Can Processed Foods Adversely Affect the Immune System?

Processed food continues to be of topical news coverage as we deal with an epidemic of heart disease, type II diabetes and obesity related to dietary choices. As if you needed another reason to avoid processed food, a new study suggests that common additives can also harm the human immune system. In the world driven by COVID-19 concerns, anything we’re doing to inhibit or cause a malfunction of our immune system is worth reconsidering.


As referenced by the FDA, immunotoxicity refers to:

Any adverse effect on the structure or function of the immune system, or on other systems as a result of immune system dysfunction. An effect is considered adverse or immunotoxic if it impairs humoral or cellular immunity needed by the host to defend itself against infectious or neoplastic disease (immunosuppression) or it causes unnecessary tissue damage (autoimmunity, hypersensitivity, or chronic inflammation)


So, if the immune system is either hyper-stimulated (ie, a cytokine storm) or diminished in its function, the driver of this immune system malfunction is considered immunotoxic. It’s not news that processed foods contain preservatives, but most of us don’t know which preservatives are “acceptable” or which can be more dangerous. The FDA has typically tested and approved preservatives to be used in food, but they do so largely under conditions that suppose the consumption is under a threshold, so it’s not going to affect the human body. But what if the consumption exceeds that threshold? What if we’re eating significantly more processed foods with preservatives that can be dangerous at high levels?


Tertiary butylhydroquinone, or TBHQ, is a common preservative used to dramatically extend the shelf life of processed foods, preventing them from going rancid. In part, it acts to prevent foods with iron from discoloration. It is often used with other additives like propyl gallate, butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT). BHA and TBHQ are usually discussed together, as the chemicals are closely related. In fact, TBHQ forms when the body metabolizes BHA.

TBHQ is approved by the FDA to use in foods in small amounts, however, what happens when the amount consumed exceeds the FDA limit? We don’t know. But, studies done on laboratory animals have linked TBHQ to tumor development, liver enlargement, neurotoxic effects, convulsions and paralysis. There is also medical concern it can contribute to the development of ADHD in children. So, how widespread is it used?

The attached .pdf contains over 30 pages(!) of common foods that use TBHQ.

Think the foods are from obscure manufacturers? Well-known branded products from Kellogg’s, Pillsbury, Reeses, Nestle, and dozens of others are using TBHQ as a preservative. So, think about families that are eating Pop Tarts, frozen pizzas or any other variation of processed foods on a daily basis. Is it possible, if not probable, their consumption of TBHQ is much higher than the FDA would consider “safe?” Is it possible a heightened level of consumption could impair an immune system to reduce its ability to fight off, say, a viral pathogen? Obviously, more research is needed, but you can act now by making better choices.

Better Choice Example

We’ve covered the concerns around processed foods at, and strongly urge you to eliminate processed foods from your diet. At a minimum, if you are going to eat a processed food, know what’s in the food by reading the nutritional panel and reviewing the quality and quantity of ingredients. If the first few ingredients are questionable, understand those ingredients are most prevalent in the food, so select something else.

I’d like to share a recent example to help underscore the importance of knowing what’s inside and making better choices. I’m helping a relative change her dietary behaviors, and she loves egg salad, but is concerned that it is not healthy. In looking through the ingredients she can use to make it from scratch, such as eggs, various seasoning, celery and the like, the biggest question is mayonnaise. Full disclosure, you can make egg salad without using mayonnaise, but in the spirit of this example, let’s assume mayonnaise is the preferred option. Below is a comparison of two variations of mayonnaise. Which one would you choose?

The Primal Kitchen variant starts with avocado oil, has no vegetable oils, uses organic eggs, has zero preservatives like TBHQ, and has no catch-all words like “natural preservatives.” It has a clean and simple ingredient panel, and does not include ingredients that will spike insulin or cause inflammation. It has one downside: the price. It is about 2X as expensive (both are sold at Target).

On the other hand, the Hellmann’s, even though it’s made with olive oil, has several issues. Soybean oil is the #2 ingredient, a poor, inflammatory oil choice. It also includes potato starch, sugar, and at least one preservative. This option will be inflammatory and insulin spiking, and one from which to steer clear. However, it will be thought of as “healthy” because it says it’s made with olive oil. Don’t be lured by clever marketing. Learn about the importance of ingredients, read the nutrition panel AND the ingredient list, and make better choices.