Spring is upon us. The season of new beginnings, a time to rejuvenate and refresh. And, of course, this means it’s a popular time to undertake a ‘detox’ diet. Detoxification is certainly an attractive concept, which is why it so often makes the headlines. But, what does it really mean? What are these so called ‘toxins’? Does a ‘detox’ diet actually work, or is it all just a fancy myth? First, the science bit.
What is a toxin?
To understand the concept of detoxification, we must first understand what it is we are trying to rid ourselves of; toxins. In conventional medicine, the word “detoxification” is usually used to describe the process of weaning people off addictive substances such as drugs, or alcohol. But, the term ‘toxin’ also has a broader use; to describe the exogenous (environment derived) substances that get into our bodies. These can include agricultural chemicals, food additives, cosmetic and household pollutants, and environmental oestrogens (xenoestrogens), as well as drugs – both medical and recreational – and alcohol. Normal body chemicals can also start to have toxic effects if they build up in the body to levels which are higher than normal. For example, an overactive thyroid gland can lead to “thyrotoxicosis”. Detoxification may be considered the handling and eliminating of these chemicals from the body. Interestingly, our body uses the same pathways to process endogenous toxins (end or waste products of our own metabolism, such as urea (which is made when our bodies recycle protein) as it does environment derived toxins, so detoxification really is a normal and essential physiological process which goes on in our bodies all the time.
What role does the liver have in detoxification?
As a primary function of the body, detoxification is perpetually happening and involves many organs and systems. The liver is the primary organ for detoxification, though the lining of the gut, the kidneys, lungs and skin are also involved. In the liver toxins go through a process of biotransformation. That is the process of transforming a toxic molecule into something that can be safely excreted from our bodies. This process is split into two phases: Phase I involves a group of enzymes called the cytochrome P450 enzymes. Various reactions take place and toxins are transformed into compounds known as ‘intermediary metabolites’.
Phase II then receives these intermediary metabolites and adds extra compounds to them, making the metabolite more fat or water soluble. Consequently, it can be excreted either via the bile and into the stool, or via our urine.
When it comes to detoxification, are we all the same?
Several factors influence the detoxification process. Firstly, our genetics. There is a great variation among individuals in detoxification capacity with some having a significantly better function than others. These people will have a greater capacity to detoxify both medication and environmental toxins and, consequently, may experience less side-effects from medication than someone who is considered a ‘poor metaboliser’.
In addition to genetic variation, the degree and efficiency of detoxification lowers with age and body size and varies by gender where it is influenced by the ratio of oestrogen to progesterone. Pre-menopausal women will have significantly more enzymes available than post-menopausal women, for example. This explains why there is a difference in the “safe alcohol” recommendations for men and women.
What impact, if any, do individual differences in detoxification capacity have on cancer, both in terms of risk and treatment?
Research has looked at whether these individual differences affect our risk of developing several different forms of cancer. For a handful of liver enzymes, evidence demonstrates an association between these differences and cancer susceptibility. However, the pathways of carcinogen metabolism are complex and single genetic differences, such as these, are likely to have limited impact. Although, interesting, further research is needed to reliably evaluate the link between individual differences in liver enzymes and cancer risk.
In terms of cancer treatment, Cytochrome P450 (CYP) enzymes are involved in the metabolism of therapeutic drugs, including anti-cancer drugs such as tamoxifen and cyclophosphamide. Because of the large individual differences in enzyme capacity, there is significant variation in the metabolism of these drugs. For example; reduced activity of the enzyme CYP2D6 may worsen the outcome of tamoxifen treatment in hormone receptive positive breast cancer, since tamoxifen is metabolised into its active form primarily by this enzyme. It should be noted, however, that there is still a lack of robust clinical data and again further research is needed. Commercial tests are now available which may help to individualise tamoxifen therapy for patients with HR positive breast cancer. However, current NICE guidelines state that the evidence linking poor metaboliser genotypes to treatment outcome is inconclusive, so, genetic testing is not currently recommended before tamoxifen treatment.
Selective serotonin reuptake inhibitor (SSRI) antidepressants inhibit the enzyme CYP 2D6, which is used to metabolise tamoxifen. Some studies have demonstrated a link between the use of certain SSRI anti-depressants and an increased frequency of breast cancer recurrence, while others have suggested there is no association. NICE guidelines currently recommend a cautious approach when prescribing certain antidepressants to people taking tamoxifen.
So, that’s the technical stuff. But can you tell me more about a detox diet?
Let’s get back to the do’s and don’ts of a detox! Detox diets commonly reported in the media involve a short-term dietary intervention designed to eliminate ‘toxins’ from the body. They tend not to specify which ‘toxins’ they are attempting to eliminate, though. Indeed, probably one of the main effects of such diets is putting fewer toxins into the body, rather than increasing elimination. One of the most popular ‘detox’ programmes involves fasting (for up to 10 days) and drinking only a lemon juice-water concoction. There is no scientific evidence to suggest this ‘detox’ diet has any health benefits other than short-term weight loss. Furthermore, many people report side effects including low energy, gastro-intestinal problems and mood swings. Due to the extreme nature of this detox – coupled with the lack of scientific evidence for its health benefits – we do not recommend it.
- a short period of fasting
- fruit and vegetable juices
- elimination and/or inclusion of certain foods
- the use of supplements
- colon cleanses and/or enemas
The first thing to know is that there is little evidence to suggest that a short-term detoxification programme will remove any ‘toxins’ from our body. Our bodies can cleanse themselves and they do this constantly, every day, eliminating waste products through our stools, urine and sweat. But that doesn’t mean a detox diet is pointless and, indeed, many people report improved well-being after a period of ‘detoxification’. This may be because several positive aspects of ‘detox’ diets are known to improve health biomarkers; eating a nutrient dense diet, regular exercise & sweating, drinking enough water, prioritising sleep, avoiding alcohol, and fasting. Furthermore, undertaking a short-term detox diet may help you to break unhealthy habits, and motivate you to lead a healthier life.
So, what do you recommend for people wishing to undertake a ‘detox’ diet?
Firstly, we recommend you take a look at our ‘Healthy Eating Plate’ and also have a read of our ‘Whole Life Approach to Healthy Eating’. These guidelines show you how to eat a nutrient dense, anti-inflammatory diet, which will support your body’s natural detoxification processes.
Secondly – and since we are discussing detoxification – it may be helpful to know that both phase I and phase II metabolic pathways are dependent on certain nutrients, all of which are included in a healthy, nutrient-rich diet. In phase I, antioxidants are important as there is an increase in oxidative stress in this phase. Eating a diet rich in vitamin A, C, E, selenium and zinc will therefore support your natural detoxification processes. The best sources of vitamin A are liver, dairy, eggs and oily fish. For vegetarians, yellow and orange vegetables and fruits, along with leafy greens are a rich source of beta-carotene, which can be converted to vitamin A. Good sources of vitamin C include peppers, green leafy vegetables, tomatoes, berries and citrus fruits. For vitamin E, consider sunflower seeds, almonds, olive oil and peanuts. Brazil nuts are rich in selenium, while useful food sources of zinc include nuts, oats, sardines and lamb. A high intake of vegetables and fruit is also important since they are a rich source of phytonutrients, offering further antioxidant protection.
Phase II detoxification is dependent on amino acids which we obtain from eating protein rich food. Be sure to include a portion of good quality protein with each meal. If you are vegetarian, then include a wide variety of nuts, seeds, pulses and wholegrains. When eating animal protein, lower fat options like fish, eggs and lean meats are preferable as fat is a storage site for many toxins.
As a source of glucosinolates, cruciferous vegetables may also support phase II detoxification pathways and have a beneficial effect on hormone metabolism. We will be taking a closer look at the detoxification of hormones in a separate blog later this year. Cruciferous vegetables include broccoli (and broccoli sprouts), kale, cauliflower, Brussels sprouts and cabbage. The best way to cook them is to lightly steam since excessive cooking reduces the level of glucosinolates.
Despite the positive effect cruciferous vegetables may have on hormone metabolism, research has not yet established a robust link between consumption and reduced risk of hormone sensitive cancers in humans. However, since cruciferous vegetables have a range of health promoting properties, we strongly encourage you to regularly include them in your diet.
Herbs and spices are a rich source of antioxidants and some studies suggest they may support phase II detoxification enzymes. Due to their many beneficial properties, we recommend using a wide variety of herbs and spices, including turmeric, coriander, cumin, parsley and fennel.
In addition to antioxidants, vegetables and fruit are an important source of fibre. Eating fibre is the most effective way to ensure a healthy transit time – that is the time it takes for you to fully digest a meal, resulting in a stool that is formed and easy to pass. The average time to complete the digestive process is 24 hours, though this varies between individuals. Try to eat 8-10 portions of vegetables and fruit, daily, with the majority of these being vegetables. If you are not used to eating this much, increase your intake gradually.
Some foods increase the toxin burden on our bodies, and we recommend you reduced or avoid these. They include: alcohol, burnt or charred food, damaged oils from processed foods (including take-aways), ready meals and processed meats which contain toxic nitrates.
Be sure to regularly sip water throughout the day as this helps to support the kidneys by increasing urinary output, one of the main routes of toxin elimination.
Is there anything else I could consider to get my new year off to a flying start?
Yes! Your new year healthy habits don’t have to be restricted to dietary changes alone. For example, you may wish to change your exercise regime. Whilst there is no direct evidence to suggest exercise improves liver detoxification, it does speed up gut transit time and is considered an important part of any holistic health regime.
Saunas and hydrotherapy are often included in detox programmes, despite their being minimal evidence for their benefit. But this doesn’t mean you shouldn’t do them if you enjoy them. They can be extremely relaxing and energising.
Many detox programmes include a period of fasting which, again, may be something you wish to consider. If you have lost weight unintentionally or are at risk of losing weight as a result of cancer or cancer treatment, it is essential that you seek advice from your medical team before undertaking any fasting or calorie restriction. For more information on how to introduce fasting, and importantly when it may not be safe or appropriate, have a read of our fasting blog.
And, finally: if you really want to challenge yourself, how about a digital detox? Taking a break from your smart phone, tablet or laptop may give you an opportunity to slow down and breathe more deeply. It may help you find time to read, sing, or dance – whatever it is you want time for. It’s amazing how much time a digital detox can create – for some of us, it feels huge.
IMPORTANT: If you have a diagnosed medical condition, do check with your medical team before introducing major changes to your diet and exercise programme. Also before you experiment with fasting, saunas or hydrotherapy. Whatever changes you choose to make this year, be kind to yourself, and proceed gently, modifying things as you go along if you feel they are not suiting you or your situation.