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Food allergy and its clinical symptoms in Nigeria

Simeon C. Achinewu
Department of Food Science and Technology, Rivers State University of Science and Technology, Port Harcourt, Nigeria

EDITOR'S NOTE

The frequency of food allergies is not sufficiently appreciated because they are difficult to investigate. This is because the reactions are subjective and hard to verify. Almost all of the reported prevalence rates are from industrialized countries, and they vary from four to 30 per cent. The following paper indicates that food allergies must also be taken into account in nutrition advice in developing countries.

INTRODUCTION

Adverse effects resulting from ingestion of certain foods have been recognized by rural Nigerian people for a long time. Some attributed these effects to poisoning by enemies, others to the anger of the gods, and only a few understood that they could have been caused by constituents in foodstuffs. Abnormal reactions to food may be the result of either food allergy or food intolerance. Food allergy can be defined as hypersensitivity mediated by one or more forms of immunological reaction to certain food components. This is different from intolerance induced by other mechanisms, such as lactase deficiency and milk intolerance (1).

A wide range of illness has been attributed to food allergy. For example, Dohan (2) has shown that psychiatric symptoms, including schizophrenia, could be caused by food allergy. The mechanism by which such adverse effects are mediated is not fully understood. The problems of food allergy are of great public health concern, and hence an investigation was initiated to identify some of the offending foods and the symptoms they cause.

MATERIALS AND METHODS

A prepared questionnaire was distributed to fairly literate communities throughout the Rivers State of Nigeria. All age groups in all walks of life were covered. There was no attempt to interview equal numbers of age or sex groups. Individuals were given sufficient time to answer the quest tions asked on the forms. They were allowed to recount previous symptoms of food allergy from childhood, and how many times such food was eaten with definite adverse effects. Individuals were asked whether other family members, including parents, grandparents, children, and other relatives had similar reactions to the same food. Children's questionnaires were completed by their parents. The questionnaire sought to determine whether the reaction was immediate or prolonged, mild or violent, and whether any medical advice was sought. The criterion for confirming suspected allergy to a specific food was occurrence of symptoms more than three times in the same individual after eating that food.

RESULTS

In ail, 972 people responded to the questionnaire and 275 reported allergies to various foodstuffs. This represented about 28 per cent of total respondents.

Table 1 shows the various foods reported to cause allergic reactions. The figures represent the number of people who stated that they were affected by the particular food or food group, expressed as per cent of the total number of people affected by all foods. Foods of plant origin together caused more complaints of allergy than other foods did. This was followed by marine foods, which affected 14.7 per cent of the people. The 9.8 per cent who reported allergic reactions to milk and milk products were mostly children. Meat, especially pork, affected only 1.6 per cent, while eggs caused reactions in 5.4 per cent. Some people reported allergy to more than one food. About 5.2 per cent of those with food allergies reported that other members of their immediate families reacted to the same food in the same manner, an indication that allergic tendency may be hereditary.

TABLE 1. Various Foods that Caused Allergic Reactions

Table 2 shows the clinical symptoms and parts of the body affected. About 58 per cent had gastrointestinal symptoms. Some 17.5 per cent developed skin reactions, while the respiratory and central nervous systems were involved in 9.6 and 5.4 per cent, respectively. Fewer people complained of circulatory, muscular, ear, nose and throat, and eye or mouth symptoms.

Only a few of the people who suffered allergic reactions (less than 30 per cent) sought medical advice. The rest had local treatment or put up with the inconvenience. Many simply abstained from eating the offending foodstuffs. Some suffered the same symptoms when they unknowingly ate the food again.

DISCUSSION

Many different kinds of food caused allergic reactions, and affected various parts of the body. Similar findings have been reported by Denman (1) and Bender and Matthews (3). Several workers have associated other ill health with food allergy. For example, bed-wetting in a normal child over three years old was associated with a food allergy. Gerrard and coworkers (4) showed that the capacity of the bladders of such children to expand was severely restricted by swelling of all layers of the bladder wall. The bladders resumed normal size when allergenic foods were removed from the diet. Denman (1) and Dohan (2) suggested that food allergy might provoke psychiatric symptoms and abnormalities in the heart rate. Dickerson (5) concluded that special facilities are necessary to investigate and treat people with food allergies. The provision of these facilities is necessary for disease prevention and health care.

In the present study, some of the people affected discontinued eating the offending food. However, some of these foodstuffs are staples supplying a wide range of nutrients, and complete abstinence from these foods when there may be no alternatives may lead to malnutrition. Some others who had not much variety of foods to choose from continued to eat some of the allergenic foods and suffered discomfort. This makes food allergy a public health problem and it becomes necessary for affected individuals to seek dietary advice. Food allergy should be more recognized as a problem and should be given adequate attention in a nation's public health programme.

REFERENCES

1. A. M. Denman, "Nature and Diagnosis of Food Allergy," Proc. Nutr. Soc., 38: 391 (1979).
2. F. C. Dohan, "Cereals and Schizophrenia, Data and Hypothesis, "Acta Psychiat Scand., 42: 125 (1976).
3. A. E. Bender and D. R. Matthews, "Adverse Reactions to Foods," Brit. J. Nutr., 46: 403 (1981).
4. J. W. Gerrard, B. Jones, and M. K. Shorkier. "Allergy and Urinary Infection: Is There an Association?" Pediatrics, 48:994 (1971).
5. J. W. T. Dickerson, "Adverse Effect of Food on Human Health," Roy. Soc. Hlth J., 101 (No. 5): 200 (1981).

TABLE 2. Clinical Symptoms Caused by Floods.*

*The figures represent the number of people affected by the group of symptoms expressed as percentage of the total number affected.

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