The Gut-Hair Loss connection: Fix the Gut to Stop Hair Loss

Hair loss isn’t just an external problem.

It might be an eye sore (for you), but it’s also a gut sore.

It’s only a symptom that shows that things in the body aren’t functioning optimally. And the symptom doesn’t have to appear immediately when things start to go wrong internally. For example, developing nutrient deficiencies often happen a decade or more earlier, before something like Celiac disease manifests. The body is oftentimes very resilient and can tolerate suboptimal lifestyle habits, dietary measures (a suboptimal diet), etc, for a very long time before things actually start to surface and show that there’s some stuff going wrong.

Similarly with hair loss; lifestyle and diet aren’t optimal, hence gut issues start to develop, and after a few years, hair loss might also appear as a symptom.

Gut-hair loss connection

There are many different kinds of hair loss.

According to this multicenter study (from twenty-two specialist hair clinics, with a total of 2,835 patients), 57 different types of alopecia were characterized (R). The most frequent types were:

  • Androgenetic alopecia (AGA) (37.7%)
  • Alopecia areata (AA) (18.2%)
  • Telogen effluvium (TE) (11.3%) (a form of temporary hair loss that usually happens after stress, a shock, or a traumatic event)
  • Frontal fibrosing alopecia (FFA) (10.8%)
  • Lichen planopilaris (LPP) (7.6%)
  • Folliculitis decalvans (FD) (2.8%)
  • Discoid lupus (1.9%)
  • Fibrosing alopecia in a pattern distribution (FAPD) (1.8%)

However, regardless of the type of hair loss, it always involves some form of inflammation. And if you don’t know already, the gut can be a major source of inflammation.

Most people might think that what happens in the gut stays in the gut. But by now we know that that is far from true. Inflammation in the gut can have a negative influence on almost all tissue in the body.

How the gut and scalp are connected

Most hair loss types (e.g. alopecia areata (patchy hair loss), androgenetic alopecia, Telogen effluvium, etc.), if not all of them, are connected to stress. Stress releases cortisol, which causes leaky gut.

Leaky gut allows undigested food particles, endotoxins and other bacterial products to enter the body where the immune system attacks them. This create a massive amount of inflammation.

This inflammation isn’t just limited to the gut or close to around the gut, but it can reach tissue far from the gut, such as the heart, thyroid, brain, scalp, etc.

There is evidence that a gluten-free diet (since gluten can cause leaky gut and an immune response) can stimulate hair regrowth in alopecia areata patients with concomitant celiac disease (R). Point being, eliminating the source that is causing you inflammation could potentially stop hair loss and promote regrowth.

Gut microbes and the immune system

As mentioned above, an overactive immune system and inflammation could potentially speed up hair loss (in e.g. Alopecia areata (R), Androgenetic Alopecia (R), Cicatricial alopecia (R), etc.).

And it’s not just leaky gut or stress that can cause it, but the microbes themselves. The gut microbiota influences the differentiation of adaptive immune cells not only in the gut but also in the skin (R).

Small intestinal bacterial overgrowth (SIBO) is a bacterial infection of the small intestine
caused by too much bacteria, or the wrong type of bacteria in the wrong place.

SIBO can also cause inflammation and increased intestinal permeability. SIBO is increasingly common and tightly coupled to 50+ diseases, many of which are autoimmune conditions.

There is some clinical and experimental evidence indicating that Alopecia Areata is the demonstration of an autoimmune attack against hair follicles which causes an inflammatory condition of the hair follicle (R).

There are 2 case reports where two male subjects with alopecia universalis experienced hair regrowth after a fecal microbiota transplant (FMT) for the treatment of recurrent C. difficile infections (R).

Even bacteria that are thought to be beneficial, such as Lactobacillus, could cause issues. Nair et al. demonstrated the necessity for Lactobacillus in the gut microbiome for the induction of Alopecia Areata (R).

Having a balanced microbiome is thus essential for a tight epithelial barrier and a functional and regulatory immune system.

Furthermore, according to this study, TLR9 (which senses bacterial DNA), is significantly upregulated by 2.37 fold in Alopecia Areata PBMCs (peripheral blood mononuclear cells).

Notably, TLR9 was most significantly upregulated in patients with active AA, as shown by a positive hair pull test, compared to stable AA patients. In hair follicle bulbs from AA patients, IFNG and TLR7 exhibited statistically significant 3.85 and 2.70 fold increases in mRNA, respectively. Immunohistology revealed TLR7 present in lesional follicles, while TLR9 positive cells were primarily observed peri-bulbar to AA affected hair follicles. The increased expression of TLR7 and TLR9 suggest components of the innate immune system may be active in AA pathogenesis.


Although I can’t find much on the other TLR proteins in hair loss, I’m sure their are involved if there is also SIBO present.

Endotoxins, produced by gram negative bacteria (especially the Enterobacteriaceae family) are highly inflammatory, and are involved in many degenerative diseases, so I can’t see why they are not involved in hair loss as well. A few good TLR2 and TLR4 antagonists include: white willow bark, uva ursi, Ceylon cinnamon, sweet chestnut leaf extract, etc.

The gut-micronutrient-hair loss connection

Gut inflammation causes destruction of the part of the gut (e.g. villi) that are necessary for the absorption of nutrients, such as vitamins and minerals. This can lead to a reduction in the absorption of highly beneficial micronutrients, such as magnesium, zinc, selenium, iron, B-vitamin, etc.

Furthermore, enhanced absorption of endotoxins and exaggerated gut inflammation significantly increases the risk of developing liver conditions (e.g. NADLF, NASH, cirrhosis) (R) as well as kidney dysfunction (R, R). This disrupts normal hormone activation, micronutrient metabolism, glycogen storage, toxin deactivation and detoxification, etc.

Reduced organ function can also contribute to micronutrient wasting.

Micronutrient deficiencies by itself can contribute to impaired gut barrier integrity, suboptimal immunity, exaggerated inflammation, thyroid dysfunction, hormonal imbalances, hair loss, etc.

Furthermore, the inability to detox toxins can also contribute to hair loss. This study in 30 patients with Alopecia areata found that serum zinc and manganese levels were significantly lower and serum cadmium, iron, magnesium, lead, cobalt, and copper levels were significantly higher in the patient group compared to that of the control group (zinc, for example, is needed for the detoxification of heavy metals) (R). Heavy metals such as mercury, cadmium, and lead have been shown to trigger the induction of autoimmunity and to be associated with autoimmune disorders.


Even if the gut is not the major contributor to your hair loss, it’s most likely still involved. So optimizing gut health on your journey to regrowth is a good idea. The more areas you can cover to restore health, the better.

A few major things that can negatively influence the gut include:

  • Lack of sunlight
    • Lack of sunlight can negatively affect the microbiome of your gut, skin and hair. If your hair is rarely exposed to sunlight, but frequently to shower water, cosmetics (shampoo, hair styling gels, etc.), moldy indoor air, dust mites, etc., your scalp microbiome will be negatively modulated and you can start getting scalp inflammation.
  • Stress
  • Drug use (a recent study showed that 24% of non-anti-biotic drugs have anti-microbial properties. This includes anti-depressants (SSRIs, SNRI, atypical anti-depressants, etc.), PPIs, fibrates, statins, etc.)
  • Slow transit time
    • This could be due to eating too much fiber, having gut inflammation, not moving enough, eating the wrong kinds of foods, stress or other bad emotions, etc.
  • Having micronutrient deficiencies

If you’re interested in improving gut health through non-diet related tactics, check out this article.

In summary, the gut can be a major source of inflammation and can also mess with the absorption, storage, turnover and excretion of valuable vitamins and minerals that you may need for optimal health.

Download this PDF that will show you 5 major things you can do to stop further hair loss and promote hair regrowth

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