Although nutrition, as a science, has always been part of conventional medicine, doctors are not taught, and therefore do not practise, much in the way of nutritional therapeutics. Dieticians in conventional settings tend to work mainly with particular patient groups—such as those with diabetes, obesity, digestive or swallowing problems, or cardiovascular risk factors. Apart from the treatment of gross nutritional deficiencies and rare metabolic disorders, other nutritional interventions generally fall outside the mainstream and can therefore be described as complementary medicine.
Background
There is a wide spectrum of complementary nutritional practices. These range from specific, well researched, biochemically understood treatments that are given by well trained practitioners to unresearched, biochemically implausible interventions popularised by spectacular claims in the lay press and largely used without professional supervision.
Just which treatments are “conventional” and which are “complementary” is subject to debate. Some, such as fish oil supplements for patients with rheumatoid arthritis, have many of the features of a conventional medical treatment—a biochemical mechanism and support from randomised trials— but are, none the less, often considered unconventional. Other interventions were originally considered “complementary” but are now part of conventional practice. Probably the best example is the high fibre diet, rich in fruit and vegetables. “Alternative” practitioners of the 19th century, such as John Kellogg, advocated such a diet at a time when conventional nutritional authorities tended to see meat and potatoes as the best food, even to the extent of denigrating the importance of vegetables and describing wheat bran as “refuse.”
Nutritional interventions
Unconventional nutritional interventions can be broadly divided into three categories: nutritional supplements, dietary modification, and therapeutic systems.
Examples of nutritional supplementation
High dose vitamin C for cancer
Zinc for the common cold
High dose vitamins for learning disability (“orthomolecular” therapy)
Evening primrose oil for atopic dermatitis
Evening primrose oil for premenstrual syndrome
Vitamin B-6 for morning sickness
Vitamin B-6 for premenstrual syndrome
Garlic for lowering cardiovascular risk
Multivitamins for improvement in general health
Nutritional supplements
As well as various vitamins and minerals, the range of nutritional supplements includes many animal and plant products. Some of these have known active ingredients, such as γ-linolenic acid in evening primrose oil. Others, such as blue-green algae and kelp, have not been fully characterised biochemically. Some supplements are taken to improve general health and performance, while others are for specific clinical indications. Most are taken in pill form. There is some overlap between herbal and nutritional supplements.
Examples of diets claimed to improve general health
Hay diet—Proteins and carbohydrates eaten separately
Raw foods diet—Avoidance of cooked foods
Stone Age diet—Avoids grains, pulses, and other products of the agricultural revolution
Macrobiotic diet—Largely grains and vegetables. Foods are chosen and balanced in accordance with traditional oriental principles such as yin and yang
Veganism—Avoids all animal products
Dietary modification
This involves more comprehensive changes in eating patterns. Many diets, such as vegetarianism and veganism, originated as “movements” characterised by political and ecological concerns, a moral stance towards food, and a view of diet as inseparable from lifestyle. Many diets are based on theoretical considerations rather than empirical data. For example, the rationale for the Hay diet's principle that starch and protein should not be eaten together is that each type of food requires a different pH for optimum digestion. The principle of the Stone Age diet is that humans are not adapted by evolution to eat grains and pulses.
Examples of dietary interventions claimed to help in specific conditions
Dong diet for arthritis—Recommends a diet similar to that of Chinese peasants
Feingold diet for attention deficit disorder—Recommends elimination of food additives
Polyunsaturated fatty acid diet for multiple sclerosis
Gluten-free diets for schizophrenia
Atkins diet—Recommends elimination of all carbohydrates for weight loss
“F-plan”—High fibre diet for weight loss
Dairy-free diet for recurrent respiratory disease
Gerson diet for cancer—Strictly vegetarian, largely raw food, diet with coffee, enemas, and various supplements
Therapeutic systems
These include techniques such as elimination dieting and naturopathy. Elimination dieting is based on the principle that foods particular to each patient may contribute to chronic symptoms or disease when eaten in normal quantities. Unlike classic allergy, these “food intolerances” do not involve a conventionally understood immune mechanism or inevitably have a rapid onset.
Diagnosis consists of eliminating all but a few foods from the diet and then reintroducing foods one by one to see if they provoke symptoms. After a period of complete exclusion, the problem substances can usually be gradually reintroduced without recurrence of symptoms. Although practitioners commonly diagnose wheat and dairy “intolerance,” each patient is said to be sensitive to a different set of foods.
Naturopathy is a therapeutic system emphasising the philosophy of “nature cure” and incorporating dietary intervention among other practices such as hydrotherapy and exercise. For example, a naturopath might advise a patient with recurrent vaginal candidiasis to undertake a limited fast, reduce intake of foods containing sugar and yeast, and take herbal and probiotic preparations.
Another therapeutic system tests patients for “subclinical” nutritional deficiencies—thought to arise where systems of food intake, digestion, or absorption are not fully functional—and gives appropriate supplementation.
Key studies of efficacy or reliability
Systematic reviews
Douglas RM, Chalker EB, Treacy B. Vitamin C for the common cold. In: The Cochrane Collaboration. The Cochrane Library. Issue 2. Oxford: Update Software, 1998
Fortin PR, Lew RA, Liang MH, Wright EA, Beckett LA, Chalmers TC, et al. Validation of a meta-analysis: the effects of fish oil in rheumatoid arthritis. J Clin Epidemiol 1995;48:1379-90
Budeiri D, Li Wan Po A, Dornan JC. Is evening primrose oil of value in the treatment of premenstrual syndrome? Controlled Clin Trials 1996;17:60-8
Wyatt KM, Dimmock PW, Jones PW, O'Brien PMS. Efficacy of vitamin B-6 in the treatment of premenstrual syndrome: systematic review. BMJ 1999;318:1375-81
Randomised controlled trial
Schmidt MH, Mocks P, Lay B, Eisert HG, Fojkar R, Fritz Sigmund D, et al. Does oligoantigenic diet influence hyperactive/conduct-disordered children—a controlled trial. Eur Child Adolesc Psychiatry 1997;6:88-95
Study of reliability
Sethi TJ, Kemeny DM, Tobin S, Lessof MH, Lambourn E, Bradley A. How reliable are commercial allergy tests? Lancet 1987;i:92-4
What happens during a treatment?
Many people make unconventional nutritional changes without consulting a practitioner (see below). Where practitioners are involved in treatment, consultations may involve some form of testing for deficiencies of particular nutrients or hidden allergies. Such tests include biochemical assays of the vitamin and mineral content of blood or hair. In “Vega” or electrodermal testing an electrical circuit is made that includes both the patient and the foodstuff suspected of causing disease. In applied kinesiology practitioners claim to be able to diagnose allergy or deficiency on the basis of changes in muscle function.
Evidence of therapeutic scope
Randomised controlled trials have favoured a small number of indications for high dose vitamin and mineral supplementation. These include both vitamin C and zinc for treating (though not for preventing) the common cold, vitamin B-6 for premenstrual syndrome (though trials are not of high quality) and autism, and vitamin E for angina.
There is evidence that exclusion dieting can be of benefit for various conditions including rheumatoid arthritis, hyperactivity, and migraine. However, only a minority of patients with such conditions seem to benefit, and it is not yet possible to select these in advance. Randomised trials have shown that increasing consumption of polyunsaturated fatty acids—for example, by supplementation with products such as fish oils or evening primrose oil—and reducing saturates can be beneficial in hypertriglyceridaemia, rheumatoid arthritis, and inflammatory bowel disease.
The evidence for most other unconventional nutritional interventions in treating disease is generally either negative or non-existent. For example, randomised trials have failed to show any benefit from high dose vitamin C for cancer; megadose therapy for Down's syndrome, learning disability, or schizophrenia; the Dong diet for arthritis; essential fatty acid supplementation for psoriasis or premenstrual syndrome; and vitamin B-6 for carpal tunnel syndrome.
Many unconventional diets are claimed to have benefits in specific conditions and general effects on physical health, mental wellbeing, and even spiritual development. Apart from those discussed above, these have not been evaluated systematically. There has been no rigorous research on the naturopathic approach to chronic disease or on individualised nutritional therapy.
Nutritional tests
While some unconventional laboratories use assays and methods of quality control similar to those used in mainstream biochemical laboratories, others may be less reliable.
In studies where duplicate samples of hair or blood were sent to “alternative” nutritional testing laboratories there was low agreement in results for the same individual. In one investigation several laboratories which advertise services to the general public failed to report fish allergy in subjects who were allergic to fish but ascribed numerous (but inconsistent) allergies to healthy controls.
There is insufficient evidence on the validity of “Vega” testing. Studies have also found that practitioners of techniques such as applied kinesiology are unable to obtain consistent results from duplicate blinded samples.
Safety
Most unconventional diets recommend generally healthy patterns of eating (reduction or elimination of fat, sugar, alcohol, and coffee and an increase in fresh vegetables and fibre) which most people with a normal digestion can tolerate without side effects.
Some diets, such as veganism or macrobiotics, are highly restrictive and can lead to complications such as reduced bone mass or anaemia, especially in children. Children, pregnant and lactating women, and patients with chronic illness should undertake such major dietary changes only under professional supervision. A drawback of any dietary change can be social disruption when a patient cannot share meals with friends and family.
High dose nutritional supplementation can lead to acute adverse effects such as diarrhoea (vitamin C) and flushing (niacin) during treatment. Persistent or more serious adverse effects are rare for water soluble vitamins, although chronic use of high dose vitamin B-6 can lead to neuropathies. Adverse effects, though still uncommon, are more likely to result from high doses of fat soluble vitamins: vitamin A has been linked with birth defects and irreversible bone and liver damage, and vitamin D with hypercalcaemia. High doses of single minerals or amino acids may induce deficiency in nutrients that share similar metabolic pathways. Excessive doses of zinc and selenium can cause immune suppression, and evening primrose oil may exacerbate temporal lobe epilepsy.
Practice
Decisions to make unconventional nutritional changes are reached by many routes, often through the use of self help books, leaflets, and magazine articles or advice from friends, relatives, and staff of health food stores. People may also make changes on the basis of nutritional tests provided by commercial companies which advertise laboratory services in the pages of health magazines.
Regulatory bodies in nutritional medicine
General Council and Register of Naturopaths
2 Goswell Road, Street, Somerset BA16 0JG. Tel: 01458 840072. Fax: 01458 840075. Email: admin@naturopathy.org.uk. URL: www.naturopathy.org.uk
British Association of Nutritional Therapists
BCM BANT, London WC1N 3XX. Tel: 0870 606 1284
Nutritional consultations may be given by a wide range of practitioners with varying levels of training and experience, from complementary practitioners who mainly practise other disciplines through trained nutritional therapists and naturopaths to nurses and doctors who have undertaken further training in nutrition.
Training and educational organisations
Institute for Optimum Nutrition
Blades Court, Deodar Road, Putney, London SW15 2NU. Tel: 0181 877 9993. Fax: 0181 877 9980. Email: ion@cableinet.co.uk
British Society for Allergy, Environmental and Nutritional Medicine (BSAENM)
Membership organisation for doctors only
For publications: PO Box 28, Totton, Southampton SO40 2ZA. Tel: 01703 812124
For inquiries: PO Box 7, Knighton LD7 1WT. Tel: Premierline 0906 3020010
Nutritional medicine can be a relatively expensive form of complementary medicine. Diagnostic tests can cost from £15 to over £100 per test, nutritional supplements may cost £10-£50 a month, and dietary changes involving organic produce or wholefoods may also have substantial cost implications.
Regulation
The General Council and Register of Naturopaths registers and regulates the 180 or so naturopaths practising in the United Kingdom. Most of these are also trained osteopaths. Regulation for other nutritional practitioners is not as well established. The British Association of Nutritional Therapists registers and arranges mandatory insurance for about 200 practitioners who have completed one of the more thorough courses at selected training colleges. A few smaller registers also exist.
Further reading
Anthony H, Birtwhistle S, Eaton K, Maberly J. Environmental medicine in clinical practice. Southampton: BSAENM Publications, 1997
Brostoff J, Gamlin L. Complete guide to food allergy and intolerance. London: Bloomsbury, 1992
Davies S, Stewart A. Nutritional medicine. London: Pan, 1987
Murray M, Pizzorno J. Encyclopaedia of natural medicine. 2nd ed. London: Little, Brown, 1999
Training
Various courses in nutritional therapy exist, ranging from short courses of a few days leading to a certificate in basic nutrition to three year, part time courses leading to qualification as a nutritional therapist. Naturopaths in Britain usually undergo a four year, full time training which includes anatomy, physiology, biochemistry, and pathology as well as naturopathic and osteopathic principles and practice.
The British Society for Allergy, Environmental, and Nutritional Medicine is an association of doctors with a special interest in nutrition. It organises educational events and publishes the Journal of Nutritional and Environmental Medicine.
Figure.
Conventional doctors only rarely make use of nutritional interventions, which is perhaps one reason why nutritional medicine has come to be regarded as part of complementary medicine
Figure.
In the Hay diet proteins and starch must be eaten separately, though fruit and vegetables can be eaten with either
Figure.
In the Stone Age diet grains, pulses, and other products of the agricultural revolution must be avoided. Such exclusion diets can be highly restrictive, socially disruptive, and expensive
Figure.
Vega testing is said to identify patients' individual food intolerances. Although its validity remains uncertain, it is often used to draw up personalised elimination diet programmes
Figure.
Some typical nutritional supplements. Though often perceived by the public to be inherently safe, supplements can sometimes be associated with adverse effects, especially when taken in high doses for long periods
Figure.
Many patients undertake unconventional diets without advice from a practitioner of any kind
Acknowledgments
The pictures of foodstuffs are reproduced with permission of CEPHAS/ Stockfood. The picture of Vega testing is reproduced with permission of Hattie Young/Science Photo Library. The picture of nutritional supplements is reproduced with permission of BioCare. The picture of diet books is reproduced with permission of BMJ/Ulrike Preuss.
Footnotes
The ABC of complementary medicine is edited and written by Catherine Zollman and Andrew Vickers. Catherine Zollman is a general practitioner in Bristol, and Andrew Vickers will shortly take up a post at Memorial Sloan-Kettering Cancer Center, New York. At the time of writing, both worked for the Research Council for Complementary Medicine, London. The series will be published as a book in spring 2000.