Question: I have been diagnosed with IBS and have used the low-Fodmap diet to help with it. However, one of my “triggers” is dark-green leafy vegetables, such as spinach. I can safely eat silverbeet, but leafy green recommendations do not mention it. How do I obtain the same nutrition that I would have from dark-green leafy vegetables without exacerbating my IBS problem?
Answer: Irritable bowel syndrome, like politics and religion, is a topic often avoided at dinner parties. Yet if you’re throwing a dinner party, there’s a good chance one of your guests has IBS, as an estimated one in seven adults experiences it.
IBS is characterised by abdominal pain, bloating, wind and altered bowel habits, whether diarrhoea, constipation or a combination of both. Because these symptoms overlap with other conditions such as inflammatory bowel disease, coeliac disease, endometriosis and bowel cancer, a medical professional must rule these conditions out and diagnose IBS, rather than it being self-diagnosed.
Fodmaps (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) is an acronym coined by researchers at Monash University in Melbourne for a group of short-chain carbohydrates. These carbs draw water out of the body into the small intestine, thereby increasing water delivery to the colon, and they are rapidly fermented by colon bacteria that produce hydrogen, carbon dioxide and methane.
Along with the rapid production of gases, these short-chain carbohydrates may lead to bloating, pain, discomfort, wind, diarrhoea and/or constipation in people with IBS, who are more susceptible to these effects. The major dietary Fodmaps of interest are the excess fructose found in certain fruits, honey and high-fructose corn syrup; fructans found in wheat, onions, certain other vegies (including baby spinach) and fruits; polyols such as sorbitol; lactose in dairy products; and galactans in various beans and gassy vegetables. Only lactose and fructose can potentially be absorbed in the small intestine, reducing colon symptoms, but even these are malabsorbed by some 10% (lactose) and 30% (fructose) of New Zealanders.
However, trials in Australia found that about 75% of patients achieve sustained and substantial relief from all IBS symptoms by avoiding Fodmaps.
But there is no reason to avoid all Fodmap groups if some do not cause symptoms. With a low-Fodmap diet, advice from an experienced dietitian is highly recommended due to the complexity of this nutrition field and for the very reason you have highlighted – balancing the reduction of symptoms with optimal nutrient intake. A dietitian knowledgeable about Fodmaps can ensure you individualise your level of short-chain carb restriction while ensuring your nutrient intake is sufficient. Once symptom relief is achieved, the dietitian can guide you through a rechallenge phase in which you systematically identify which Fodmap groups are problematic for you and which are not.
There are indeed limitations as to which nutritious foods IBS sufferers can enjoy without symptoms. For example, baby spinach contains fructans, and large servings (150g or more) could cause problems for individuals sensitive to fructans. So can other fructan-containing foods such as wheat-based bread, pasta, onions and garlic. In such cases, managing your daily fructan load is essential.
Your dietitian can help you find other suitable nutritious dark-green leafy vegetables that are lower in fructans. Examples include the silverbeet you mentioned and small servings of other green vegetables such as cabbage (green or red), kale, broccoli heads (but not stalks), bok choy and more. However, both green cabbage and bok choy contain sorbitol, which may cause IBS symptoms in people sensitive to polyols.
On that note, Monash University’s Fodmap Diet smartphone app is a valuable tool, with a traffic-light system indicating which groups of Fodmaps are high (and thus cause symptoms) in a wide range of foods. The app also has a tab that lists experienced Fodmap dietitians in New Zealand who are qualified to guide you. So, you can maximise symptom relief with minimal food restriction and meet your nutrition needs.
