And you do -- in quantity. Whether it's ploughing through several courses, or just consuming lots of whatever's in sight, you love to eat. Mealtime, snack time, bedtime, any time at all is just fine with you.

And of course your mother brought you up to clean your plate, so that's another good reason to finish up whatever is within your grasp.

Then, you probably have a drink or two -- or three or four -- to "wash it all down,'' cheer you up, or be sociable.

Phew! By the end of it all you're bloated and full.

So full, in fact, that before long you've got a burning sensation in your stomach or chest, and maybe a knotted feeling inside.

Hello, indigestion or heartburn! No problem -- you'll just reach for your favourite antacid and the problem will be cured in a jiff. That's what the ads promise, isn't it? It sure is. That mixture of honey-tongued announcers, soothing and humorous scenes, bubbles and fizz, is so convincing that over $1 billion a year is spent supporting this group of over-the-counter remedies.

Admittedly, antacids can quickly relieve the symptoms of indigestion and occasional heartburn. But are they a good idea? Yes and no because they are a drug.

Used occasionally, and in moderation, by people in good health, antacids are a useful drug. But they also have a "dark side.'' Take too much over a short period, or use frequently over a long period (weeks, months or years), and antacids can cause irreparable harm to the heart, kidney or bones.

Even if used occasionally, and in moderation, they can spell bad news for people with special medical conditions. It is always best to consult your doctor before using antacids if you: Are on any kind of medication; Are pregnant or breast-feeding; Have kidney problems; Have chronic constipation, diarrhoea or colitis; Have stomach or intestinal bleeding; Have an irregular heartbeat; Have any kind of chronic illness; Have symptoms that may indicate appendicitis.

Of course, the surest way to prevent indigestion and heartburn is to eat sensibly in the first place. How? Don't eat big meals. Your stomach has to work long and hard to process them, which means it has to produce a lot of acid. It helps to eat more frequent -- but smaller -- meals.

Eat more slowly. Downing a lot of food in a hurry can overwhelm your stomach, which responds by producing extra digestive acids.

After you eat, don't lie down right away. If you do, you're more likely to have heartburn, because gravity is now preventing food from going speedily to the intestines. It's also a good idea to eat your last big meal at least three hours before bedtime. When you go to sleep, everything slows down, including your digestive system, so food you've eaten right before bedtime will stay in your stomach longer. It won't feel good.

Don't wear tight-fitting garments. They can literally compress your stomach, making it more likely that the stomach's acid contents will enter your oesophagus and cause a burning sensation.

Cut down on caffeine, it makes your stomach produce more acid. Caffeine-heavy items include coffee, tea, chocolate and some sodas.

Avoid foods that contain a lot of acid, such as citrus fruits and tomatoes, and any other food that gives you problems.

Cut back on alcohol and smoking. Both irritate the lining of your stomach and tend to lower oesophageal sphincter pressure. (The oesophagus is the tube which extends from the throat into the stomach. The sphincter is the "door'' between the oesophagus and the stomach). When this happens, it's easier for the contents of your stomach to shoot back up into your oesophagus. Sleep with your head and shoulders propped up six to eight inches, so that your body is at a slight angle. This gets gravity working for you and not against you, and the digestive juices in your stomach are more likely to head for your intestine instead of back up into your oesophagus.

If you find yourself taking antacids frequently, or symptoms last more than two weeks, see your doctor. And if you are experiencing any symptoms severe enough to interfere with your lifestyle -- continuous vomiting, diarrhoea, extreme discomfort or pain in your gastrointestinal tract, vomiting of blood, for example -- you should seek professional treatment without delay.

Using antacids to alleviate serious symtoms is like trying to put out a building fire with a hand-held extinguisher.

To appreciate how antacids work, it is first necessary to understand the construction of the digestive system -- or alimentary canal.

About 30 feet long from beginning to end, it includes the mouth (where digestion actually begins), oesophagus, stomach, small intestine, and colon (large intestine).

Antacids do most of their work in the stomach, which acts as a kind of "holding tank'' for food before it moves on to the intestines, where the major part of digestion takes place.

The stomach helps with digestion by secreting pepsin and hydrochloric acid, which work together to break down proteins into simpler compounds.

On a pH scale of zero to 14, the normal acid level in the stomach is between three and four. (The pH scale measures acidity or alkalinity of an environment).

Indigestion -- which some call sour or upset stomach, or acid indigestion -- occurs when the pH level goes awry.

This may be caused by inflammation of the stomach lining (gastritis), or simply when too much food has been eaten at once, and it is just sitting there like a heavy bowling ball.

Heartburn is another matter. It occurs when the stomach's contents, along with all its corrosive digestive juices, goes into reverse and shoots back up into the oesophagus, perhaps announcing itself with an embarrassing belch.

Left alone, these symptoms will generally disappear on their own, but for those not willing to wait, antacids -- because they are fast-acting -- can help. Antacids make you feel better by increasing the pH balance in your stomach.

The opposite of an acid is a base, and that's precisely what antacids are.

However, a base cannot, on its own, neutralise the acid inside you. It needs some chemical "helpers'' to assist in its neutralising mission in your stomach.

All antacids contain at least one of these four primary "helpers'': sodium, calcium, magnesium and aluminium.

The market is filled with an abundance of antacids, so which one should you choose? The answer lies in reading the labels. Take into consideration the job you want the antacid to do, study the ingredients, weigh up any possible side effects, and learn if you are excluded by any medical condition or medication.

Here is a brief synopsis of the composition and some potential side effects of various antacids: Sodium (Alka-Seltzer, Bromo Seltzer and others): Sodium bicarbonate or baking soda, is potent and fast-acting. As its name implies, it is heavy in sodium.

Consult your doctor before taking any product containing this ingredient if you are on a salt-restricted diet or are being treated for high blood pressure.

Calcium (Tums, Alka-2, Titralac and others): Antacids in the form of calcium carbonate or calcium phosphate are potent and fast-acting. Regular or heavy doses (more than five or six times a week) can cause constipation. Heavy and extended use may clog kidneys and reduce the amount of blood they can process.

Can also cause kidney stones.

Magnesium (Maalox, Mylanta, Camalox, Riopan, Gelusil and others): Magnesium salts come in many forms: carbonate, glycinate, hydroxide, oxide, trisilicate, and aluminosilicates. Magnesium has a mild laxative effect and can cause diarrhoea. For this reason, it is usually combined with aluminium, which counteracts the laxative effect.

Like calcium, magnesium may cause kidney stones if taken for a very prolonged period, especially if kidneys are functioning improperly to begin with. A serious magnesium overload in the bloodstream can also cause drop in blood pressure, leading to respiratory or cardiac depression -- a potentially dangerous decrease in lung or heart function.

Aluminium (Rolaids, AlternaGEL, Amphogel and others): Salts of aluminium (hydroxide, carbonate gel, or phosphate gel) can cause constipation, so usually used in combined with the other three primary ingredients. Used heavily over an extended period, antacids containing aluminium can weaken bones, especially in people with kidney problems. Aluminium can cause dietary phosphates, calcium and fluoride to leave the body, eventually causing bone problems such as osteomalacia or osteoporosis.

Aluminium-containing products present no danger to people with normal kidney function who use these products occasionally and only as directed.

Simethicone: A gastric defoaming agent that breaks up gas bubbles, making them easier to eliminate from the body. Safe and effective in combination with antacids for relief of gas associated with heartburn. Not all antacids contain this ingredient. If you're looking specifically for relief of symptoms associated with gas, read labels carefully to make sure product contains simethicone.

( This article is based on information provided by the US Food and Drug Administration.

YOU CAN'T BELIEVE YOU ATE THE WHOLE THING . . . But think twice before you reach for that antacid.