FOODS THAT MAY CAUSE GAS
The International Foundation for Functional Gastrointestinal Disorders (a non-profit) is a handy website to head over to if you are looking for reliable digestive health knowledge, support, and assistance about functional gastrointestinal (GI) and motility disorders (FGIMDs). Here’s a slightly edited version of what they say about the foods that cause gas.
Most foods that contain carbohydrates (sugars, starches and dietary fibres) can cause gas. By contrast, fats and proteins cause little gas (although certain proteins may intensify the odour of gas).
SUGARS The sugars that cause gas are raffinose, lactose, fructose, and sorbitol.
- Raffinose — Beans contain large amounts of this complex sugar. Smaller amounts are found in cabbage, Brussels sprouts, broccoli, asparagus, other vegetables, and whole grains.
- Lactose — Lactose is the natural sugar in milk. It is also found in milk products, such as yoghurt and ice cream, and processed foods, such as bread, cereal, and salad dressing. Many people, particularly those of African, Native American, or Asian background, have low levels of the enzyme lactase needed to digest lactose. Also, as people age, their enzyme levels decrease. As a result, over time people may experience increasing amounts of gas after eating food containing lactose.
- Fructose — Fructose is naturally present in onions, artichokes, pears, and wheat. It is also used as a sweetener in some foods and drinks.
POLYOLS (SUGAR ALCOHOLS)
- Sorbitol — Sorbitol is a sugar found naturally in fruits, including apples, pears, peaches, and prunes. It is also used as an alternative sweetener in many dietetic foods and sugar-free candies and gums. (GI eds: It’s not the only polyol that can cause gas. Isomalt, lactitol, maltitol, maltitol syrup, and mannitol do too. You won’t find most polyols on the supermarket shelf. They are primarily used by the food industry as sugar substitutes, so read the ingredient panel on packaged foods.)
STARCHES Most starches, including potatoes, corn, noodles, and wheat, produce gas as they are broken down in the large intestine. Rice is the only starch that does not cause gas.
FIBRE Dietary fibre is carbohydrate that is indigestible in the small intestine and reaches the colon relatively intact. In the colon, certain bacteria digest fibre (fermentation), which produces gas. Dietary fibre can be classified as either soluble or insoluble.
- Soluble fibre dissolves in water and becomes a soft gel. It is found in oat bran, beans, barley, nuts, seeds, lentils, peas, and most fruits.
- Insoluble fibre does not dissolve or gel in water. It absorbs liquid and adds bulk to stool. Cellulose (found in legumes, seeds, root vegetables, and vegetables in the cabbage family), wheat bran, and corn bran are examples of insoluble fibre.
High fibre substances containing both soluble and insoluble fibres have the properties of both. They include oat bran, psyllium, and soy fibre. Methylcellulose is a semi-synthetic fibre. It is soluble and gel forming, but not fermentable.
The solubility and fermentation of a particular fibre affects how it is handled in the GI tract. However, the effect of identical fibres varies from person to person. A gradual increase in dietary fibre can modify and improve symptoms. But individual responses vary and too much of a type of fibre can worsen symptoms. It may be necessary to try different types of fibre. With any dietary fibre it is best to start out low and go slow.
BRING ON THE BEANS
A 3-month randomised controlled trial with a group of 121 people with type 2 diabetes by Dr David Jenkins and colleagues found consuming about 1 cup (190g or 7oz) of cooked legumes (beans, chickpeas or lentils) helped people with diabetes manage their blood glucose and reduce their heart disease risk through a reduction in blood pressure. After three months, hemoglobin A1c levels had dropped from 7.4% to 6.9% in people eating beans, while it had fallen from 7.2% to 6.9% in those getting extra whole wheat. Even though the drops were not huge says Jenkins, they were impressive in part because the whole-grain comparison diet is a healthy one and in part because people in the study were already on diabetes and blood pressure medications. “We hope that this could be the point that allows a person with diabetes to delay medication use,” he said.
What about wind? The study didn’t find any more gastrointestinal complaints in the legume group, although the comparison group also got a lot of fibre, which could have drowned out a potential effect.
- Effect of Legumes as Part of a Low Glycemic Index Diet on Glycemic Control and Cardiovascular Risk Factors in Type 2 Diabetes MellitusA Randomized Controlled Trial
THE FIBER–FODMAP CONTROVERSY
In an article in Cereal Foods World, Prof Fred Brouns and colleagues discuss whole grain foods and their contribution of significant amounts of dietary fibers that are crucial for optimizing gut health. Here we post their key points summary of what is known and what is new/needs attention.
WHAT IS KNOWN
- Dietary fibers and prebiotics are important for gut health and function, and increased consumption is generally recommended.
- Avoidance of FODMAPs (nondigestible, rapidly fermentable carbohydrates) is being recommended for persons suffering from irritable bowel syndrome to alleviate abdominal distress due to intestinal gas production and fluid shifts that lead to bloating.
- Small osmotic effects and gas formation are normal processes in a healthy gut and are not disease symptoms.
- Cereals contain small quantities of rapidly fermentable carbohydrates.
WHAT IS NEW/NEEDS ATTENTION
- Avoidance of fermentable dietary fibers may impair favorable gut flora metabolism, gut function, and health.
- Eliminating grains from the diet to avoid FODMAPs means also eliminating a wide range of other components that are known to be beneficial.
- Increasingly FODMAP-free foods are being marketed and promoted to the general public and the hype surrounding them seems to be increasing.
- Avoidance of FODMAPs to relieve intestinal discomfort is only recommended on an individual basis and under medical/dietetic supervision.