A gastrointestinal condition called “leaky gut” is gaining
worldwide attention, particularly among the natural health
Some medical professionals deny that leaky gut exists, while
others claim it is the root of nearly every disease.
Leaky gut is somewhat of a medical mystery. Scientists are
still trying to determine exactly what it is and what causes
it. Some people think that gluten causes leaky gut, but the
role of gluten in the condition is complicated.
This article examines the research about gluten and leaky gut
What Is Gluten?
Gluten is a mixture of
proteins found naturally in grains like wheat, barley and
It is responsible for the elastic nature of dough, which helps
the dough hold together and rise. Gluten is also what gives
bread its chewy texture (1).
It is also sometimes added to bread dough to increase its
ability to rise.
The two major proteins that make up wheat gluten are gliadin
and glutenin. Gliadin is the portion of the gluten that
some people react negatively to.
Bottom Line: Gluten is a group of proteins
found in wheat, barley and rye. One of these proteins causes
negative health effects in some people.
What Is Intestinal Permeability?
The digestive system performs several very important functions
in your body.
The digestive tract is where food is broken down and nutrients
are absorbed into the bloodstream.
The walls of the intestines also serve as an important barrier
between the gut and the rest of the body.
The intestinal wall serves as a gatekeeper, determining which
substances pass through to the bloodstream and organs.
Intestinal permeability is a term that describes how easily
substances pass through the intestinal wall. Normally, there
are tiny gaps between the cells in the small intestine called
If these are damaged or become too loose, it causes the gut to
become “leaky,” allowing substances and organisms in the gut to
leak into the bloodstream.
This phenomenon of increased intestinal permeability is also
known as leaky gut syndrome. When bacteria and toxins are
leaking into the bloodstream, it causes widespread inflammation
in the body.
Bottom Line: When the barrier function of
the small intestine is impaired, bacteria and toxins can leak
from the gut, causing inflammation and disease.
Gluten Causes Significant Problems for Some
Most people are able to digest gluten just fine.
That said, a small proportion of people
cannot tolerate it.
The most severe form of
gluten intolerance is called celiac disease. Celiac is a
hereditary autoimmune disease.
For individuals with celiac disease, gluten can cause diarrhea,
stomach pain, excessive gas and skin rashes. Over time, it can
cause damage to the intestines, which impairs their ability to
absorb certain nutrients (5, 6).
However, some people test negative for celiac disease but still
react to gluten. This is referred to as non-celiac gluten
The symptoms are similar to celiac disease, but without the
autoimmune response. People with non-celiac gluten sensitivity
may experience diarrhea, bloating and gas, along with joint
pain and brain fog (7).
There is currently no clinical method of diagnosing non-celiac
gluten sensitivity. If you react negatively to gluten and your
symptoms are relieved with a gluten-free diet, you probably
have gluten sensitivity (8, 9, 10).
The topic of gluten remains highly controversial. Some medical
professionals believe that gluten is harmless unless you have
celiac disease. Others claim that gluten is the root cause of
all kinds of health problems and autoimmune disorders.
Bottom Line: Most people can tolerate gluten
just fine. However, gluten causes significant problems in
Gluten Activates Zonulin, the Regulator of Intestinal
Several studies have shown that gluten can increase intestinal
permeability and cause an immune response in the body (11).
The immune system responds to substances it recognizes as
harmful by causing inflammation. Inflammation is the body’s
natural self-protection mechanism, but persistent
inflammation is associated with multiple chronic diseases.
In sensitive individuals, gluten is deemed a foreign invader,
leading to inflammation. However, there is conflicting evidence
regarding gluten and intestinal permeability.
How Gluten Affects Zonulin and Gut Permeability
Zonulin is a protein that regulates the tight junctions of the
small intestine. When zonulin is released in the intestines,
the tight junctions open slightly and allow larger particles to
pass through the intestinal wall (12, 13).
One of these studies found that gluten activated zonulin in
cells from individuals with and without celiac disease.
However, zonulin levels were much higher in cells from celiac
How Does This Affect People With Gluten Sensitivity?
There are mixed results when it comes to individuals without
celiac disease. Test-tube studies have shown that gluten
increases intestinal permeability, but this has not been
confirmed in human studies (17).
One clinical study also found that gluten increased intestinal
permeability in patients with irritable bowel syndrome (IBS)
Individual Health May Play a Role
Gluten does activate zonulin, but it does not affect everyone
the same way.
It is clear that gluten does increase intestinal permeability
in those with celiac disease and possibly in those with IBS.
However, it appears that gluten does not increase
intestinal permeability in healthy people.
Bottom Line: Gluten activates zonulin and
increases intestinal permeability in people with celiac
disease. Gluten does not increase intestinal permeability in
Factors That Contribute to Leaky Gut Syndrome
Gluten may play a role in the development of leaky gut syndrome
in those with celiac disease or IBS, but it is certainly not
the only cause.
Medical professionals are still trying to understand exactly
what causes leaky gut syndrome, but there are a few factors
that are known to contribute to the condition.
Here are some of the contributing factors:
Unhealthy diet: A diet high in fat and
carbs may increase intestinal permeability (22, 23, 24).
stress can alter the gut-brain interaction and lead to
all kinds of gastrointestinal issues, including increased
intestinal permeability (25).
Non-steroidal anti-inflammatory drugs
(NSAIDs): Overuse of NSAIDs, such as ibuprofen, can
increase intestinal permeability (26, 27).
Inflammation: Chronic widespread
inflammation contributes to multiple chronic diseases, as
well as increased intestinal permeability (28).
Poor gut flora: When the balance between the
beneficial and harmful bacteria lining the gut is
compromised, it can contribute to leaky gut syndrome
Zinc deficiency: A lack of zinc in the diet
can alter intestinal permeability and contribute to multiple
gastrointestinal problems (29).
Yeast is naturally present in the intestinal tract. When
the growth of yeast, mainly Candida, gets out of
hand, it causes problems (30).
Bottom Line: There are many factors that
contribute to the development of leaky gut syndrome. In those
with celiac disease or IBS, gluten may be a contributing
Should Everyone Avoid Gluten?
Gluten causes significant problems for some people.
For individuals with celiac disease, gluten increases
intestinal permeability and triggers the autoimmune response
However, the relationship between gluten and intestinal
permeability is complex and not yet clearly understood.
Currently, there is no solid evidence to support that gluten
increases intestinal permeability or causes leaky gut in
If you have symptoms of gluten sensitivity, it may be
beneficial to remove gluten from your diet. You can read more
about eating gluten-free here.
Bottom Line: Those with celiac disease or
gluten sensitivity should avoid gluten. However, there is no
significant evidence that healthy people need to avoid
Factors That Can Improve Your Gut Health
One of the keys to improving your gut health and preventing
leaky gut syndrome is to improve your gut flora. That means
increasing the beneficial bacteria in your gut so they far
outnumber the harmful bacteria.
Here are some ways to improve your gut health:
Probiotics are beneficial bacteria that can improve gut
health. Probiotics are found in foods like yogurt, kefir,
sauerkraut and kimchi. They are also available in a
supplement form (31, 32, 33).
Avoid refined carbs: Avoid
sugar-sweetened beverages and foods with added sugars or
refined wheat flour. The harmful bacteria in your gut thrive
on these foods (22).
Eat plenty of fiber-rich foods: Fruits,
vegetables and legumes are high in soluble fiber, which feeds
the good bacteria in your gut (34, 35).
Bottom Line: Increasing the beneficial
bacteria in your gut may improve your gut health and help
prevent leaky gut syndrome.
Take Home Message
Gluten causes significant problems for sensitive individuals.
Research shows it can increase intestinal permeability, also
known as leaky gut, in people with celiac disease and possibly
However, this does not appear to be the case for healthy
If you think you have symptoms of gluten sensitivity, it may be
beneficial to talk to your doctor and consider trying a