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Do green pills help athletes?

I was recently asked whether there was any basis for the claims that were made about a particular supplement (see this article in Outside Magazine by Erin Beresini). The supplement has been around for a long time but is more recently targeted towards athletes in an attempt to help their performance. The first step of any analysis is that you check the claims. One should always be suspicious if a product claims to do everything from improving performance to immune function to preventing diseases etc and it works for athletes in sports like sprinting to ultrarunning, as well as skill based sports. If something seems too good to be true, it usually is.

Algae spirulina chlorella supplements for athletes

Spirulina and chlorella

The supplements in question were spirulina and chlorella, two types of algae. The algae are dried and processed into powder and it is sold as a green powder or pills. The claims included improved performance, immune function, recovery, energy etc. So what is the magical ingredient? Apparently it is because of a high protein content, high vitamin B2 (riboflavin) and vitamin B12 and because it is extremely nutrients dense. No magical ingredients. Ingredients we find in foods compressed in a pill.

A source of protein?

One consistent message on all spirulina and chlorella supplement web sites is that they are great sources of protein. Are they? Per gram this is correct, but there are much easier and cheaper ways to get protein. One pill (tablet) will contain approximately 150 milligrams of protein. The advice that is often given to athletes is 20-25 grams of protein. That means you would have to ingest approximately 150 tablets. A lot of tablets!!

One pill (tablet) will contain approximately 150 milligrams of protein. Athletes are often advised to have 20-25g of protein.

One serving is typically 30 tablets. The amount of protein found in 30 tablets is the equivalent of half a glass of milk. One almond has more protein than 1 tablet of spirulina. Small servings of turkey, chicken breast, steak, and nuts will provide more protein than a handful of pills, and will be a lot cheaper as well.

Vitamin B12

It has been shown that the high vitamin B12 contents are mainly due to contamination with insect or animal fecal matter. This is not surprising since spirulina grows in open lakes and ponds and is not thoroughly washed before it’s dried. If you don’t care about this as an athlete and you just want Vitamin B12 to boost your energy levels, there is another disappointing message: There is no evidence that vitamin B12 supplementation has any effect on performance.

The high vitamin B12 contents are mainly due to contamination with insect or animal fecal matter

I read with great interest the claims on chlorella that related to its component chlorophyll! Chlorophyll is the compound in plants (and algae) that gives it its green colour. It is extremely important for plants as it helps to absorb energy out of sunlight. This energy is used for photosynthesis and this is how plants grow. But now the claims seem to be that chlorophyll helps us humans to make energy out of light!! Really?? Humans do have photosynthesis??? I always learned that plants grow through photosynthesis and produce oxygen in the process. I did not know humans could do the same. I was intrigued and read a little more.


The evidence provided is a paper that shows very interesting results:

Worms exposed to sunlight make more ATP (the molecule that is used as energy in cells). Worms fed a chlorophyll metabolite accumulate this metabolite, and when exposed to light produce more ATP.

This is certainly interesting! The paper also shows that a metabolite of chlorophyll can also be found in cells of rats and pigs if fed chlorophyll metabolites. This is probably true for many things we eat: metabolites of what we eat end up in the cells of our body. What the paper did NOT show is that these rats and pigs can now produce more energy. In humans there is no data.

Even if chlorophyll metabolites accumulate say in our muscles, how much light is getting into the muscle to start photosynthesis? And IF small amounts of light would actually reach the muscle and IF this starts the process of ATP production, how much ATP could actually be produced? The authors of the paper clearly state that there is no evidence and these are mere suggestions and possibilities that need to be studied further.

I could continue to examine all the claims and all the ingredients of these green pills and check the evidence. Here, I have only discussed some of the most important claims and ingredients and unfortunately I would have to stick with my first conclusion: If the claims seem too good to be true, they probably are.



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