Dr Charles Forsyth

Ecological Physician


There is no real consensus yet on terminology.  I tend to use the term ‘food sensitivity’ to cover all forms and mechanisms of food intolerance and allergy - the fact that a food produces definite symptoms, whatever the mechanism of action.  The term ‘Type A Allergy’ is used to denote those forms of allergy where there are clear, well recognised and accepted immunological mechanisms at work.  ‘Type B Allergy’ is the type that I am describing in this article.  I use the term ‘food intolerance’  to cover those types of food sensitivity where there are other mainly non-immunological mechanisms at work, including digestive enzyme deficiencies, metabolic enzyme deficiencies, food toxins, dysbiosis (gut flora imbalance), etc.


Type A allergy includes those types of allergy  where there are classical allergic mechanisms, the most common being  atopy, which is immunoglobulin E (IgE) mediated.  The reaction to the allergen is pretty immediate, with onset of symptoms within seconds or minutes, the most common reactions being asthma, urticaria (hives), hay fever/allergic rhinitis, atopic eczema (dermatitis), anaphylaxis, vomiting, diarrhoea, etc.  The allergen exposure may be through: 1) inhalation, such as pollens, animal fur, moulds, dust mite; 2) ingestion, eg. peanuts, strawberries, fish, milk, egg, wheat, etc.; 3) contact with skin or mucus membrane, eg. substances in cosmetics, nickel, wool, latex, etc.; 4) injection, eg. insect bites, drugs & vaccines, etc.  The causative relationship between allergen exposure and symptoms is usually fairly clear due to the immediacy of the reaction, but certainly not always.


Type B food allergy is far more difficult to suspect or recognise because there is sensitivity to one or more foods that are usually eaten most days and the relationship between food and symptoms is far from obvious.  In general the onset of symptoms is usually between thirty minutes and a few hours and may last for an hour or so to a few days.  When the duration of the reaction exceeds the interval between exposures, the symptoms become continual and the cause and effect relationship is usually not made, which is why this is often called ‘masked’ or ‘hidden’ food allergy.   The symptoms are usually taken for granted or attributed to some other cause, particularly if their appearance has been gradual.  The foods that are causing the symptoms are very often (but by no means always) those that are loved or craved - which makes avoidance much less likely - in fact they are usually the foods that are eaten most of in quantity and frequency.  What also makes diagnosis and identification of Type B food allergies even more difficult is that allergy can occur to literally any one or more foods or drinks (even tap water) and literally any symptom may be caused by food allergy.  The mechanisms underlying Type B allergy are not yet understood and may be multiple.  Unfortunately Type B allergy is still hardly recognised by mainstream medicine, despite there being a huge amount of published peer-reviewed research - it is very much a reality and is one of the major causes or contributing factors to many of the diseases so common in the Western world in the last century - and is very easy to prove on an individual basis. 


Food allergy may be a cause of literally any symptom or problem but some far more commonly result from food allergy than others.  The following are some of the most common, and the likelihood of food allergy being the cause progressively increases the greater the number of these a person has.

  1. Multiple chronic symptoms

  2. Lethargy, malaise, inappropriate fatigue (esp. on waking in the morning)

  3. Cognitive impairment (poor concentration, forgetfulness, difficulty with speech, writing, and spelling, mental fogging, lack of mental clarity, easily mentally overloaded, confusion)

  4. Mood swings, irritability, anxiety, depression, insomnia

  5. Fluid retention (facial swelling, esp. around the eyes, abdominal bloating, swelling of extremities, rapid weight fluctuations)

  6. Obesity, difficulty loosing weight

  7. Food cravings/addiction

  8. Inappropriate thirst

  9. Chronic catarrh and cough, rhinitis, sinusitis, nasal polyps, asthma

  10. Palpitations, high blood pressure (hypertension), cold extremities

  11. Irritable bowel syndrome, mouth ulcers, indigestion, anal itching

  12. Urinary frequency, irritable bladder, recurrent non-infective cystitis

  13. Headaches, migraine, variation in eyesight/focusing

  14. Recurrent urticaria (hives), rashes, eczema, easy bruising, inappropriate sweating

  15. Neck & back pain (esp. sacroiliac), joint pains (arthritis), painful tender muscles

  16. Restless legs, muscle cramps


Having any one or more of the following progressively increases the likelihood of type B food allergy being a major cause of ill health.

  1. Symptoms that start or worsen during or soon after meals

  2. Symptoms that are worse before meals or if a meal is missed

  3. Symptoms that improve during or soon after meals

  4. Symptoms that are worse on waking in the morning

  5. Having one or more known food allergies

  6. Having had one or more food allergies anytime in the past, eg. milk intolerance as a baby

  7. Having other allergies/sensitivities: to drugs, chemicals, airborne substances, through contact

  8. Having symptoms that have improved or disappeared when diet has changed: on holidays, during previous elimination diets, ‘detoxification’ diets, weight losing diets, religious fasts, when ill

  9. Allergic ‘shiners’: creases in the lower eyelids, discolouration under the eyes, swelling around the eyes - ‘eye bags’


Although it is possible to be allergic to literally any food, some are far more common than others.  The most common are: wheat, rye, barley, oats, corn (maize), rice, milk (cow, goat, sheep) and it’s products, sugars, yeasts and fungi, soya and other legumes, tea, coffee, cocoa, food additives, citrus fruits, tomato/potato family, nuts, egg, chicken, beef, pork.  Multiple food allergies are very common. 


  1. Any that are eaten every day

  2. Those that are eaten/drunk the most - in quantity and/or frequency

  3. Any that there are cravings for - the greater the degree of craving, the greater the resistance to giving them up, the more excuses that are found for not eliminating them - the greater the degree of addiction - and likelihood of allergy

  4. Any that have been a cause of symptoms/problems at any time in the past

  5. Any that belong to the same food family of a food already known to be allergenic - now or at any time in the past


If there is an allergy to a particular food, it is frequently the case that there is also an allergy to some of it’s closest botanical or zoological relatives - or this may develop in the future.   This is even more true of subfamilies.  The allergy is most likely to a specific naturally occurring chemical or group of chemicals in a food, and this same chemical or group of chemicals is often most concentrated in other members of the same family - but this is not always the case.  For example, allergy to chilli is often accompanied by an allergy to one or more of the rest of the tomato/potato (Solanaceae) family, of which it is a member.  Another example is that a high proportion of people who are allergic to cow’s milk are also allergic to goat’s milk and a smaller proportion to sheep’s milk, these animals all being closely related mammals, belonging to the Bovidae family. 

Allergy to wheat is commonly accompanied by allergy to rye, barley and oats, with which it shares the subfamily Pooideae - but it is not uncommon to be allergic to members of the other subfamilies of the grass (Gramineae or Poaceae) family, namely corn, millet, rice, sorghum and sugar cane.  Most people with nut allergy are allergic to many different nuts - although most nuts come from very different botanical families, but this is because nuts share many chemical similarities.  See “Food Families”.


Wouldn’t it be nice to have a simple test that can reliably tell one if one has food allergies or not and what they are?  Unfortunately there just isn’t one yet.  The RAST test is good for identifying Type A allergies (IgE mediated), and there are a number of different blood tests for Type B food allergy, some which measure changes in white blood cells (eg. Alcat) and others that measure levels of immunoglobulin G (IgG) to foods (eg. YorkTest) but neither type are very reliable in practice and can give false negative and false positive results.  They are also quite expensive, being around £200 for testing 100 foods.  There are a number of less scientific, unconventional testing methods, such as bioelectrical tests (eg. Vega test), muscle strength testing (kinesiology), dowsing, etc - and they may be useful, but in my experience also give quite a lot of false negatives and false positives.  Until we know what the underlying mechanisms are, we will probably not be able to devise an adequately reliable test.


The most reliable and obvious test is food exclusion - withdrawal of the offending foods must, by definition, result in disappearance of the symptoms they are causing, and bring them back when the foods are reintroduced.  The problem is which foods to suspect and exclude when one can be allergic to any (and many) foods?  The ideal and certain way would be to do a complete fast - exclude all food and drink except purified water - for a week or so (and preferably change no other variables) - then any symptoms that resolve are due to food withdrawal and the offending foods and the symptoms they cause can be identified by systematic food challenges.  But of course this is not at all practical or possible for most of us!  So there are all sorts of permutations of this approach, excluding various combinations of foods.  The problem is that the majority are generalisations for particular disease types, such as arthritis or irritable bowel syndrome, and don’t usually recommend subsequent challenge testing - they do not recognise the very individual nature of food allergy.  I find the following three types of elimination diet the most useful and practical.

Full Hypoallergenic Elimination Diet (Dr John Mansfield’s)

This is, in my view, is by far the quickest and most reliable way to identify type B food allergies.  Stage 1 is just seven days on a diet restricted to 25 very “safe” hypoallergenic foods - foods that are the least commonly allergenic.  If there has been a very marked improvement in symptoms, then foods are reintroduced one at a time, no more than three a day, according to a set protocol in order to identify which produce symptoms and which are safe.  There are variations of the diet for vegetarians, those with probable intestinal candidiasis and those with arthritis.

Pro’s:  Will identify most food allergies most of the time, quickly and reliably.

Con’s:  Not appropriate for everyone as it requires high levels of motivation, organisation and self control, good observation and record keeping and and a life that is not too stressed or rushed for a few weeks.

Stone Age Diet

This is an approximation to the type of diet that our ancestors ate in pre-farming days - a mere 5-10,000 years ago.  There are still just a few cultures left in the world living a hunter-gatherer existence - and they are some of the healthiest on the planet with an extremely low incidence of cancer, cardiovascular disease, high blood pressure, strokes, diabetes, dementia, allergies, migraine, irritable bowel syndrome, autoimmune diseases!  The following are eliminated: wheat, rye, barley, oats, corn (maize), all milk products, sugars, yeasts/fungi, alcohol, tea, coffee, chocolate, egg, citrus fruits, food additives, tap water.  There is an option to also eliminate: soya, the tomato family (potato, tomato, aubergine, capsicum, chilli, cayenne, paprika, etc), beef, pork and chicken.  The diet therefore includes: most vegetables and fruits, nuts, legumes, rice, millet, quinoa, fish, lamb, turkey, most herbs and spices.  If there has been a marked improvement after  two to four weeks on the diet, then foods are tested in a similar way to that above.

Pro’s: 1) Less restrictive, 2) Eliminates the most common allergenic foods.

Con’s: Won’t identify the less commonly allergenic foods - if any symptoms aren’t relieved, it won’t be known whether they are due to not having eliminated all the allergenic foods or are not due to food allergy.

Single Food Group Elimination

If there are suspicions about certain foods from the history and past experience, they can be eliminated, along with their close relatives.  Examples would be to eliminate: all animal milk products, or all gluten grains, or all the potato/tomato family, etc.

Pro’s:  The least restrictive.

Con’s:  1) Only appropriate if there are strong clues to which foods may be responsible, 2) takes a lot longer if there are multiple food allergies, 3)  if any symptoms aren’t relieved, it won’t be known whether they are due to not having eliminated all the allergenic foods or are not due to food allergy.


  1. Patients who have little motivation/enthusiasm for the process

  2. Patients who will find compliance difficult - for whatever reason

  3. Patients who are malnourished

  4. Patients with eating disorders

  5. Patients who are pregnant or lactating

  6. Children

  7. Patients on already restricted diets, eg. vegetarians, vegans, multiple food allergies, etc.

  8. Patients who have already done one or more elimination diets

  9. Patients with multiple allergies: foods, drugs, chemicals, etc.

  10. Patients with a history of severe reactions/ unstable conditions, eg. asthma or anaphylaxis


It is very common that withdrawal symptoms occur on the first or second day of an elimination diet.  The symptoms are usually those that are experienced on a regular or continuous basis, it is rare to develop any that have never occurred before.  They can be mental and emotional as well as physical and may be quite severe and accompanied by strong cravings for one or more foods. The reaction usually lasts just a few days and has almost always passed by day 5.  The good news is that if any worsening in symptoms occurs, you can almost guarantee that 1) many of your health problems are due to food allergy, and 2) that you will have a dramatic improvement in the symptoms and your health very soon. 


Whether a food allergy is temporary or permanent is dependent on whether the underlying predisposing factors are adequately modified or one has successful desensitisation. 

Food Avoidance

If one has just a few food allergies it may not be too much trouble to just avoid the offending foods.  Knowing which foods one is sensitive to, to what extent and what the effects are, enables one to make a conscious choice - do I eat the food and suffer the consequences or not!  Which hurts more - eating it or not?  I don’t believe in restricting ones diet any more than one has to, without very good reason!  Why completely avoid something natural and healthy if it is having only minimal adverse effects?  My motto is “be practical”.  The first thing is to avoid the foods strictly for some months to allow the system to recover and see how good one’s symptoms get.  Prolonged avoidance (six months or so) may well result in a reduction in or disappearance of the sensitivity - but it may not be permanent, and resumption of frequent consumption may bring it back.  Once an allergy has developed, it is unlikely that the susceptibility will be completely lost and sufficient stimulation will most likely reawaken it.  Most food allergy is due to overconsumption of foods that are not the most natural to us.

After the initial phase of avoidance it is often possible to have the food again on an intermittent basis.  The main thing is to avoid eating the food more than once every four or five days or so, for the simple reason that the effect of the last dose will not have completely worn off by the time the next is taken, and it is very easy to slip back to eating the food regularly and loose the association of it and the symptoms it causes.  It is also much less stressful for the body if it is allowed to fully recover from each exposure.  This is called a ‘rotation diet’.

General Health Measures - Self Help

  1. Diet - make your diet the best it can possibly be -  fresh, natural, wholefood, organic, vegetable dominated, satisfying, broad and varied - as outlined in my information sheet “General Dietary Advice”.   The nature, quality and quantity of what is eaten has a major effect on gut function!  Especially keep sugar to an absolute minimum as it encourages yeast overgrowth (amongst other things) and eat much less starch than most of us are used to.

  2. Good Digestion depends on Good Eating Habits

  3. Try and eat when relaxed, not when stressed. Take your time over meals - don’t eat in a rush - eat slowly.  Have a rest or a nap after lunch.

  4. Make your main meal at lunchtime if possible.  Avoid eating a meal within two hours of going to bed; a gentle walk after the evening meal is good.

  5. Avoid big meals, the less food there is to digest, the more efficiently it will be digested.

  6. Chew your food really well - digestion starts with the saliva in the mouth and the more the food is chewed up, the more available it is for digestion.

  7. Drink relatively little during and immediately after meals - don’t dilute your digestive juices any more than necessary.

  8. Exercise - take plenty of regular physical exercise - see “ Exercise for Health” for more info.

  9. Sleep - get enough good quality sleep - see “Relaxation Essentials” & “Management of Insomnia”.

  10. Stress Management - good self pacing, regular rest periods, realistic and appropriate expectations, regular holidays, relaxation exercises, etc - see “Relaxation Essentials” & “A Simple Relaxation Exercise”.

  11. Bugs - be sensible about cleanliness, hygiene and exposure to infection; use specific preventative measures when and where appropriate; use natural approaches to treat infections; avoid antibiotics whenever possible; eat live yogurt or/and take a probiotic occasionally and always after antibiotics; optimising health (all the above and below) will maximise immune function.

  12. Toxins - minimise toxic exposures - chemicals and other toxins in your environment: air, food, water, cosmetics, cleaning agents, etc; minimise medical and social drug usage, etc - see “Environmental Cleanup”, “Natural Cosmetics”, etc.

  13. Radiation - minimise exposure to x-rays and microwaves (DECT, mobile phones, microwave ovens, wireless networks), avoid getting sunburnt, etc - see “EMF/EMR”.

  14. Psychological - be actively working towards resolving emotional, personal, occupational, relationship and life goal issues, recognising those things that are important to you and making them priorities in your life, nurturing your creativity, contributing to society and living in harmony with your environment.  See “Psychological Resources”.

  15. Nutritional Supplements - take a good multivitamin and mineral supplement, omega 3 essential fatty acids, extra magnesium, vitamin C, flavonoids and also vitamin D in the winter months (and summer if you don’t spend much time outdoors bearing some skin to the sun) - see “Nutritional Supplements” for more info.

  16. Probiotics - eat live yogurt or similar regularly or/and take a good probiotic supplement.

Specific - Medical

  1. Improve Gut Ecology - see “The Management of Gastrointestinal Problems”

  2. Identify and correct intestinal flora imbalance - reduction or absence of the friendly bacteria (esp. Lactobacillus acidophilus, Bifido bacteria and E coli).

  3. Identify and, if present, eradicate overgrowth of or infection with unfriendly/pathogenic intestinal organisms, and the predisposing factors:

  4. Helicobacter pylori - mainly in the stomach, the main cause of peptic ulcers.

  5. Other bacteria - called “bacterial dysbiosis” or “bacterial overgrowth”.

  6. Yeasts - usually Candida albicans - called “Candida overgrowth”, “fungal-type dysbiosis”, “auto-brewery syndrome”, etc.

  7. Parasites - eg. Blastocystis hominis, Dientamoeba fragilis, Entamoeba histolytica, Giardia lamblia, Endolimax nana, Cryptosporidium, Cyclospora.

  8. Identify and, if present, correct poor stomach acid or/and enzyme production.

  9. Identify and, if present, correct the causes of increased small intestinal permeability or “leaky gut syndrome”.

  10. Identify and, if present, correct secretory IgA (sIgA) deficiency.

  11. Identify any toxins that may be having a direct effect on the gut (eg. alcohol, tobacco, food additives, mercury from dental amalgams, etc), and eliminate, where possible.

  12. Nutrition - identify and correct any nutritional deficiencies and their causes - optimise nutrient status.

  13. Allergies - identify and treat any other allergies (inhalant, chemical, drug, etc.) and their causes, and avoid the allergens or/and desensitise - see “Allergy”, “Type B Food Allergy”, etc.

  14. Bugs - identify and eradicate any hidden chronic systemic or local infections (eg. chronic tonsillitis, chronic dental infections, leaking dental root canal treatments, Lyme disease, etc.) and treat their causes - see Gut Dysfunction”, “Fungal Type Dysbiosis” and Bacterial Dysbiosis”, etc.

  15. Toxins - identify any toxins and their sources, avoid further exposure and reduce tissue levels to an absolute minimum - see “Tests for Assessing Toxic Status”, “Detoxification Program”, etc.

  16. Radiation - identify and reduce exposure to any harmful radiation.

  17. Psychological - identify any causative, predisposing or limiting factors on the psychological level - emotional, mental, spiritual; personal, occupational, relationship and life goal issues, etc.

  18. Rebalance Control Systems - homeopathy, acupuncture/ TCM, Ayurveda, polarity therapy, kinesiology, healing, etc.

  19. Desensitisation

  20. Neutralisation - Miller series 1:5 dilutions - see Neutralisation

  21. Enzyme Potentiated Desensitisation (EPD)

  22. Homeopathic

  23. Bio-electrical:  eg. Mora, Bioresonance

  24. Anti-Allergy Drugs  - not a long term solution at all but may be helpful when other approaches are ineffective

  25. Sodium cromoglycate (Nalcrom) - expensive

  26. Antihistamines



Allergy. A Practical Guide to Coping.  Maberly J, Anthony H.  Crowood Press 1989.  ISBN: 1-85223-172-6.  112 pages.  A brief succinct practical guide for the lay person.

Food Allergy and Food Intolerance - The Complete Guide to their Identification and Treatment - Jonathan Brostoff and Linda Gamlin.  Healing Arts Press 2000.  ISBN:  0892818751.  470 pages.  A comprehensive guide for the lay person.

Not All In The Mind - Richard Mackarness  Harper Collins Publishers Ltd; Rev Ed edition 1994 . ISBN-10: 072253020X  ISBN-13: 978-0722530207.  160 pages.  The book that brought food allergy to public consciousness in 1976, written by a British psychiatrist.

Food Allergy and Intolerance.  Brostoff J. & Challacombe S J , eds., 2nd edition, Elsevier  July 2002.  ISBN: 0702020389 / 9780702020384.  992 pages. £169.  The standard comprehensive medical text book on the subject.

An Alternative Approach to Allergies. Randolph TG, Moss RW.  Revised edition.  New York:  Harper and Rowe 1989. 338 pages.  An excellent overview of the field of clinical ecology, includes food allergy and chemical sensitivity, written by one of the great pioneers in the field.  For the interested lay person and a good introduction for doctors.

Dealing With Food Allergies - by Janice M. Vickerstaff Joneja - 416 pages.  A comprehensive guide written primarily for the lay person.

Dietary Management of Food Allergies and Intolerances.   Janice Joneja.  2nd edition.  J A Hall Publications Ltd.  Vancouver, Canada.  IBSN: 968209823.  426 pages.   Ditto.

Effective Allergy Practice.  A Document on Standards of Care and Management for the Allergy Patient.  BSAEM/BSNM Subcommittee 1994.  A good overview, mainly for doctors, also the interested lay person.

Environmental Medicine in Clinical Practice.  Anthony H, Birtwistle S, Eaton K, Maberley J.  BSAENM Publications 1997. IBSN 0-9523397-2-2.  The standard UK textbook for doctors.

Food Allergy:  Its Manifestation and Control and the Elimination Diet.  A compendium.  Rowe AH, Rowe A jr. Springfield III, published by Charles C Thomas in 1972.  One of the original works on the subject, written by one of the great pioneers.


Food Allergy & Intolerance

  ECOLOGICAL MEDICINE:  Overview   Nutrition   Allergy   Microbes   Toxins  EMR

  Allergy:   Allergy Overview    Food Allergy