Spirulina and Constipation – What You Need To Know

toilet-paper-150912__180Constipation seems to be one of the most common talked about side effects to consuming spirulina. But is there any truth to this? Are spirulina and constipation linked? To answer this question I looked into what it is about spirulina that could potentially cause constipation.

And what I found is somewhat of a mixed view. While some of the many nutrients in spirulina can cause constipation, there are also properties of spirulina that should actually reduce the chances of constipation.

But lets begin by going over some of the reasons why spirulina may be causing constipation.

Why Spirulina Might Be Causing Constipation

Iron May Be The Cause

Studies show that too high of a dietary iron intake will indeed cause constipation. And spirulina does contain a hefty amount of iron, about 2mg of iron for every tablespoon (7g) of spirulina.

Iron is absolutely an essential nutrient that is active in the production of red blood cells in the body. It should definitely not be avoided if you are experiencing constipation. Instead, you should asses the amount of iron you are actually taking.

Of course you don’t want to be constipated from taking in too much iron, but on the other hand you definitely don’t want to be deficient.

Could It Be The Protein?

The fact that too much protein can cause constipation is well known. Protein digestion uses a lot of water causing you to become dehydrated in some cases. And this in turn can cause constipation.

Spirulina just so happens to be the most protein dense food on the planet, with anywhere from 55-70% of its dry weight being protein.

Now I know that if you are taking spirulina supplements, chances are you aren’t taking very much. Most spirulina supplements have recommended daily doses of anywhere from 2-10 grams. And thats really not that much. Even if you took 10 grams per day and that was 70% protein (on the higher end) you still would only be getting 7 grams of protein from the spirulina.

But here is my theory. Its more concentrated in protein than any other food. So your body isn’t used to this. There is too much protein compared to the water, fiber, etc. that you are eating with your spirulina. And with a ratio of protein to water & fiber that is too large, constipation is a side effect.

If this is potentially the reason spirulina causes constipation, I would simply suggest that you drink more water or even eat some other foods while you are supplementing your spirulina.

There was really not that much information that I could find on why spirulina is causing constipation. But I do know that there are a lot of people that are experiencing constipation from spirulina. This is an area where there needs to be more research done.

Besides the reasons of why spirulina might cause constipation, I found reasons why spirulina should actually prevent and stop constipation.

Why Spirulina Also Prevents Constipation

One reason for constipation is inflammation. This is the cause in problems like Irritable Bowel Syndrome and Inflammatory Bowel Disease.

Spirulina has some very effective anti-inflammatory agents that are used to treat a wide range of problems. Two of its most powerful are Gamma-linolenic acid and phycocyanin, which I will go over.

Gamma-linolenic Acid Is A Treatment

Gamma-linolenic acid (GLA) is commonly supplemented to treat conditions like constipation. And you guessed it, spirulina contains GLA, and is one of the most concentrated GLA food sources there is, with about 94.5mg of GLA for every tablespoon (7g) of spirulina.

GLA is converted into prostaglandins in the body. Prostaglandins are hormone-like substances that control various processes. They are able to influence inflammation in the body, decreasing it and increasing it depending on the situation..

Phycocyanin, The Powerful Anti-Inflammatory Agent

Phycocyanin is the blue protein pigment that gives spirulina part of its blue-green color. It is a fascinating part of spirulina and has been the subject of many studies. It has a lot of benefits, anti-inflammation being one.

Phycocyanin inhibits the COX-2 enzyme, which is the enzyme responsible for much of the inflammation that goes on in the body [1]. There are many synthetic drugs that are designed to block this enzyme, but phycocyanin does it all naturally, which in my opinion is better.

The anti-inflammatory effects of phycocyanin are well documented and all seem to agree with the fact that it is a great natural anti-inflammatory agent.

Both GLA and phycocyanin are great natural sources for anti-inflammatory effects. They can both be used to treat constipation depending on the cause of constipation. Irritable Bowel Syndrome and Inflammatory Bowel Disease both often cause constipation and can be treated with anti-inflammatory agens like GLA and phycocyanin.

So with that in mind, spirulina is a great anti-constipation supplement.

Should You Take Spirulina?

Well it seems that spirulina would be very effective in treating constipation arising from certain problems that cause inflammation. But then again, it seems to give people constipation.

If you do have Irritable Bowel Syndrome or Inflammatory Bowel Disease then I think it would be worth a try. But if you don’t and suddenly started to experience constipation after taking spirulina then I have a different suggestion.

If your constipation isn’t that bad I would continue to take the spirulina to see if the body gets used to it. Because I know that when I first started supplementing spirulina that my stomach was uneasy. It took me about a week to get over that and know I’m fine.

But if your constipation is severe I would suggest seeking medical advice and stop taking spirulina for the time being.



1) Selective inhibition of cyclooxygenase-2 by C-phycocyanin, a biliprotein from Spirulina platensis. Biochem Biophys Res Commun. 2000 Nov 2;277(3):599-603.

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