If you’re feeling a bit sluggish, there’s typically no quick fix; nurturing your health is a long-term endeavor. But that doesn’t stop marketers from gumming up the airways with advertisements about the latest fad diets. One such diet that keeps being revived is called …
Aka “detox diet”. But whichever label you prefer, you’ll be hard-pressed to associate it with a clear-cut definition. Presumably, the goal of a detox is to cleanse the body of harmful substances, often called toxins, usually through some type of highly restrictive diet (with a possible seasoning of supplements). Some cleanses are aimed at specific organs, while others aim to purify you from head to toe.
As a rule, detox diets are very restrictive. Food is commonly limited to fruit and vegetable juices, or other approved drinks. The Master Cleanse, for example, prescribes 6–12 glasses of lemonade with maple syrup and cayenne pepper. Ingested daily as your only sustenance, this concoction supposedly removes all toxins from your body and, according to its creator, supports the elimination of every kind of disease.
While detox diets differ in their minutiae, no specific protocol is worth dissecting in detail since it will soon fall out of favor as another variant becomes the next fad.
In a nutshell, detox diets hinge on the premise that the human body accumulates toxins which various super-restrictive diet protocols can eliminate.
According to the U.S. National Library of Medicine, “toxins are substances created by plants and animals that are poisonous to humans. Toxins also include some medicines that are helpful in small doses, but poisonous in large amounts.” (As we shall see, any substance can be toxic, depending on dosage.) In colloquial speech, “toxins” can also refer to toxicants, which are man-made poisons found in the environment, usually due to pollution.
In the context of detox diets, however, a “toxin” is any substance that is believed to be toxic or noxious and presumably accumulates in the body over time, which is why you need this detox right now to get rid of them before they do more damage to your health. Notable mentions include heavy metals, pollutants, pesticides, preservatives, food additives such as food colorings and artificial sweeteners, added sugars like high-fructose corn syrup (HFCS), and synthetic chemicals in general.
However, while breathing pesticides or drinking pollutants is unambiguously harmful to your health, the same cannot be said of all non-natural food additives and modifications. Rather than falling prey to fear-mongering and naturalistic fallacies, let’s see what a little science can shed on those gray areas of nutrition.
Toxins and toxicants cover a wide variety of substances, but non-natural substances are not automatically noxious.
Context is crucial. Natural or synthetic, any substance can be noxious, depending on many factors, such as the target species. Cocoa, for example, can be safely eaten by people, but its theobromine content makes it potentially lethal to dogs. Conjugated linoleic acid (CLA) causes fatty liver in mice, but not in humans. This is important to keep in mind because animal studies are often cited to “prove” that a substance is harmful to humans.
Dosage is another factor to consider. Even water can kill you if you drink too much over too short a period of time, since it lowers the concentration of electrolytes needed for muscles (including the heart) to function. Likewise, those same electrolytes the heart needs to keep beating aren’t always your friends. In the United States, for example, the adequate intake (AI) for potassium for adults is 4.7 grams. When this much potassium is consumed through food, it is digested for hours, making it not only safe, but healthful. However, just one gram of pure potassium taken on an empty stomach, with or without water, can have adverse health effects, which is why multivitamins and sports drinks are limited to 99 milligrams (0.099 grams).
But surely some substances are always bad for you, right? Tobacco, for instance, or alcohol? The answer is yes. For tobacco. But alcohol isn’t an unmitigated evil. While overconsumption can lead to cirrhosis and an increased risk of cancer, small amounts may provide modest health benefits (e.g. some protection against coronary heart disease).
And what about this modern devil, high-fructose corn syrup (HFCS)? Sure, it is a heavily refined extract made from corn, but this compound is close to regular table sugar in composition and likely no worse for you. Neither HFCS or sugar are intrinsically harmful, and an occasional can of soda isn’t going to derail your health. However, regular consumption of these added sugars through soft drinks and processed foods can lead to unintentional increases in caloric intake and potential health problems from the resulting fat gain.
Some substances can accumulate in body tissues, leading over time to serious health problems. This is well recognized with heavy metals. Because fish can contain mercury (a heavy metal with a half-life in humans of approximately 50 days), some people have banned it from their diet, thus depriving themselves of its healthful omega-3 fatty acids. Keeping in mind that the dose usually (but not always) makes the poison, however, you could decide instead to eat fish less frequently, vary the type of fish you eat, or focus on fish with a lower mercury content.
Pesticide residues in food are another common concern. Yet, the Pesticide Data Program (PDP) of the United States Department of Agriculture (USDA) has consistently found that the vast majority of the food on the market contained residues below the tolerable limits set by the Environmental Protection Agency (EPA). In addition, rinsing, peeling when possible, and cooking can all reduce the amount of pesticide left on your food.
Calling a compound toxic, without providing context, is too simplistic. Other factors, such as dosage, determine if a substance (be it synthetic or natural) is a threat to your health.
Even if a substance really is noxious, a cleanse won’t help. Acute toxicity would likely constitute a medical emergency, while chronic toxicity is best addressed by a well-fed body — not one weakened by a diet of pepper-infused lemonade. The liver, kidneys, lungs, and several other organs work around the clock to remove harmful substances and excrete the waste products of metabolism. They don’t need help from fad diets.
What they can benefit from is a healthy diet and smart supplementation. The detoxification systems of the liver, for example, benefit greatly from eating cruciferous vegetables such as broccoli, which provide sulforaphane, a compound that up-regulates the liver’s detox processes. These effects may extend to other bioactive compounds in plants as well. In terms of supplements, compounds like N-acetylcysteine and milk thistle have strong evidence supporting their use in liver health.
So, no pepper-infused lemonade. But what about commercial products? Unfortunately, a 2009 investigation found that not a single company behind 15 detox supplements could supply any form of evidence for their efficacy (or safety). Worse still, the companies couldn’t even name the toxins targeted by their products or simply agree on a definition for the word “detox”.
The fact that no company can name the toxin their product targets reveals just how little of an effect cleanses have. To scientifically determine the efficacy of a treatment, researchers must first identify the toxin, so as to accurately measure its accumulation in the body. Only then can they investigate the effects of different compounds, and should they find one that affects the toxin, explore a hypothesis regarding its mode of action.
For example, scientists researching the effects of organochlorine pesticides, which accumulate in mammals, not only know the name of the toxin they are researching, they have also determined that its accumulation can be limited by Orlistat, an anti-obesity drug. In fact, the mechanism behind this pharmaceutical’s effect is largely understood: Orlistat confines these particular pesticides to the intestines, through which they are removed as waste. Similarly, heavy metal poisoning is treated with chelating agents that bind the metal and prevent further absorption.
The human body does accumulate noxious elements such as heavy metals or certain fat-soluble substances. It also has mechanisms in place to eliminate many of these over time. If the body does need help detoxing, there are well-studied compounds that are in medical use, such as orlistat for pesticide poisoning. In contrast, most detox supplements have little to no evidence regarding their efficacy or safety.
Studies on cleanses are scarce and, according to a review from 2015, not very convincing, as they suffer from “small sample sizes, sampling bias, lack of control groups, reliance on self-report, and qualitative rather than quantitative measurements”.
For example, one controlled trial investigating the Master Cleanse detox program reported no significant difference in weight loss or health improvements between middle-aged women assigned to the cleanse or to a group that simply cut their caloric intake to the same extent. Both groups ate a mere 400 kcal per day and saw reductions in their weight, blood lipids, and insulin resistance, but this wasn’t because of any lemon-juice-maple-syrup magic - it was because the women were eating hardly anything. Regardless, the study lasted a mere 11 days, so we don’t know whether these health improvements would be maintained when regular eating is resumed.
But many people don’t consider the evidence (or lack thereof) and simply notice the weight and fat loss from eating so much less than usual. Thus, detox diets and commercial cleanses remain popular. A friend losing weight on an extreme cleanse? That doesn’t need any explanation. Scouring the evidence and analyzing studies in depth? The average person has neither the time or knowledge to dive into toxicology and systematic evidence reviews. Every now and then a case report emerges about potential risks, such as kidney damage from green smoothies or liver failure from detox teas.. But again, the audience for these papers is usually limited to researchers, not those who regularly employ detoxes and cleanses.
There is little-to-no evidence investigating commercial detox programs. What evidence does exist is fraught with methodological problems and suggests that possible short-term benefits are mostly due to extreme calorie restriction, rather than detoxification.
Why do fad cleanses spread through word of mouth despite the proven lack of benefits? One answer is: rapid weight loss. Which could be great … if weight loss always meant fat loss.
To store one gram of glycogen in the liver and muscles, the body uses three grams of water. Glycogen stores are easily depleted in 24–48 hours if the body isn’t getting enough carbohydrates, which results in a weight loss of several pounds. Once a regular eating schedule is resumed, however, the glycogen and water come rushing back.
Nevertheless, the temporary weight loss leads many people to attribute health benefits to the cleanse they just completed.
In addition, most people eat poorly, and detox diets usually revolve around vegetables and fruits. Therefore, for most people, a detox diet means consuming fewer calories but, paradoxically, more vitamins and other valuable micronutrients. In that case, the diet could be seen as beneficial, but it would still not be as good as simply eating better, especially because the detox diet is more temporary than sustainable.
So, instead of doing a “spring cleanse”, focus on healthy habits you can sustain, such as eating nutritious food on a daily basis. Ample protein, leafy greens, and foods chock-full of vitamins are not just tastier and more satisfying than a cleanse, they’re also way better for you.
The evidence in support of detox diets or products just isn’t there. You (and your wallet) are better off allowing your all-natural detoxification system to deal with the “toxins”, bolstered by a healthy diet and lifestyle. And in the off chance you are actually poisoned, rely on medical professionals, not commercial cleanses.