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Strengthening your immune system
How the immune system works
The immune system consists of special cells that move around in the blood and lymphatic system, an army on a 24-hour "search and destroy mission". They look for alien invaders - rogue cells, viruses, bacteria or substances we are allergic to. These special cells travel between the cells of our body, but are mainly concentrated in our network of lymphatic vessels. They drain into lymph glands, concentrated in the neck, armpit and groin, and from there lead into the central lymphatic system where our immune system is strongest.
Once an intruder has found its way inside the body, our immune army is alerted. Its troops consist of many different battalions of blood cells. These include special "scout cells" that squeeze in and out of blood vessel walls on the lookout for trouble. Once they find an invader they attempt to engulf it. If they have difficulty they summon up more troops called T-Iymphocytes. These ingest any invader they come across. To keep them in check there are T-suppressor cells, that "turn them off" and T-helper cells that "turn them on". (The AIDS virus, for example, selectively destroys T-helper cells which leads to a relative excess of the T-suppressor cells and to an eventual weakening of the immune system.).
Perhaps even more important than T-lymphocytes are B-lymphocytes. These cells have the ability to produce tailor-made antibodies that stop the invader dead in its tracks. So if you have an allergy to milk, the B-lymphocytes will produce hundreds of thousands of antibodies seconds after you drink the milk. It was the discovery of this, the body s ability to produce a specific weapon to deal with each invader, that led to the development of immunisation. When a battle is raging between your blood cells and an invader, the body turns up the temperature which helps the immune cells to fight. A high temperature and swollen lymph glands are the classic signs of infection, coupled with effects of the particular virus- a sore throat for example, or nausea and diarrhoea. The consequences are familiar to us all. Headache, excessive mucus production and coughing are just some of the symptoms of a viral or bacterial attack. If it s any consolation, the worse the symptoms, the harder your system is fighting.
Strengthening your defences
By keeping your body s guard up, you can win the war against invaders before the battle has even begun. You have three strategies at your disposal. Firstly you need strong walls to keep out invaders, including viruses and bacteria; secondly you need to maintain a stout army of immune cells with healthy production of new immune cells; and thirdly you need to be armed against weapons of free radicals. Your first line of defence is the skin, including the "inside skin" which lines the lungs and digestive system. Many viruses, for example hepatitis and the AIDS virus, cannot cross the skin barrier and need to enter the body via fluids. Even carcinogens - substances that are thought to induce cancer, of which cigarette smoke is an example - are less likely to do damage if your first line of defence is strong. This strength depends on maintaining the integrity of your cell walls. To keep your cell walls strong, you must maintain your level of vitamin A. Carrots and other orange-yellow foods like tomatoes, beetroot and apricots are rich in this vital vitamin. So are liver, kidneys and cashew nuts. Children need more vitamin A than adults because it stimulates growth and the maturing of the immune system.
Calcium and magnesium are also important for strong cells and a healthy immune army. These are particularly needed by the elderly and by post-menopausal women whose decline in oestrogen production means that calcium is poorly absorbed. Dairy products, while rich in calcium, are a poor source of magnesium. Only green leafy vegetables, nuts and seeds provide these essential elements. Vitamin C is important too. It increases the production of T-lymphocytes cells and helps produce antibodies and improve their performance. Vitamin C is also a crucial weapon, along with vitamins A and E, in your defence against free radical attack.
Free radical attack
Many viruses try to force an entry into our cells. Cancer cells go one step further and try to destroy neighbouring cells and take over their space. This is done by releasing a barrage of toxic and other substances, including "free radicals".
Free radicals are atoms, or groups of atoms, with an uneven electrical charge. Because they are uneven they try to balance themselves by stealing an electron from a neighbour. The easiest electrons to steal are from essential fats that form part of every single cell wall which then becomes weakened, making it easier for invading toxins, bacteria and viruses to get in. Free radicals are also created by eating fried foods, from pollution and smoking. But nature has devised specific protectors, called anti-oxidants, that help to mop up these enemies. They are vitamins A, C and E - most of all vitamin E because it is fat-soluble designed to protect fats. All natural foods rich in polyunsaturated fats and oils are also rich in vitamin E. But as we process these oils, for example in cooking, the vitamin E is destroyed and the oil left open to free radical attack. So adequate vitamin F is another requirement for keeping our cell walls intact. One mineral, selenium, helps complete our defence against free radicals. Although needed in tiny amounts of 50 mcg a day (less than a millionth of our daily requirement of protein) it is no less important.
How to boost your immune power
So what can you do to boost your immune power? The answer is a lot. Many factors are involved in keeping your immune system working well. Getting plenty of light stimulates the thymus, and exercise stimulates movement of lymph and boosts the immune system. Stress causes the release of a hormone called cortisol, which is a powerful suppressor of the immune system. Pollution can overload the body's defences, so it is best to avoid additives and eat organic food where possible. Ensuring that you get a good night s sleep is also important to keep your immune system in good shape. Diet is perhaps the most important factor. Fat and fat-soluble vitamins are transported in the lymph, so a diet high in fat makes the lymph thicker and less mobile. Some nutritionists think that an excess of dairy produce, which is particularly mucus forming, also clogs up the lymph. Fried foods are doubly bad because they are high in both fat and free radicals that damage and weaken body cells.
Getting enough protein in your diet is important. Fish, chicken, beans and lentils are good sources of protein. While eating less fat and getting enough protein are not too difficult, few people get enough immune boosting vitamins and minerals from their diet. Vitamins and minerals are vital for immune power. Many B vitamins, including B5 (pantothenic acid). B6, B12 and folic acid, are needed to produce immune cells. In severe B6 deficiency no antibodies are produced at all! B vitamins are found in fresh vegetables, grains, nuts and seeds.
Vitamin C is the most important of all. It helps to knock out viruses by increasing T-lymphocyte production. It destroys many bacteria. It helps produce antibodies and seems to improve their performance. All fruit, but especially oranges and kiwis, are rich in vitamin C. So are red peppers. Vitamin A also strengthens cell walls, keeping invaders out. Of the minerals, calcium, magnesium, selenium and zinc are the most important. According to Dr. Stephen Davies, 'zinc has a profound effect on the immune system responses'.
Zinc increases T-lymphocyte production, the cells that destroy alien invaders, and helps the thymus gland, the cornerstone of the immune system, to work. Although immune cells are produced in different parts of the body, mainly in the bone marrow, T-lymphocytes only become mature in the thymus gland in the chest.
Today we have a new understanding of the immune system and its importance in helping us combat disease. We also know a lot more about how optimum nutrition can help keep our "defence troops" in fighting trim. Our thanks to Patrick Holford for permission for this chapter from his book Optimum Nutrition to be reproduced below. Patrick s book is available from Ion Press, London. Patrick has also written The Optimum Nutrition Bible (ISBN 0749918551, price £12.99) and Boost Your Immune System (ISBN 0749918640, price £5.99) which can be purchased in high street book shops, or by contacting Holford Associates, tel 0208 8712949.
