The CRP blood test is very sensitive and will pick even low levels of inflammation. This means that you should avoid taking the test if you have any acute infections such as a cold or flu or an injury. It's also best not to test until a few days after very strenuous exercise (such as running a marathon).

Reducing your CRP level really depends on the cause. If there's acute inflammation from an infection, injury or inflammatory condition such as inflammatory bowel disease then treating the underlying cause will reduce the CRP level.

On the other hand, if the high CRP level is related to chronic, low-grade inflammation then lifestyle changes can help. For example, losing weight, stopping smoking, reducing alcohol intake, exercising and improving your diet can all reduce CRP levels. In general, a Mediterranean-style diet is associated with lower CRP levels.

Occasionally there are specific but hidden issues that are causing a low-grade inflammation. For example, gum disease is a common cause of low-grade inflammation and high CRP levels. In these cases, treating the gum disease can reduce the CRP level. Similarly, some individuals may be sensitive to certain foods such as wheat or dairy, in which case removing these foods can reduce CRP levels.

With a few exceptions, foods don't directly cause inflammation or protect against it. Some dietary patterns are associated with higher levels of CRP. For example, the "Western diet" which is high in processed foods, sugar and unhealthy fats is associated with higher CRP levels. On the other hand, the Mediterranean diet which is high in fruit, vegetables, whole grains, nuts, seeds and olive oil is associated with lower CRP levels. But this is an association, not causation. It's likely that the Mediterranean diet is associated with lower CRP levels because it's also associated with lower levels of obesity, high blood pressure and diabetes. All of which raise CRP levels.

Similarly, if your CRP is high because you have gum disease or smoke then eating a so-called "anti-inflammatory" diet won't help. You need to treat the gum disease and stop smoking.

Talking about foods as "pro-inflammatory" or "anti-inflammatory" is an oversimplification that misses the point. It's far more helpful to look at the impact that your diet is having on your weight, blood pressure, cholesterol levels and blood sugar levels.

A food "intolerance" or "sensitivity" is when someone experiences symptoms, such as bloating diarrhoea or rashes, after eating certain foods. This is different from a food "allergy" which is a specific type of immune reaction to a food.

In some individuals, food intolerances can cause low-grade inflammation and a slight increase in CRP. In these cases, it can be useful to try excluding a potential food cause from the diet and monitoring the effect on the CRP and any symptoms. Dairy and wheat-containing products are the commonest culprits.

However, it's important to point out that in the majority of people, wheat and dairy do not cause inflammation. In fact, dairy consumption has consistently been shown to be associated with lower levels of inflammatory markers in the blood^ref.