Everybody eats potatoes. They belong to the family Solanacae that was brought to Europe from South America by the Spaniards 500 years ago. The family includes tomato, aubergine, peppers, tobacco and deadly nightshade. Potato is normally considered such a bland food that is included in diets for food intolerance and for weaning babies – but research from Finland has established that potatoes contains several powerful allergens. During my years of practice I have seen 39 cases in which a remarkable variety of serious problems were caused by potato.
Definite allergy to potato: a severe asthma attack being brought on by being in a kitchen where potatoes are being cooked, for example.
The only case I have seen developed whooping cough as a a baby. But the cough persisted along with swelling of the lips, tongue and eyes. The mother finally made the diagnosis when she noticed that the attacks always happened during meals containing potato or when the child was near a cooking potat. With difficulty she convinced the doctors that if a potato was strictly avoided her daughter would remain well. Even a trace of potato on a serving spoon was enough to trigger an attack of asthma. Tomato also caused a reaction but a lesser one.
Delayed reactions: these can cause all sorts of problems anywhere in the body are more common.
In housewives, the commonest indicator of a possible potato allergy is sneezing or wheezing when scraping new potatoes as the scraping creates a fine spray of juice from the potato skin. Itching of the hands or worsening of eczema after peeling potatoes is also suggestive of sensitivity. Potato is such a common food that the possible significance of this observation is seldom realised. Skin prick testing with a drop of fresh potato juice was strongly positive in 32 out of 39 cases.
Effects on behaviour and the nervous system
Potato effected behaviour in seven of the 38 other cases I have indentified.
The first case which alerted me to this possibility was a ten-year-old girl attending the clinic for the seasonal and perennial hay fever, who seemed also to be mildly mentally retarded and very lethargic. She had frequent headaches, slept most of the day, and had no initiative.
Nine years later she was living away from home and cooking for herself when a shortage made potatoes so expensive that she did without. I was fortunate to see her at this time when it was obvious that her personality had changed dramatically, she was quite vivacious and she told me that her headaches and lethargy had vanished overnight. Three deliberate open challenges with potato reproduced headache and lethargy and finally an accidental challenge when she was unaware she had had potato confirmed the association beyond doubt. The case heightened my awareness, but the presentations were so variable and bizarre that the most striking cases are worth describing in some detail.
The most dramatic was a boy of five who had had a frightful behaviour problems from babyhood followed by asthma since the age of three. The mother was labelled ‘neurotic’ and blamed for his behaviour thirst, bed wetting and large smelly floating stools. She had observed that if he could not eat for a few days he became a lovable little boy. But his dreadful behaviour reappeared as soon as he started to eat again.
The paediatrician dismissed the possible significance of this observation. The boy was almost impossible to examine but a wide range of skin tests were negative. He had a distended stomach, very heavy shadows under his eyes, and severe asthma. On a lamb and rice diet all his problems vanished in days. And he became a lovely little boy who allowed me to take blood without complaint. At school he could sit and concentrate for the very first time, as shown by a dramatic improvement in his writing and art work. Reintroduction of potato, milk and wheat reproduced his problems, suggesting he had intolerance to gluten and milk as well as potato. He remind well on a restricted diet and his blood tests were all negative.
His parents also went on the diet to encourage him, and to everyone’s surprise the father’s personality also improved markedly. When both father and son ate potato they both became nasty and aggressive. Further enquiry revealed that the only time the father ate potato chips was at lunch on Fridays, explaining why by the time he got home from work he was always unpleasant and aggressive. Milk or cheese would also make both of them miserable and depressed. It also found that a sibling’s colic and diarrhoea were also caused by cow's milk intolerance.
Another boy aged three and a half, described by his mother as a Jekyll and Hyde personality also had severe eczema. After three days on a test diet of lamb and rice both eczema and misbehaviour disappeared. Test feeds showed repeatedly, that potato, milk and orange squash would reproduce tantrums and eczema. He was transformed from a stubborn, resentful, withdraw whining child to a normal happy little boy.
Two other children with perennial rhinitis also had behavioural problems caused by potato. One aged sixteen suffered uncontrollable emotional disturbances on exposure to tobacco smoke (tobacco also belongs to the solanacae family); he also had learning difficulties, which vanished on avoiding potato. And he rapidly ascended to the top of his class. Challenges with potato reproduced his systems every time although eventually he could tolerate potato without problem.
Potato and migraine
A farmer's wife aged seventy recently sought advice regarding migraine headaches she had suffered several times a week for fifty years. The clue was that she had a definite craving for potato and that tomato also seemed to cause a headache next day. She has had no headache since she stopped eating potato and tomatoes – except when provoked by deliberately eating one or the other. It is a pity she had to wait so long for the answer.