The role of inflammation in modern diseases

Inflammation is necessary for healing in the body – but it can also cause a great deal of harm.

19 November 2013
by Rachel McGregor

If you’ve ever had a sore throat, bee sting, cut, twisted ankle or rash, you'll be familiar with inflammation. It’s our immune system’s response to infection and injury, and it has only one goal: to neutralise and eradicate toxic or harmful substances around damaged tissue before they can spread to the rest of the body.

Heat, pain, sensitivity and perhaps swelling – these are symptoms of inflammation, and while unpleasant, they indicate that our immune system is working, that it has dispatched its SWAT team of white blood cells to help jump-start the healing process.

These cells go on a seek-and-destroy mission to neutralise viruses and potential infections. But there’s a catch. Under certain circumstances, our bodies deploy white blood cells when there is no threat, which end up attacking healthy tissue.

According to Prof Ronald Anderson of the Department of Immunology at the University of Pretoria, “although our immune system is indispensable for countering the unrelenting danger posed by the microbial and viral pathogens (disease-producing agents) which abound in our environment, coexisting with our immune system also carries major health risks. This is because many of the defence mechanisms utilised by the immune system to neutralise micro-organisms and viruses, although potent and effective, are also indiscriminate, posing the potential hazard of damage to neighbouring cells and tissues. It is therefore crucial that activation of these defences is transient and protective.”

If activation is not “transient and protective,” your immune system’s ability to quell inflammation is impaired, and you may be headed towards serious illness.

Chronic, low-grade inflammation has long been associated with conditions such as rheumatoid arthritis, asthma, multiple sclerosis and inflammatory bowel diseases such as Crohn’s disease. But now scientists are discovering that inflammation may play a much bigger role than previously believed in a group of dysfunctions (high blood pressure and high LDL/“bad” cholesterol, for example) known as metabolic syndrome, which is strongly associated with the dread diseases of our time: cardiovascular disease, diabetes, stroke, certain cancers and even dementia.

If there’s no infection, no injury, no virus – what could be causing our immune system to dispatch white blood cells that cause more harm than good and that may lead to disease?

Stress

A research team at Carnegie Mellon University in the US found that prolonged psychological stress may cause the body to lose its ability to regulate the inflammatory response. Cortisol is called “the stress hormone” as it is excreted by our body at higher levels when we experience a fight-or-flight response, for example during a stressful experience.

But it’s also critical for many other functions in the body, including inflammation. “Inflammation is partly regulated by cortisol, and when cortisol is not allowed to serve this function, inflammation can get out of control,” said Prof Sheldon Cohen, who suggests that stress alters the effectiveness of cortisol to regulate the inflammatory response because it decreases tissue sensitivity to the hormone.

Junk food

When researchers from the University at Buffalo fed volunteers a high-kilojoule fast-food meal, they found high levels of inflammatory markers in their blood for the next four hours. Lead researcher Dr Paresh Dandona said: “If people eat fast food-type meals every three to four hours, as many do, they are constantly setting the stage for more inflammation.”

Sugar

Refined carbohydrates and sugar can stoke the fires of inflammation. A diet high in sugar and refined carbs means your body’s insulin levels probably spike regularly – and high insulin levels can cause your body to produce prostaglandins, a group of lipids made at sites of tissue damage or infection, which cause inflammation (usually as part of the healing process).

Obesity

When your fat cells become overwhelmed, they send a ‘false’ SOS signal to your immune system, triggering an inflammation response. Over time, this can make cells resistant to insulin, which spells D-I-A-B-E-T-E-S.

Lack of exercise

Active people have lower levels of C-reactive protein, one of the most important markers of chronic inflammation.

Your anti-inflammation strategy

Apart from reducing stress, exercising regularly, avoiding junk food and losing weight (if you’re obese), what can you do to help quell the fires of inflammation? It’s pretty simple really. Prof Anderson recommends a diet with a range of antioxidants, which means a wide range of fresh fruit and vegetables, and plenty of them. Good fats, such as omega-3 fatty acids found in walnuts and flaxseeds, and fish like mackerel, tuna, sardines and salmon, also help your body produce anti-inflammatory hormones.

“In general, it is best not to single out a particular food but rather focus on your overall eating pattern and lifestyle,” says registered dietitian Ayesha Seedat from the Heart and Stroke Foundation SA. She also recommends making “high-fibre starchy foods and whole grains part of most meals, such as whole-wheat bread, oats and brown rice” and flavouring food with spices and herbs, rather than salt, an excess of which has also been linked to inflammation.

It’s advice we’ve been given plenty of times before, but it helps to understand exactly how these practices influence our health, as the link between lifestyle, inflammation and disease becomes even clearer.