The May-June 2019 issue of Harvard Magazine has an excellent review of the latest research on inflammation, showing how pro-inflammatory foods can cause diseases and anti-inflammatory foods can help to prevent them (Harvard Magazine, May-June 2019, 40-52). Chronic inflammation increases risk for heart disease, diabetes, Alzheimer's disease, certain cancers, and many other diseases. The more anti-inflammatory foods you eat, the greater your protection from chronic inflammation and the diseases it causes.
What is Inflammation?
When germs invade your body, your immune system sends out cells and proteins to kill the invading germs. Your immune system responds with exactly the same cells and proteins in the same way when cells in your body are injured, to remove damaged tissue and start the healing process. As soon as the germs are conquered, or tissues heal, your immune system stops sending out huge amounts of these cells and proteins. However, if your immune system stays overactive, you develop inflammation in which these same cells and proteins attack and damage your own cells. Chronic inflammation damages healthy tissues in the body to cause many diseases and chronic health problems.
How Foods Affect Inflammation
Your immune system is turned on by the surface proteins on the cells of germs that try to invade your body, by anything that damages cells in your body, and by substances in foods that look the same as the surface proteins of germs. The pro-inflammatory foods turn on your immune system to cause these cells and proteins to attack and damage your own normal cells, while the anti-inflammatory foods dampen down this response to protect your cells from damage from an overactive immune system.
The pro-inflammatory foods include sugar-added foods, sugared drinks, unfermented dairy products, mammal meat, processed meats, and fried foods.
• When sugar-added foods and other refined carbohydrates cause a high rise in blood sugar, the excess sugar sticks to the outer membranes of cells and destroys them. Your immune system is turned on by this cell damage (inflammation).
• All drinks with sugar in them, including fruit juices, cause high rises in blood sugar to cause cell damage. However, whole fruits are anti-inflammatory despite their sugar content.
• Milk, butter and other non-fermented dairy products contain the pro-inflammatory sugar called galactose.
• Mammal meat contains a surface sugar-protein called Neu5Gc that acts just like a germ invading your body to turn on your immune system.
• Processed meats usually also contain Neu5Gc, and may have added nitrates that combine with proteins to form nitrosamines that damage cells in your body and increase cancer risk.
• In fried foods and other foods that are cooked at high temperatures without water, sugars bind to fats, proteins and DNA to form chemicals called advanced glycation endproducts (AGEs). AGEs have been shown to turn on your immune system to cause inflammation.
Why Do Plants Have Polyphenols?
A study from the University of Liverpool showed that fruits and vegetables are anti-inflammatory because they contain polyphenols that help to protect you from chronic inflammation (Br J Nutr, May 28, 2016;115(10):1699–1710). The authors showed that inflammation was reduced by substances such as isorhamnetin, resveratrol, curcumin, and vanillic acid found in onions, turmeric, red grapes, green tea and açai berries. Polyphenols such as these are found in virtually all fruits and vegetables.
Since fruits and vegetables cannot run away from their enemies — insects, bacteria, viruses, fungi, animals and humans — they protect themselves by producing large amounts of poisons called oxidants that can harm the invaders. To protect themselves from their own oxidants, plants produce antioxidants called polyphenols. When you eat fruits and vegetables, you get the benefits of these polyphenols, which include helping to protect you from your own immune system and keep it from remaining too active (called inflammation). This particular study showed that the polyphenols tested helped to reduce the release of pro-inflammatory chemicals in people who were at risk of chronic inflammation.
Anti-inflammatory foods include:
• whole (unground) grains
• coffee and tea
• oily fish such as salmon, mackerel, tuna, sardines
Pro-inflammatory foods include:
• sweetened beverages and sugar-added foods
• foods made with flour and other refined carbohydrates
• meat from mammals
• processed meats
• milk, butter, margarine, shortening, lard
• fried foods
A healthful anti-inflammatory diet is high in vegetables, unground whole grains, beans, fruits and nuts; and low in the pro-inflammatory foods (sugar-added foods, sugared drinks, most animal products, and fried foods). Try to follow this pattern most of the time and adapt it to your special needs and preferences.