How SIBO Causes Hair Loss and How to Reverse It

Jannika is a Functional Nutrition Counselor and gut health practitioner specializing in chronic digestive issues, including bloating, constipation, IBS, SIBO, and IBD. Through personalized, holistic care and functional lab testing, she helps women identify and address the root causes of dysfunction, restore gut health and reclaim their vitality.

Hair loss has been a huge topic over the last few years and seems like something we collectively experienced after COVID. The internal and external stress of that time was a major catalyst for widespread inflammation, nutrient depletion, and hormonal dysregulation — three things that are deeply intertwined with gut health and hair health. Much like any viral infection, gut-related conditions like Crohn’s, Colitis, and Small Intestinal Bacterial Overgrowth (SIBO) often come with secondary symptoms, and hair loss is a big one.

Over the last year, I’ve noticed a significant change in my hair texture as well as increased thinning, breakage, and shedding. I can’t count the number of times I’ve experienced that dreaded moment of seeing a pile of hair collect in my shower drain…it happens after nearly every shower. And the shedding! There have been way too many times I’ve gotten up from lying on my couch and counted 20+ individual strands of hair left behind on the pillow. That image haunts me.

But the one thing that has given me comfort is knowing that there’s a reason behind my hair loss. Because when you know what’s causing it, you can take the necessary steps to reverse it. With a recent SIBO diagnosis, I have a much clearer understanding of what’s happening in my body and how that correlates to hair loss and poor hair health. If you, too, have been diagnosed with SIBO (or another gut-related condition like IBD) and are struggling with a shine-less mane and shedding like a golden retriever in summer, then this article is for you!

How SIBO Causes Hair Loss

If you’re eating a colorful, nutrient-dense diet and still experiencing hair thinning, brittle strands, and excessive shedding, the issue isn’t a lack of nutrients. It’s a problem with absorption. SIBO creates an internal environment that makes it difficult for your body to properly digest and absorb essential vitamins, minerals, and amino acids required for healthy hair growth.

One of the biggest culprits is iron deficiency, which is incredibly common in those with SIBO. Iron is required to transport oxygen to the hair follicles, and when levels are low (particularly ferritin, the stored form of iron) the follicles become starved of oxygen, leading to excessive shedding and slower regrowth. Many women dealing with hair loss are unknowingly iron deficient because the bacterial overgrowth in the small intestine blocks proper iron absorption, leading to chronic low ferritin levels even when dietary intake is sufficient.

SIBO also disrupts B vitamin absorption, particularly B12, biotin, and folate, which are essential for strong, healthy hair. Biotin is often hailed as the “hair vitamin,” as it plays a direct role in keratin production, the structural protein that makes up hair, skin, and nails. When biotin is deficient, hair becomes weak, brittle, and more prone to breakage. B12, on the other hand, is required for red blood cell formation and oxygen delivery to hair follicles. Without enough B12, hair growth slows, and excessive shedding occurs. Folate deficiency can also contribute to thinning hair by impairing cell turnover and DNA synthesis in the hair follicle.

SIBO also impairs the absorption of key minerals like zinc and magnesium. Zinc is necessary for hair follicle health and plays a role in keratin production, the protein that makes up hair structure. When zinc is deficient, hair becomes thin and weak, and the scalp can become dry and irritated. Magnesium, on the other hand, helps regulate stress hormones and supports overall scalp health. Without sufficient magnesium, stress-induced hair shedding becomes more common, further exacerbating the issue. When SIBO is present, bacterial overgrowth competes for these minerals, leading to deficiencies that can weaken hair structure and contribute to excessive shedding.

Another major way SIBO impacts hair health is by disrupting protein and amino acid uptake, which is essential for strong, resilient hair. Hair is primarily made of keratin, which requires amino acids for its structure. If your gut isn’t properly breaking down and absorbing proteins, your hair lacks the building blocks it needs to remain strong, leading to breakage and slowed growth.

Finally, chronic inflammation and increased stress hormones caused by SIBO can trigger telogen effluvium, a form of hair loss where hair prematurely enters the shedding phase due to internal stressors. When inflammation is high and the body is under stress, whether from gut infections, malabsorption, or chronic digestive distress, cortisol levels rise, pushing hair follicles into the resting phase, leading to hair loss. 

Identify Nutrient Deficiencies

If you’re losing hair despite eating a nutrient-rich diet, the problem isn’t a lack of nutrients — it’s that your body isn’t absorbing them effectively due to SIBO. The first step to reversing hair loss is addressing malabsorption and correcting nutrient deficiencies while healing your gut. 

To determine which nutrients you’re deficient in, it’s best to get a comprehensive blood chemistry test. I recommend checking:

✔ Iron Panel: Ferritin, Serum Iron, TIBC, and Transferrin Saturation to assess iron status and oxygenation of hair follicles

✔ RBC Zinc & RBC Magnesium to evaluate mineral levels in red blood cells, which is more accurate than serum

✔ Vitamin B12 & Folate which is essential for hair follicle health

✔ 25-Hydroxy Vitamin D which plays a role in hair growth and follicle cycling

✔ Plasma Amino Acids to assess protein and amino acid absorption

Once you have your test results, you can correct deficiencies while simultaneously addressing SIBO. Since SIBO blocks absorption, simply taking supplements won’t be enough unless digestion is properly supported. You also need to support nutrient absorption while treating the root cause. You can do this by taking digestive bitters before meals to stimulate digestive enzymes and bile flow. A Betaine HCl supplement that also contains Pepsin can help boost stomach acid to improve protein digestion. 

To improve iron levels, opt for heme iron sources like grass-fed liver, red meat, or iron bisglycinate supplements. Pairing iron with vitamin C-rich foods enhances absorption. For B vitamins, a methylated B-complex ensures better utilization, especially if you have genetic mutations like MTHFR. Zinc and magnesium should be taken in bioavailable forms such as zinc picolinate and magnesium glycinate to maximize absorption and minimize digestive distress.

Since amino acid uptake is impaired with SIBO, increasing collagen peptides, bone broth, and quality animal proteins can help restore keratin production and strengthen hair. These protein sources are also gut-healing, which can help repair the intestinal lining over time.

Managing Stress for Hair Growth

Since digestion and hair loss are both directly impacted by stress, you’ll also want to incorporate a stress-soothing routine that supports your nervous system. Hair shedding is often triggered by stress, whether physical, emotional, or psychological. When cortisol is chronically elevated due to emotional or physiological stress, it signals the body to prioritize survival over non-essential functions like hair growth. This is why women often experience shedding after major life events like breakups, illness, childbirth, or trauma.

Supporting your nervous system is essential for long-term hair health. Vagus nerve stimulation through deep breathing, cold exposure, or humming can help regulate stress responses. Adaptogenic herbs like ashwagandha, rhodiola, and holy basil can reduce cortisol levels and promote hair regrowth. Prioritizing high-quality sleep and balancing blood sugar through can also help stabilize stress hormones and minimize hair fallout.

Targeted Hair Growth Nutrients

Once digestion is restored, your gut heals, and nutrient absorption improves, your hair will naturally regrow. To further support healthy hair, here are some targeted nutrients and practices:

✔ Collagen Peptides & Bone Broth → Rebuilds keratin & supports gut lining 

✔ Grass-Fed Liver → Best natural source of iron, B12, biotin, zinc, vitamin A 

✔ Silica-Rich Foods → Horsetail tea, bamboo extract, nettle tea 

✔ Scalp Massage with Rosemary Oil → Increases blood flow and supports follicle stimulation 

✔ Red Light Therapy for Hair Growth → Improves circulation & follicle health

If your hair is thinning, breaking, or shedding excessively, don’t ignore your gut health. Hair loss isn’t just about what you eat, it’s about what you absorb. Addressing SIBO, restoring nutrient levels, and managing stress will help you regain stronger, healthier hair. Healing takes time, but with a targeted approach, your hair will grow back thicker, shinier, and healthier than before.

Let me know in the comments: Have you noticed hair loss alongside gut issues? What’s been your biggest struggle? 💛