Individual Reactions to Treatments

The summer meeting of the British Society for Ecological Medicine ( addressed the complex question of individuality. Why do different individuals react to nutritional, medicinal and environmental inputs in different ways? James Mallinson reports.

Alcohol toxicity - not every drinker

Dr Victor Preedy, head of the Nutritional Sciences Research Division at King’s College London’s Genomics Centre, asked why some drinkers can OD on alcohol with little apparent toxic effect whereas others cannot.

It is generally believed that cirrhosis and brain damage are the most common physiological results of alcohol misuse; in fact there is good evidence that alcohol can affect a wide range of body systems. Alcoholic myopathy, characterised by muscle weakness and loss of bulk, is five times more common than cirrhosis and is arguably the most prevalent skeletal muscle disorder in the western hemisphere. But, not every alcohol misuser will develop a disease.

The key lies in the way alcohol is metabolised. A major product of the metabolism of alcohol is acetaldehyde. Acetaldehyde is normally oxidised to acetate, which is not overtly toxic. This reaction is catalysed by aldehyde dehydrogenase, which is where genes come into play. Depending on the individual’s genetic make-up, the level of acetaldehyde resulting from a similar amount of alcohol will be very different.

Parallel reactions in the metabolism of alcohol include the generation of free radicals and oxidative imbalance, so dietary factors such as vitamin E are important in counteracting the damaging effects of alcohol. Individual responses to alcohol are due to a combination of genetics, diet and other lifestyle factors.

Why are some patients harmed by medicines and others are not?

Professor Munir Pirohamed of the Department of Pharmacology at Liverpool University quoted some frightening statistics.

It is estimated that up to 65% of the patients in hospital at any one time are there because of adverse drug reactions (ADRs). Around 28% of ADRs are easily avoidable and probably over 70% could be avoided with correct prescribing practices.

The most common cause of ADRs is the prescription of multiple drugs that interact with each other. It is common practice, for instance, to prescribe aspirin with a non-steroidal drug when the combination is more dangerous than either drug alone and, in most cases, less effective.

One dose size does not fit all. Individuals can have radically different dose requirements and the effectiveness or otherwise of a particular drug depends on getting the dose right. The medical profession needs strategies to personalise drugs doses to individuals. There can be severe interactions between herbal medicines and prescription drugs yet doctors seldom ask patients about, or note, herbal and other alternative remedies they may be taking. Doctors need to educate their patients to tell them about their drug regimes - and they need to educate themselves to listen.

Of the UK population over 80, more than 60% is on warfarin, but it is very difficult to titrate the correct warfarin dose for the individual patient. The warfarin dose requirements of 54% of those over 80 could be determined by genetic tests, but unfortunately for 46% the tests are not yet effective.

Genotype analysis is likely to be the way forward for determining drug dosage of warfarin but there is still a long way to go.

Diet and individuality in detoxification

Dr Rosemary Waring, Reader in Human Toxicology at the University of Birmingham, asked why it is that different people respond differently to diet and environmental factors? Her research indicates that that the answer lies in a combination of inborn susceptibility (genetics) and the precise cumulative input from the environment. This leads to some interesting conclusions.

The answer to the perennial question ‘is coffee bad for me?’ depends on the individual’s acetylator status. Fast acetylators are not affected by coffee whereas slow acetylators are. The UK population is split roughly 50/50 between fast and slow acetylators, so probably 50% of the customers of the local Starbucks should not be there, as almost nobody knows their acetylator status.

Generalisations about diet and health are often hard to justify. For instance, epidemiological cancer studies show no real benefit from the much hyped five portions of fruit and vegetables. In some individuals fruit and veg enhance important enzymes, whereas in other cases they inhibit them. Certain foods do have widespread and detectable benefits. Onions and bananas are good for the hearts of most people.

Allergic responses can be made worse by the presence of sulphite (often found in food preservatives). Patients with allergies frequently have high urinary sulphite levels, which may reflect an inability (either genetically or environmentally induced) to oxidise sulphite to non-toxic sulphate.

Blood group diets

Drs Tom Greenfield and Laura Power both discussed blood group diets but this has been covered in some detail in Dr Greenfield's article. More information can also be had at where Dr Greenfield has a regular blog.

First published in 2006

If this article was of interest you will find many other articles on unlikely allergies and allergy connections here – and links to many relevant research studies here.

For more on the more 'mainstream' allergies check in to our 'allergy and intolerance home page' – and for ideas on alternative foods go here.

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