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OK, this is quite complicated.
Our immune system reacts to particles and chemicals that we are sensitive to; for example, pollen and washing powder. It also reacts to: incomplete food particles that pass through the gut wall; bacteria, viruses and parasites; dead cells and cancer cells. All these things can be described by the blanket term ‘antigens’. Antigens that stimulate an allergic reaction are defined as allergens. Allergens provoke the immune system to an immune response, which releases antibodies.
There are five different types of antibody or immunoglobin: IgA, IgD, IgE, IgG and IgM. A classic, Type I immune reaction involves the production of the IgE antibody to specific allergens; it is acute and immediate (and can be anaphylactic).
IgE binds to receptors on mast cells; further contact with the allergen cross-links the IgE, and the cell degranulates, releasing histamine, which causes vascular permeability, mucus secretion and bronchial constriction. In other words, once the IgE is attached to the mast cell, if you encounter your particular allergen again you will suffer from a reaction to it, which involves the production of histamine and other chemicals and all the attendant discomfort, depending on which part of the body is involved. What seems like an innocuous substance becomes an allergen because the body misguidedly produces IgE antibodies which fit the antigen. In an allergic individual, the controls that prevent the immune system from producing IgE antibodies have broken down.
In normal people, the chemicals, including histamine, released by the mast cells act as mediators; they cause changes in the body. Different mediators have different effects: some make smooth muscles (the muscles that operate our lungs, stomach, intestine and bladder) contract, and, when these muscles contract, we expel the contents of our lungs, stomach, bladder or intestine as appropriate. This is great when you’ve got some sort of bug; you get diarrhoea and it’s flushed out of your system, or if it’s in your blood, inflammation causes phagocytes (cells which eat unwanted invaders) to rush to the spot. It’s less helpful if it’s something you’re eating, and which shouldn’t be causing problems.
Further down the process, a group of phagocytes the macrophages can perpetuate the inflammation reaction, producing an enzyme known as phospholipase, or PLA to its friends. PLA cuts up fat cells (phospholipids), which are then converted into prostaglandins. All prostaglandins have an effect on the immune response, particularly on inflammation. Those which are produced after a mast cell reaction have a similar effect on the body to histamine: they are there to keep up the attack on the invader. And they are responsible for ‘late phase’ reactions; ones which are not immediate.
People who are atopic usually have a higher level of IgE in their blood, in line with the idea that the control mechanisms have gone awry. IgE levels can be used to help define what substances a person is allergic to; however, they are not the most accurate indication, and should always be used in conjunction with an exclusion diet.
The other antibody of interest to the atopic individual, or the individual with a food intolerance, is IgG. IgG is responsible for immune responses that have a short term memory. It provokes a Type III insensitivity reaction (IgE provokes a Type I reaction); in other words, there is no full scale attack on the antigens. But, IgG can trigger a more powerful immunological response and aggravate IgE allergies. It is the predominant immunoglobin in the blood stream, and is responsible for passing antibodies from the mother to her baby. IgG levels can also be used to help identify potential food intolerances, although opinion is divided as to how helpful this is. Tracking IgG is difficult because it is a delayed and wide-ranging reaction, but the cascade reaction it can cause over these ten-twelve hours is a useful tool. It is also important to note that IgG reactions can occur when you are recovering from an IgE hypersensitivity, such as a childhood allergy.
Since we’ve established that the immune system is intrinsically involved in allergic reactions, encouraging its health can only help. It is not simply a question of avoiding the foods which cause problems (and replacing them with nutritional equivalents); but also avoiding those foods which may suppress the immune system, and eating those which may have a beneficial effect. Prevention is better than cure, after all!
Stimulants can have a negative effect on the immune system; they make you feel good in the short term but are addictive and have a detrimental effect in the long term. A good illustration of this problem is the office worker who, drinking vast amounts of tea and coffee while at their desk, finds themselves restless and irritable at the weekends due to lack of caffeine. Avoiding caffeine, alcohol, sugar and cigarettes can improve your health sufficiently to be able to deal effectively with allergens, and foods you are intolerant to. Avoiding stimulants alone is not enough to solve all problems.
Antioxidants, such as vitamins A, C and E are very useful. They counteract the damage done to tissues by free radicals, produced as a consequence of our bodies needing oxygen in large amounts in order to react with glucose, so that we have the warmth, motion and energy to fuel the chemical reactions that keep us alive Antioxidants are best taken in food rather than as supplements. Vitamin A is found in liver, fish oils, egg yolks, and full fat dairy products. Vitamin C is found in all fresh fruit and vegetables, particularly citrus fruits, strawberries, kiwi fruit, broccoli and cabbage. Vitamin E is found in wheatgerm, vegetable oils, eggs, olive oil, nuts, seeds, whole grain cereals and brown rice.
The UK government advises eating a minimum of five portions a day of fresh fruit and vegetables, and this is most easily done by having a fruit bowl of those fruits that you actively like, fully stocked and looking attractive (fruit is one of those things that it’s worth spending money on). Vitamin C is almost a ‘wonder vitamin’: it helps make white blood cells; it builds collagen strengthening the mucus membranes and making them less permeable; it is anti-viral, anti-bacterial, and anti-parasitic. It is an antioxidant which acts as a catalyst to the other antioxidants; it detoxifies histamine and is hence beneficial in reducing allergic potential. , However, it is worthwhile noting that it is possible to have too much Vitamin C, and overdoses can cause headaches and dizziness.
Herbs can also help the immune system. Various studies have indicated in laboratory conditions that Echinacea, a traditional American-Indian remedy has a beneficial effect, however, none of these have investigated how effective orally ingested Echinacea is. It doesn’t seem to be possible to overdose on Echinacea but some people have had allergic reactions to it, so the atopic individual should proceed with caution and, if in doubt, avoid it completely. Personal experience suggests that, if you are going to take dried Echinacea in capsule form, it‘s a very good idea to wash them down with lots of liquid, otherwise Echinacea burps may occur, and they’re very unpleasant, not to mention quite potent. Devil’s Claw Root Tea is a traditional Peruvian remedy for boosting the immune system.
The other vital component of a healthy immune system is a healthy gut – and this is particularly important for those with food sensitivities. Avoiding the foods which cause the problems is half the battle; keeping the gut itself healthy is the other half. Vitamins A, C and E all help to keep the gut’s mucus membrane healthy, as does zinc (found in nuts, pumpkin and sunflower seeds, red meat, liver, sardines, oysters, egg yolks, rye, tuna, berries and brown rice). Essential fats, i.e. mono-unsaturates and poly-unsaturates also play a part. Mono-unsaturates, particularly the omega-9 fat found in olive oil are useful for replacing saturated fats in our diet. Polyunsaturates, or essential fats, have a powerful anti-inflammatory effect. The two essential families are omega-3 fats, found in oily fish, flax seeds, walnuts, pumpkin seeds, soya and hemp seeds, and omega-6 fats, found in vegetable, seed and nut oils, and the seeds and nuts themselves.
The gut’s health is most affected by the balance of the bacteria which live in it. There is around 1-2kg of bacteria inhabiting our gut walls, made up of around 400 different species; there are more individual bacteria in our gut than there are cell types in our body.
‘Friendly’ bacteria
• help keep the bowels acidic,
• produce various useful vitamins (specifically B-vitamins and vitamin K),
• kill off harmful bacteria by producing natural antibiotics,
• produce butyric acid from fibre to feed the cells of the digestive tract, finish off digesting proteins and milk sugars,
• stimulate the contractions of the bowel walls (peristalsis).
‘Unfriendly’ bacteria
• produce endotoxins, which drain the immune system and cause headaches, skin problems and digestive problems
• they can crowd out the friendly bacteria and give you diarrhoea.
Imbalance can be caused by:
• courses of antibiotics,
• the contraceptive pill,
• pregnancies,
• a high sugar/refined carbohydrate diet.
Increased fibre (whole grains, fruit, vegetables, beans and pulses, and nuts and seeds; as well as supplements such as rice bran, psylliym husks, oat brain and linseeds), ‘live’ yoghurts, olive oil and garlic, as well as ‘live’ bacteria supplements (either as capsules or drinks – and, since all have different strains of bacteria, it can take time to work out which helps most) can help improve the gut’s health.
In summary (and this is a fantastic table based on information in Suzannah Olivier’s “Allergy Solutions” book)
Things that suppress the immune system | Things that boost the immune system |
excess alcohol | laughter |
refined carbohydrates and high fat convenience foods | at least five servings of fruit and vegetables daily (one serving weighs about 80g) |
allergies and sensitivities | regular, moderate exercise |
smoking | stable blood sugar levels |
excess sugar | drinking 2 litres of water a day |
stress, whatever its form | meditation, yoga or tai chi |
two or more pregnancies very close together | good bowel health |
recreational drugs | satisfying sleep |
environmental pollution | a happy home and work life |
multiple courses of antibiotics | antioxidant supplements that contain vitamins A, C and E, and selenium and zinc |