Anti-inflammatory diets – The Food Medic

This article was written by registered dietitian – Maeve Hanan

Anti-inflammatory diets are promoted for preventing and treating a number of medical conditions. But what do these diets involve and are they backed by solid evidence?

What is inflammation?

Inflammation is an important bodily process that occurs as part of the body’s defence system in response to a perceived harm such as infection or injury. 

Inflammation that occurs quickly in response to an injury or infection is called acute inflammation. This usually only lasts for a short period of time and tends to involve: pain, swelling, redness, heat and loss of function in a specific area (1).  

Although inflammation plays a vital role in our immune system and healing, when this occurs at a lower level over months or years this can cause harm. This chronic inflammation is associated with a higher risk of diseases such as heart disease, diabetes, dementia, arthritis and certain types of cancer (2). 

Types of anti-inflammatory diets

There is no one “anti-inflammatory diet” as a number of different eating patterns have been seen to be beneficial when it comes to balancing inflammation levels. 

Examples of these ways of eating include:

• The Mediterranean diet – the most commonly referred to anti-inflammatory diet in the Western world, based on traditional diets of Mediterranean countries such as Greece, Italy and Spain.
• The DASH (Dietary Approaches to Stop Hypertension) diet – similar to the Mediterranean diet, but targeted specifically towards treating high blood pressure.
• The MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay) diet – a combination of the Mediterranean and DASH diet that was developed to improve brain and cognitive health, and reduce the risk of issues such as dementia. 
• The Nordic diet – based on traditional eating in Nordic countries like Sweden, Denmark, Norway, Finland and Greenland.
• The Okinawan diet – this is based on the traditional eating pattern of the Japanese island Okinawa which is famous for its long life span, although there is some controversy related to this claim. 
• The Nicoya diet – based on a traditional diet within a region of Costa Rica.

As you can see in these examples, the word “diet” is referring to a way of eating rather than a weight-loss diet. 

There are slight variations between these diets, but they tend to be based on:

• vegetables
• fruit
• beans and pulses
• wholegrains
• nuts and seeds
• vegetable oils – like olive and rapeseed oil
• fish
• herbs and spices

These include moderate amounts of:

• alcohol – often red wine 
• dairy
• poultry
• meat
• wine
• potatoes

They also tend to be lower in:

• red and processed meat
• sugary food and drinks
• highly processed foods

It’s important to note that these anti-inflammatory diets don’t avoid or demonise any specific food but are based on a varied intake of food. Some of these diets and the related research also include overall lifestyle factors such as: eating together, movement, reducing stress and prioritising community and social wellbeing. 

What’s the evidence?

Research has looked into the effects of specific nutrients and staple foods that feature within anti-inflammatory diets, as well as the diets themselves. Let’s take a look at these. 

Omega-3:

Omega-3 is a fatty acid which is known for its anti-inflammatory properties (3). The best source of omega-3 is oily fish like salmon, mackerel, herring and trout. 

We also find omega-3 in (4):

• seaweed
• crab
• nuts* – like walnuts and hazelnuts
• seeds* – especially flaxseeds and chia seeds
• vegetable oils* – like soya bean oil and rapeseed oil

*However, only a small percentage of the omega-3 in plant-based foods like nuts, seeds and plant oils can be used by the body. 

This article goes into more detail about omega-3.

Polyphenols:

Polyphenols are natural compounds that have a number of health benefits, including acting as antioxidants which help with balancing oxidative stress levels in the body. As oxidative stress can lead to chronic inflammation, maintaining the right balance between free radicals and antioxidants is important for overall health, and reducing chronic inflammation and hence the risk of a number of chronic diseases. 

Olive oil is a well-researched food that contains both healthy fats and polyphenols. Olive oil and the polyphenols it contains have been seen to reduce oxidative stress and inflammation (5, 6).  

Polyphenols are also found in:

• fruit – especially berries
• vegetables – most are high in polyphenols 
• tea
• coffee
• dark chocolate
• herbs and spices
• wholegrains 
• nuts and seeds 
• red wine*

*Although there are polyphenols like resveratrol in wine, due to its alcohol content this should only be consumed in moderation and it isn’t advised to start drinking wine purely for health reasons if you don’t already drink it. Also, the same type of polyphenols are found in grapes, blueberries,  peanuts, pistachios and cocoa.

Glycaemic index & load

Although the research is mixed, the glycaemic index (GI) and glycaemic load (GL) of a diet may impact inflammation levels (3). GI is how quickly a food raises blood glucose levels, and GL takes into account both the GI of a food and how much carbohydrate a typical serving contains. A number of low GI foods are common within anti-inflammatory diets, such as wholegrains, all types of pasta, beans and pulses, certain fruit and vegetables. 

These low GI foods also tend to be high in fibre and contain a variety of vitamins, minerals and antioxidants which can benefit health and inflammation levels (7, 8).   

The Mediterranean Diet

There’s a lot of research to back up the health benefits of the Mediterranean diet. 

This way of eating is associated with (9, 10, 11, 12):  

• a lower risk of early death
• a lower risk of heart disease and stroke
• a lower risk of diabetes
• improved cognitive health 
• a lower risk of certain types of cancer, such as breast, prostate and colorectal cancer
• improved fertility in women and men
• improved mental health
• better quality of life

These benefits are thought to be related to a number of features of this diet, including (13):

• reducing oxidative stress and inflammation
• maintaining healthy cholesterol levels
• promoting a healthy and diverse gut microbiome
• impacting hormones and growth factors related to cancer risk

The DASH Diet

The DASH diet has been found to improve blood pressure levels and reduce the risk of heart disease (14, 15).

As this diet overlaps a lot with the Mediterranean diet, it is likely that the mechanisms behind this are similar. However, the lower salt content of the DASH diet is of particular benefit when it comes to blood pressure and heart health.  

The MIND Diet

This diet is associated with improved cognitive health and a lower risk of cognitive issues such as dementia (16, 17).

These benefits are thought to be at least partially related to reduced oxidative stress and inflammation in the brain (17). However, there isn’t much research that has specifically looked at the impact of this diet on overall oxidative stress or inflammation. 

See here for more information about the MIND diet.

The Nordic Diet

The Nordic diet shares a lot of similarities with the Mediterranean diet, the main difference being that rapeseed oil is the main fat used in the Nordic diet rather than olive oil. A recent comparison of the two diets found that although much fewer studies have investigated the Nordic diet, the existing research implies that it may be as beneficial as the Mediterranean diet in terms of health and disease-reduction (18). 

For example, this dietary pattern has been linked with improvements in cholesterol levels, such as reductions in total and LDL cholesterol, as well as significant improvements in blood pressure (19).  

The Nordic diet has also been associated with a lower risk of (20): 

• all-cause mortality
• heart attack and death from heart disease
• death from cancer
• type 2 diabetes 

The Okinawan Diet

The Okinawan diet includes:

• grains – like noodles, rice, and millet
• high protein foods – like tofu and other soya-based products, fish, chicken, and lean pork 
• fruit & vegetables – like sweet potato, pumpkin, shiitake mushrooms, carrots, bitter melon, bamboo shoots, cabbage, and seaweed
• a variety of herbs and spices

This eating pattern is high in plants, fibre, nutrients, polyphenols while being low in fat and having a low GI/GL (21). Along with other lifestyle factors, this may impact the low rates of chronic disease on the island (22). The relatively low protein, high carbohydrate content of this diet has also been suggested as a contributing factor (23).  

Although this diet follows a lot of evidence-based principles related to good nutrition, there isn’t much research specifically related to the Okinayan diet and health outcomes. 

The Nicoyan Diet

This diet is based on foods like:

• grains – like corn tortillas, rice, and wholegrain bread 
• high protein foods – like black beans, cheese, chicken, and eggs
• fruit – like banana, papaya, and mango
• vegetables – like squash, plantain, peppers, and yams
• fats – like butter, avocado, sunflower, and rapeseed oil

The Nicoya region in Costa Rica is known for low rates of heart disease and a long life expectancy among men (24). 

The low GI, high-fibre and plant-focused content of the Nicoyan diet is thought to play a role in this (25).  

There isn’t a lot of research related to this diet, but a study from last year found that the traditional Nicoyan diet was associated with a lower risk of chronic disease (using a marker called leukocyte telomere length) (26). 

Summary:

A number of different eating patterns are linked with improvements in chronic inflammation, which is likely to play a role in overall health and disease risks. 

The most well-researched anti-inflammatory diet is the Mediterranean diet which has been found to be really beneficial for health outcomes such as: heart, metabolic, cognitive and mental health; as well as a lower risk of early death and improvements in quality of life. 

Other anti-inflammatory diets linked with health benefits include the DASH, MIND, Nordic diet, Okinawan and Nicoyan diets.

Although inflammation most likely plays a role in this, these dietary patterns are also nutritious, high in plants, fibre and antioxidants, and low in GI and GL. None of these diets cuts out any food groups, and they also involve healthy lifestyle factors such as social connection, movement and reducing stress.

References:

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Anti-inflammatory diets was last modified: October 4th, 2022 by Maeve Hanan