The mysterious food intolerance - FODMAPS
It’s an all too common complaint - digestive pain and discomfort which seems to be related to diet but you just can’t put your finger on the offending foods. Cutting back on gluten seems to help a little but it doesn’t resolve the symptoms completely. After numerous visits to the doctor, who has investigated for the more insidious signs of coeliacs and Crohn’s disease, you are labelled as having the dreaded Irritable Bowel Syndrome (IBS).
So what is IBS?
The diagnosis of IBS relies on a set of symptoms - the most telling of these symptoms is alternating bowel habits. This basically means sometimes being constipated and at other times having diarrhoea, with an accompanying sense of urgency and incomplete evacuation, but you may also have one or the other. The other cardinal symptoms are that of abdominal pain and cramping which may feel a little better after a bowel motion. Bloating which gets worse as the day goes on and an increase in stomach noises are also often present. It is thought that as many as 25% of all people may have these symptoms at some time or another during their lifetime, and for some they are ongoing, significantly affecting quality of life.
From altered gut motility, to an increased awareness of internal gut processes, to bacterial overgrowth, to inflammation to physiological disturbances - IBS seems to have a raft of contributing influences. But one area which has been mooted again and again for the amelioration of IBS symptoms is addressing possible food intolerances. However, this is more difficult than it sounds. Commonly, gluten and dairy are removed producing a slight improvement in IBS symptoms. But then a meal containing none of the offending items results in tummy troubles and a visit to the toilet anyway; what could it be?
The answer may come in the guise of Fermentable, Oligosaccharides, Disaccharides, Monosaccharides, and Polyols, conveniently named FODMAPS. These are complex names for a collection of molecules, found in a wide range of foods, that are poorly absorbed by most people. This malabsorption in the small intestine produces the symptoms so familiar to those with functional gut disorders such as IBS. It seems that these little molecules produce these particular problems as they are left undigested in the small intestine and upper colon.
Osmosis:When FODMAPS are not absorbed properly, they act osmotically to draw fluid into the bowel. This basically makes the contents of the bowel become more fluid, increasing the speed of passage of foodstuffs through the gut, resulting in diarrhoea. To put this into perspective, one synthetic FODMAP - lactulose – is a liquid which is widely prescribed for the treatment of constipation.
Bacterial fermentation: Gastro intestinal symptoms like cramping, diarrhoea and particularly gas and bloating often occur as a consequence of the fermentation of undigested food by bacteria in the small intestine. The structure of FODMAPs makes them resistant to digestion and therefore prone to fermentation by the bacteria, causing a build-up of hydrogen gas with its aforementioned side effects. Bacterial fermentation in the small intestine can also limit the absorption of folic acid, vitamins B12, iron and tryptophan which may produce the symptoms of lethargy and depression which often accompany IBS.
Promotion of mucosal biofilm: Alongside possibly acting as ‘fast food’ for bacteria in the gut, FODMAPS may promote the proliferation and adherence of pathogenic or ‘nasty’ bacteria to the intestinal wall. This can instigate inflammation and damage to the intestinal wall, producing a sticky film which protects harmful bacteria from antimicrobial agents. This makes them extremely difficult to eradicate and can lead to chronic gut issues such as those of IBS.
So what are FODMAPS exactly?
Fructose: This very sweet little sugar is absorbed inefficiently when it is delivered in a higher concentration to glucose. This is an issue in this day and age, as so many food producers are using high fructose corn syrup (HFCS) as a cheap sweetener in their products. Similarly, an orange may have a balanced fructose to glucose profile yet orange juice has significantly more fructose than glucose. Problematic foods include apples, pears, nashi, mangoes, tinned fruit, watermelon, fructose, HFCS, dried fruit, fruit juice and honey.
Lactose: This disaccharide, found most notably in milk, is broken down by enzymes present in the brush border of the small intestine and is another short chain sugar which is infamously difficult to absorb. As many people can attest, malabsorption of lactose can cause osmotic diarrhoea and, as it is fermented by gut bacteria, bloating and gas. Problematic foods include cows, goats and sheep’s milk, yogurt, ice cream, soft and fresh cheeses.
Oligosaccharides: Including FOS, fructans and GOS or galactans are very common in the diet. The human small intestine does not contain the enzymes required to break up these molecules making them almost entirely indigestible. Their fermentation in the gut causes bloating and wind. Problematic foods include wheat and rye, artichokes, beetroot, asparagus, Brussels sprouts, cabbage, fennel, garlic, leeks, okra, onions, spring onions, watermelon, custard apples, persimmons, chickpeas, lentils, kidney beans and baked beans. It is worth noting that some products intended to support digestive function contain inulin and FOS precisely because they are fermentable fibers, meant to encourage the growth of friendly gutbacteria. While this makes sense in general, these food additives may be poorly tolerated by people with IBS.
Polyols: These are sugar alcohols which are also very poorly absorbed by most people, but are particularly poorly absorbed when they are administered in products also containing fructose. These molecules are widely distributed in the diet, as they are present in certain fruits and also come in their pure form as low calorie sweeteners. Problematic Foods include apples, apricots, cherries, lychees, nashi, nectarines, pears, peaches, plums, prunes, watermelon, avocados and mushrooms and the sweeteners sorbitol, mannitol, xylitol, maltitol and isomalt.
As you can see this list is extensive; but the list also contains primarily good healthy foods or “healthy” food additives, which have not likely been considered as contributing factors to your irritable, functional gut issues. The point is that for some individuals these foods and ingredients can be quite problematic. To date, the management of functional gut disorders by the medical profession, and indeed even the naturopathic profession, has been largely unsatisfactory. For some people, seeing these lists may provide a Eureka! moment. Years of being unable to ascertain the food triggers which cause the pain and suffering of IBS are suddenly illuminated. What’s more, proponents of the low FODMAP diet suggest that over 80% of people with a functional gut disorder like IBS may see improvements with the adoption of this diet.
It must be said that as this diet is relatively restricted, it may be pertinent to seek the guidance of a naturopath, nutritionist or dietician to guide you in the right direction.