Fat, Fiber, Polyphenols & Immune Health
Diet Tips for Immune Health

DrBonnie360 deep dives into three of dietary components--fibers, fats, and polyphenols--to elucidate their role in immune health and why they are necessary.

The health and wellness community is increasingly interested in food as medicine or therapy. Chronic disease patients, especially autoimmune, are seeking health benefits from their diets. Many healthy people are also adopting personalized diets. For example, autoimmune, gluten-free, low-FODMAP, paleo, Wahls and others. Such diets focus on protein, carbs, fat and fiber to address symptoms and optimize immune health. So, what foods make up the best diet? What exactly are fibers, fats, and polyphenols and why are they important for immune health? What is the difference between anti-inflammatory and antioxidant? We have a lot to unpack here, so let’s get to it.

Anti-inflammatory, antioxidant, proinflammatory

Before we dive into fats, fibers, polyphenols and their impact on immune health, let’s explain some common but confusing terms.

Anti-inflammatories are substances that reduce inflammation. They may block inflammatory pathways or stimulate cells that reduce inflammation. You are probably most familiar with the NSAIDS (Non-Steroidal Anti-Inflammatory Drugs). For example, ibuprofen and aspirin that reduce fever and pain. Many foods and spices have naturally occurring anti-inflammatory components.

Antioxidants are substances that reduce cellular damage by binding to and inactivate reactive oxygen molecules. Consequently, antioxidants can reduce inflammation. Because of this, many antioxidants act as indirect anti-inflammatories. There are plenty of foods and spices that contain antioxidants, and therefore may have anti-inflammatory properties as well (1)

Avoiding pro-inflammatory foods: in addition to anti-inflammatory foods, there are also many pro-inflammatory foods. Unfortunately, these include processed meats, sodas, salty snacks, packaged sweets, and refined carbohydrates. If you suffer from an autoimmune disease, these types of food are likely to intensify any symptoms you’re already experiencing.

Soluble and insoluble fiber

Before we get to fats, what does fiber have to do with immune health? First, recall that there are three categories of macronutrients: proteins, fats and carbohydrates. Dietary fiber (aka roughage) is a category of long-chain carbohydrates. Contrast those with sugars, which are short-chain carbohydrates.

There are two types of food fiber: soluble and insoluble. Soluble fiber is digestible by us, while insoluble is not. Both are extremely important. Soluble fiber gets digested into glucose, the simple sugar that fuels our cells. However, insoluble fiber molecules can be prebiotics. This means that while we cannot digest them, our beneficial microbes can. In turn, feeding our friendly flora supports a healthy microbiome and therefore overall health. Learn more about fiber, pre- and probiotics in an age of antibiotics here.

As the name implies, your diet gives you dietary fiber (or at least, it is supposed to). Processed foods remove most of the fiber to boost taste, refine texture and increase shelf life. Therefore, most people don’t get enough fiber from a diet of processed or fast foods. High-fiber foods include vegetables, fruits, legumes, seeds and nuts. You can also take supplemental fiber, like bran or psyllium husks, or prebiotic supplements to help you get enough fiber. (One of our personal favorite prebiotic supplement is from Hyperbiotics. Read more about their prebiotic powder here)

Fat is where it’s at

Are fats good, bad, or both?

OK, so fiber is good for immune health, but what about fat? Since the official promotion of low-fat diets in the mid-20th Century, many people consider eating fat a bad thing. And it’s true, with twice as many calories per gram as protein or carbs, eating too much fat will produce excess body fat. More recently, the debate has changed from fats in general to which types of fat. Fats are essential macronutrients, we can’t live without them. They are an important source of energy and key components in many cell functions. Importantly, fats are only available to us by eating them.

All fats are lipids, but not all lipids are fats. Lipids are made up of two kinds of smaller molecules: glycerols plus fatty acids. There are three main types of lipids: phospholipids, sterols and triglycerides. While phospholipids and sterols are necessary bodily components, our bodies make them from other molecules. For our purposes we are going to focus on triglycerides, that is, fats.

Fats are essential in another sense. Our bodies cannot create them from other molecules. Triglycerides are composed of one glycerol and three fatty acids. The glycerol molecule remains constant, but the fatty acids change. The specific fatty acids in a given triglyceride is what makes a fat “good” or “bad.”

Saturated vs unsaturated fatty acids

So what’s the difference between “good” fat and “bad” fat? There are several categories of fat, of which saturated and unsaturated are most familiar. The distinction has to do with the number of single or double hydrogen bonds. Well, there are two types of fatty acids that you are probably familiar with: saturated and unsaturated.

Saturated fatty acids

Fatty acids are built out of chains of carbon and hydrogen molecules hence called hydrocarbons. Saturated fatty acids have predominately or all single carbon-carbon bonds. The second bond is occupied by a hydrogen molecule. So, the carbons are fully saturated with hydrogens. Because these saturated chains are straight, these fats can easily stack on top of one another. This causes them to be solid at room temperature and harder to digest. Perhaps they are not the best for your health.

Unsaturated fatty acids

On the other hand, carbons that are not fully saturated with hydrogens are unsaturated. They have at least one carbon-carbon double bond. The double bond is very important because it causes kinks and bends to form in the chain. This prevents multiple fatty acids from stacking, which makes them liquid at room temperature. As a result, they are easier to digest and better for your overall health.

The difference between saturated fatty acids and unsaturated fatty acids. These fats are distinguished by the presence of a double bond.
Source: healthline

What is trans fat?

As you can see in the image above, unsaturated fats have a kink in the center of the carbon chain. These kinks prevents them from stacking on one another. That may be one reason why unsatruated fats lower cholesterol levels and reduce heart and artery disease risk. But notice how the double bond causes the two sides of the chain to dip towards the same direction. In organic chemistry, this is called the “cis” conformation. That means the groups held together by a double bond are on the same side.

However, food chemists may remove these kinks in food processing in order to increase stability. They basically add hydrogens to the fatty acid chain: hydrogenation. This removes the kinks and creates a “trans” rather than cis orientation of the carbon chain. In cis the groups point to the same side of the double bond. In trans the groups point to opposite sides. This allows the fatty acids to stack easier, so they are now solid at room temperature. That makes them easier to store at room temperature. Trans fat, although still considered an unsaturated fat, is not a natural fat and should be avoided. Hard margarine is a common example of a processed trans fat.

Fats Important In Immune Health

Remember, triglycerides have one glycerol molecule and three fatty acids. Triglycerides can include both essential and non-essential fatty acids. The carbon at the very end of the fatty acid chain is called the omega carbon. How far away the double bond is from the (omega) carbon end is how we name them. Our bodies can only make fatty acids with the double bond on the 9th carbon and beyond. Therefore, our bodies can produce Omega-9 fatty acids and so on. But we are unable to synthesize Omega-3 and Omega-6 fatty acids, we have to get them from our diet.

With the obesity epidemic, Omega-3 and Omega-6 fatty acids have gotten a lot of attention. Thus, Omega-3 fatty acids have a good connotation and Omega-6 a bad one. The point is not to eliminate all Omega-6 from the diet, but to aim for a 1:1 ratio of Omega-3 to Omega-6. Obesity has been linked to the increase of this ratio in typical diets to almost 20:1 towards Omega 6. While these are both still healthy fats, be mindful of your consumption ratio(2).

To summarize, as long as we don’t overconsume them, certain fats are essential to our bodies. We cannot produce Omega-3 and Omega-6 fatty acids, so we must eat them. Nevertheless, people should avoid saturated and trans fats should as much as possible.

Omega-3, Omega-6 & Omega-9 fatty acids

Omega fats breakdown

Omega-3 FA – polyunsaturated fatty acids that have immune benefits by acting as anti-inflammatories (3). Think fatty fish, such as salmon and mackerel, as well as many nuts, seeds and oils like walnuts, flax seeds, chia seeds, olive oil and avocado oil. Some vegetables have them as well, such as brussel sprouts and basil.

Omega-6 FA– polyunsaturated fatty acids that help lower cholesterol and support healthy skin. Specifically, think certain meats, seafood and vegetables. Meats: beef, lamb, ham, turkey, veal, chicken, liver. Seafood: shrimp, clams, scallops, tuna, Mackerel. Vegetables: spinach, sweet potatoes, kale, collards, string beans, broccoli.

Omega-9 FA – Oleic acid is the most common form of Omega-9 fatty acids. This is a monounsaturated fatty acid that has important anti-inflammatory functions. Unlike Omega-6 and Omega-3, they are not essential, and can be made in the body. Found in many oils, nuts, dairy and meats.

What Are Polyphenols?

Polyphenols are a subgroup of a large and broad category of plant chemicals called phytochemicals. There are many types of phytochemicals such as phytoesters, terpenes, and polyphenols. We are going to zoom into polyphenols. Among polyphenols are multiple subgroups, but let’s focus on the Flavonoids and Lignans (sometimes referred to as non-flavonoids).

The family that polyphenols come from.

Polyphenols important in immune health

Polyphenols for immune health

In addition to fat and fiber, another class of chemicals is particularly important to immune health. Polyphenols are anti-oxidants found abundantly in fruits and vegetables.


Curcumin – is a yellow-pigmented chemical that acts as a powerful antioxidant and anti-inflammatory. It may even hold anti-tumoral properties as well and is the main active substance in turmeric (4).

Beta-carotene – is an orange-pigmented chemical that our body can convert into vitamin A. This is important because vitamin A is a key nutrient in many body functions in addition to having an important role in immune health (5). Found naturally in many fruits and vegetables, such as cantaloupe, apricots, sweet potatoes, carrots, squash and green leafy vegetables.

Anthocyanins – blue, red or violet flavonoid pigments that interact with other phytochemicals. They have complex reactions that are believed to be important in human health (6). Found in many fruits, particularly berries such as pomegranates, blueberries and cherries. Additionally, it is also found in some vegetables including eggplant, red cabbage and radishes.

Lignans/non-flavonoid polyphenols:

Lignans – a type of polyphenol found in plant-based foods such as legumes, vegetables, fruits, seeds and nuts. These organic chemicals comprise more than 500 micronutrients. They act as phytoestrogens and as strong anti-oxidants, the help mediate immune function and decrease inflammation (7). Furthermore, there has also been some research describing them as having anti-tumoral and anti-diabetic properties (8). While lignans are most abundant in flax seeds, they are also in whole grains, other seeds, legumes, apricots, berries and peaches.

Summary: fat, fiber & immune health

In conclusion, the right fibers, fats, and polyphenols are important for everyone, especially for immune health. They may be of particular importance to those with autoimmune diseases due to their strong anti-inflammatory and antioxidant properties. With this background, we hope to ease your journey through understanding the information about these dietary components. For further information, check out our e-book on food therapy.

What are some of your favorites? Any recipes to share? Please comment below! 

Written by: Bonnie Feldman, DDS, MBA, Becca Malizia, BS, Ellen M. Martin


  1. Palanisamy Arulselvan et al. “Role of Antioxidants and Natural Products in Inflammation.” Oxidative Medicine and Cellular Longevity. Vol. 2016. 2016. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5075620/
  2. Simopoulos, Artemis. “An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity.” Nutrients. Vol. 8(3). 2016. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4808858/
  3. Wall, Rebecca et al. “Fatty acids from fish: the anti-inflammatory potential of long-chain omega-3 fatty acids.” Nutrition Reviews. Vol.68(5). 2010. https://academic.oup.com/nutritionreviews/article-abstract/68/5/280/1829259
  4. Aggarwal, Bharat, Harikumar, Kuzhuvelil. “Potential therapeutic effects of curcumin, the anti-inflammatory agent, against neurodegenerative, cardiovascular, pulmonary, metabolic, autoimmune and neoplastic diseases.” The International Journal of Biochemistry & Cell Biology.” Vol 41(1). 2009. https://www.sciencedirect.com/science/article/pii/S1357272508002550
  5. Burton, GW, Ingold, KU. “Beta-Carotene: an unusual type of lipid antioxidant.” Science. Vol 224(4649). 1984. http://science.sciencemag.org/content/224/4649/569?casa_token=OaC21QwRwSMAAAAA:UBaUhbttnnJFACAZXnDKlgJ7BPt4u87cPH1CegxZudXmOrhmMNkG3aLm9Wl3jdO99uqSSCBcCttQVA
  6. Stintzing, Florian et al. “Color and Antioxidant Properties of Cyanidin-Based Anthocyanin Pigments.” Journal of Agricultural and Food Chemistry.” Vol 50(21). 2002. https://pubs.acs.org/doi/abs/10.1021/jf0204811
  7. Eklund, Patrik et al. “Chemical studies on antioxidant mechanisms and free radical scavenging properties of lignans.” Organic & Biomolecular Chemistry. Vol 2005(18). 2005. https://pubs.rsc.org/en/content/articlelanding/2005/ob/b506739a/unauth#!divAbstract
  8. Takasaki, Midori et al. “Anti-tumor-promoting activity of lignans from the aerial part of Saussurea medusa.” Cancer Letters. Vol 158(1). 2000. https://www.sciencedirect.com/science/article/pii/S0304383500004997


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