This has become a hot topic in recent years, and a whole host of books about the anti-inflammatory diet are available today. I’m getting more and more questions on the subject, and I can see that more and more people are interested in the diet and choosing to adopt it. The diet involves not only eating foods that reduce inflammation in the body – but also excluding foods that are said to increase inflammation. So, what is really true, and has any scientific research been done on these claims to date?

What is an anti-inflammatory diet? 

Anti-inflammatory foods are foods that are said to reduce inflammation in the body. Constant inflammation in the body is considered unhealthy as studies have shown it to be linked to chronic diseases such as cardiovascular disease, diabetes, stroke and cancer. Another argument used by its proponents is that it is associated with autoimmune diseases such as coeliac disease and rheumatism.

Foods that are said to increase inflammation in the body include sugar, gluten-containing foods, dairy products, red meat, coffee, alcohol, potatoes, rice, pulses, and vegetable oils such as sunflower oil, corn oil and trans fats (omega-6 fats).

Foods that are said to be anti-inflammatory include vegetables, fruits (although some fruits should be avoided) and berries, fish and shellfish, nuts, wholegrain products, sweet potatoes, garlic and onions, ginger, turmeric, olive oil, coconut oil and green tea.

The lists differ somewhat from one advocate to another – some consider that a certain food should be avoided, while others consider it acceptable.

So, what is meant by inflammation?

The inflammatory response is necessary to protect the body. It’s part of our immune system. When the body deals with infections, it reacts with an inflammatory response, destroying or inactivating the virus or bacteria that caused the infection, and then starts the healing process. The inflammatory response is energy-intensive and affects the metabolism through increased blood sugar levels and insulin resistance, changes in blood lipids and the breakdown of muscle mass. The hormone cortisol is then released to suppress the inflammation and to prevent the inflammatory response from destroying the body’s cells.

Excess weight and inflammation 

Being overweight or obese produces more inflammatory markers in body fat, resulting in an overactive immune system. This creates low-level inflammation in the body. Studies have linked this inflammation to cardiovascular disease and type 2 diabetes. Losing weight and maintaining a normal weight reduces the risk of these diseases.

So what does the current scientific research say?

Advocates of an anti-inflammatory diet suggest that specific foods can reduce low-level inflammation in the body and thus prevent disease.

There is currently no scientific research to support claims that specific foods such as gluten, milk, red meat and sugar can cause inflammation or can exacerbate ongoing inflammation in the body. Similarly, there is a lack of scientific evidence showing that specific foods can reduce inflammation in the body, such as studies that have looked at the consumption of spices (cinnamon, cardamom, ginger, saffron and garlic). To draw any firm conclusions about a food’s anti-inflammatory effect, well-designed studies on humans are needed. There needs to be an intervention group (a group of people who eat the diet being studied) that is carefully monitored and a control group that eats a different, carefully monitored diet. Of the well-designed studies on humans that have been done on this topic, very few have been able to demonstrate any level of effectiveness of the ‘anti-inflammatory’ foods.

However, some studies have shown that a few foods have the potential to have a positive effect on inflammatory markers.

Fish: Some studies have found a slight positive effect on inflammation when consuming either oily or lean fish (about 150 grams twice a week). Other studies have found that fish that are rich in omega-3 (oily fish) have a better effect on inflammatory markers than leaner fish with a lower omega-3 content (on an intake of about 150 grams of fish two to five times per week). These findings can only be interpreted as suggesting that fish may have a slight anti-inflammatory effect.

Fruit and vegetables: Studies that have been able to demonstrate a positive effect only saw this with a very high fruit and vegetable intake – equivalent to six to twelve portions of fruit and vegetables per day. This was in comparison with a lower intake of two portions of fruit and vegetables per day. Large portions of fruit and vegetables could therefore have an anti-inflammatory effect, but it could also be the effect of participants replacing more unhealthy foods with fruit and vegetables.

Olive oil: One study suggests that inflammation markers are reduced in the body after eating a meal containing olive oil. However, the results are difficult to evaluate because there was no control group that ate oils other than olive oil.

Dairy products: Some studies have found a link between fermented dairy products (e.g. yoghurt and soured milk) and low-fat dairy products, and a reduction in the level of inflammation in the body.

Diet according to Nordic Nutrition Recommendations

There are several studies that have examined the effects of a healthy diet as a whole (following the Nordic Nutrition Recommendations) in healthy, overweight people with obesity or metabolic syndrome. This is a diet rich in fruit, vegetables and wholegrains, with a low intake of refined flour and sugary foods, and often just a small amount of red meat. Some studies found that the level of inflammation was reduced in participants eating a healthy diet compared with those who ate a ‘normal’ diet.

Mediterranean diet

The greatest number of studies have been done on the Mediterranean diet and inflammation. The Mediterranean diet is a diet consisting of vegetables, fruits, berries, pulses, root vegetables, fish and shellfish, nuts and seeds, wholegrain products, vegetable oils such as olive oil, chicken and eggs. It also includes moderate amounts of red meat, sugar, salt and alcohol.  Some of these studies have shown a significant difference in the beneficial effect of the diet on lower levels of inflammation (which means that the evidence is strong enough to draw conclusions from the study). However, not all studies demonstrated a significant effect.

In summary

Current scientific research shows that low-level inflammation in the body decreases with weight loss. Apart from that, the current scientific evidence for anti-inflammatory diets is lacking. There is evidence, however, that certain foods and diets affect inflammatory activity in the body, but these connections need to be studied more extensively and in more detail in order to draw conclusions.

There is a lot of scientific research to indicate that fruit, vegetables and wholegrains are good for your health and reduce the risk of common diseases. There is strong scientific evidence that the Mediterranean diet reduces the risk of several diseases such as cardiovascular disease, type 2 diabetes, stroke and obesity – and part of this reduced risk could possibly be linked to lower levels of inflammatory markers.

So, if we generally eat a diet in line with current nutrition recommendations and maintain a healthy weight with a moderate amount of physical activity, the risk of developing several of the most common chronic diseases is reduced.

Sources Sahlgrenska University HospitalNutritionsfakta