Are FODMAPS – the gasifying foods – your problem?

Margaret Moss explains that being sensitive to FODMAPs is not a food allergy but a food sensitivity. In other words you may be able to tolerate some high FODMAP foods, but not all – or you may only be able to tolerate them in limited quantities. The issue is knowing which you need to avoid and how stringently you need to avoid them.

Fodmaps vegThere are various causes of bloating, gut pain, flatulence, belching and diarrhoea. Among them are short chains of sugars which we cannot pull apart. So we cannot absorb the sugars, and they remain in the gut, feeding bacteria, which can break them down, and which make gas from them. These short chain carbohydrates come in various categories. The FODMAP diet is designed to reduce these and other fermentable carbohydrates. The initials stand for Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols.


Starch is made up of chains of glucose. We are programmed to be able to break these chains apart, and absorb the glucose into the bloodstream, providing us with fuel. Starch is in many foods, including wheat, rye, oats, barley, maize, rice, potato and banana. Because it is well used by the body, starch is not usually a problem. If you are sensitive to some starchy foods, it may not be because of the starch or FODMAPS mixed with the starch, but instead because of the lectins, which are concentrated in the skins of seeds, including wheat bran and potato skin.


Lactose is milk sugar, and is in animal milk, whether from human beings, cows, goats, sheep or buffalo. It’s a disaccharide, or double sugar, made of glucose and galactose. We have an enzyme called lactase, that breaks down lactose into glucose and galactose. In the past, people breastfed for a few years, and this enzyme was for dealing with our mother’s milk.

Vitamin D increases our ability to absorb calcium. In the tropics, there was plenty of vitamin D to be made from the sun, and people could safely lose their lactase, and hence their milk tolerance, at around four years of age, without becoming calcium deficient. Lactase can also diminish after a gut infection. If we drink milk, and do not break down the lactose, it remains in the gut, feeding bacteria.

People with lactose intolerance are protected from heart disease, as they do not produce much of the galactose which damages the arteries. Taking the lactase enzyme is not advisable, as it removes their protection from heart disease. Drinking “lactose free milk” means consuming galactose, which damages arteries. If you are lactose intolerant, you can almost certainly tolerate the trace of sugar in hard cheese, which can provide all the calcium you need. You don’t need milk.


Galactans are chains of galactose. Short chains are called galactooligosaccharides. (GOS). They are in the seeds of beans, for example kidney beans and baked beans. French and flat beans do not contain much, as they mostly consist of the bean pod. An enzyme galactosidase is sold to reduce gas production from beans, but it also produces galactose, which harms arteries.


Fructose is not a chain of sugars. It is a simple sugar, or monosaccharide, which does not need to be broken down. It is in cane and beet sugar, fruit and fruit juice, honey, high fructose corn syrup (often known as glucose syrup), and agave. However, we evolved when sugar was in short supply, and many of us cannot absorb all the fructose that is in modern diets. Our ability to absorb fructose varies, but anyone with a high fructose intake may fail to absorb it all. What we don’t absorb feeds gut bacteria. Fructose malabsorption is fairly common. Inherited fructose intolerance is not common. It involves an inability of the body to process fructose after absorbing it. Fructose allows cancer cells to multiply, and feeds bacteria that cause ulcerative colitis.


Sucrose is a disaccharide, which splits into glucose and fructose. High sugar consumption has caused the worrying increase in type two diabetes.


Fructans are chains of fructose. Short chain fructans are called fructooligosaccharides (FOS). They feed good bacteria in the gut. Some people with constipation improve if they take FOS, but other people cannot cope with the gas it produces. Fructans are in wheat, rye, barley, garlic, onion, the white part of spring onions and leeks, globe and Jerusalem artichokes, beetroot, Brussels sprouts and Savoy cabbage. Some probiotic capsules contain FOS. Traditionally bread was made by a slow souring process, that broke down fructans. Many people who are wheat sensitive may be affected by fructans or by lectins in wheat.

Sugar alcohols

Sugar alcohols are part of a group of chemicals called polyols. They are used as sweeteners. They include sorbitol, isomalt, maltitol, mannitol, and xylitol. People buy xylitol, thinking it is a good sugar, but it can cause gut problems.

Managing FODMAP sensitivity

In food allergy, even tiny amounts of the wrong food can cause terrible results. In food sensitivity, which is much more common, small amounts can often be tolerated, but large amounts cause problems.

The idea of a low FODMAP diet should not be to eliminate all foods containing any lactose, fructose, galactans, fructans or sugar alcohols, but rather to reduce the level, so that they do not cause discomfort.

Most people do not need to eliminate all the foods listed as high FODMAP. Anyway, the lists conflict. For example some say celery is to be avoided, and others say you can have it. It depends where the individual's cut-off point is, between high and low FODMAP foods. You have to find where your cut-off point is. You may be able to eat a little leek, but not onion, to have red lentil soup, but not a kidney bean stew, to have a few Brussels spouts, but not many, and to eat only one piece of sweet fruit a day. You may not cope with Jerusalem artichoke, but may tolerate some celery. It can be a healthy and palatable diet. If you are avoiding fibrous foods like wholemeal bread, fruit and kidney beans, celery can be a useful source of fibre, to feed good gut bacteria, and prevent constipation.

Just because you can’t process one of the FODMAPs, it doesn’t mean you cannot tolerate any of them. You may have lactose intolerance, or fructose malabsorption, and not have any problem at all with fructans or galactans.

If a low FODMAP diet doesn’t solve your problems, then consider other causes of sensitivity, like lectins in whole grains and pulses, low sulphate levels, foods or supplements high in boron, or a shortage of digestive enzymes.

March 2018

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