The Role of Diet in Inflammation
By Jill Horn
Though acute inflammation is an important component of innate immunity, chronic low-grade immune system activation can be harmful to one’s health. Chronic inflammation has been identified as a pathological feature shared by various chronic diseases, including metabolic syndrome, non-alcoholic fatty liver disease, type 2 diabetes, and cardiovascular disease.
Although the association between chronic conditions and low-grade systemic inflammation has been well-researched, the pathophysiological role of inflammation in the development of these conditions is incompletely understood.
“Chronic inflammation has been identified as a pathological feature of various chronic diseases, including metabolic syndrome, non-alcoholic fatty liver disease, type 2 diabetes, and cardiovascular disease.”
It is well established, however, that diet can play a critical role in modulating the body’s inflammatory state, both in a pro-inflammatory and in an anti-inflammatory direction.
Pro-inflammatory diets can stimulate the immune system through mechanisms that involve the gut microbiome. Foods that stimulate the growth of “bad” bacteria and reduce the abundance of “good” bacteria (so called intestinal dysbiosis) can result in an increased permeability of the intestinal barrier, a condition often referred to in the lay press as “leaky gut”. Gram-negative bacteria that signal through the compromised intestinal epithelium can then stimulate local and systemic inflammation. This signaling is initiated by a molecule contained in the cell wall of gram-negative microbes called lipopolysaccharide (LPS). LPS binds to receptors on immune cells in the gut, an important mechanism through which gut-based immune cells normally recognize pathogens, and stimulate them to produce cytokines, a family of molecules involved in inflammation. While these receptors are normally stimulated only by harmful bacteria, in the case of diet induced immune system activation (metabolic endotoxemia), even “good bacteria” can engage in this process in the presence of a “leaky gut”.
“Foods that are known to affect the body in these pro-inflammatory ways include red meat (particularly processed meat), refined carbohydrates such as white bread or pasta, white rice, and refined sugar-containing foods such as desserts or sweetened beverages, all of which are very prevalent in a traditional Western diet.”
Foods that are generally considered to play a role in increasing the risk for metabolic endotoxemia include red meat (particularly processed meat), refined carbohydrates such as white bread or pasta, white rice, and sugar-containing foods such as deserts or sweetened beverages, all of which are very prevalent in the Standard American Diet. There is converging largely epidemiological evidence that the chronic engagement of the gut based immune system associated with a poor dietary may be an important risk factor in the development of a variety of chronic diseases.
In the same way that certain foods can be pro-inflammatory and cause a state of disease, “anti-inflammatory” foods can affect the gut microbiome in a way that may reduce inflammation in the body.
It has particularly been shown that foods high in polyphenols and fiber (as found in many different fruits, vegetables, and whole grains) can affect the gut microbiome in a way that supports a healthy intestinal barrier and promote optimal microbiome-gastrointestinal tract interactions. If the intestinal epithelium is kept in good health with an abundance of bacteria that enhance mucus production and bacteria that produce health-promoting secondary metabolites from fiber and polyphenols, systemic low-grade inflammation may be counteracted.
“These ‘good’ bacteria thrive on diverse, colorful diet rich in fresh, organic vegetables and fruit, as well as certain whole grains, green tea, and limited amounts of red wine that provide polyphenols and fiber, facilitating a cultivation of a health-promoting gut microbiome.”
The “good” bacteria thrive on a diverse, colorful diet rich in fresh, organic vegetables and fruit, as well as certain whole grains, green tea, and limited amounts of red wine that provide polyphenols and fiber, facilitating a cultivation of a health-promoting gut microbiome.
Furthermore, consuming certain fermented foods such as sauerkraut, kimchi, yoghurt, and kombucha in addition to high-fiber and polyphenol-rich foods is a great way to increase the diversity of the gut microbiome and the relative abundance of health-promoting bacteria. The best studied anti-inflammatory diet is the Mediterranean diet, which has been shown to be associated with a reduced prevalence of several chronic conditions such as depression and other mental health conditions, cognitive decline, cardiovascular disease, and other diseases that are associated with low-grade chronic inflammation.
“Make sure to buy fresh, organic produce, keep cooking temperature rather low, and shorten the length of cooking time or even eat some fruits and veggies raw to make sure a high polyphenol concentration is maintained when ingesting the foods.”
To incorporate more anti-inflammatory foods into your diet, I will share a few tips and tricks for a day-to-day shift to a healthier gut, decreased inflammation, and an experience of enhanced overall health and vitality.
Fiber is found in many fruits, vegetables, legumes, nuts, and seeds and can be increased by replacing processed foods such as refined grains with whole-grain, fresh foods such as quinoa, black or brown rice, or starchy vegetables such as sweet potato and squash.
To provide your gut microbes with more polyphenols, ingest lots of red, orange, and yellow vegetables and fruits such as berries, bell peppers, eggplant, tomatoes, as well as using spices such as turmeric, pepper, cinnamon, garlic, and ginger when preparing food. If you have an insufficient consumption of such polyphenol rich foods, you may consider supplementing your intake with supplements containing the polyphenol flavanol contained in apples and other pommes fruits as well as in cocoa beans. The regular intake of such supplements has recently been shown to be associated with a 27% reduction in cardiovascular mortality.
Make sure to buy fresh, organic produce, keep cooking temperature rather low, and shorten the length of cooking time or even eat some fruits and veggies raw to make sure that both fibers are not broken down by the cooking process and that a high polyphenol concentration is maintained.
Last but not least, make sure you ingest lots of healthy fats high in omega-3-fatty acids and other mono- and poly-unsaturated fats. To increase your intake of omega-3-fatty acids, eat plenty of walnuts, flaxseeds, and fatty fish like salmon, sardines, anchovies, and mackerel. For other health-promoting unsaturated fats, use extra-virgin olive oil for stir-fries or dressings, add avocado to your salads, and consider sprinkling seeds such as pumpkin or sunflower seeds onto your dishes.
Jill Horn is an international student from Switzerland on a pre-med track, currently majoring in Neuroscience at UCLA.