Are fat-rich diets making you sick?

We all learnt that carbohydrates are pro-inflammatory and that it is better to eat coconut oil than white bread to less arthritis or any inflammatory condition, however…..

Lately, new research has been exploring the mechanisms that could explain an increase of bacteria toxins in the blood and a systemic (in the plasma) inflammation in people who are obese, have diabetes 2 or eat too much fat.

Several studies from different laboratories and universities tested the reaction of the body to high-fat diets. They fed people high doses of fats (simple food types or simple mixes of food) to then follow their blood reaction after such meals. They all found an increase in bacterial toxins (called lipopolysaccharides, in short LPS) but not all of them recorded an increase in systemic inflammation (in the blood, i.e. generic inflammation, affecting everywhere in the body) after the artificial meal (Pendyala et al 2012).

The response of the tested meals were different according to the type of fats, and they were somehow conflicting among the studies: saturated fats of animal (milk cream) or vegetable source (coconut or palm oil) caused a higher increase on some trials or a lower increase in the concentration of LPS, compared to vegetable unsaturated fats (rapeseed oils) and fish oil (Lopez-Moreno 2009, Deopurkar et al. 2010, Pendyala et al.,2012, Candido et al. 2017).

The tested LPS come from bacteria that normally live in the gut and sometimes in the plasma of even healthy individuals. Their increase in the plasma is however a worry and the body reacts by considering it as an infection (or sepsis).

How to explain an increase of LPS in the blood when their normal site is the lumen of the intestine? These LPS could be more abundant in the blood than normal if the intestinal permeability is increased, as in patients with some sort of inflammatory bowel disease or with an altered composition of gut bacteria (dysbiosis) that weakens the wall of the gut. Both an elevated gut permeability and dysbiosis are commonly observed in obese people. However, in addition to these reasons, these studies explained an increase of LPS in the blood as result of a facilitated crossing of the intestinal wall by the toxins thanks to the presence of ingested fats. The more fats, the more toxins would go through and into the blood.

The effects of such absorbed LPS once they are in the blood depend on different types of transporters. One route would increase the inflammation response of the body, which goes on alert for the presence of ‘infection’ (toxins from bacteria), but an alternative route would eliminate the toxins through the liver (if there is a good quantity of HDL cholesterol, chylomicrons and other transport systems).

Overall, these studies would prove that high fat diets, which are so on the high in these days, can lead to infection and inflammation of the blood in the long run. This is in fact what is observed in obese and diabetic people, and which can easily lead to increase of atherosclerosis and cardiovascular disease.

However, it is dangerous to draw conclusions for a general habitual (*balanced!*) diet. The meals tested in these trials were often unbalanced, with excessive fats and usually no carbohydrates (including no fibers) and no proteins. Trials with more balanced diets should be performed in order to reach decisions on a recommended diet suitable for patients at risk of metabolic syndrome or also for healthy people who want to avoid cardiovascular diseases.

Nevertheless, exceeding in fats and eliminating or minimizing other macronutrients, is probably not a wise behaviour and can lead to inflammation, the source of most diseases.

And it is not only what you eat but also how the industry prepares it for us or how you cook it that makes a difference between health and disease. But this is the subject of my next blog….so be patient!


Cândido FG, Valente FX, Grześkowiak ŁM, Moreira APB, Rocha DMUP, Alfenas RCG. 2017 Impact of dietary fat on gut microbiota and low-grade systemic inflammation: mechanisms and clinical implications on obesity. Int J Food Sci Nutr. 2017 Jul 4:1-19.

López-Moreno J et al. 2009 Effect of Dietary Lipids on Endotoxemia Influences Postprandial Inflammatory Response. Curr Pharm Des. 2009;15(13):1546-58.

Pendyala S. , Walker, J.M., and Holt P. 2017 A High-Fat Diet Is Associated With Endotoxemia That Originates From the Gut J Agric Food Chem. Sep 6;65(35):7756-7763.

Rupali Deopurkar, PHD, Husam Ghanim, PHD, Jay Friedman, PHD, Sanaa Abuaysheh, BSC, Chang Ling Sia, BSC, Priya Mohanty, MD, Prabhakar Viswanathan, PHD, Ajay Chaudhuri, MD, and Paresh Dandona, MD, Differential Effects of Cream, Glucose, and Orange Juice on Inflammation, Endotoxin, and the Expression of Toll-Like Receptor-4 and Suppressor of Cytokine Signaling-3, Diabetes Care. 2010 May; 33(5): 991–997.

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