrates or protein (4 kcal/gram), and almost no beneficial vitamins and minerals to help properly use those calories. This robs the body of these vital nutrients, putting further strain on proper immune function.

Be honest – when was the last time you reached for a salad or steamed vegetables after having a few drinks? It’s much more likely that you reach for some rich and savory foods – commonly referred to as comfort foods – and that you eat more than you would normally, as alcohol stimulates the appetite and depresses your ability to recognize when you’ve eaten enough. This is all to say: go go easy on the alcohol to improve your immunity.

Processed Foods

Processed foods often contain unhealthy fats, sugars and additives designed to improve taste, texture (mouth feel) and shelf life; unfortunately, this combination of anti-nutrients has the undesirable effect of weakening the immune system.

Processed foods include almost anything in a bag, box or package that can sit on the shelf for an extended period of time without spoiling.

Typical offends include:

  • Fast food – anything that can be served to you through a window or a drive through
  • Microwave meals
  • Cookies, cakes, crackers and breads
  • Soda and sweetened beverages
  • Chips, crisps and salty/sweet snacks
  • Processed meats, including bacon, hot dogs, salami, deli meats, sausage and ham

What you eat matters; in the case of immune function, it matters a LOT. By making better food choices, you can give your immune system the support it needs to keep you healthy and fight off any invaders that you may encounter as you enjoy your life.