Can an “anti-inflammatory diet” really improve immunity?

This is the 4274th article of Da Yi Xiao Hu

Recently, "anti-inflammatory diet" and "pro-inflammatory diet" have become popular terms. Many people ask in confusion, an anti-inflammatory diet can prevent infection by pathogens such as bacteria and viruses and prevent inflammation, while a pro-inflammatory diet will aggravate inflammation. Is this true?

In fact, inflammation is divided into two types: chronic and acute. The "inflammation" in pro-inflammatory and anti-inflammatory diets refers to chronic inflammation, which is generally not perceived by people. The symptoms such as colds, fevers, coughs, etc. that we usually talk about mostly refer to acute inflammation, which can often be perceived by the body. The two are not the same thing.

Inflammation is a defensive response of the body's own immune system to external stimuli. A moderate inflammatory response is a normal physiological response of the body to resist the invasion of external pathogens and clear its own necrotic tissues, so it is beneficial to the human body. However, if the inflammatory response persists, it will develop into chronic low-grade inflammation, which is a non-specific, sustainable low-grade inflammatory state presented by the body under long-term, low-dose stimulation of specific immunogens. It is different from acute inflammation such as pneumonia and gingivitis. Acute inflammation is mostly caused by external bacteria, viruses and other pathogens. They come and go quickly. When the pathogens are eliminated, the inflammation will soon subside. Chronic inflammation is a chronic and persistent damage and the basis of many chronic diseases. It is characterized by the increase of pro-inflammatory markers such as interleukin-6 and tumor necrosis factor-α, which affects the state of surrounding tissues and may cause severe tissue damage, and ultimately lead to damage to one or more organs (such as adipose tissue, liver, pancreas, muscle and brain, etc.). If the human body is in a state of chronic inflammation for a long time, it will increase the risk of obesity, diabetes, gout, cardiovascular and cerebrovascular diseases and even cancer. Since chronic low-grade inflammation is not noticeable and is not easily detected through routine physical examinations, chronic inflammation is an invisible "killer" of health and needs to be regulated, improved or eliminated through various methods to avoid threatening human physical and mental health.

Modern research shows that among the regulatory factors involved in chronic inflammation, diet is one of the key adjustable factors in the occurrence and development of such diseases. In 2009, the University of South Carolina developed a tool to calculate the inflammatory properties of food, called the Dietary Anti-Inflammatory Index. It arranges common foods in a continuous form from the most anti-inflammatory to the most pro-inflammatory, forming a common food dietary anti-inflammatory recipe library to guide patients with chronic inflammation to eat rationally, thereby achieving anti-inflammatory effects. After the dietary anti-inflammatory index was proposed, it has been widely used and verified worldwide. In 2020, a study involving 210,000 participants and a follow-up period of 32 years showed that the inflammatory state in the body is related to cardiovascular health, and pro-inflammatory or anti-inflammatory foods can aggravate or improve the inflammatory state in the body. Another 2021 review of 15 meta-analyses of 4 million people found that a pro-inflammatory diet can increase the risk of 27 chronic diseases and the risk of premature death. It can be seen that pro-inflammatory or anti-inflammatory foods are indeed closely related to chronic low-grade inflammation in the human body.

The common food dietary anti-inflammatory recipe library includes 45 kinds of food and nutrients, including trace and macro nutrients, spices, teas and flavonoids, including vitamin A, vitamin B1, vitamin B12, vitamin B6, vitamin C, vitamin D, vitamin E, carbohydrates, cholesterol, ω3 fatty acids, ω6 fatty acids, beta-carotene, caffeine, alcohol, total fat, energy, protein, eugenol, garlic, ginger, selenium, iron, magnesium, zinc, onion, saffron, dietary fiber, trans fat, saturated fat, monounsaturated fatty acids, polyunsaturated fatty acids, flavanols, flavan-3-ols, saffron, turmeric, flavonoids, flavonoids, isoflavones, niacin, anthocyanins, riboflavin, pepper, thyme, rosemary, green tea/black tea.

Common anti-inflammatory foods

Whole grains

Whole grains refer to grains that have not been refined or have been processed by milling, crushing, flaking, etc., but still retain the bran, germ, endosperm and natural nutrients of intact grains. The latest 2022 version of the Chinese Residents' Dietary Guidelines recommends eating 50-150g of whole grains every day. Whole grains are rich in dietary fiber and have a higher nutritional density. They can prevent cardiovascular disease, diabetes and many other diseases. The top ten "Chinese Good Grains" are recommended: whole wheat flour, brown rice, oatmeal rice/flakes, millet, corn, sorghum rice, highland barley, buckwheat, coix seed, and quinoa.

Fruits and vegetables

Fruits and vegetables are rich in dietary fiber, vitamin C, beta-carotene, anthocyanin, lycopene, polyphenols, etc. Most of them are good helpers for anti-oxidation and also help reduce inflammation in the body. However, there are many varieties of fruits and vegetables, and their nutritional values ​​vary greatly. Only by choosing a variety of colorful fruits and vegetables and matching them reasonably can we ensure health.

Fish

Fish is rich in high-quality protein, polyunsaturated fatty acids, selenium, zinc, iodine, etc. The liver is rich in vitamins A and D. Marine fish is relatively more nutritious than freshwater fish. Hairtail, conger eel, mackerel, salmon, yellow croaker, etc. are rich in anti-inflammatory ω3 fatty acids.

Tea

Tea contains tea polyphenols and other ingredients that are beneficial to health. It has antioxidant and anti-inflammatory effects. After being soaked in plain water, it can be dissolved into the tea. Drinking light tea in moderation regularly can not only replenish water, but also is beneficial for anti-inflammatory.

Some condiments

Foods such as ginger, garlic, chili, curry, cinnamon, rosemary and thyme contain natural anti-inflammatory substances such as allicin and curcumin. It is recommended to use less oil, salt and sugar. At the same time, you can choose these seasonings when cooking.

Common pro-inflammatory foods

Foods high in sugar and refined carbohydrates

White rice, white steamed buns, white bread, fried dough sticks, rice cakes, macaroni, cakes, biscuits, desserts and other refined carbohydrate foods contain a lot of starch.

High-fat and fried foods

Foods cooked with lard and butter, as well as deep-fried foods are high in calories and fat. Long-term and excessive intake can promote inflammation, leading to an increased risk of hyperlipidemia, obesity, cardiovascular and cerebrovascular diseases, diabetes, gout, and some "rich" cancers.

Red meat, processed meat and other processed snacks

It mainly refers to processed meat such as pork, beef, mutton, ham, bacon, sausage, and smoked meat. There are also various processed snacks containing trans fatty acids and various additives, and high levels of oil, salt, and sugar.

However, it is important to remind you that diseases are caused by a variety of factors. Relying solely on food is not enough to resist various diseases. Everything needs to be done in moderation. Therefore, you should not be picky about your food or overeat. For example, ginger and garlic, which are anti-inflammatory foods, have certain irritation to the gastrointestinal tract. If they are consumed in large quantities, they can damage the gastrointestinal mucosa for patients with underlying gastrointestinal diseases. On the contrary, it is not a big problem to eat pro-inflammatory foods occasionally, but do not eat them in large quantities for a long time. In particular, although you should not eat too much red meat, you should not not eat it. After all, red meat is a good helper for the human body to supplement iron and protein.

For acute inflammation, diet is also an important factor affecting immunity. An appropriate amount of high-quality protein, vitamins A, C, D, E, and nutrients such as iron and zinc can indeed help maintain the body's normal immune function and prevent infection by pathogens, but excessive intake can also increase the body's burden, inhibit immune function, and even cause poisoning. Therefore, a balanced diet and a healthy lifestyle are the only real anti-inflammatory "weapons".

Author: Department of General Medicine, Huadong Hospital

Tong Yili Attending Physician

Reviewed by: Nutrition Department of Shanghai Tongji Hospital

Wu PingChief Physician