How DAO Enzyme Deficiency Affects Histamine Intolerance and Why Zinc & B6 Matter

Editoral Team
Feb 1
3 min read

Updated: Feb 17

Introduction

When it comes to histamine intolerance, most people focus on avoiding trigger foods or taking DAO supplements. But have you ever wondered why some people react to histamine even when their DAO enzyme levels seem normal?

A 2024 study by Seidl, Kellner, and Maier, titled "Unraveling Histamine Intolerance: Exploring DAO Quantity, Elimination Ratios, and Cofactor Influences," digs deep into the biochemical puzzle of histamine intolerance. The research reveals how not just the amount of DAO matters, but also how efficiently it works—and how nutrients like vitamin B6, copper, and zinc play a critical role in this process.

A wooden tray with assorted cheeses and red grapes on a dark surface. Cheeses include wedge shapes, round brie, blue, and aged pieces. — A diverse selection of aged cheeses, known for their rich flavors but potentially high histamine content, which can be problematic for individuals with histamine intolerance.

What Is DAO and Why Does It Matter?

Diamine oxidase (DAO) is the primary enzyme responsible for breaking down histamine in the body, especially histamine from foods. When DAO levels are low—or when the enzyme isn’t functioning properly—histamine can build up, leading to symptoms like:

Headaches and migraines
Digestive issues (bloating, diarrhea, nausea)
Skin reactions (hives, flushing, itching)
Heart palpitations and blood pressure fluctuations

But here’s the twist: some people with normal DAO levels still experience these symptoms. This study explains why.

Key Findings from the Study

1️⃣ It’s Not Just About DAO Quantity—It’s About DAO Efficiency

The researchers found that having normal DAO levels doesn’t guarantee that the enzyme is working effectively. This is where the concept of DAO elimination ratios comes in.

DAO Elimination Ratio: This measures how efficiently DAO breaks down histamine over time.
Some individuals had normal DAO levels but poor elimination ratios, meaning the enzyme wasn’t processing histamine fast enough to prevent symptoms.

2️⃣ The Role of Nutritional Cofactors

DAO is like a car—it can have a full tank (enzyme quantity), but without the right parts (nutritional cofactors), it won’t run efficiently. The study highlights the importance of:

Vitamin B6: Essential for DAO activity; a deficiency can reduce the enzyme’s effectiveness.
Copper: Acts as a cofactor that supports the structural integrity of DAO.
Zinc: Helps regulate DAO function and supports the immune system, which can indirectly affect histamine levels.

Without these cofactors, DAO can’t do its job properly, even if you have enough of it in your system.

3️⃣ Nutrient Deficiencies and Histamine Intolerance

The researchers discovered that many individuals with histamine intolerance symptoms had suboptimal levels of vitamin B6, copper, or zinc. When these nutrient deficiencies were corrected, histamine-related symptoms improved, even without increasing DAO levels.

What Does This Mean for You?

If you’re dealing with histamine intolerance symptoms, this study suggests that you should look beyond just DAO supplements. Consider:

✅ Testing for nutrient deficiencies, especially vitamin B6, copper, and zinc

✅ Improving DAO efficiency through dietary changes and targeted supplementation

✅ Working with a healthcare provider to explore both DAO levels and cofactor status

How to Support DAO Function Naturally

1️⃣ Eat a Nutrient-Rich Diet:

Vitamin B6: Found in chicken, bananas, avocados, and potatoes
Copper: Found in shellfish, seeds, nuts, and dark chocolate
Zinc: Found in red meat, legumes, and pumpkin seeds

2️⃣ Consider Supplements (If Needed):

DAO supplements may still be helpful, but make sure you’re also supporting the cofactors that help DAO work.

3️⃣ Manage Gut Health:

Gut inflammation can reduce DAO production. A healthy gut = healthier DAO activity.

4️⃣ Track Symptoms:

Keep a histamine symptom diary to see how changes in diet or supplementation affect your symptoms.

Final Thoughts on DAO Enzyme Deficiency and Histamine Intolerance

Histamine intolerance isn’t just about how much DAO you have—it’s about how well that DAO works. This study by Seidl, Kellner, and Maier shows that nutritional cofactors like vitamin B6, copper, and zinc are key players in the histamine equation.

If you’ve been struggling with unexplained symptoms despite normal DAO levels, it might be time to look deeper into nutrient deficiencies and enzyme efficiency.

Disclaimer

This blog post is for informational purposes only and presents findings from recent research on histamine intolerance. It is not intended as medical advice, diagnosis, or treatment. If you suspect histamine intolerance or have concerns about your health, consult a qualified healthcare professional.

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