Finding FODMAPs

“Food chemistry is really the foundation of this diet,” says Jane Muir, a dietitian and biochemist who is part of the Monash team. “We had to understand what was in the food and identify those trigger carbohydrates.”

These logos, from two certification companies, are used to label low FODMAP foods.

Muir developed a systematic method for analyzing foods for FODMAPs. For example, to determine the FODMAP content of fruit and vegetables, her team will collect 500-g samples from five different supermarkets and five different green grocers. The researchers cut and pool the edible portions of the produce and use a food processor to blend it into a homogeneous mixture. They perform a similar homogenizing process for grains, cereals, and packaged foods.

From the homogeneous mix, they portion out and freeze-dry 100-g samples. They then use hot water to extract saccharides and polyols from those samples. Ultra-high-performance liquid chromatography analysis measures amounts of lactose and galacto-oligosaccharides. The scientists use high-performance liquid chromatography with a different column and mobile phase to measure fructose in excess of glucose and sugar polyols. They also use enzyme assay kits to measure total fructans—oligosaccharides that contain fructose—in food. This procedure employs highly purified and specific enzymes to hydrolyze sucrose, maltose, maltotriose, starch, and fructans. Calculations are then necessary to determine the total fructan content (J. Agric. Food Chem. 2007, DOI: 10.1021/jf070623x; J. Agric. Food Chem. 2009, DOI: 10.1021/jf802700e; J. Hum. Nutr. Diet. 2011, DOI: 10.1111/j.1365-277X.2010.01139.x).

Many of these analytical techniques were in the literature, Muir says, but she had to find the methods that worked best for identifying FODMAPs. “What’s so time-consuming is looking at all these different sugars in the same foods,” she says. “Often people will concentrate on one or two sugars in the same food, but we have to track so many. That’s where it becomes very labor intensive.”

To develop the diet, the team has analyzed more than 1,000 different food products from across the globe in the past 12 years, Muir estimates. In some instances, people have sent them canned and packaged foods from other countries. Because of quarantine restrictions in Australia, the team cannot receive international shipments of fresh fruit, vegetables, or dairy products, so the researchers have developed some work-arounds. For instance, when they wanted to know the FODMAP content of collard greens, a staple in many diets in the American South that isn’t available in Australia, they grew the leafy greens from seeds.

“The highest FODMAP foods are wheat, corn, apples, and onions.” —Robin Foroutan, spokesperson, Academy of Nutrition & Dietetics, Credit: Shutterstock

For packaged foods, it’s not always obvious from reading the label if a food is high or low in FODMAPs. Garlic, a high-FODMAP food that’s rich in oligosaccharides, is often added to food and simply labeled as “natural flavor.” To help consumers adopting a low FODMAP diet navigate their way through food labels, Monash University offers a FODMAP certification process for food companies. For example, Nestlé’s ProNourish nutritional drink was certified as a low FODMAP food using Monash’s analysis.

The FODMAP Friendly program, also based in Australia and cofounded by Susan Shepherd, who was previously part of the Monash team, and Timothy Mottin, offers a similar certification system. Products that have received the program’s certification bear a logo that features two shades of green divided by a squiggly line. The program has already certified more than 200 products found in popular supermarkets, such as Woolworths in Australia and Kroger, Hy-Vee, and Wegmans in the U.S.

The Monash team recently assembled the information from all their analyses into the Monash University Low FODMAP Diet app. It tells users which foods are low or high in FODMAPs using a stoplight system. For example, uncooked white onions get a red rating because of their high oligosaccharide content. Experiments have shown that cooking and processing can change food’s FODMAP content. Pickled onions get a green rating in the app. The app also breaks down which specific FODMAPs are present at high or low levels in a particular food. It costs $7.99, and the proceeds go to FODMAP research at Monash, Gibson and Muir say.