Intestinal gas is a normal part of life and everyone passes gas, many people doing so multiple times per day. The production of intestinal gas is a direct result of the food we eat, some foods causing more gas than others. Essentially, when food is broken down by the bacteria in the gut, gas is produced. There are five gases that are produced by our bodies: nitrogen (N2), oxygen (O2), carbon dioxide (CO2), hydrogen (H2), and methane (CH4). It depends on which bacteria are in the gut and which foods are being broken down as to which gas is produced. Actually, 50% to 60% of the gas produced is the direct result of the bacterial breakdown of carbohydrates. Beans cause so much gas because they are complex carbohydrates that are maldigested. Other foods, such as mushrooms and onions are the same. There is also gas that comes from swallowing air and this is the gas that goes into the stomach and then is belched out. Lastly, there is the gas that gets into the intestinal tract by diffusion from the blood.
Since diving is an activity that is done under great pressure and since gas reacts to increased and decreased pressure, it is important to consider what the presence of intestinal gas during a dive may mean for the diver. First and foremost, intestinal gas of any type is going to spell pure discomfort for the diver. You might experience cramps and very bad odor, depending on what you have eaten. However, having intestinal gas is generally not a hazard during a dive. If the gas was somehow trapped and unable to be released, there would be a risk that the expansion of the gas could cause a rupture, but generally the gas can escape as it usually does, either through flatulence or belching.
The best thing to do in order to avoid intestinal gas is to beware of what you eat a day or two before your dive. Stay away from those foods that are bound to give you severe intestinal gas. This includes beans and legumes, mushrooms, onions, and any other foods that you suspect may cause problems. For those who are lactose intolerant, milk products can cause a significant amount of gas. Others may experience more gas with grains. You need to know your own body. In addition to this, you should avoid carbonated drinks, chewing gum, sugar-free foods and chew slowly and carefully and sip drinks instead of gulping them. If you are at all concerned about the production of gas and its presence during a dive, you can also take over-the-counter medications to help reduce the amount of gas that builds up in your body.
If you have persistent problems with intestinal gas that are not resolved with a change in diet and/or have other symptoms such as nausea, vomiting, diarrhea, constipation, bloody stools, weight loss, fever, or chest pain, then you should see your doctor. There are underlying intestinal conditions that can cause the production of gas. If you experience discomfort and or pain due to intestinal gas while you are diving and are making your ascent to the surface, the best thing to do is to stop and expel the gas before continuing. If you do not do this, your discomfort may increase in severity and you may experience an overexpansion injury of the stomach and/or intestines.
Diving is a fantastic and wonderful activity. It is also directly dependent on pressure and when there is gas in your intestinal tract, this gas will act according to Boyle's Law, which states that the volume of gas is inversely proportional to the pressure. The means that on ascent, when the pressure decreases; the volume of gas in your body increases. Don't get caught in the water with gas in your intestines. By choosing an appropriate diet, avoiding foods and drinks that cause you problems, and by taking an over-the-counter medication if needed, you can ensure a safe and pleasant dive.