Quick answer: Calprotectin is a protein released mainly by neutrophils, the white blood cells that gather where tissue is inflamed, and it can be measured in stool. A higher level generally reflects more inflammation in the intestinal lining, while a low level suggests that this kind of inflammation is not very active. It does not say where the inflammation is or what caused it.
Key takeaways
Calprotectin is a protein released by white blood cells in the gut.
A low stool calprotectin makes inflammatory bowel disease unlikely in adults with gut symptoms.
Medications such as anti-inflammatory pain relievers and infections can raise it temporarily.
How can a stool sample say anything about inflammation? Calprotectin is a protein found mostly inside neutrophils, the white blood cells that rush to areas of inflammation. When the lining of the intestine is inflamed, neutrophils move into it and calprotectin spills into the stool, where it stays stable enough to measure. That makes it one of the most widely used noninvasive windows into inflammation inside the gut. It is a useful signal, but it does not say where the inflammation is or why it started. The habits most often discussed around gut inflammation are eating plenty of fiber from a variety of plants, staying active, keeping a healthy weight, sleeping well and reviewing regular medication use with your provider.
This article is educational. It explains what the marker reflects and how researchers connect it to the deeper mechanisms of aging, so you can have a more informed conversation with your own provider.
What does a high calprotectin result mean?
A higher calprotectin result generally reflects more neutrophil activity in the intestinal lining, which is a sign of inflammation. A low result suggests that this kind of inflammation is not very active. Clinicians in many countries use the test to help tell inflammatory bowel conditions such as Crohn’s disease and ulcerative colitis apart from irritable bowel syndrome, which does not usually raise calprotectin. NICE, the health guidance body in England, recommends faecal calprotectin as an option to support clinicians in making that distinction in adults with recent lower digestive symptoms when cancer is not suspected.
Calprotectin is not specific to one condition. Infections, some medications and other sources of gut inflammation can raise it, so a single result is a starting point for a conversation rather than an answer.
How does calprotectin connect to aging and root causes?
Calprotectin is more than a passive leftover of inflammation. It is made of two proteins, S100A8 and S100A9, and a review in Frontiers in Immunology describes how this pair is actively released during inflammation, where it recruits more white blood cells and stimulates the release of inflammatory messengers. That places calprotectin squarely in the story of chronic low-grade inflammation, one of the processes most closely linked with aging. The same review notes that S100A8 and S100A9 bind receptors that also respond to advanced glycation end products, which hints at a shared inflammatory pathway, though how much this matters for aging in people is still an open question.
Age itself seems to shift the baseline. In a study of healthy volunteers in the Annals of Clinical Biochemistry, adults aged 60 and older had higher stool calprotectin than adults aged 10 to 59. This fits the broader idea that the gut barrier and the immune cells that guard it change over time, although the reasons are not fully understood.
The gut is also where the microbiome and the immune system meet. When the balance of gut bacteria shifts or the lining becomes more permeable, immune cells are drawn in, and calprotectin is one of the ways that activity shows up. A review in BMC Gastroenterology found that obesity, low physical activity and low dietary fibre intake were each associated with higher calprotectin, and it noted that proton pump inhibitor use was associated with markedly higher levels. These are exactly the kinds of everyday factors that root-cause thinking looks at.
So when calprotectin is high, the functional question is why. Food quality and fiber intake shape the microbiome. Movement and body weight influence inflammation throughout the body. Sleep and ongoing stress affect gut motility and immune balance. Regular use of anti-inflammatory pain relievers or acid-reducing medications can irritate the lining or change the bacteria that live there, and genetics shape how strongly each person’s immune system responds. Infections also need to be ruled out, which is why calprotectin is read alongside a person’s symptoms and other stool markers.
What does the research show about Calprotectin?
A clinical meta-analysis pooled 13 studies of people with symptoms suggesting inflammatory bowel disease, all confirmed by colonoscopy and biopsy. In 670 adults, fecal calprotectin correctly flagged 93% of those with inflammatory bowel disease and was negative in 96% of those without it, while in 371 children and teens the second figure was lower at 76%. Cutoffs and test kits varied between studies. (van et al., 2010)
A meta-analysis of prospective adult studies estimated how well blood and stool markers separate irritable bowel syndrome from inflammatory bowel disease. A calprotectin of 40 micrograms per gram or lower, or a CRP of 0.5 or lower, meant a 1% or lower chance of inflammatory bowel disease, while lactoferrin alone had little added value, and no marker separated irritable bowel syndrome from healthy people. Only a few studies met the inclusion criteria, especially for lactoferrin. (Menees et al., 2015)
These studies make calprotectin the best-studied stool marker for separating inflammatory from non-inflammatory gut symptoms.
Related reading
If you would like to explore related topics, my articles on IL-6 and inflammation, intestinal permeability and fermented foods and the gut microbiome go deeper. You can also see the specialty tests I commonly recommend on my functional labs page.
Common questions about Calprotectin
Can anything besides gut disease raise calprotectin?
Yes. Infections, proton pump inhibitor use, obesity, low physical activity and low fiber intake have all been associated with higher calprotectin.
Does calprotectin change with age?
A study of healthy volunteers found that adults aged 60 and older had higher stool calprotectin than younger adults, so age is part of the context.
Is calprotectin the same as a blood inflammation marker?
No. Calprotectin in stool reflects inflammation inside the gut, while blood markers such as CRP and IL-6 reflect inflammation throughout the body.
Sources
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before making changes to your diet, exercise, supplements, or medications, especially if you are pregnant, nursing, or managing a health condition.
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