Scientists believe they have discovered why psychological stress can lead to physical pain.
A research team at Carnegie Mellon University in Pittsburgh found that chronic psychological stress is associated with the body losing its ability to regulate the inflammatory response.
Published in the Proceedings of the National Academy of Sciences today, the research shows for the first time that the effects of psychological stress on the body's ability to regulate inflammation can lead to the development and progression of disease.
Sheldon Cohen, professor of psychology at the university's Dietrich College of Humanities and Social Sciences, said prolonged stress alters the effectiveness of cortisol to regulate the inflammatory response because it decreases tissue sensitivity to the hormone.
Specifically, immune cells become insensitive to cortisol's regulatory effect and in turn runaway inflammation is thought to promote the development and progression of many diseases.
He said: "Inflammation is partly regulated by the hormone cortisol and when cortisol is not allowed to serve this function, inflammation can get out of control."
Prof Cohen, whose early work showed that people suffering from psychological stress are more susceptible to developing colds, used the common cold as the model for testing his theory.
With the common cold symptoms are not caused by the virus. They are instead a side effect of the inflammatory response that is triggered as part of the body's effort to fight infection.
The greater the body's inflammatory response to the virus, the greater is the likelihood of experiencing the symptoms of a cold.
In Cohen's first study 276 healthy adults completed an intensive stress interview and were then exposed to a virus that causes the common cold and monitored in quarantine for five days for signs of infection and illness.
It was found that experiencing a prolonged stressful event was associated with the inability of immune cells to respond to hormonal signals that normally regulate inflammation. In turn, those with the inability to regulate the inflammatory response were more likely to develop colds when exposed to the virus.
In the second study, 79 healthy participants were assessed for their ability to regulate the inflammatory response and then exposed to a cold virus and monitored for the production of pro-inflammatory cytokines, the chemical messengers that trigger inflammation.
Prof Cohen found that those who were less able to regulate the inflammatory response as assessed before being exposed to the virus produced more of these inflammation-inducing chemical messengers when they were infected.
He said: "The immune system's ability to regulate inflammation predicts who will develop a cold, but more importantly it provides an explanation of how stress can promote disease.
"When under stress, cells of the immune system are unable to respond to hormonal control, and consequently, produce levels of inflammation that promote disease. Because inflammation plays a role in many diseases such as cardiovascular, asthma and autoimmune disorders, this model suggests why stress impacts them as well.
"Knowing this is important for identifying which diseases may be influenced by stress and for preventing disease in chronically stressed people."
According to previous research, turmeric is more effective in tackling pain relief and inflammation than steroid medications. According to researchers from the National Institutes of Health, the pain relief properties from turmeric are more prevalent to rheumatoid arthritis sufferers, as it inhibits the destruction of joints from arthritis. Turmeric contains a protein called NF-kB, which, when turned on, activates the body's inflammatory response, which helps battles aches and pains.
Red grapes are packed full of resveratrol, a powerful antioxidant compound that blocks enzymes that degenerate tissue damage, which can lead to joint and muscle pain. According to the Rush University Medical Center, resveratrol helps protect against cartilage damage that causes back pain in particular. Another study by the Michigan State University found that cherry extract is ten times more effective than aspirin when it comes to relieving inflammation in the body. Other berries rich in back-pain fighting resveratrol include blueberries, cranberries and blackberries.
Ginger is well known for its ability to block the pain-causing prostaglandin levels in the body. Ginger has long been used as a natural method of pain relief, particularly in India, where researchers regularly test its inflammation and pain relief properties. According to research by the University of Miami, researchers discovered that two third of patients with chronic knee pain reported less soreness after taking a daily dose of ginger extract for six weeks. Health experts recommend a daily dosage of 500 to 1,000mg of ginger a day to help ward off aches and pains.
Research by the Oklahoma State University found that osteoarthritis sufferers who consumed 40g of soy protein a day for three months, reported a 30% improvement on their arthritis-related knee pain. Soy contains bundles of isoflavones, a plant hormone with strong anti-inflammatory properties, which helps reduce the discomfort of osteoarthritis and other related joint pains.
Omega-3 fatty acids are crucial for keeping the immune system healthy - and warding off inflammation and chronic neck pain. During research at the University of Pittsburgh, 60% of participants experienced enhanced pain relief from eating more fish or taking fish oil supplements for three months. The effect was so great, almost as many stopped taking their daily pain relief as a result. Besides salmon, other fish that contain high levels of the essential EPA and DHA omega-3 fatty acids include halibut, tuna, trout, mackerel and sardines.
Cherries, like the other members of the berry family, contain high amounts of antioxidants called anthocyanins - the key compound to the cherry's pain fighting power. According to research by the Department of Agriculture, participants who ate 45 big cherries daily for 28 days reduced their inflammation levels significantly. Researchers found that cherry anthocyanins are especially effective in treating arthritis symptoms, as participants of the study said their joint pain had improved as a result of consuming cherries or cherry juice. Anthocyanins contain antioxidants, anti-inflammatory and anti-diabetic properties.
If you ever wondered why over-the-counter painkillers contain caffeine, it's because coffee enhances the effects of common pain relief. It also acts as a natural pain reliever itself, particularly good for post-workout aches and pains. Researchers from the University of Georgia discovered that patients who drank two cups of coffee after working out, reduced common post-workout aches and pains by almost 50%. Experts also claim that caffeine is good for a pre-workout boost too, as it has been proven to raise the body's pain threshold.
The humble sage is commonly used to treat throat ailments, like tonsillitis, mouth ulcers, gum disease, laryngitis, as well as other problems like headaches, bruises, bad memory and common menopause symptoms. Sage contains rosmarinic acid, which is absorbed into the body and acts as an anti-inflammatory agent, which soothes inflamed muscles. Add it to boiling water and make your own sage tea, or sprinkle it as a seasoning on your food.