The Dark Side of Dietary Supplements

hand-pillsThe supplement industry is today a billion-dollar market that provides dieters with weight loss pills, protein bars, vitamin pills, and a range of other nutritional products that supposedly enhance human health and well-being. Supplement manufacturers have done such a good job of promoting the idea that their products are the missing piece people need to attain their health and fitness goals that a significant part of the general population is now convinced that supplements are an essential part of a healthy nutritional regimen. This is unfortunate, because the fact is that many, if not most, dietary supplements probably do more harm than good.

Why it’s important to be cautious when interpreting the results from studies on dietary supplements

If you’ve read about popular supplements such as protein powders, vitamin and mineral pills, probiotics, and Branched-Chain Amino Acid (BCAA) pills online or in a health & fitness magazine, you may have gotten the impression that these products provide a range of positive health effects – and that even if they for some reason shouldn’t live up to their promise, no harm has been done, as the potential side effects are minor. As for multivitamin pills, some diet authors and bloggers say that everyone, including those who eat a healthy, nutrient-packed diet, should take a capsule or two with their breakfast every day. After all, more vitamins can’t be a bad thing, right?

Since the potential adverse effects associated with the use of dietary supplements are given little attention in the health & fitness community, it’s not surprising that a lot of people are under the illusion that adding some pills and powders to their diet poses no health concerns. Even a lot of so-called science-based websites make the case that there are no real dangers associated with the use of nutritional supplements such as the ones mentioned previously, and that many, if not most, people will benefit from including various pills and shakes in their nutritional arsenal.

There are indeed many studies out there that seem to show that probiotics, BCAAs, and many of the other products you can find at the shelves in your local health food store enhance human health and physical fitness. The problem is that most of the studies in this area are of short duration, only include one or a couple of endpoints, don’t account for the long-term effects of supplement use, and fail to pick up subclinical adverse effects.

An inharmonious relationship

The systems in the human body that are involved in the digestion and metabolism of food were designed by evolutionary forces to handle a diet of natural, whole foods. The evolutionary mismatch model predicts that the consumption of food products for which the human genome has had scant evolutionary experience will elicit some adverse effects.

One of the main problems with our modern diets is that they largely consist of foods and nutritional products that have a nutrient composition that differs markedly from that of the foods our ancestors ate. The most obvious example is perhaps highly processed, man-made products such as doughnuts, pizza, and chocolate bars, which contain a combination of fat, starch, sugar, micronutrients, and so forth that isn’t found anywhere in nature.

What a lot of people don’t know is that many, if not most, of the other food products you can find at your local supermarket and health food store also have a nutrient composition that deviates substantially from the evolutionary norm. This doesn’t immediately tell us that we shouldn’t eat them, but it should prompt us to think twice and do a little digging in the scientific literature before we put them on our dinner plate.

Just like with highly processed food, the main problem with nutritional supplements is that they have a nutrient composition that differs markedly from that of whole foods. Humans evolved to eat foods in their natural form; natural selection never acted to adapt our bodies to a dietary regime that consists of products with isolated nutrients in a highly concentrated form.

I want to make it clear that this doesn’t immediately lead us to conclude that we should avoid all supplements. After all, the circumstances under which we live today are very different from that of our Paleolithic forebears, and hence, our nutritional requirements may differ somewhat from theirs. Also, it’s of course important to consider what the scientific literature has to tell us about the healthfulness of dietary supplements before we jump to conclusions…

Supplements aren’t harmless

It’s obviously impossible to take an in-depth look at all supplements here, without turning this into a 10.000 word article. Rather, I thought I would summarize the potential adverse effects of some of the most popular dietary supplements that are on the market today.


Multivitamin supplements may interfere with quorom sensing in gut biofilms, cause nutritional imbalances, and increase chronic disease morbidity and mortality (1, 2). If we think about it, this isn’t surprising, because multivitamin supplements contain an abnormal combination and quantity of the different micronutrients.

Taking a multivitamin pill every now and then is unlikely to do you any harm; however, if you take multivitamin supplements on a regular basis, you may obtain a supernormal intake of certain vitamins and/or minerals and impair various absorptive processes.

Whey protein

As I explained in my comprehensive article on whey protein, whey protein supplements have an abnormal nutrient profile, are highly insulinogenic, may destabilize the gut microbiota, can promote the onset or aggravation of acne vulgaris, and contain peptides and hormones that may negatively impact human health. Moreover, most protein supplements contain artificial ingredients that could promote sugar cravings and glucose intolerance, and some also contain high levels of toxic heavy metals.

That said, if you for some reason find it impossible to meet your protein needs through whole food, buying a supplement may be worth considering. In that case, you should look for a high-quality product from a well-renowned manufacturer that contains as few additives and sweeteners as possible. Also, perhaps more importantly, if you’re going to use whey protein powders, it’s probably wise to consume the powder in combination with food, rather than as a stand-alone protein shake, as this may ameliorate some of the negative health effects.


As I explained in my recent article on the topic, probiotic supplements (the ones that are on the market today) don’t provide the range of microorganisms needed to build a diverse, healthy gut microbiota, and the vast majority contain bacteria that are incapable of colonizing the gut. Furthermore, some probiotic supplements and probiotic-enriched drinks may block the development of a diverse, healthy gut microbiota.

One of the few probiotic strains that have displayed an ability to colonize the gut is Escherichia coli Nissle 1917, which is found in products such as Mutaflor (3). The reason many, if not most, probiotics aren’t able to colonize the human gut is simply that they aren’t adapted to live there. Just like a zebra probably wouldn’t make it very long on the streets of Manhattan, a microbe that has evolved to live in milk may not do so well in the human gut. When we isolate specific strains of bacteria for the use in probiotic supplements, we often forget that the organisms we pick don’t necessarily do well outside of their “natural” habitat.

That said, in a not so distant future, a new range of “probiotics” and other microbiome modulators that are a lot more effective than today’s supplements may make their way onto the market. These products will likely consist of different microbes than today’s product, contain a much wider spectrum of microorganisms, and be able to induce more long-lasting effects on the microbiota.

Other popular supplements

Not all supplements are equally bad. While products such as weight loss pills, meal-replacement shakes, and capsules containing various antimicrobial herbs tend to be highly problematic, others have a lot fewer side effects.

Besides probiotic capsules, whey protein powder, and multivitamin pills, supplements containing vitamin D and omega-3 are high on the list of the most popular nutritional products on the market today. Much less is known about the potential negative health effects of these products. Most people today consume suboptimal amounts of omega-3 and spend too little time in the sun, and consequently, the pros associated with using vitamin D and omega-3 supplements may for some outweigh the cons.

Last words

I want to make it clear that certain populations (e.g., severely sick people, elderly) may benefit from using dietary supplements. Also, as mentioned, some people may benefit from supplementing with vitamin D and/or omega-3.

That said, in my mind, there is no doubt that if you can, you should get all your nutrients from real, whole food. To finish off, let’s look at a quote from a 2013 scientific paper entitled Lifestyle and nutritional imbalances associated with Western diseases: causes and consequences of chronic systemic low-grade inflammation in an evolutionary context that elegantly explains why this is the case…

Our diet is composed of millions of substances that are part of a biological network. In fact, we eat “biological systems” like a banana, a fish or a piece of meat. There is a connection between the various nutrients in these systems. In other words, there is a balance and an interaction that is part of a living organism. This balance can be found in the reconstruction of our Paleolithic diet. (4)

Picture: Creative Commons picture by Victor, Some rights reserved.


  1. Hi Eirik. I completely agree. Years ago, when I was doing a lot of hodge-podge supplementing on a “just in case” basis, I happened to mention this to my homeopath. He told me it was a bad idea. One major problem with supplementing with high-dose isolates is that it can eventually disrupt the natural chemical balance of the body. You won’t drop dead on the spot, of course, but it could open the door to problems down the road.

    Another problem with the idea that more is always better is the supplementing of trace minerals that are meant to be in the body in minute amounts, Since these minerals are available in proper proportion in almost everything we eat, assuming one eats a relatively healthy diet, supplementing is usually unnecessary. As you said, it’s much better to derive what we need from real food.

    All that said, I do supplement with vitamin D3 and magnesium. For me, these are probably necessary. I know I don’t get enough sun, and for whatever reason, I don’t seem to process magnesium very efficiently. I tend to get muscle spasms and occasional heart palpitations that disappear when I supplement the mag., even though I eat a pretty healthy diet. I would be interested in your opinion on that.

    • Hi Shary!

      Hope you’re doing well.

      It’s not surprising that you experience these effects when you supplement magnesium, as magnesium helps promote normal heart rhytm and muscle and nerve function. Muscle spasms and heart palpitations can occur as a result of magnesium deficiency.

      As for the cause of your magnesium deficiency, I don’t have much insight to offer, in part because I don’t have detailed information about your medical history, pharmaceutical use, diet, etc.

  2. Hi Erik, I found this article very interesting, I wish it were longer and had gone into a greater array of supplements. Particularly I found the idea that whey protein may be harmful fascinating as there is so much conflicting evidence on this out there. This article from Mark Sisson seems to show quite a wide array of health benefits to consuming whey Have you seen this article before? Would love your thoughts…

    • Hi Evan!

      First of all, let me say that I think Mark Sisson seems like a great guy. There’s no doubt that he has done a very good job in terms of promoting Paleo and bringing people into the ancestral health sphere. Also, his overarching philosophy regarding health & nutrition seems similar to mine.

      That said, I disagree with him on some issues (e.g., supplements, fiber/dietary bulk, saturated fat, dairy).

      If you go to my comprehensive article on whey protein and scroll down to the section entitled “What about the studies that seem to indicate that there are a wide range of health benefits associated with the consumption of whey protein?”, you’ll find an in-depth answer to your question.

      The main problem is that most of the studies in this area are of short duration, only include one or a couple of endpoints, don’t account for the long-term effects of supplement use, and fail to pick up subclinical adverse effects.

      I’d also like to add the following:
      The milk of a species has been “designed” by natural selection to promote the immune maturation and rapid growth of the developing infants of that species. For example, human breast milk contains a range of substances (e.g., whey protein (60% of the protein in human milk), lactoferrin) that have immunomodulatory and/or growth-enhancing properties.

      Given this, it shouldn’t come as a surprise that cow’s milk has been shown to stimulate the growth of children, or that studies have found that foods and supplements (e.g., colostrum capsules, whey protein powder) that contain large amounts of certain compounds found in milk stimulate our immune system and enhance hypertrophy and growth.

      The question we have to ask ourselves is: Are these effects truly beneficial/desirable?

      There’s no doubt that a growing human infant should receive breast milk – and consequently, all of the powerful compounds it contains. However, I’m very skeptical when it comes to isolating specific compounds found in milk, making a concentrated supplement out of them, and then giving that supplement to a human child or adult (Regardless of whether the milk comes from a human, cow, or any other animal).

  3. Hi Evan. Mark Sisson sells supplements, probably including whey protein. That automatically makes his viewpoint a bit suspect since he’s not going to badmouth his source of income. Conversely, Eirik doesn’t appear to sell anything at all; therefore, there’s no conflict of interest.

    I did read the MDA article when it came out but disagree that “most” people have no problem with whey protein. I’ve experimented with several different brands over the years and can’t consume either the concentrate or the isolate without incurring severe stomach upset and diarrhea. There are a lot of lactose/casein intolerant people in the world, so I can’t imagine I’m the only one with a good reason to steer clear of the stuff.

    • You’re definitely not alone in experiencing those adverse effects, Shary.

      I’ve met a lot of people over they years who say they experience digestive issues such as bloating, gas, and/or loose stools when they consume whey protein shakes. This makes complete sense to me, as whey protein powder is a processed food item with a nutrient composition that is very different from that of natural, whole foods. Moreover, as I’ve pointed out before, whey protein shakes can disrupt the gut microbiota.

      That said, I don’t want it to sound like whey protein supplements are on top of the list of things you should stay away from, as there are certainly other supplements out there that are more harmful.

  4. I’d be interested in learning more about the sourcing for supplements. my understanding is that a lot of supplements are manufactured abroad in places like China, where environmental toxins may adulterate many of the minerals and vitamins.


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  2. […] supplements you’re using are doing you more harm than good Replace protein powders, energy drinks, vitamin pills, and other fancy nutritional products with […]

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  4. […] I’ve pointed out on here on in the past, most dietary supplements do more harm than good. “Functional foods” are also problematic. As for pharmaceuticals, some are obviously useful in […]

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