Retested Foods (just in time for Aussie Summer!) – Strawberries & Grapes

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Lyndal Collins - Research Dietitian, 14 December 2021

Can you believe that it has been almost 20 years since the FODMAP concept was born? From humble beginnings in our small Melbourne laboratory, our FODMAP food testing program has continued to grow and inform our working knowledge of the FODMAP diet. More importantly, it has become the cornerstone of our Monash FODMAP Diet App! 

As the years go on, we occasionally like to retest foods from the past, to ensure that the information we provide to app users is up-to-date. This is important as changes in agricultural and food industry practices and environmental factors can influence FODMAP levels in food. 

Our most recently re-tested foods were grapes and strawberries. We chose these fruits in part, because some people over the years had reported to us discomfort after eating them. Our app has since been updated with this new data.

New grape results 

White/green, seedless:

32g (6 grapes) - Low FODMAP serve

48g (10 grapes) - Moderate in FODMAPs (excess fructose) 

75g (15 grapes) - High in FODMAPs (excess fructose)

Red, seedless: 

28g (6 grapes) - Low FODMAP serve

42g (9 grapes) - Moderate in FODMAPs (excess fructose) 

75g (15 grapes) - High in FODMAPs (excess fructose)

New strawberry results: 

65g (5 medium strawberries) - Low FODMAP serve

75g (6 medium strawberries) - Moderate in FODMAPs (excess fructose) 

100g (8 medium) - High in FODMAPs (excess fructose)

Why has the FODMAP rating of strawberries and grapes changed so significantly?

We know that this is BIG news, so let’s discuss in more detail the many factors that may account for these changes that we are observing over time. 

In recent years, our international research partnerships have grown, and we have had more of an opportunity to test foods sourced from other countries. Unsurprisingly, we have found that the FODMAP content of foods (especially fresh produce) can vary significantly from country to country. Why might this be? Keep reading to learn more…

Geographical variation and changes to environmental conditions

The impact of climate change on agriculture is already becoming obvious. Broadly speaking, increased drought conditions has seen soil become drier and more nutrient-depleted, leading to increased use of fertilisers and other agro-chemicals to help crops grow (1). Fertiliser use and type is thought to influence the nutrient content of crops(2). Crops themselves have had to adapt, with more hardy, drought tolerant varieties now being favoured by farmers as they are more likely to survive(1)

But what does this have to do with FODMAPs? Well, research has already demonstrated that plants are capable of changing their chemical structure to help ensure survival when exposed to stressors in their environment(3). One of these natural defence mechanisms is to increase their production of fructans, which provide plant cells with greater structural integrity, making them more hardy and resistant to damage from environmental changes, pests and disease(3). We have previously seen an example of this when we retested bananas

These factors, in addition to increases in the number of cultivars (varieties) of produce grown, climate and differences in agricultural methods between countries (2), likely account for the natural variation we observe in the FODMAP content of the same type of food from different sources.  

Post-harvest storage and treatment of fresh produce

Did you know that some fresh produce may be over a year old by the time you eat it? It is now common practice that many fruits and vegetables are kept in cold storage for long periods. In fact many are even harvested unripe, transported and stored in cold and/or controlled atmosphere storage, then later artificially ripened just prior to sale(4). These practices not only prevent spoilage, but ensure consumers have access to seasonal produce all year round! 

Unfortunately, cold storage is another factor known to increase fructan production in plants(3). Increases in fructose content are also known to occur in these environments. Under these conditions, plants begin to break down long-chain carbohydrates (such as starch) into oligosaccharides (such as fructans), fructose and other sugars(5). Fructose in particular seems to act like an antioxidant and ‘anti-freeze’ to prevent cold-related damage to the plant. This phenomenon is known as ‘cold-induced sweetening’, and is the reason why many root vegetables taste better when they are grown in cold climates(6)

More research is certainly needed in this area to better understand how food storage conditions may alter the FODMAP content of fresh foods.

Selective breeding of crops for desirable characteristics

Have you noticed how some varieties of fruits and vegetables just taste better than others? This is not a coincidence - as consumers demand tastier fresh food, scientists and farmers are driven to supply produce with more desirable characteristics. If we use strawberries and grapes as an example, most consumers will prefer sweeter tasting varieties(7). By nature (or nurture), these varieties may have a higher sugar content, of which fructose is one of the key sugars present(7). It is certainly possible that the increased fructose content observed in the retested strawberries and grapes may (at least partially) be explained by increasing consumer preference for sweeter varieties of these fruits. 

So what do these new results mean for me? 

Firstly, if you already include strawberries or grapes in your diet and tolerate these well, then there is no reason to change anything! Your FODMAP diet only needs to be as restrictive as your individual symptoms require. 

However, if you have struggled with strawberries or grapes in the past, these new results may offer an explanation. You may even like to try reintroducing them again in the new green serving size amounts to see if you tolerate these better. 

On a practical note, these new testing results have encouraged us to move away from labelling any food as ‘FODMAP free’, as we know now that this label may not stand the test of time. Instead, we are working hard behind the scenes to add more information about serving size limits for every food in the app. 

As always, our ongoing commitment is to keep testing and retesting foods and communicate these results via regular app updates. We hope this will continue to empower people with IBS to live happier, healthier lives! 

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