I have been an avid fitness enthusiast / bodybuilder for a few years. It was about 3 years ago that I quit and started practicing kickboxing. Last week I resumed fitness and it feels good to be lifting weights again. I really enjoy my sport and am planning to treat my food intake et cetera seriously in order to get the best results.

My ex-father in law who was a doctor said whey will clog your intestines.

Something that haunted my head for the last week is the question if whey protein shakes are bad for your health? I remember my ex girlfriend saying something like that and now I want to know the facts. In fact it was her stepfather who now is a retired general practitioner who said the powder can be harmful. Do whey and other protein shakes leave a residue in your colon, are they bad for your liver, do they damage your kidneys, or is this a fable? Here’s a write-up on what I have learned.

Mixed views are abundant

When searching online both proponents and opponents of proteins shakes come up with convincing arguments. At first. When digging some more I do think I have a pretty clear and sound view on this matter. I must say that I did not find much study reports or other research findings regarding this subject. This post is more of a view of my opinion than a well-researched paper. Nevertheless I think I’m spot on.

Whey proteins are a quickly digested source of amino acids which makes them available for the muscles almost direct after training. These branched-chain amino acids (BCAAs) as they are called help recover muscles after working out and stimulate muscle repair, thus growth.

Healthy use of whey as a supplement?

Those who warn for the dangerous health benefits of whey protein commonly state that its quality isn’t by far as good as the proteins present in meat, eggs, or fish. I can relate to that opinion. Vitamins in fruit and vegetables are of a better quality than those in supplements. But sometimes you can’t get it all from your food intake and that’s where vitamin pills or protein shakes come into play.

Another frequently heard warning is that these shakes are loaded with toxins. I don’t think this is true because I didn’t find any trustworthy source confirming this claim. There may be tiny, negligible quantities of heavy metals and other less wanted substances but that applies to many other nutrients as well.

Intestinal toxemia

I could not find any proof that the statement that whey protein powder clogs in your colon is true. I did read that intestinal toxemia is supposed to be caused by protein shakes. In fact this ailment occurs due to many different nutrients and yes, it may be caused by excessive whey intake. Not by taking a few shakes a week. I believe avoiding such ailments is merely a matter of a varied diet and perhaps being lucky not to be genetically predisposed to such conditions.

Protein shakes also don’t, by definition cause stomach problems, unless you have some kind of special sensitivity to them. As for any nutrient, if it hurts your stomach, stop using it. Whey protein is reported to make some people pass gas or belch a little bit. Whey does not cause ‘weight to stick’. Yes it potentially does, as will any nutrient do, if you take too much of it.

Too much of anything is never good… Well except for a few things of course..

I am convinced that whey protein shakes CAN cause kidney, liver, and colon damage. But only if you overdo taking them. Excessive intake of protein may result in your kidney having difficulties to metabolize the proteins. Scientific backing to support the claim that excessive intake of protein may cause kidney damage lacks. As is the same for the other health compromising claims regarding whey.

In fact, several studies show beneficial effects of whey protein supplements regarding treatment of diseases;

“Results from animal studies suggest that whey protein, but not casein protein, may provide protective effects against experimentally induced breast cancer in animals.”
Source: American Association for Cancer Research.


We and others have demonstrated that whey protein diets result in increased glutathione (GSH) concentration in a number of tissues, and that some of the beneficial effects of whey protein intake are abrogated by inhibition of GSH synthesis.
Source: Whey Proteins In Cancer Prevention – Anticancer RESEARCH 15: 2643-2650, 1995


I think the claim that whey protein powders and creatine are just worthless, harmful by-products of the dairy industry production dumped on the sports market to make some easy bucks is an old wives tale. Protein shakes are a valid option to increase protein when you are a bodybuilder or other type of athlete that wants to grow muscles more quickly.

On the one hand I do believe that natural sources are the best option but whey protein shakes can provide something extra. For example when you don’t have the opportunity to eat five or more meals a day containing meat, chicken, fish, cottage cheese, yogurt, milk, eggs, tofu, nuts and seeds. And let’s be realistic, who has that much time and opportunity. So I will be happily ordering my whey protein powder. (This is my favorite whey protein)

But I won’t drink two shakes a day like a friend of mine does. That may very well be unhealthy. I’m convinced about that. I don’t take multivitamin supplements each day as well. I take them a few times a week. Moderate behavior is healthy. Even when it comes to things that are good for you. In the end it’s all about common sense. If you have another opinion, or know about some studies I missed please let me know below.


Recently I spoke with a nutritionist and he told me that you actually need (whey) protein shakes in case you exercise a lot like I do. It’s very difficult to get all those proteins from your daily food intake.

At the moment I also take MMA classes but lately I noticed being tired all the time. I was told to take probiotics for recovery since balance in the intestinal flora seems to be very important. It’s been three weeks now and I feel fitter already. Anyone else experiences with probiotics for overall well-being and fitness?

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Filed under: fitness supplements

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