Monday 17 December 2018

Do anti-inflammatory diets have any medical basis?

The bookstores are heaving with 'anti-inflammatory ' diets. But what exactly are we talking about when we talk about inflammation, and can what we eat have any impact? GP Brian Higgins takes a closer look

Certain foods have been found to have anti-inflammatory properties
Certain foods have been found to have anti-inflammatory properties

In 2017 a study was produced showing that patients with a higher blood levels of the inflammatory marker C Reactive Protein (CRP) were more likely to die from cardiovascular disease. The fitness and food community quickly caught on and the idea of anti-inflammatory diets spread like wildfire. Now we are all talking about it, but do we really know what inflammation is?

Despite popular misconception, inflammation is generally not a negative thing. It's the body's amazing response to a stress. When damage such as an infection, burn, bone fracture or skin laceration occurs, the body responds by becoming inflamed. This makes the area painful so that we avoid further damage - and it increases local blood flow causing redness, swelling and heat. But the increased blood flow brings nutrients and immune cells to the site that begin a healing process. This is known as acute inflammation.

In some cases, this inflammatory response can become prolonged, or chronic, and the very same response which was helpful in the short-term results in pain and cellular damage in the long-term. Common recognisable examples of this include the pain and swelling of osteoarthritis and gout. Inappropriate inflammation is also the underlying cause of other conditions, such as allergy, coeliac disease, autoimmune disease and many cancers. An autoimmune disease is any condition where the body causes inflammation in error affecting how organs work, causing illness.

Many environmental factors that cause chronic inflammation can lead to ill health. Smoking is the most common factor with which I as a GP deal on a daily basis. The stress caused by inhaled cigarette smoke within the lung, results in inflammation that over time hardens the lung tissue, resulting in chronic obstructive airways disease. The inflammation from cigarette smoke also alters the lung cell DNA. If an unfortunate series of DNA alterations occurs, then cancer develops when these damaged cells begin to overgrow and invade local tissues and eventually spread, or metastasise, throughout the body.

Another common environmental cause is UV radiation. UV radiation penetrates the dermis (deep skin layer) and the inflammatory response causes melanin cells to darken to prevent further burning. Over time, chronic sun exposure will cause premature ageing and may result in skin cancers know as, squamous cell and basal cell carcinomas. Acute severe burns, especially in childhood, can also cause permanent DNA damage that can lead to melanoma later in life.

There are many other inflammatory conditions with underlying environmental factors that we do not fully understand including, coeliac disease, diabetes, rheumatoid arthritis, lupus and multiple sclerosis

A broad range of medications have been developed to help treat inflammatory disease. These "anti-inflammatory" medications work in different ways to dampen our body's innate response to stress. The most readily available is ibuprofen but there are many others such as corticosteroids, antihistamines and even targeted biological therapies.

As well as medications, there are naturally occurring substances in the environment which help reduce inflammation. Some of these have been used for centuries to treat many ailments. White willow bark is one of the best known and we have purified the chemical into a medication called salicylic acid that is used in many medicated skin creams. Many other foods have been found to have anti-inflammatory properties including, turmeric, blueberries, ginger, green tea and certain root vegetables to name a few.

However, it's crucial is to be mindful that when a substance has been found to have properties in a laboratory, it is not understood how well these translate to day-to-day life. Many blogs, diet books and public figures make statements about these food sources without sufficient supportive evidence.

Turmeric is a compound that has been studied extensively and a good example of this.

It absolutely has anti-inflammatory and anti-oxidant properties. It can reduce symptoms in arthritis and improve cholesterol levels when compared to a placebo. However, it has not been shown to be superior to prescription medication or to have long-term benefits. Turmeric is now promoted as a type of superfood, used in many recipes and sold as a food supplement. What is not made clear in these promotions is that this chemical is poorly absorbed. So when taken on its own, is of very little benefit. Although it should be noted that taken with piperine, the major component of black pepper, the body's ability to absorb turmeric increases by 2000pc.

Anti-oxidants are different to anti-inflammatories in their properties, but are equally if not more relevant when discussing healthy diets. However, while they are generally accepted as being healthy, it is not known how much of these foods, what dose, and frequency are needed in a diet to have a long-term health effect. I am sceptical of the selection-box approach to medical research that is becoming more and more common in fitness and lifestyle literature and media. Medical research is often taken out of context as headlines like "a glass of wine a day is good for you" are interesting to read, but aren't necessarily an honest representation of the truth. If you look at the common healthy diets be they paleo, anti-inflammatory or anti-oxidant diets, they all have a similar underlying structure of limiting saturated fats and processed food while increasing healthy fats, fruits and vegetables. My advice when it comes to anti-inflammatory diets and anti-oxidant diets is entirely supportive. I am happy to see my patients eating lots of fresh fruit, root vegetables and oily fish, while avoiding calorie dense processed foods and smoking. I am not supportive because I truly believe that is due to a reduction in "inflammation" but because these diets advise sensible portions of well-balanced meals that are simply are good fuel. The body is a machine and like any machine, running it on good fuel yields good results.

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