You Are What You Eat. How Diet Effects Immune Function.

We may not often think about how our immune system functions on a daily basis or its relation to the food that we eat. However, the age old saying “You are what you eat” may have some scientific truth to it. Studies have suggested that eating a healthy, well-balanced diet can improve your immune systems ability to fight off infections and chronic disease. But how and why does the food we eat impact how our immune system responds to illnesses? In this article we’ll break down how food effects our immune response and the kinds of nutrients your body needs to keep you healthy and happy.

The immune system is a complex network of cells, chemicals and processes that function to protect the skin, respiratory passages, intestinal tract, and other areas from foreign antigens. These foreign antigens include bacteria, fungi, parasites, viruses, cancer cells, and toxins. Beyond the structural and chemical barriers which protect us from infection, the immune system can be viewed as having two lines of defense: innate immunity and adaptive immunity. Innate immunity represents the first line of defense to an intruding pathogen. It is an antigen-independent defense mechanism that is used by the host immediately or within hours of encountering an antigen. The innate immune response has no immunologic memory and, therefore, is unable to recognize or memorize the same pathogen if the body is exposed to it again in the future. It consists of physical barriers, such as the skin, mucous membranes, chemical defenses, and cellular defenses.

Adaptive immunity works very differently, it is antigen-dependent and antigen-specific requiring a lag time between exposure to the antigen and maximal response. Unlike innate immunity, adaptive immunity has the capability of memorizing particular pathogens/antigens which allows the host to have a more rapid and efficient immune response after being exposed. It consist of specialized blood cells and proteins that target the specific cause of infection. Innate and adaptive immunity work in a complementary manner in order to keep your body healthy and safe. A defect in either system leaves your body vulnerable to foreign pathogens and antigens that cause illness.

According to a study conducted by Dr. Carina Venter, PhD, RD (University of Colorado-Denver, School of Medicine) and Dr. Tara Sarin MD (University of Colorado-Denver, School of Medicine), as well as several other doctors, a person’s diet influences their immune system like all other aspects of health. The food you consume can affect your microbiome (genetic material of all the microbes that live on and inside your body), gut barrier function, inflammatory processes, and white blood cell function, all of which play a part in your immune system and its functionality. Dietary patterns and the individual food you eat have associations with increased disease risk, greater risk of allergy, and impaired immune response. Western-type diets tend to contain high levels of saturated fat, ultra-processed food, added sugar and salt, and overall calories. This diet has low amounts of vegetables, fruits, and fatty fish, and is strongly linked to increased risk of chronic disease. Their research suggests that western-type diets create inflammation throughout the body and alter the way your immune system functions, promoting disease development. The increased inflammation created by eating this way reduces the mucus layers in your digestive system and can lead to low microbial diversity amongst the healthy bacteria that lives in your gut. This can cause a variety of diseases such as cancer, type 2 diabetes, and heart disease.

On the other hand, diets rich in whole foods such as vegetables, fruits, nuts, legumes, whole grains, and seafood, and low in ultra-processed foods can reduce disease risk and promote healthy immune function. This kind of diet is called a Mediterranean diet. Studies such as Dr. Venter’s have shown that diets high in these kinds of food can reduce the risk of disease, lower inflammation, and beneficially modulate gut bacteria. Diets high in fiber, such as the Mediterranean diet, promote the production of short-chain fatty acids which act locally and systemically to regulate your immune response and improve the immune defensive function of the intestinal epithelium. This part of the immune system is vital since it serves as a barrier against microorganisms. Diets high in fruits, vegetables, olive oil, nuts, seeds, and fatty fish contain high levels of nutrients, such as vitamin A, Vitamin C, Zinc, Vitamin D, B6, B12, Copper, Folate, Iron, and Selenium which the immune system needs to function optimally.

Additionally, a deficiency or insufficiency of nutrients essential to immune function, including vitamin D, Zinc, and vitamin C, can also affect immune response. According to Dr. Venter and Dr. Sarin’s study, nutrient deficiencies may be more common in people who consume highly-processed diets that are low in nutrient-dense foods. Although it is very clear that the choices you make in your diet impact your overall health, including immune function, the interaction between our immune system and the food we consume is highly complex. Scientists are still learning how the foods we consume may help or harm our immune function. In addition to a healthy diet, reducing stress, sleeping properly, and exercising can all help you keep your immune system healthy and you disease free.

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