5 Things that Cause a Weak Immune System

When it comes to proven strategies to boost your immune system, one factor that is often left out of the equation is to avoid those things that hinder your immune response in the first place. In other words, you have to stop the bleeding before healing can begin.

The theory is your immune system will function at full capacity if left alone to do its job. If lifestyle factors, both physical and mental, harm the immune system, it will never be free to do what it was designed to do, and no amount of “boosting” will help because you’ll always be running in a negative equity situation – like taking one step forward, but two steps back.

Closely linked with neurological and hormonal functions, the immune response is altered when we are under heavy stress or are not recovering well with good sleep habits. A sedentary lifestyle can also lead to sluggish body systems, and the immune system is no exception.

The human body processes, distributes, and responds to everything we consume. One classic study, in particular, demonstrated the effect that sugar consumption has, especially on the immune system.

When sugary drinks were consumed, the immune system operated about half as well as it should have, and this deficiency extended for at least five hours after the sugar was consumed. Similarly, an overabundance of omega-6 fatty acids, found in processed carbs and meats, can produce inflammation throughout the body, causing pain and inflammatory disease.

These are five primary things that cause a weak immune system:

  1. Length of life
  2. Poor eating habits
  3. Inadequate exercise
  4. Anxiety
  5. Altered Environment

1. Length of Life Endangers the Immune System

Regrettably, one of the enormous opponents of the immune system is also unalterable: length of life. As the body ages, immune functions dwindle. Lymphocytes are not as widespread, and the innate response is sluggish. But while we can’t stop time, we can actively strive to turn back its influence. The same basic activities that help us to feel youthful also seem to help the body to function as though it is young. Mature men and women who exercise routinely have a more powerful immune system later in life than those who continue to be inactive.

Eating a diet loaded in antioxidants helps to turn around the loss that time, stress, and pollutants have done, which in turn permits the immune system to keep going. Being up to date about what will cause a weak immune system, and strengthening the body with healthy habits, encourages us to slow the march of time and retains immune function into our golden years.

2. Eating Habits Impact Immune System

Two distinctive aspects come into play when thinking about our eating habits and the immune system. The first is how we ingest unhealthy items and then feel defeated (the innate response we just talked about), and the second is the way our eating habits shock immune function. Stomach acid is a tough substance, but it doesn’t wipe out everything that comes its way. The intestines attack antigens that make it through the stomach. Immune cells contribute to some of this effort, and the intestinal flora help as well. The body consists of a notable supply of microbes, and an abundance of them are on our side, helping to stop the ones that aren’t. The remainder of these microbes is determined in a large part by what we eat and drink.

Standard American Diets (SAD) normally result in a very different “view” of intestinal bacteria than what we assume from more conventional diets. This, combined with our knowledge that sugar can diminish the immune system, and vitamins (notably vitamin D) can fortify the immune system, helps to show us how our food usage can cause or crush our immune response.

People have never been more curious about strengthening the immune system than they are right now. This pandemic has us all thinking seriously about our health and what it means to have immune strength, now and in the future.

Dr. Jeffrey Bland is the Founder of the Institute for Functional Medicine and always has a way of looking at our health in ways others never have before. He says the New Mindset in 2021 shifts our focus from supporting the immune system to REJUVENATING the immune system! I love this new paradigm shift! 

How Do We Rejuvenate Our Immune System to do its Work?

The #1 way: Eat phytonutrients! These are the compounds within plants that keep them healthy and protect them from nature, and there are over 25,000 of them! Phytonutrients are able to speak to the plant’s immune system, and they can promote rejuvenation within the plant. Within the human body, phytonutrients work similarly and interact in all sorts of amazing ways with the cells of our bodies.

Aside from eating as many brightly colored fruits and vegetables as possible, adding superfoods is another way to add a high quantity of phytonutrients.   

3. Exercise is Wound Together with Immunity

It has become standard norm now: eat well and exercise regularly. But we cannot become insensitive to these basic needs. We may not quite recognize the connection that exercise has to immunity, but we are aware they are connected. Continuing to be inactive, as reported above, can decrease immune function. On the other end of the spectrum, very demanding exercise can also lead to impairment. We know the way we take care of our bodies influences the way our bodies serve us. Exercise is vital when it comes to immune function and avoiding illness, particularly chronic illness. The key is to make viable, pleasurable changes toward regular moderate exercise. To put exhausting demands on the body is not only challenging but will likely do more harm than good.

4. Stress Destroys the Immune System

While most stressors in our Western way of life are mental or emotional, they have no less effect on the immune system than continued physical stress. As with exercise, not all types of stress and nervousness are equal, and not all have the same effect on the body.

A weak immune system is sensitive to stress. Short term anxiety, even at high levels, is not usually a difficulty for the immune system. However, constant stress drains the immune system enough to cause the body to be susceptible to major illnesses. Releasing anxiety – through enjoyable exercise or a wholesome diet – can therefore be valuable to the immune system. Do you see a pattern yet? Read more about ideas for coping with external stressors and nutrition tips to support normal, healthy stress levels. 

5. Environment Can Alter Immune Strength

We are constantly touching, ingesting, and breathing pollutants that our body never intended to experience. Fortunately, our lungs and respiratory system, lined with mucous able to catch antigens with every breath, are at the forefront of immune function. Environmental pollutants are an assault on the immune system, taking up immune resources and even affecting cell function. We often think of smog and chemical pollution, but excessive alcohol and any cigarette smoke can be just as harmful. We cannot begin to eradicate all of the toxins in our environment, but what we do have authority over can be eliminated, to the benefit of the entire body. 

Eliminating the main immune system destroyers is a critical part of repairing and rebuilding your own personal immune system. Understanding immune function and how it works is the first line of defense against disease and is the key to having a healthy immune system.

Toxins in our everyday environment that destroy immunity:

  • Organophosphates and other pesticides used in homes and schools that accumulate in the body.
  • Chlorine, pesticides, and preservatives added to or sprayed on foods. These chemicals can cause multiple health problems.
  • Overuse of antibiotics, leading to antibiotic resistance. These medications destroy healthy gut bacteria, an important contributor to a healthy immune system. Many are fed to the animals we eat as well.
  • Processed Sugar

Toxins in the body that also disrupt hormone balance are called xenoestrogens. They are particularly worrisome because they are everywhere. 

These are the ways you are absorbing xenoestrogens through your skin.

These are the ways you are inhaling xenoestrogens.

These are the ways you are ingesting xenoestrogens via your food, beverages, and water. 

Two Immune-Supporting Smoothies


This vitamin C and fiber-packed smoothie is a great way to boost antioxidants and support your immune system all year long.

Yield: about 6 cups

½ fresh pineapple, peeled or 2-3 cups frozen pineapple (fiber, vitamins, antioxidants, phytonutrients)

1 small avocado, pitted and peeled (fat)

½ bunch kale or spinach (greens, fiber, vitamins, antioxidants, phytonutrients)

Small handful fresh mint, optional (greens, fiber, vitamins, antioxidants, phytonutrients)

2 to 3 cups coconut water or water | for additional fat, substitute full-fat coconut milk

Your favorite protein powder or collagen powder

Add all ingredients to a high-powered blender, and blend until smooth. Serve immediately.


Blueberries are loaded with vitamin C and contain anthocyanins, which both support immune function. Turmeric contains curcuminoids, which are antioxidants, and shown to have many different health benefits.

Yield: about 2 cups

1 cup almond milk | for more fat, substitute full-fat coconut milk

1 teaspoon vanilla powder or 2 tsp liquid vanilla extract

1 cup fresh/frozen wild blueberries (fiber, vitamins, antioxidants, phytonutrients)

½ banana, frozen (vitamins, antioxidants, phytonutrients)

¼  - ½ teaspoon turmeric, depending on preference (antioxidants, phytonutrients)

1 tablespoon coconut oil, or any fat you prefer (ie: MCT oil, nut butter, coconut butter, ghee)

1 tablespoon chia seeds (protein, fiber)

1 tablespoon hemp seeds (protein, fiber)

Your favorite protein powder or collagen powder

Add all ingredients to a high-powered blender, and blend until smooth. Serve immediately.

Kelly Harrington, MS, RDN

Registered Dietitian Nutritionist for Healthy Goods

Recipes courtesy of The Institute of Functional Medicine

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