Liver function tests are blood tests that can help determine the overall health of the liver. These tests look at enzymes, proteins, and waste products made by the liver. A person’s blood is tested for proteins made by the liver such as albumin and prothrombin, enzymes such as alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate aminotransferase (AST), and bilirubin (a waste product).^[5] Imaging tests such as ultrasounds, computed tomography CT, and magnetic resonance imaging (MRI) are also done to detect and measure liver scarring.

If you’re feeling a bit sluggish or looking to kickstart your journey to better health, you’ve likely come across any number of quick-fix detox or cleansing programs that promise to restore vitality.

Such programs can claim to cleanse your whole body or specific organs. They commonly consist of a highly restrictive diet, with a possible array of supplements. The Master Cleanse, for example, prescribes 6–12 glasses of lemonade with maple syrup and cayenne pepper as your only sustenance. According to its creator, this program promotes the elimination of every kind of disease and is the most successful healing diet in the world.

If you’re thinking that “every kind of disease” is conveniently vague, you have a point. In 2009, an investigative report of 15 detox-program manufacturers found that none could provide a clear-cut list of the harmful substances being eliminated, and that no two even defined “detox” the same way.

Not only are most commercial detox programs ambiguous, almost none have been tested for their safety or efficacy.^[6] Even the National Center for Complementary and Integrative Health states that “there isn’t any convincing evidence that detox or cleansing programs actually remove toxins from your body or improve your health”. They also warn that “some of the products and procedures used in detox/cleansing programs may be harmful to your health” — a warning supported by case reports on kidney damage from a green-smoothie cleanse^[7] and liver failure from drinking too much “detox tea”.^[8]

Commercial detox programs claim to eliminate harmful substances that accumulate in the body, usually through highly restrictive diet protocols. Those programs, however, are largely untested for their efficacy or safety, and most can’t even agree on a definition for “detox”.

Does your body need detoxification?

It definitely can — just not as detox companies sell it.

The Centers for Disease Control and Prevention’s Agency for Toxic Substances & Disease Registry defines detoxification as “the process of removing a poison or toxin or the effect of either from an area or individual”.

Medically, you need detoxification when you poison yourself with drugs, such as alcohol.

Standard medical detoxification involves shoving 25–100 grams of activated charcoal down your throat every couple of hours to prevent the swallowed chemicals from being absorbed from your gut into your bloodstream.^[9][10] The charcoal binds the chemicals, allowing you to poop them out.

But then, can’t you simply take activated charcoal supplements every day “just in case”? No, you can’t, or rather you shouldn’t, because activated charcoal doesn’t differentiate between friends and foes: it will bind vitamins and essential minerals just as readily as it will dangerous chemicals.^[11] Moreover, the doses in those pills are well below the 25–100 grams used medically, and activated charcoal can only bind chemicals in your intestinal tract — so not chemicals you’ve already absorbed, and not chemicals in your lungs.

Medical detoxification is warranted only in case of acute poisoning, and should be performed only under medical supervision.

Do you accumulate toxins?

The short answer is yes: your body, like that of any animal, can accumulate toxicants (poisons), including toxins (poisons produced by a living organism). This process is called bioaccumulation. Mercury, for instance, is known to accumulate in predator fish and in people who eat those fish,^[12] and even our beloved protein powders may not be entirely safe,^[13] according notably to Consumer Reports and the Clean Label Project.

Of particular concern are environmental persistent organic pollutants (POPs), a type of toxicant that accumulates in body fat.^[14] In the short term, your fat can protect the rest of your body from acute harmful effects such as metabolic and hormonal disruption.^[15] Over time, however, your fat releases POPs back into your system, causing low-level chronic exposure that has been associated with metabolic diseases.^[14][15]

Your body can accumulate toxins and other toxicants, notably heavy metals, such as mercury, and liposoluble chemicals, such as persistent organic pollutants (POPs).

A side note on POPs and dieting

Few studies on obesity and fat loss consider the role of POPs,^[16] yet POPs might help explain why weight loss doesn’t improve everyone’s health equally — in some people, the increased toxic load from POPs offsets the benefits of carrying around less fat.^[16] More precisely, an inefficient excretion of the POPs released when dieting may reduce health improvements, as well as increase the risk of weight regain.^[17]

Whether POP redistribution results in adverse effects in humans remains to be studied, but some data is suggestive. For example, in people whose weight loss was induced by gastric bypass surgery, higher levels of POPs in the blood was associated with lesser health improvements from weight loss.^[18] Weight loss induced by regular dieting also leads to an accelerated release of POPs from fat cells into circulation, with the increase in serum POPs being proportional to the weight loss.^[19]

Fat loss appears to accelerate the release of POPs from fat cells into circulation, and more POPs in the blood correlates with less improvement in health biomarkers. However, there is still little research on the role of POPs in obesity and weight-loss interventions.

Detoxing done right

Your body has a built-in detoxification system: your lungs and other organs work around the clock to remove harmful substances. Your liver, for instance, transforms noxious chemicals into benign substances that are excreted in the urine (via the kidneys) or feces (via the gallbladder).^[20]

There are three ways a realistic detoxification program could work:

1. By decreasing your exposure to known toxicants

It is wise to reduce your exposure to airborne pollutants such as smoke, smog, and chemical fumes. You don’t always get to choose where you live (e.g., rural areas tend to have less air pollution than urban areas^[21]), but you can at least reduce pollution accumulation in your home through proper air conditioning and ventilation.^[22] You can also, if you live in a smoggy area, wear a face mask — how much it’ll filter will depend on its design, including how well it fits on your face.^[23][24]

Pesticide residues in food are a valid concern too, though it should be noted that 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 contain either no detectable residues or residues below the tolerable limits set by the Environmental Protection Agency (EPA).

While the USDA does not currently test for residues of pesticides commonly used on organic foods, it does test for residues of pesticides not approved and some approved for limited application. Unsurprisingly, organic produce (notably fruit) less often have synthetic pesticide residue than conventional produce do.^[25] Trials in adults and children have shown that switching from conventional to organic produce can reduce biomarkers of organophosphate-class pesticides, which are used in conventional agriculture and may be harmful, in as little as a week.^[26][27] Fortunately, in the US, this class of pesticide has consistently dropped from use in favor of less acutely toxic ones since 2000.

When found, pesticide residues were similarly low in organic and conventional produce, but there is some evidence that even very low doses of pesticides might still elicit physiological effects.^[28] These effects, be they beneficial, neutral, or harmful, and be they from organic or conventional pesticides, are not well studied. So, what is a consumer to do? The practical solution is quite simple: rinsing, peeling when possible, and cooking can reduce the amount of pesticide left on your produce, whether this produce is organic or not.^[29][30]

(Alas, organic products are not unilaterally safer than conventional ones: a 2018 test of protein powders revealed that organic ones had about half the amount of BPA (an industrial chemical) but twice the amount of heavy metals.)

2. By improving your liver’s ability to metabolize toxicants

Current evidence suggests that some compounds in plant foods can upregulate your liver’s detoxification process and antioxidant activity.^[31][32] One such compound is the sulforaphane in broccoli and other cruciferous vegetables, as was shown in humans^[33] as well as in rats.^[34]

Of the many supplements marketed for liver health, four are supported by strong evidence from human studies: milk thistle, NAC, SAMe, and TUDCA.

3. By enhancing your body’s ability to excrete toxicants

Fiber, especially soluble and/or fermentable, can enhance detoxification both directly and indirectly. Directly, by binding bile and its associated toxins, thus facilitating their excretion. Indirectly, by feeding the bacteria in your digestive tract, some of which create short-chain fatty acids and other metabolites that act on the liver and kidneys to increase their ability to excrete toxicants.^[35][36]

Sweating may help excrete heavy metals,^[37] but sauna studies are scarce and rely mostly on subjective assessments, such as questionnaires about quality of life, rather than on objective measures of toxicant burden or excretion.^[38]

As for the notion that a juice-only cleanse can shift your guts away from digestion and toward the excretion of toxicants — it is one of those catchy ideas that lack scientific backing. If you want your organs to do their best, including to rid you of toxicants, then you should not deprive them from the nutrients they need to function. That means that, rather than the occasional cleanse, what you need is a daily diet rich in varied fruits and vegetables.

Toxicants, notably heavy metals and liposoluble chemicals, can accumulate in your body. Avoid them whenever possible. You can support your inborn detoxification system by eating a diet rich in fruits and vegetables (preferably organic ones, which have less known harmful pesticide residue) and possibly by sweating. Some supplements, such as NAC, can also help.

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Do commercial detoxes work?

A 2011 survey reported that 92% of naturopaths prescribed detoxification therapies, commonly as treatments for environmental exposure to toxicants. Said therapies consisted mainly in eating more “cleansing foods,” such as Brassica vegetables; eating more fruits and vegetables in general; opting for organic foods; supplementing with vitamins, minerals, and fibers; and minimizing environmental exposure to toxicants. More questionable treatments, such as homeopathy, were less common.^[39]

But what about commercial detox programs, or “cleanses”? Studies on those 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 assessments rather than quantitative measurements.^[6] A more recent study shared these limitations: with no control group, it showed that following a detox program centered around eating a whole-food diet improved self-reported health.^[40]

The one randomized controlled trial (RCT) we could locate separated middle-aged women into three groups: Master Cleanse (MC), placebo, and control. The control group kept eating as usual, whereas the MC and placebo groups ate only 400 Calories per day. As a result, both the MC and placebo groups lost weight and showed related health improvements, with no difference between groups.^[41] In short, the “magic” was found to be in the caloric restriction only, not in the combination of lemon juice and Neera syrup (a blend of maple and palm-tree syrups designed to have high amounts of minerals and trace elements).

Finally, the one RCT on a commercial detox supplement without caloric restriction reported that this supplement didn’t have much of an effect on anything.^[42]

What little evidence there is on “cleanses” (commercial detox diets) is fraught with methodological problems. Cleanses’ short-term benefits (weight loss and related health improvements) seem to be mostly attributable to caloric restriction and placebo effects, not to special detoxification effects.

Explaining why it feels like detoxes work

Why do fad cleanses spread through word of mouth so quickly? The answer is threefold: rapid weight loss, removal of problematic foods, and the placebo effect. This could be great … if weight loss always meant fat loss.

If you slash your caloric intake, you probably slash your carbohydrate intake, and if you slash your carbohydrate intake, you don’t replenish your glycogen stores. Not only do you lose your stored glycogen, but you lose the associated water. To store 1 gram of glycogen, you need about 3 grams of water.^[43][44] The average man carries 341–593 grams of glycogen in his liver and muscles, so about 1,364–2,372 grams (3–5 pounds) of glycogen+water.

Therefore, by depleting your glycogen stores, you can lose several pounds in a couple of days.^[45] And of course, less food consumed also means less food (and its associated weight) moving through your intestines.

The result? Spectacular weight loss — in the short term. But cleanses are short term, so people never get to see them fail. All they see is the spectacular weight loss; they feel better because of it, and they attribute both their weight loss and perceived better health to their cleanse. And they still do when they resume eating normally and most of the weight they lost (all the weight from glycogen+water and food-in-transit) comes rushing back.

The short-term weight loss from a cleanse can be spectacular, but most of what is lost is glycogen and water, which come rushing back when normal eating habits are resumed.

So when people feel better from a cleanse, is it just a placebo effect? Not always. People who undergo a cleanse might also feel better because they stop consuming foods that don’t agree with them. In other words, cleanses work as de facto elimination diets.

An elimination diet is a diet that removes a food or category of foods that you suspect might negatively affect your health. Some people, for instance, will stop consuming milk (or all dairy products) to see if, after a few weeks, they feel better. Sometimes, people remove many foods at once; then, after a few weeks, if they feel better, they start adding the foods back, one by one, to determine which ones are problematic.

Bottom line

Toxicants, notably heavy metals and liposoluble chemicals, can accumulate in your body. Avoid them whenever possible. A diet rich in protein, vegetables, and fruits will provide your organs with the nutrients they need to function optimally, and some supplements may support your liver specifically. Sweating may also help you excrete heavy metals.

As sold to the public, cleanses (detox diets) do not work. Most of their benefits — notably a rapid, but mostly short-term, weight loss — can be attributed to the drastic caloric restriction, not to detoxification. A cleanse might also help by removing foods that don’t agree with you (they work as a de facto elimination diets).

In case of acute poisoning by a toxicant, go to the hospital.

While “detox diets” are better avoided, some supplements can support liver health. Check out our Liver Health Supplement Guide to learn which supplements are backed by the evidence and which are dangerous or simply a waste of money. You’ll also find practical, specific information on dosages, combinations, etc.

Bone health

The acid-ash hypothesis states the following: The metabolism of certain foods — namely protein and grains — increases acid production in the body, as evidenced by an increase in urinary acidity.^[52] To counteract this increase in acidity, bone is broken down to release calcium bicarbonate (a base) corresponding with an increase in urinary calcium excretion, which is thought to reflect negative body calcium balance or bone loss. Therefore, a high-protein or acid-producing diet accelerates bone loss and increases the risk of osteoporosis.

However, changes in urine pH don’t necessarily reflect changes in blood pH, which is maintained within a narrow range primarily by the renal and pulmonary systems in healthy people.^[53] Additionally, variations in diet have virtually no effect on blood pH, as any nutritional influence that slightly disrupts acid-base balance is immediately corrected by biochemical buffering systems that do not involve bone.^[53]

While an increase in urinary acidity has been correlated with an increase in urinary calcium excretion, dietary changes that increase urinary acidity do not lower body calcium balance.^[54] Relatedly, a higher-protein diet does not negatively affect dietary calcium retention because although it increases urinary calcium excretion, it increases intestinal calcium absorption by a similar magnitude.^[55][56]

Ultimately, the available evidence does not support the acid-ash hypothesis,^[57] and in accordance, higher-protein diets do not have a negative effect on bone health.

Meta-analyses of prospective cohort studies have reported that a higher-protein diet was either not associated with the risk of hip fracture,^[58] or, compared to the group with the lowest protein intake, there was an 11%–16% lower risk of hip fracture in the group with the highest protein intake.^[59][60][61]

With respect to bone mineral density (BMD), a meta-analysis of randomized controlled trials 12–24 months long reported that a higher-protein diet had a protective effect on lumbar spine BMD.^[62] A higher-protein diet also tended to have a protective effect on total hip BMD, although this finding was not statistically significant. The data from prospective cohort studies is mixed on whether higher-protein diets have a protective effect on BMD (some studies suggest a benefit with more protein, while others have reported no impact), but there is a lack of evidence indicating that higher-protein diets are associated with lower BMD.^[60][62]

Concerning protein intakes significantly greater than the Recommended Dietary Allowance (RDA), there are a couple of long-term prospective cohort studies in older adults that shed light on the topic. In one four-year study that included older men and women (average age of 75), the quartile with the highest protein intake (1.24–2.78 grams of protein per kg of body weight per day) showed the least BMD loss at the femur and lumbar spine.^[63] Compared to the quartile with the highest protein intake, the quartiles with the lowest (0.21–0.71 g/kg/day) and second-lowest (0.72–0.96 g/kg/day) protein intakes experienced a significant reduction in femoral neck BMD.

In a separate five-year cohort study that only included older women (average age of 75), a higher protein intake was associated with greater whole-body bone mineral content, and the tertile with the highest protein intake (about 1.6 g/kg/d) had significantly higher whole-body and appendicular bone mineral content than the tertiles with lower intakes.^[64]

Kidney health

The idea that a high-protein diet puts undue stress on the kidneys stems from early research in rodents and dogs that reported increased urea excretion, renal blood flow, glomerular filtration rate (GFR; a marker of kidney function), and kidney size in animals fed a high-protein diet.^[65] From this data, it was determined that a high-protein diet increases the workload of the kidneys, and thus may damage the kidneys over time and increase the risk of chronic kidney disease (CKD).

A 2018 meta-analysis of randomized controlled trials that compared the effects of a high-protein diet (1.8 grams of protein per kilogram of body weight per day, on average) to a low-protein diet (0.93 g/kg/d) in healthy adults reported that higher protein intakes may slightly increase GFR.^[66] Other data indicates that a high-protein diet does not adversely affect blood markers of kidney function or blood pressure.^[67][68]

Given these findings, a high-protein diet does not appear to pose a serious threat to kidney health. In further support of this conclusion, the issue at hand can be viewed through a different lens altogether; that is, is an increase in GFR a risk factor for CKD in healthy people? Such a relationship has yet to be clearly established.^[66]

In fact, an increase in GFR in response to an increase in solute load (e.g., nitrogen from protein) is a normal adaptive mechanism.^[69] For example, GFR can increase by as much as 65% during pregnancy^[70] but does not increase the risk of CKD.^[71] Also, surgical removal of a kidney is not associated with a deterioration in kidney function in the long term (> 20 years), despite the increase in workload.^[72][73][74]

While a low-protein diet is recommended for people with CKD to help prevent disease progression,^[75] this does not mean that a high-protein diet is harmful in all cases. The available evidence suggests that, in healthy people, a high-protein diet does not adversely affect kidney function or increase the risk of CKD.