Nutrition, SARS and the Immune System

What we eat affects our immune system. Our cells can keep us healthy, alert, and energetic, if we feed them what they need.

The immune system is the body's defender against illness. It identifies, tracks down, and destroys biological trouble-makers before they can damage the body. These may be a corona virus that cause SARS, a bacterium from a cut, a cold "bug", or even a cancer cell. Invaders try to feed from our body's nutrients. If they succeed, we become ill or even die. It is therefore important to know how the immune system works for us, in their job to destroy invaders before they destroy us.

There are four key players of the immune system, namely: lymphocytes, the chemicals produced during interactions, antibodies, and macrophages. Lymphocytes number as many as a trillion, or about 3,000 in every drop of blood. Some of these lymphocytes pass through the thymus. Here, special hormones turn lymphocytes into aggressive fighting cells called T-cells. They attack everything that is foreign to our bodies. Whenever an immune cell encounters a trespasser, it slots into it like a key into a lock, holds on tight, and sounds the alarm, to which the troops swing into action.

First, T-cells start reproducing in order to outnumber the virus. Some of the cells, the natural killer (NK) cells, surround the invading cells then suffocate them. They release deadly chemicals that make invading cells burst. Then comes a new weapon - the antibodies. Antibodies surround the virus and eventually kill them. Enter the last fighter, the macrophages, another kind of white blood cells. Whenever they see something covered with antibodies, they "eat" it.

Now you see why these four parts of the immune system are the key to your overall health. But what does nutrition have to do with all of this?

Because what we eat can either strengthen or weaken our immune system, it is absolutely essential that our body gets the nutrients it needs to stay battle-ready at all times. What we eat provides the body with the vital elements to build those millions of immune cells. These are amino acids, proteins, minerals, vitamins, lipids, and carbohydrates.

Vitamins play a key role at every stage of the immune battle. Lack of vitamin A lowers the number of T-cells, which means fewer soldiers to mount an attack. Without enough of B- vitamins, particularly B6 and B12, our cells cannot make crucial germ-fighting antibodies, and that means one less line of defense. Vitamin C has been shown to be crucial to macrophage activity - because without it, these crucial "cell eaters" cannot do a good job.

Minerals, too, profoundly affect different parts of the immune system. Zinc is perhaps the most vital immune mineral. Without zinc in our bodies, many of the lymph system tissues actually shrink, including the thymus where crucial T-cells develop, and the lymph nodes where immune soldiers are stored. The concentration of zinc in our cells also affects how energetically the macrophages attack invaders. Insufficient selenium reduces antibodies.

Amino acids like tryptophan, phenylalanine, lysine, and methionine, are necessary for the production of antibodies. Because amino acids are the building blocks for all of the body's cells, they clearly affect how many T-cells we will have available to fight off invading germs.
Good sources of Vitamin A are liver, deep yellow foods like ripe mango, melon, papaya, carrots, green leafy vegetables like alugbati, ampalaya leaves, kamote tops, kangkong, gabi leaves, malunggay and saluyot.

Vitamin C-rich foods include green bell peppers, guavas, green mango, ripe papaya, and vegetables like alugbati, kulitis, malunggay, sinkamas pods. Best sources of Vitamins B6 (Pyridoxins) and B12 (Cobalamin) are fish, poultry, lean meats, bananas, prunes, dried beans, whole grains, avocado, seafood and milk products. Zinc and selenium sources include seafoods, meats, whole cereals, eggs, pulses and certain mushrooms. Excellent sources of amino acids phenylalanine, tyrosine, tryptophan, and arginine include liver, cheese, skim milk, eggs, fish, pili nut, peanut and lentils.

For information on recipes for good health, contact us at the Food and Nutrition Research Institute, Department of Science and Technology (FNRI-DOST) at Tel. No. (632) 837-2071 local 2287 or 837-8113 to 14 local 325 or 326.