‘Optimising digestion and liver detoxification processes should be the first priority in any nutritional programme?’


By Camilla Elms BSc. (mBANT, mCNCH)




A nutritional programme will start with a thorough assessment all aspects of an individuals lifestyle and dietary principles. Optimising digestion and detoxification pathways may often start to occur naturally through the promotion of a healthy lifestyle, improved dietary habits and by reducing toxic exposure (British Association of Nutritional Therapists (BANT) 2015). Studies have shown that exposure to toxins has significant bearing on elevated risk of diseases including cardiovascular disease, type 2 diabetes, obesity and neurodegenerative disorders (Mostafalou and Abdollah 2013). Depending on individual phenotype and genotype, it is not always safe to assume that the process of detoxification should be the first priority however. In this review I aim to examine the precise nature of toxins and detoxification pathways and why it is important to reduce the overall toxic load on the body and also to discuss some circumstances whereby detoxification may not be the best first priority in restoring optimal health.



Toxins, which compromise the subtle balance of good health, are now ubiquitous in the environment. The period during and after the first World War and the inter-war period saw chemical compounds being devised and engineered on a scale never seen before; Wexler et al. (2000) explain, how, as the World Wars ended, new markets were created for the surplus stores of poisons and plastics and exponential growth in pesticides and synthetic products generated new markets with the creation of persistent, bio-accumulative or toxic chemicals (PBTs). Now in wide circulation, xenotoxins, metals and pharmaceutical chemicals are able to penetrate the human body systems; chemical cosmetics and body lotions enter the body cutaneously via the skin, traffic pollution, industrial gases, moulds and cigarette smoke penetrate the respiratory system via the lungs, and food and food preparation co-transport toxins into the gastro-intestinal (GI) tract. Endotoxins form as endogenous metabolic by-products within the body from sources such as dysbiosis, proteolysis and stress. Continual surges of adrenaline and cortisol from the HPA axis cascade and generate an allostatic load on the body, leading to increased inflammation and suppression of the immune system. Detoxification is a term classified as assisting the body to rid itself of xenobiotics and endotoxins (Schaeffer 2014). Thiel (2011), when examining the nature of disease, stated that ‘so-called disease is nature’s effort to eliminate toxin from the blood’ and that ‘all so-called diseases are crises of toxaemia’.



To rid itself of xenobiotics and endotoxins the body has 2 distinct detoxification pathways, which are modifiable by diet and nutritional status. Ingested water-soluble compounds are filtered via the hepatic portal vein for enzymatic detoxification in the liver, and fat-soluble compounds are detoxified via the Gut-Associated Lymphoid Tissue (GALT) in the Gastro Intestinal (GI) mucosa. 


Water-soluble nutrients pass from the GI tract into the body’s blood stream via the portal vein, which is connected to the liver. In the liver nutrients are filtered through a process of hepatic biotransformation before being either utilised by the body or safely excreted and eliminated via the faeces or urine.  The three phases of detoxification include hydrophilic bio-activation, conjugation with specific enzymes, including glucoronidation, sulfation and glutathione to neutralise toxic damage potential, and finally transportation for elimination. In phase I hydrophilic biotransformation, cytochrome P450 enzyme reactions are dependent upon a number of nutrient co-factors, Vitamin A, C, E and B Vitamins 1-3 to isolate toxins from the body (Müller and Yeoh 2007). R.T. Williams (1959) highlighted the contradiction that xenobiotic metabolism and detoxification pathways may actually increase toxicity within the body; he noted that Phase I biotransformation, by isolating toxins, created potentially harmful Reactive oxygen Species (ROS), which must be conjugated into water-soluble compounds in order to be safely excreted in the urine or bile (faeces). Otherwise metabolism may increase toxicity and cause the detoxification pathways to become unbalanced (Machearey and Dansette 2008). Dietary modifications, which include specific foods and their component vitamins, can up-regulate metabolic pathways to assist with detoxification. Flavonoids present in many cruciferous vegetables (broccoli, cabbage, sprouts), soy, garlic, turmeric and berries are modifiers of CYP enzyme activity (Moon et al. 2006). This CYP metabolism is responsible for the detoxification of pro-carcinogens and pharmaceutical drugs, which, dependent upon phenotype and genotype, may express inter-individual variability either by inducing or inhibiting actions.  Onion and garlic consumption, more specifically the organosulfur compounds contained therein, is inversely related to the risk of cancer via the cellular protective role of phase II enzymes such as glutathione-S-transferases (Guyonney et al. 2001). Conversely grapefruit juice has well researched inhibitory effects on CYP3A enzymes, as it contains high levels of naringin, which, prevents the breakdown and elimination of pharmaceutical drugs used for cholesterol-lowering statins, sedatives and immune suppressants (Murray and Pizzorno 2006). Individuals with autism disorders (AD) may not respond to detoxification programmes as they have shown to be poor metabolisers of the hepatic sulfation pathway and autoimmune functionality and other GI functionalities tend to be impaired – these abnormalities are also evident in in other neurological diseases including Alzheimers, Parkinsons and Motor Neurone Disease (MND) (Kidd 2002).


For individuals presenting with symptoms of poor digestion, a thorough understanding of these metabolic detoxification pathways enables a nutritional practitioner to recommend the whole foods and nutritional supplements to support and enhance detoxification. Hodges and Minich observe that a whole foods approach may be wise due to the bi-phasic and dose-dependent effects of some nutrients (Hodges and Minich 2015). So depending on dose, using whole foods to modify the body’s natural detoxification pathways may inhibit or down-regulate certain enzyme activities, for example curcumin, black tea and soybean “bi-functional modulators” (Hodges and Minich 2007) 2. Hodges and Minich (2007) state that curcumin at 0.1% of the diet, has been shown to induce CYP1A in animals for example, where a diet comprising 1% turmeric proved inhibitory. Genetic variations in detoxification enzymes affect how we respond to diet and detoxification and influence not only hepatic detoxification but also renal and biliary transport mechanisms for elimination (Lampe 2007). Singular nucleotide polymorphisms (SNPs) are the differentiators of genetic predisposition to detoxification and immunity, and researchers have found SNPs, which predispose specific individual responses to pharmaceutical drugs as well as susceptibility to environmental toxins and to the risk of contracting some cancers (Genetics Home Reference 2015). These inter-individual variables may first need to be evaluated by functional lab tests such as genomic profiling before a nutritional programme can be embarked upon (Genova Diagnostics 2015). As not all clients will present with symptoms outwardly relating to the gut, further assessment will be required to gage the degree to which detoxification intervention might be beneficial. 


Lipid-soluble compounds enter into the circulation via the lymph system, passing first through the GALT. Made up of Peyers patches and inter follicular regions containing dendritic cells, the GALT provides an immune resistance to antigens in the gut. The GALT is sited within the gut mucosa; therefore any changes to the composition of the microbiome can affect the immune environment of the GALT.  A thorough examination of the gut microflora may be necessary at the outset of a nutritional programme to determine the composition of the microbiome and the existence of parasites.  Many changes to the microbiome are modifiable through diet. Long-term ‘alterations in the intestinal lumen’ can lead to alterations in gene expression and compromise health (Sanderson 2007). Dysbiosis or leaky gut may also compromise detoxification pathways by allowing toxins to permeate the lumen wall. A programme of pre- and probiotics can favourably alter the ratio of beneficial to harmful bacteria in the gut rendering potentially toxic bacteria inactive and eliminating them via Phase II, sulfation and emulsification with bile acids. Elimination of waste is an important part of the natural digestive detoxification process. Being constipated will produce toxic endogenous metabolites, during slow transit through the colon and dysbiosis may cause de-conjugation of oestrogens (IBS Clinics 2013). A diet rich in fibre can assist in improving both transit time and the bacterial environment of the colon.



Existing nutritional status and lifestyle factors are in themselves a modifiable risk factor. Nutrient-poor diets, lacking in vital nutrients to act as co-factors for countless metabolic processes lead to endogenous toxicity within the body, for example, calcium, iron and zinc deficiency increase and enhance both cadmium and lead toxicity in the body (Goyer 1997). A diet rich in processed meats, high in nitrosamines, is now known to be carcinogenic (World Health Organisation (WHO) 2015) 1.  Liska (1998) states, that myriad factors leading to an increased toxic load overwhelms the bodily system to such a degree that detoxification pathways themselves are compromised and lifestyle factors such as smoking and excessive alcohol intake should be addressed before embarking on a programme of active nutritional intervention.



Some clients may benefit from support and assistance losing weight. The prevention of obesity via steady weight loss can lead to improved outcomes for diabetes, cardiovascular diseases and some cancers (WHO 2015) 2. If an individual is overweight a nutritional practitioner may suggest they embark on a slow, steady weight loss programme before specifically focusing on detoxification, as slow weight loss will prevent an overload of stored toxins being released into the system from the adipose tissue. 

An evaluation of the work environment and other modifiable lifestyle factors that have a detrimental effect on health could be the first priority for some; swapping cleaning products and beauty products for skin friendlier alternatives, which do not interfere with our natural hormones (Organic Consumers Association 2015); being mindful of the air we breathe, air pollution, the journey to work and environmental toxins within the workplace such as paints, fumes, plastics or pesticides may start to reduce the overall toxic load (Brook et al. 2004).

Some clients may benefit from specific laboratory analysis to determine any underlying conditions or parasites, for example a comprehensive Digestive Stool Analysis, or in the absence of any underlying digestive complaint, a more general assistance programme of healthy substitutions can go a long way to improving overall health outcomes (McCullough et al. 2002). Substituting mass-market vegetables with organic produce or ensuring that all vegetables are washed in a neutralising solution to remove pesticide residues from the skin; swapping non-stick pans for cast iron or aluminium and ensuring that food is not burnt over the barbeque or grill releasing toxic nitrosamines into the gut; avoiding processed meats and the saturated fat-dense red meats containing higher levels of toxicity within the adipose cells; all of the above are simple ways to reduce the overall toxic load to the body.



Exercise can act as a means of detoxification in its own right, sweating promotes the eliminations of toxins, however it also stimulates the mobilisation of fats, which, as we have seen with rapid weight loss, can increase the release of toxins and caution may be urged in the case of obese individuals starting out on a nutrition programme. Consider the many benefits of regular physical exercise to combat the risks of obesity, diabetes and cardiovascular disease, increasing oxygen and nutrient use by the muscles (Cordero et al. 2014). A healthy heart pumps blood efficiently around the body stimulating plasma filtration throughout the lymphatic organs (Mueller and Yeoh 2010) as well as preventing against obesity and diabetes (Culp 2010).


In conclusion, it is evident that myriad interconnecting factors affect detoxification pathways in the body. Any nutritional intervention, whether specifically for the purpose of detoxification or not, will serve to modify some detoxification pathways in the body in some way. I do believe that optimal detoxification helps reduce the elevated risk of disease and should be a priority in any nutritional programme, however some circumstances dictate an alternative approach; individuals taking prescription medicines, those with neurological disorders such as Autism, the obese or those with evidential high toxic load, should consider alternative approaches to restoring health other than by prioritising detoxification. Nothing should be started until a thorough personalised assessment has taken place. 






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