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Immune system 'busters and boosters'

If your immune system doesn’t seem to be fighting off infections like colds and flu, there are things you can do to help the battle against bugs.

Get tips on replacing some bad health habits with healthy ones.

Immune system busters

Lack of exercise: Sitting at your desk all day may not only make you feel sluggish, it can also leave your immune system sluggish. Studies show that regular, moderate exercise - like a daily 30-minute walk -- increases the level of leukocytes, an immune system cell that fights infection. When you’re a non-exerciser, your risk of infections -- such as colds -- increase compared with those who exercise.

Being inactive can weaken your immune system indirectly, too. A sedentary lifestyle can interfere with sleep quality at night and can lead to obesity and other problems that increase your risk of illness.

Being overweight: Carrying extra weight increases your risk of developing diseases such as diabetes, cancer, and heart disease. Part of the reason may lie in how excess fat cells in your body affect your immune system.

A high number of fat cells trigger the release of pro-inflammatory chemicals in the body, leading to chronic inflammation. When the inflammation is ongoing, healthy tissues get damaged.

Animal studies also show that being overweight or obese can impair the immune system. For example, studies have shown that obese and overweight mice make fewer antibodies after receiving common vaccinations. Antibodies are a measured immune response to vaccination.

Eating foods high in sugar and fat: Studies suggest consuming too much sugar suppresses immune system cells responsible for attacking bacteria. Even consuming just 75 to 100 grams of a sugar solution (about the same as in two 330ml cans of fizzy drink) reduces the ability of white blood cells to overpower and destroy bacteria. This effect is seen for at least a few hours after consuming a sugary drink. A diet high in saturated fat has a similar effect.

Experiencing constant stress: Everyone has some stress in their lives. Short-term stress may actually boost the immune system - the body produces more cortisol to make “fight or flight” possible. However, studies show chronic stress has the opposite effect. It makes you more vulnerable to illness, from colds to serious diseases. Chronic stress exposes your body to a steady cascade of the stress hormones cortisol and adrenaline, which suppress the immune system.

Being socially isolated: Having strong relationships and a good social network is important for your physical health as well as your mental health - and specifically your immune system. Several studies support the idea that people who feel connected to friends - whether it’s a few close friends or a large group - have stronger immunity than those who feel alone. In one study, first-year students who were lonely had a weaker immune response to a flu jab than those who felt connected to others. Another study found that isolation changed the immune system on a cellular level: Being lonely affected the way some genes that controlled the immune system were expressed.

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