it , but there are ways we can actually measure this by a blood test . And one of them is the blood test for CRP , C-reactive protein , which is a really nice marker for inflammation . And there are two different types . There ' s really severe acute inflammation , such as advanced cancer where the body is breaking down , when you could have CRP levels that are in the hundreds of milligrams per decilitre . Where it ' s very subclinical , we can use another test called hs-CRP , which is a high-sensitivity CRP test . That may not measure really high levels , but it ' s enough to show that the CRP levels are higher than normal . And CRP is a marker of the inflammatory response . So , there are ways we can measure it by a blood test , and it ' s a very robust marker of overall inflammation .
Lisa : So , do you think it would be correct to say that patients don ' t necessarily have to have elevated levels of CRP and ESR on their bloods for there to be inflammation present ?
Tim : That ' s correct , but it also depends what test is done . Most of the time , it ' s just called CRP , which is more of a measure of inflammation ; hence this other test , hs-CRP , which is really designed to pick up levels of inflammation still more in the reference range of 0.5 to 10 milligrams per litre . That ' s not as common a test , but it ’ s a good predictor of things like cardiovascular disease . So , if those tests are available , it ' s useful . But for a very low subclinical condition , a standard CRP test might not show it ( though there ' d be signs and indications it could be present as well ). So , clinical judgment is called for as well . When you ' re doing history , are there potential other things ticking off boxes related to lifestyle factors , for example , that could exacerbate that ? And we ' ll examine later the big lifestyle factors that can affect inflammation .
Lisa : Yes , I understand that ‘ sickness behaviours ’, like fatigue , altered sleep , can also be manifestations of inflammation .
Tim : Absolutely . And you could add in there , physical inactivity . Are patients carrying a lot of weight around the middle ? We know that with adiposity , particularly central adiposity , those fat cells are not at all inactive . There are actually more macrophages in fat around our middle , and these macrophages , as I ' ve already mentioned , are part of the inflammatory cascade . So , metabolically , active fat around the middle is a risk factor for inflammation , as well as for metabolic syndrome , CVD , type 2 diabetes . But having a poor diet , poor sleep , as you ' ve mentioned , that ' s a big issue . Pollution , infection and smoking can all worsen inflammation , which then can tip you over the edge for such conditions as Hashimoto ’ s disease , rheumatoid arthritis , and so on
Lisa : Really interesting , because a lot of patients have multiples of those . They don ' t just have the chronic infection and the sedentary lifestyle , they ' ve got issues with their diet , and dysbiosis , and so on .
Tim : Yes , all of those are related . And that ' s really just with clinical judgment . You don ' t just treat the condition , say , Hashimoto ’ s disease or rheumatoid arthritis , you look at all these other factors which will impact upon inflammation that are underpinning those conditions in the first place .
Lisa : In your latest edition of the textbook , there ' s a lot more focus on intestinal dysbiosis . So , what are your thoughts on the microbiome and dysbiosis and how that affects inflammation ?
Tim : Yes , the gut microbiota is the hottest of hot topics , just for the number of systems it affects . And there is unlikely to be one perfect healthy microbiome that is the same for everybody : it ' s highly individualised . We know that decreased diversity , that ' s the number of distinct species , is a big marker for dysbiosis . Now , the problem when you change your gut microbiota is that among the metabolic products they ' re involved in producing , one of them , of course , is going to be the short-chain fatty acids , which are key mediators of reducing inflammation in our body . A positive diet that ' s full of minimally processed plant-based foods , with lots of probiotics , is certainly linked with production of more of these short-chain fatty acids . And they ' re almost what I consider key signalling molecules in reducing inflammation . The opposite is true with poor diet and all the other lifestyle factors that go with it : then you see dysbiosis . That means you get less of these metabolic products , and that will loosen the handbrake on control of inflammation . That ' s probably one of the key mediators with our gut and inflammation . So , it ' s just the change in the metabolic by-products , and it ' s probably the short-chain fatty acids , I think , are the key metabolites involved in this .
Lisa : So , when it comes to dysbiosis , I know stress can very much harm our microbiome increase inflammation .
Tim : Absolutely , and I ' m not talking about just small amounts of stress every now and then , but constant stress , that will affect the HPA axis as well , cortisol responses , and so the cascade goes on . So , that ' s probably an alternative pathway feeding into inflammation or a different effector coming just from emotional stress . But we know that our gut is not in isolation . There is direct crosstalk between our gut and our brain , and that also controls our stress responses , and the vagus nerve is certainly very important in that process . So , even though stress can be external , it affects the brain . It can affect the HPA axis . Also , again , our gut microbiome will actually register that stress , and be affected by it . It ' s all very closely interrelated , but I ’ m adding a bit more detail to the molecular mechanisms that are occurring for all of these environmental lifestyle factors that we know affect our health .
Lisa : And there ’ s some really interesting research on loneliness , which is kind of a stressor in its own way . For some time we ' ve known that perceived loneliness
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