What does it actually mean to detox?

Here, nutritional therapist Katie Clare takes a look at the often controversial subject of detoxification.

Detoxification is an alluring term, surrounded by a fair amount of mystery. It has had critical media focus in recent years. Mainstream medicine states that we don’t need to detox, that our livers will take care of this for us.

On the other hand, functional medicine, a discipline that has grown out of natural medicine or naturopathy, teaches that optimising our detoxification capacities is important for wellbeing in the modern world. Meanwhile the health food world is abundant with green powders and supplements designed to help this process along. Detoxing has become a general term that can mean anything related to health, and is used in yoga or can even be used just to mean a day without cigarettes, alcohol and caffeine.

How can we navigate through all of this and make sense of what detoxing is all about? This article should help you with an overview of both the criticisms of and the evolving thinking behind the process of detoxification.


First let’s look at the criticisms…

Ben Goldacre
Ben Goldacre, a famous investigative medical journalist, brought the public spotlight to the term with his 2009 book, Bad Science, stating that there was no such thing as a detox system in any medical textbook.

He stated that engaging in a detoxing weekend is a type of purification or abstinence ritual that our culture has developed, in order to find redemption from our material indulgences of filling our faces. We know that it is wrong and we crave ritualistic protection from the consequences of our actions. We want a public ‘transitional ritual’ commemorating our return to healthier behavioural norms.

Certainly an interesting reframing of a detox or cleansing weekend retreat. A fascinating book to read.

Sense about Science
Sense about Science was quick to follow with its campaign Debunking Detox, publicising the message that detoxing was a myth. They stated ‘the human body has evolved to get rid of unnecessary substances through your liver, kidneys and colon. It isn’t possible to improve their function without medical assistance’. Its campaign was featured in Marie Claire magazine, BBC news and all the national papers.

Dieticians also spread this message. The fact sheet ‘The truth about detox diets’ says that ’the whole idea of detox is nonsense’. ‘If the human body really accumulated lots of toxins, then we would feel ill. The concept of detox diets is irrational and unscientific.’


On the other side of the story is the functional medicine model of wellbeing. It teaches that the body often experiences dysfunction a long time before it eventually becomes a full-blown disease. It is interested in supporting the key functions of the body, processes like elimination (which includes detoxification pathways), absorption and defence. It uses food and supplements to try and do so.

Detoxification or biotransformation pathways in the liver

In functional medicine, detoxification is often discussed. Also known as biotransformation, this is a term with a very specific meaning. It relates to metabolic pathways in the liver, called phase I and Phase II liver detoxification pathways. These pathways can be read about in the drug & xenobiotic metabolism page on Wikipedia.

They are there to prepare foreign particles so that they can safely be eliminated out of the body. These particles may have come from drugs, medicines, synthetic chemicals, microorganisms, hormones or foods.

Phase I & Phase II Liver Detoxification

In phase I the particle that needs eliminating from the body is fundamentally changed and prepared for phase II. Phase I is absolutely essential but the inter-rim product it creates can be a bit of a live wire, and actually be harmful to the body. For example these particles can be carcinogenic or oxidising free radicals. As bad as this sounds, it isn’t really a problem as long as the particle can quickly be passed to phase II, before it has caused any trouble, to be fully taken care of.

In healthy liver detoxification we want phase II activity to always be able to exceed phase I activity. We want the job finished off properly with no mess. Medications, foods and our lifestyles can influence these pathways – and this is why nutritional therapists and functional medicine practitioners are so interested in detoxification.

If it seems strange or extreme that what you eat or drink may have such an effect on our body’s pathways then consider grapefruit juice. Many high-cholesterol medications (statins) have long carried a written warning inside the packet, stating the patient should not drink grapefruit juice whilst on the drug. A compound in the grapefruit can alter the speed at which the drug is absorbed and this can lead to harmful side effects. Isn’t it amazing that grapefruit juice can be so powerful?

Influencing Phase I & II Activity with Foods & Lifestyle
Phase I liver activity can be increased by factors such as smoking, high alcohol intake, certain medications and even by some unhealthy foods. These lifestyle factors are all very common in modern life.

In nutritional therapy and functional medicine the focus is on encouraging the consumption of foods that support phase II activity. This includes the glucosinolate compounds in vegetables such as kale (yeah! all hail the kale), cabbage, broccoli and Brussels sprouts, citrus fruits, curcumin (in turmeric), silymarin (in milk thistle), epigallocatechin in green tea and the amino acids found in some proteins, cysteine and methionine.

Dietary recommendations for supporting detoxification pathways are very similar to general healthy food recommendations. However if somebody is actually experiencing symptoms of dysfunction and wants to see if they can support their body further with food and phytonutrients then supplements and further dietary changes may be suggested as well.

We now also know there is considerable genetic variation in how we detoxify. Tests can identify some of our individual capacities here and highlight where in our detoxification pathways we may need a bit more personalised support.


Within functional medicine there are questions about the rise in the number of synthetic chemicals that are now added to our foods, as well as in our home environments and the air that we breathe. These all need to be biotransformed, or detoxed, for elimination from the body.

There are concerns around how well the body can keep up with this new onslaught, and to what extent these chemicals are accumulating in the body, resulting in adverse consequences. There is also concern that the body now needs to eliminate particles that it is unfamiliar with and may not have detoxification enzymes for.

Many new synthetic chemicals have not been thoroughly tested for safety in long-term low-levels of exposure, even though we may know that they do not cause immediate toxicity problems. This is a topic of current research. What impact does this all have on our biochemistry in the long-term and on chronic health conditions?

Optimising Detoxification Pathways

This has all led to the concept of ‘optimising detoxification pathways’, wanting to optimise our ability to process all of these chemicals and to have our detoxification capacities working as efficiently as possible. It something to consider all through the year, not just after a big night out on the town after too much alcohol.

People who seek optimal wellbeing are interested in looking after their detoxification pathways in the same way they may also be interested in looking after their heart and cardiovascular health, choosing foods that are known to be of benefit for the function of these organs and systems.

People also talk about chelation, which is the removal of heavy metals from the body, but this is a separate topic to be discussed another time.



In summary the body is very complicated and we do not yet fully understand all of its pathways or all of the ways and reasons that our health can be affected by the environment around us. We have so much more to learn. It takes a very long time for new research and thinking to be integrated into mainstream medical practice and many people, who are interested in health and wellbeing, simply don’t want to wait that long to reap the benefits.

At the same time we want to make sure that any new information we are ingesting is coming from a reputable source and is not out of date or corrupted by online Chinese whispers. Not every cutting-edge new discovery lasts the test of time either, sometimes follow-up research and thinking will show that it isn’t true, or take the theories in another direction. It is an experimental approach to work with the latest research, but a fascinating one.

There are contradictory opinions and ways of thinking about health. There always have been and there always will be. If you are interested in natural health and functional medicine topics then it is a sensible idea to follow award-winning health writers, like the fathers of functional medicine, Jeffrey Bland and Mark Hyman, rather than believing anything that we may read online.

Katie Clare mBANT CNHCreg is a nutritional therapist specialising in gut health.  She teaches a class on fermented foods at the College of Naturopathic Medicine and works part time as inSpiral‘s PR manager. Until recently she ran her own practice at Neal’s Yard Therapy Rooms, Islington, but is about to start an MSc in Personalised Nutrition. Katie formerly worked in a clinical role for the NHS.