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Antacids and other ways of coping with excess stomach acid

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Now that we have powerful drugs (PPIs or Proton Pump Inhibitors) that stop the stomach producing acid, many people overlook antacids - chemicals (not drugs) that react with and neutralise the stomach acid that has been already produced. Antacids have been used for thousands of years and even some animals take natural antacids such as chalk. Antacids still have much use.

If you are on PPIs and think your remaining problems are caused by acid, then antacids can (and will) give immediate relief. If they do not, then the problem is probably bile reflux which is a very common problem with PPIs. See my experiments with dosage.

What are Proton Pumps

Water is neutral - neither acid nor alkaline. Acids are things like vinegar and most fruit juices. Some fruit juices, such as lemon and lime, are very acid. Alkalis are things like chalk, which react with acid to neutralise it. In practice there are few natural things which are alkaline. Most foods are acid to neutral.

Early life evolved in early oceans - which were a lot less salty than modern oceans. Life then is dependant on water. Life would not have evolved far unless it evolved a method of keeping the liquid inside its cells at the correct balance on the alkali/acid scale, somewhere probably very similar to that of the early oceans, which is mildly acid.

These chemical factories which can alter the acid/alkali balance are Proton Pumps. So they exist inside every living cell. There are several types of proton pumps, the most powerful being the type that produces relatively strong acid inside the stomachs of most animals. This strong acid kills most bacteria and breaks down meat and bone so is quite fundamental to the digestive process.

Water consists of Oxygen chemically bonded to Hydrogen, in the ratio of two molecules of Hydrogen to one of Oxygen - written H2O. Now hydrogen consists of a Proton (which is electrically charged positive) with one electron orbiting it. Electrons are negatively charged, which balances the proton's positive charge so the overall charge is zero. Oxygen has six protons with six electrons orbiting.

Now some sort of magic happens when there are eight electrons orbiting an atom. So Oxygen is "hungry" for a couple of electrons. Which is why it wants to grab a couple of hydrogen atoms to share electrons and form water.

But in water another sort of magic happens. The H2O has a tendency to be easily split into H and OH "ions". The H ion carries one electron, so is short of negative charge, therefore it is written H+ and the OH ion carries an extra electron, so has a negative charge - OH-.

In neutral water the H+ and OH- balance. If the water contains a bit of acid then there are more H+ ions than OH- ions. If there are more OH- ions than H+ ions, then the liquid is alkaline.

A proton pump can move a hydrogen ion (a Proton) across a cell wall. So the liquid on the receiving side becomes more acid. But conversely the liquid on the side that looses the proton still has the OH- ion, so becomes more alkaline. In the body this OH- ion combines with Carbon Dioxide CO2 to form an alkaline HCO3 bicarbonate ion. CO2 is a gas released by many biological processes and it is readily soluble in water (H2O) to form a mild acid H2CO3.

The measure of acid/alkali is pH. pH can range from 0 to 14, with neutral being 7. The pH scale is logarithmic, so a pH of 1 is 100 times more acid than a pH of 3.

What is stomach acid

In the stomach, special cells use a particular type of Proton Pump which contains a special enzyme (Hydrogen potassium ATPase usually abbreviated to H+/K+ ATPase) which in effect splits water and salt (Sodium Chloride, NaCl) apart so the H+ ends up in the stomach as Hydrochloric acid (HCl) and the OH- ends up as Sodium and Potassium Bicarbonates in the blood. Hydrochloric acid is a very powerful acid and Sodium/Potassium Bicarbonate is a fairly weak alkali which travels through the blood to the pancreas where it is extracted into the pancreatic fluid to be released into the Pylorus - the top bit of the small intestine, just below the stomach - to neutralise the food, processed by the stomach. This processed food, or Chyme, is of course acidic because of the Hydrochloric acid (HCl). At the same time pancreatic fluid released, the gall bladder contacts and releases bile through the same sphincter - the sphincter of Oddi.

Stomach, or Gastric fluid also contains digestive enzymes, chiefly Pepsin, to help the food processing by breaking down protein (meat).

The above is of course greatly simplified!


Water when pure is neutral. But water is rarely pure. Hard water is slightly alkaline. This alkalinity is of little use in itself. However a drink of water does flush the oesophagus of acid. Furthermore the water will dilute the stomach acid and flush that through, all quite naturally. So water should not be undervalued as an aid. The hardness and alkalinity can be increased by adding a small amount of of sodium bicarbonate, which can also improve the taste of the water - especially if this is soft.

What do antacids do and what are they

Antacids are chemicals that combine with Hydrochloric acid (HCl) to neutralise it and which are harmless. Many of these chemicals are naturally occurring and have other, sometimes culinary uses. Chemicals such as:
Sodium hydrogen carbonate - sodium bicarbonate or baking soda
Sodium hydrogen carbonate (NaHCO3), to give it its scientific name, is very common in nature. It is naturally present in the blood, in sea water and freshwater to a small extent. In fact anywhere where common salt, CO2 and water occur together, there you also have sodium bicarbonate. Which makes NaHCO3) one of the commonest, safest, cheapest and most effective antacids available!

1 gm dose of sodium bicarbonate
1 gm dose of sodium bicarbonate
Sodium bicarbonate also has the advantage that, being soluble, it reacts immediately to neutralise stomach acid. So if your symptoms are indeed caused by acid it will give instant relief. A suitable dose of is shown right - a heaped teaspoon tip. This is about 1gm of sodium bicarbonate and it will release about 250cc of CO2.

The reaction between acid and sodium bicarbonate is quite vigorous and releases bubbles of carbon dioxide, so is likely to cause belching. This tells you that the irritation was, indeed, caused by acid, and not solely by other gastric fluid ingredients so sodium bicarbonate can be a very good test. It is also very cheap and very easy to obtain so is clearly one of the first things you should try.

Disadvantages of sodium bicarbonate as an antacid

Calcium carbonate - chalk or limestone
This is probably the oldest antacid of all: some animals will consume chalk. However pure chalk is not pleasant to take. But you can get "precipitated chalk" from anywhere that sells wine-making supplies as it is commonly used in wine-making to reduce acidity. Calcium carbonate is insoluble but precipitated chalk can be swirled in water and it's so fine that it takes a little while to settle.

Calcium carbonate is the basic ingredient for most antacid tablets. It also in sold as tablets for bone health, with vitamin D which does not affect its antacid qualities. Being solid, it does not react immediately to neutralise acidity, so has a longer lasting effect than sodium bicarbonate. So many commercial antacids include both Calcium carbonate and sodium bicarbonate, sometimes with other antacids.

Potassium hydrogen carbonate - very similar to Sodium hydrogen carbonate
Potassium bicarbonate or Potassium hydrogen carbonate is an alternative to sodium bicarbonate. Both sodium and potassium are essential minerals present in the blood and there is evidence that most people don't get enough potassium in their diet: How Much Potassium Do You Need Per Day

Potassium is a heavier metal than sodium so for the same effect you need about 20% more potassium bicarbonate, but dosage is not at all critical. Potassium bicarbonate has a stronger taste than sodium bicarbonate which I find less pleasant - and it is not so freely available.

Interestingly recent studies have proven that Potassium bicarbonate has very beneficial results in curing and preventing osteoporosis.

Thee are two papers from USA government medical publications:

Aluminium hydroxide
Magnesium carbonate
Magnesium oxide
Magnesium peroxide
Magnesium hydroxide
Magnesium silicate
Magnesium trisilicate
Magnesium hydroxide

Other carbonates and bicarbonates

Other antacids

Alginates such as Gaviscon

Gaviscon and various similar "own brands" such as Acidex are freely available from supermarkets and chemists and of course Gaviscon gets wide (and expensive!) advertising on TV. These products contain antacids but their other advertised feature is that they form a raft on top of the stomach contents which prevents gastric fluid splashing the oesophagus.

This sounds like a good idea - but it assumes the stomach is at rest. However the stomach is a very mobile organ. It is a muscular sack which continually churns up to mix food and gastric fluid and to start breakdown of food. It also contracts to force packets of food into the intestine. So how can any raft form?

If the stomach is completely empty than a raft might conceivably form. Or might such a raft simply start the stomach churning again? In any event, the only time the stomach might be empty is at night, when asleep. In which case the raft will be horizontal and won't protect the oesophagus at all! Furthermore the fact that you get nocturnal reflux surely proves the stomach is indeed active!

I found Gaviscon (and other alginates) to be of little use compared with cheaper, simpler antacids. But what these alginate products do is to temporarily coat the oesophagus - which itself if a mobile organ, moving its contents down into the stomach. Nevertheless alginates are difficult to swallow and there is indeed a significant coating effect.

Of course, if you believe it is going to work, then it may well work - after all the brain not only controls the digestion, but it also registers the pain of indigestion.

Tests on these products is clearly done "in vitro" - which means in glass. I have not found any paper which proves the theory in a live stomach.

H2 Receptor Blockers

H2 here refers to a type of Histamine receptor which triggers acid production in the stomach when histamine is released in response to various hormones. Blocking these receptors does not prevent acid production but does reduce the amount produced. So it can be useful. These drugs seem to have very few harmful side effects.

There are various manufacturers of H2 Receptor Blockers

PPIs - Proton Pump Inhibitors

These are the generic names of the commonest PPIs:
  • Experiments with Omeprazole PPI dosage
  • PPIs cause cancer
  • Is Barrett's Oesophagus really a pre-cancerous condition?
  • Links to some relevant medical papers.

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