Gut Bites MD

Christopher Damman, Associate Professor of Gastroenterology, School of Medicine, University of Washington. Editor-in-Chief of Gut Bites MD.

Public health messaging has gotten it wrong for too long. Here’s a post to set the record straight. A focus on the right fats and carbs is key. Practical dietary suggestions are provided at the end.

A public health miss

If you’re like most people, you’re likely confused as to whether fats or carbohydrates are more to blame for weight gain and inflammation? Take dairy milk as an example. Low fat milk was historically recommended over whole milk to lose weight, but the bulk of the most up to date research shows whole milk is actually associated with less body fat![1,2] 

Public health messaging may be largely to blame for having vilified fat since the 1960’s.[3] People and food manufacturers turned instead to carbohydrates. With high carbohydrate consumption, (in particular simple ones like high fructose corn syrup and refined digestible starches that readily spike blood sugar levels), the metabolic and inflammatory disease epidemic has blossomed.[4,5]  

Clearing the confusion

But truth be told, neither fat nor carbohydrates are categorically unhealthy.  Standard dietary guidelines, in line with healthy diets like the Mediterranean diet, recommend 45–65% of calories from carbohydrates, 25–35% from fat, and 10–30% from protein.[6] Keto diets, which have also been shown to control inflammation and weight, shift recommended percentages dramatically to 70-80% from fat, 5-10% from carbohydrates, and 10-20% from protein.[7] 

If both diets are effective, and fat or carbs are not to blame, then what is responsible? One needs to consider fat and carb subtypes to get to the bottom of the issue.

Subtypes are important

Carbohydrates come in the form of indigestible fibers like resistant starch, complex carbohydrates like digestible starch, and simple carbohydrates like sugars. These carbohydrates are best consumed in the right ratios.[8] The removal of fiber from whole carbohydrates and the consumption of refined carbs is one big root cause of metabolic and inflammatory diseases (See blog on Fiber). `

Fats come in different forms too: trans fats (e.g. margarine, Crisco, hydrogenated oils), saturated fats (e.g. butter, animal fats, coconut oil), and polyunsaturated as well as monounsaturated fats (some fruits, nuts, seeds, and their oils). Trans fats are chemically synthesized fats and have been shown to categorically increase inflammation and be bad for health.[9,10] I would suggest avoiding anything with trans fats like the plague.  

Saturated fats have been associated with inflammation[11], but also have their role in health. We likely get too much saturated fat in our current animal meat heavy diets, but this remains controversial.[12] Monounsaturated (MUFA) and polyunsaturated fats (PUFA) are in fruits (e.g. avocado and olives), nuts (e.g. almonds, cashews, peanuts), seeds (e.g. flax, sessami) and their oils. They both generally contribute to health although the story is a bit more complex with PUFAs in particular.

Ratios of 3’s and 6’s

Omega-3’s and omega-6’s are the two types of PUFAs.  While the difference is subtle (a double bond three atoms vs. 6 atoms away from the end of the molecule), the different effects they have on the body are profound. Generally speaking, omega-3’s decrease inflammation whereas omega-6’s increase inflammation. One or the other shouldn’t be considered bad. They BOTH contribute to health, but what IS important is to balance the two.[13]  

In our current diets the balance is way off! Our dietary ratios are as high as 1:20 whereas our pre-industrial ancestors had dietary ratios closer to 1:1.[14] This essentially means that we have an immune system that is more primed toward increasing rather than decreasing inflammation, and this imbalance may be partially to blame for the rising rates of autoimmune diseases (e.g. rheumatoid arthritis, lupus, thyroiditis, etc.) and inflammatory conditions in general.[15]

Impact on gut & microbiome health

Omega-3’s decrease inflammation in the lining of the gut as they do in the rest of the body. Lower ratios of omega-3’s to omega-6’s mean more inflammatory mediators (e.g. leukotrienes and prostaglandins) that attract more immune cells to the gut (e.g. leukocytes and neutrophils) that contribute to greater inflammation and barrier disruption (aka ‘leakiness’).[16]  

Higher ratios of omega-3’s to omega-6’s mean more anti-inflammatory mediators (e.g. resolvins and protectins) that turn immune cells away from the gut and instead turn on cells that clean up debris and help to restore balance (e.g. macrophages).[17] 

Beyond a direct effect on the lining of the gut, there is more recent data showing that omega-3 fatty acids profoundly impact the gut microbiome. It is a little known fact that, similar to fiber, they serve as a prebiotic to help some bacteria grow better. They can even lead to increases in some short chain fatty acids like butyrate that also play a role in regulating inflammation (see link to blog on butyrate).[18]  

Drugs or Food?

We have developed some powerful therapies that modulate inflammation. Monoclonal antibodies, steroids, and nonsteroidal anti-inflammatories (NSAIDS) are a few examples.[19] The NSAIDS aspirin and ibuprofen are particularly interesting examples as they both decrease prostaglandins which address inflammation close to its dietary source, but all these drugs are not without their side effects.[20]  

Dietary approaches are an attractive natural complement and in some cases potential alternative. Use of omega-3’s and their mediators in studies involving animal models have shown that gut inflammation can be improved through diet.[21] More recent studies using anti-inflammatory diets with whole foods including healthy fats like omega-3’s have also shown improvement in inflammation.[22,23] All this is promising but use of anti-inflammatory diets as a treatment for specific inflammatory conditions still needs a lot of research.

Getting Practical

So where does this leave us with specific general recommendations for our diet?  Focusing on below can go a long way toward improving your healthy fat intake for healthy weight and low inflammation.

Increase omega-3’s:

• A weekly 8-12 ounce serving of oily fish (e.g. salmon, tuna in oil, sardines)
• Cooking with oils high in omega-3’s (e.g. avocado, olive)
• A handful of nuts or nut butters a few times a week (e.g. almonds, pecans, cashews, and dark chocolate)

Moderate saturated fats:  

• Focus on poultry
• Grass fed red meat
• Grass fed dairy products (milk and butter)

Avoid trans fats at all costs:

• Margarine
• Crisco
• Hydrogenated oils

A final note on the grass fed recommendation.  Cows that consume grass (high in omega-3’s) vs. corn (high in omega-6’s) have higher omega-3’s in their meat and milk.  As the old adage goes, you are quite literally what you eat, and so too is our food!

Christopher Damman, Associate Professor of Gastroenterology, School of Medicine, University of Washington. Editor-in-Chief of Gut Bites MD.

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