Did you know that the foods you eat during a detox diet actually contain the very toxins you are trying to avoid? And there’s an evolutionary explanation for this.

In this article, I am referring to those detox diets that consist of avoiding all foods except some combination of fruits, vegetables, and water. The main purpose of these diets is to give the body a break from foods containing toxins, contaminants, heavy metals, and potential allergens.

Despite widespread popularity, scientific research has not found support that detox diets actually rid the body of toxins. If you want to know more about why these diets do not detoxify, then follow this peer-reviewed article and the articles that cite it.

Not only do detox diets not work, but they also do not make sense from the standpoint of evolutionary theory. This perspective is less known to the public, perhaps because anyone who reads this is going to think I am promoting a bread and cheese diet… which, honestly, wouldn’t be such a bad idea (totally kidding).

From an evolutionary biological perspective, toxins are actually found in the very plant-based items that cleansers are consuming during their detox diets. WHAT???

Yes, you read that correctly. In fact, plants evolved chemical defenses to ward off herbivores. Also known as plant secondary compounds (PSCs), these naturally occurring chemicals can have “toxic” effects on consumers, such as immediate vomiting and nausea, and in extreme cases, death. Common PSCs are alkaloids such as nicotine, caffeine, and cocaine. Side effects of consuming these toxins are both positive and negative – depending on an individual’s unique physiology and the cultural context where consumption takes place. For example, nicotine, a tabooed substance in the U.S., can increase alertness and reduce fatigue, but can also disrupt fetal development.

Throughout the course of human evolution, we have evolved specific reactions to “cope” with toxins in order to extract the beneficial constituents from plants such as antioxidants, but to buffer against the harms. You know those bitter greens you love to juice during a cleanse? Well, bitter taste is considered a signal of toxicity. Kale, broccoli, bok choy – all of these vegetables are considered cleanse-worthy consumables, yet all contain phytotoxins and taste bitter when eaten raw.

While some of you are probably thinking, “but these also have antioxidants and other nutrients that improve my health.” Yes, that is true – which means that the feel-good symptoms you experience from going on a plant-based “cleanse” are likely the health-enhancing features of consuming plants… however, you are still consuming toxins – so you are not detoxifying your body by going on these diets.

According to evolutionary theory and several lines of supporting evidence, plant-based toxins such as those bitter-tasting substances found in many vegetables, are among the most common aversions and avoidances reported by people who are vulnerable to the effects of toxins. These individuals tend to be biological females – who happen to have more bitter taste receptors than men. For more information on the biological reasons why women are more likely to have aversions to toxins, then read this article and this one. To sum up though, women – especially pregnant women – are more susceptible to the harms of toxins and therefore are more likely to experience aversions & disgust when they consume toxic plants.

Does that mean a pregnant woman should stop eating kale? NO. In fact, this whole toxin-avoidance spiel already made its rounds in the public sphere when Margie Profet, the woman who pioneered this theory, went public with her ideas and recommended that pregnant women avoid vegetables. I am not saying that we should avoid vegetables, instead, I want readers to know that aside from the fact that you are eating toxins in your detox diets, that humans have already evolved many ways to cope with toxin ingestion. Among these are physiological responses like vomiting, nausea, and bitter taste. In addition, humans created medicines, like Kaopectate, to reduce symptoms of toxin ingestion, such as nausea and vomiting. In some tropical regions of the world where red clay is common, many pregnant women report consuming clay to alleviate upset stomach and quell nausea and vomiting. Some scientific reports indicate that these clays have the ability to bind to toxins.

Again, I am not suggesting that anyone should go and eat clay, even though it is gaining popularity among celebrities. The point is that this behavior – geophagy –  is an immediate defense against consuming plant toxins that gave consumers a negative physiological reaction, such as nausea and vomiting.

In conclusion – the detox cleanses you are following are not detoxing you in the physiological way you might intend. From an evolutionary perspective, the very foods are you are consuming are actually the culprits with which humans have long-standing evolutionary relationships. If your detox diets are making you feel healthier and improving digestion, then by all means – keep doing them, but please stop calling them detox diets because you are not avoiding toxins after all. The human body has already been processing those for hundreds of thousands of years.