Does Tuna Fish Cause Constipation or Hemorrhoids?

Andy Paras

8 Jun, 2026

Does Tuna Fish Cause Constipation or Hemorrhoids?

Last Updated: May 2026 | Medically Reviewed | Based on Clinical Research

Tuna is one of the most popular proteins in the world — cheap, easy, and packed with nutrients. But if you're dealing with constipation or hemorrhoids, you might be wondering: is tuna part of the problem?

The honest answer is — it depends on how you eat it. Tuna itself isn't inherently bad for your gut, but there are a few things about it that can make constipation worse if you're not careful.

Let's break it all down.

What's Actually in Tuna?

Before we can answer the question, it helps to know what tuna brings to the table nutritionally:

High protein — around 25g per 100g serving
Omega-3 fatty acids — known for anti-inflammatory benefits
Low fiber — essentially zero
Low fat (especially canned tuna in water)
Rich in magnesium — a mineral that supports bowel regularity

The zero-fiber content is the key issue here. Your digestive system needs fiber to keep stool soft and moving. Tuna, like all animal proteins, contributes none of it.

Does Tuna Cause Constipation?

Tuna doesn't directly cause constipation — but eating too much of it, especially without balancing it with fiber-rich foods, absolutely can contribute to it.

Here's why:

1. No fiber means slower transit Fiber is what adds bulk and moisture to stool. When your diet is heavy in protein and low in fiber, stool moves more slowly through your colon, dries out, and becomes hard and difficult to pass.

2. Canned tuna in oil adds saturated fat Tuna canned in oil — especially if it's a cheap vegetable oil — can be harder to digest for some people. It's not a major driver of constipation, but it doesn't help either.

3. Sodium content in canned tuna Many canned tuna brands are high in sodium. Excess sodium pulls water out of your body, which can contribute to harder stools. If you're already dehydrated, this makes things worse.

4. The mayonnaise problem Most people don't eat tuna alone — they mix it with mayonnaise, which is high in fat and contains no fiber. A tuna sandwich on white bread is essentially a fiber desert. That combination can stall your digestion pretty quickly.

Does Tuna Make Hemorrhoids Worse?

Not directly — in fact, tuna has some properties that may actually help hemorrhoids:

Omega-3 fatty acids in tuna have anti-inflammatory effects that could theoretically reduce the inflammation associated with hemorrhoids
Magnesium supports muscle relaxation and softer stools, which reduces straining

The problem isn't the tuna itself — it's the constipation that tuna-heavy, low-fiber diets can cause. Constipation is one of the primary triggers of hemorrhoid flare-ups because straining puts intense pressure on the rectal veins.

So the real risk is indirect: eat lots of tuna, eat little fiber, get constipated, strain on the toilet, make hemorrhoids worse.

How to Eat Tuna Without the Constipation Risk

Good news — you don't have to give up tuna. You just need to eat it smartly:

Always pair tuna with fiber-rich foods — whole grain bread, a side salad, avocado, or raw vegetables
Choose tuna in water, not oil — less fat, easier to digest
Watch the sodium — look for low-sodium canned options
Skip the mayo or use it sparingly — try plain Greek yogurt as a substitute; it adds probiotics
Drink water — especially when eating high-protein meals

Conclusion

Tuna fish doesn't cause constipation or hemorrhoids on its own. But a diet that leans heavily on tuna without enough fiber and water can absolutely slow your digestion and make hemorrhoids worse over time.

Eat it in balance, pair it with plants, and stay hydrated — and tuna can actually be a solid part of a gut-friendly diet.

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📚 Medical Sources

National Institute of Diabetes and Digestive and Kidney Diseases. Constipation. https://www.niddk.nih.gov/health-information/digestive-diseases/constipation
Mayo Clinic. Hemorrhoids: Symptoms & Causes. https://www.mayoclinic.org/diseases-conditions/hemorrhoids/symptoms-causes/syc-20360268
Harvard T.H. Chan School of Public Health. Fiber. https://www.hsph.harvard.edu/nutritionsource/carbohydrates/fiber/