FODMAP: composizione degli alimenti, definizione dei “valori limite” di FODMAP tollerabili e applicazione internazionale

by luciano

Riassunto
La dieta a basso contenuto di FODMAP è una nuova terapia dietetica per la gestione della sindrome dell’intestino irritabile che sta guadagnando popolarità in tutto il mondo. Lo sviluppo della dieta a basso contenuto di FODMAP ha richiesto non solo dati dettagliati sulla composizione degli alimenti, ma anche l’istituzione di “valori limite” per classificare gli alimenti come a basso contenuto di FODMAP. Questi valori si riferiscono ad ogni particolare FODMAP presente in un alimento, inclusi oligosaccaridi (fruttani e galatto-oligosaccaridi), polioli di zucchero (mannitolo e sorbitolo), lattosio e fruttosio in eccesso di glucosio. I valori limite sono stati individuati considerando i livelli di FODMAP in porzioni tipiche di alimenti che comunemente scatenano sintomi in soggetti con sindrome dell’intestino irritabile, nonché alimenti generalmente ben tollerati. L’affidabilità di questi valori limite di FODMAP è stata testata in numerosi studi dietetici. Lo sviluppo delle tecniche per quantificare il contenuto FODMAP degli alimenti ha notevolmente migliorato la nostra comprensione della composizione degli alimenti. La composizione di FODMAP è influenzata dalle tecniche di trasformazione degli alimenti e dalla selezione degli ingredienti. Negli Stati Uniti, l’uso di sciroppi di mais ad alto contenuto di fruttosio può contribuire ai livelli più elevati di FODMAP rilevati (tramite eccesso di fruttosio) in alcuni alimenti trasformati. Poiché le tecniche e gli ingredienti di trasformazione degli alimenti possono variare da paese a paese, sono necessari dati più completi sulla composizione degli alimenti affinché questa dieta possa essere implementata più facilmente a livello internazionale.

Extrat from the study:
A – “ omissis The Monash University Department of Gastroenterology has performed extensive work for over 10 years to quantify the FODMAP composition of hundreds of foods. Foods tested for FODMAP content represent a range of categories, including fruit and vegetables; grains, cereals, pulses, nuts, and seeds; dairy products and dairy free alternatives; meat, fish, poultry, and eggs; fats and oils; beverages; and condiments and confectionary. Some of these data have been published previously (12 -14) and are summarized in Figs 1 and 2. With growing international interest in the low-FODMAP diet, our program of FODMAP food analysis is expanding to include more international foods. This paper will dis- cuss the criteria for classifying food as low in FODMAPs and the challenges encountered in analysing food for FODMAP content.

B – “omissis.. Cutoff values were initially derived by considering (based on clinical experience) the FODMAP content and typical serving size of food, consumed in a single sitting or meal, that commonly trig- gered symptoms in individuals with IBS (e.g. onion, garlic, wheat bread, and apple). Foods that were generally well tolerated were also considered. This enabled the establishment of threshold levels for each FODMAP, above which most people experience symp- toms. The levels were set conservatively to allow people to include a number of low-FODMAP foods at each sitting. Table 2 provides examples of how cutoff values are applied to individual food items, to classify them as low in FODMAPs.
The reliability of these FODMAP cutoff values was tested in a number of dietary studies (2-4) An upper limit of 0.5 g of total FODMAPs (excluding lactose) per sitting was applied to the low-FODMAP arm of these studies, and this was generally well tolerated….”

C – The coexistence of gluten and FODMAPs in grain and cereal foods is evident in Fig. 5, which shows that many gluten- containing cereal products are high in FODMAPs (mostly fructans), while most gluten-free grains are low in FODMAPs.

D – The effect of ingredients on final FODMAP content may be me- diated by food processing techniques. Food processing techniques known to affect FODMAP levels include processes that involve heating and water, which can result in water-soluble FODMAPs (such as fructans and GOS) leaching into the surrounding liquid. For instance, canned lentils are lower in FODMAP, GOS, than boiled lentils.

F – The mediating effect of food processing on final FODMAP con tent is highlighted in spelt-containing products. While spelt flour is typically lower in FODMAPs (mostly fructans) than modern wheat, the use of spelt flour does not necessarily result in a low-FODMAP product. As shown in Fig. 8, while spelt flakes and spelt pasta are high in FODMAPs, sourdough spelt bread is low in FODMAPs. It appears that the spelt flour requires additional processing to lower the oligosaccharides (fructan) content. When a traditional sourdough culture (naturally high in lactobacilli) is used, together with a long proving time, bacteria metabolize the oligosaccharides (fructan) present in the spelt flour, thereby lowering fructan levels of the final product.

Approfondimento
FODMAPs: food composition, defining cutoff values and international application
Jane Varney, Jacqueline Barrett, Kate Scarlata, Patsy Catsos, Peter R Gibson and Jane G Muir Journal of Gastroenterology 9 dicembre 2016