Many of us have heard of them but few really know what they are and how they can affect our health. Margaret Moss explains.

The old nutrition was about the good things in foods and drinks. Milk was ‘good for you’, because it contained calcium. Meat was ‘good for you’, because it contained protein and iron. You should eat your fruit and vegetables because of the vitamin C and roughage in them.

The new nutrition is more sophisticated. It is about obtaining the good things from foods, while avoiding too many of the bad things. Plants and animals do not grow in order to provide us with food. They grow in order to keep their species going. So the foods we eat contain a mixture of what is necessary for us, and other substances we would be better avoiding.

Neither good nor bad...
Too often people think there are two completely separate categories: good food and poisons. It really is not like that. There is a spectrum of foods that suit most people, and substances that everyone should avoid, with a grey area inbetween. More sensitive people become ill if they eat foods from the grey area while the rest of the population seems to cope but may end up with something nasty like cancer, heart disease, diabetes, or motor neurone disease.

...just the right ratio
The new nutrition is also about having the good things in the right ratio. Yes, milk contains calcium, but it also contains a sugar that is bad for the arteries. Also calcium is not the only mineral we need. We need magnesium, and there isn’t much of that in milk. Calcium and magnesium need to be consumed in the right ratio, and too much calcium makes you short of magnesium.

Drs Burkitt and Trowell worked at Makerere University in Uganda, a pioneering university in research on diet. They realised that Ugandans, who eat steamed green bananas by the kilogram, have so much fibre in the diet that they rarely suffer from constipation or colon cancer. It also happens to be one of the most enjoyable staple foods you could desire.

Unfortunately, Western doctors decided that, in the absence of delicious and healthy green bananas, they should tell everyone to eat wholegrain wheat and bran. They did not know that all fibre is not the same, and they did not know about lectins in foods.

For some reason, the Romans used the same word, ‘lego’ to mean either ‘I read’ or ‘I choose’. So the reader in church may use a lectern. We select clothes in the shops. We elect our MPs. Children play lego, a game without rules. You simply choose to use the pieces in any way you like.

Lectins are substances in seeds, concentrated in the bran layer. Each lectin chooses one particular sugar, and wherever it finds it in the body, it binds tight, interfering with the normal functioning of wherever it binds.

Wheat, tomato and potato lectins bind to an important sugar called n-acetyl glucosamine, which is sometimes called NAG. Unfortunately, NAG is in the mouth, the intestines, the muscles, the pancreas, the thyroid, the kidney, the myelin that insulates the nerves, and in all sorts of other parts of the body. Is it surprising that people who eat lots of wholemeal bread or bran come to me with arthritis, IBS, auto-immune kidney disease, multiple sclerosis, and all sorts of other chronic diseases?

Fibre and vitamin, yes, but...
The old nutrition said that wholemeal bread was good for you, because it contained fibre, minerals and B vitamins.

The new nutrition says that, while some people can cope with wholemeal bread and potatoes in their jackets, they do have the disadvantage of these powerful lectins, and also phytic acid, which reduces how much of various minerals we absorb. Some people have to avoid jacket potatoes and wholemeal bread, but cope with peeled potatoes and refined bread. Others have to avoid bread and potatoes altogether. Some avoid tomato seeds, but can eat the rest of the tomato.

Peas, lentils, peanuts, kidney beans, soya beans, mushrooms and edible snails have different lectins, which choose different targets in the body. Some people have to avoid all these foods. Others cope with yellow and green split peas and red, yellow and white lentils that do not have skins. Red lentils are the insides of brown lentils. Yellow lentils are the insides of green mung lentils, and white lentils are the insides of black urd lentils. Some foods like peas and lentils have two favourite sugars, rather than just one.

People who are very sensitive to food sometimes do well on a diet rather like that of the stone age, just eating meat, fish and leafy vegetables.

A disastrous dinner
Some lectins are made less harmful by cooking, but others are not. Beans must be well cooked.

In 1988, a hospital decided to have a healthy eating day for its staff. You would think it was a pity they didn’t try to serve healthy food to staff and patients every day but, given the results, maybe it was a pity they tried even once.

They served chilli con carne, but people complained that the beans were hard. Three hours later, a registrar vomited in the operating theatre. This was followed by profuse vomiting by various other members of staff, and in some cases by diarrhoea. The incident was caused by beans that started with very high amounts of lectin, and which were not properly cooked.

Lectins and terror
You may have heard of the vicious poison, ricin, that killed a Bulgarian BBC employee in London some years ago. He was poisoned by ricin on the tip of an umbrella. Ricin was found in a flat occupied by terrorists in London more recently, and suspicion of the presence of ricin in Manchester led to the shooting of a policeman.

Ricin is a lectin, but not from a food. It comes from the castor oil plant. People used to take castor oil for constipation. The oil did not kill them, at least not quickly – because oils contain little lectin and are therefore the easiest part of a seed to cope with. Some people who cannot eat any bread, whether refined or not, may still be able to eat wheat germ oil without obvious ill effects.

‘Flu - swine and other
Another name for a lectin is a haemagglutinin. You may know that the 2009 ‘swine flu’ is called H1NI and the vicious ‘bird flu’, H5N1. The H in these refers to haemagglutinin. It is probably lectins that make you ache when you have flu.

GM potatoes
You may remember there was some research that led to suspicion about some genetically engineered potatoes. Potatoes that had snowdrop lectin in them were found to affect the guts of laboratory rats.

Blood groups - a red herring
Lectins are used to determine a person’s blood group before providing a blood transfusion. Unfortunately, some people have been led to believe that food intolerance is simply due to your blood group. It would be nice if it were that simple. However, there is no one simple reason why people are sensitive to particular foods.

There are many genes that affect our susceptibility to disease. You may have a perfect gene, that enables you to make a particular protein correctly. You may have a missing gene, leading to early death or disability. Many genes however cause us to produce a protein that is not quite right. We function, more or less, but our bodies are inefficient, and we may well have chronic health problems, or die young.

It is too simplistic to suggest that the only genes that matter are to do with our blood groups, and that these determine the diet we should eat. Beware of anyone who says they can tell exactly what you can eat, and what you cannot, simply on the basis of a blood test or by using a machine.

Rheumatoid arthritis
In rheumatoid arthritis, certain antibodies are not formed properly. This means that NAG is exposed, and wheat lectin can attach itself to it. In a properly formed antibody, there is nowhere for the wheat lectin to attach.

I have seen arthritic people regain their mobility by taking NAG. Then wheat and potato lectins can attach themselves to this extra NAG, rather than to bits of you. I have never found other forms of glucosamine as effective.

If we want to find the best foods for ourselves and our families, one of the things we need to understand is how lectins can affect us.

You will find Margaret at www.nutritionandallergyclinic.co.uk
+44 (0)161 432 0964

John Scott suggests a couple of websites if you wish to investigate lectins further:
The lectin report
Vitamin Research Products
'Ezine Articles

First published in 2009

Top of page