Bananas & Resistant Starch Revisited

Research on the FODMAP content of food is constantly evolving, and today's findings may differ tomorrow. That's because the scientific methods used for testing FODMAPs are continually improving, affording greater sensitivity and accuracy. But perhaps even more important are changing environmental and agricultural factors that can greatly influence FODMAP levels in foods. 

 For these reasons, the researchers at Monash University often retest foods to provide the most up-to-date and accurate FODMAP information. Even small changes in how foods are grown and stored can significantly alter their FODMAP content by the time they hit grocery store shelves. Bananas are an excellent example of this. Increasingly, many farmers are selectively breeding banana varieties with a higher fructan content because fructans make plants hardier and more resistant to damage from pests, environmental fluctuations, and disease.

Additionally, ripening and storing bananas in cold storage has become the routine procedure in most supermarkets. This practice ensures more even ripening and prevents the fruit from premature spoilage. However, it also increases fructan content.

Although prior tests had shown fully ripe (soft and speckled) common bananas (also called Cavendish bananas) to be an acceptable low-FODMAP choice, many people with IBS complained the ripe fruit was causing them discomfort. In response, researchers at Monash University decided to do some retesting, and what they discovered was startling: ripe bananas are high in FODMAPs (particularly fructans)! Their results confirmed how seemingly simple growing and storage practices can greatly affect FODMAP content. Their revised low-FODMAP recommendation per serving is now one-third of a ripe common banana, one firm (yellow but not speckled) sugar banana (also called Ladyfinger banana, Data banana, and Fig banana), or unripe medium (green) common banana.

Bear in mind that unripe common bananas, though lower in FODMAPs, are higher in resistant starch. Resistant starches don’t get broken down completely in the small intestine, so instead much of the starch passes through to the large intestine, where it becomes food for bacterial growth. This is somewhat similar to how poorly absorbed FODMAPs can contribute to IBS symptoms. However, resistant starches are fermented more slowly than FODMAPs, and therefore they are less likely to be as problematic. That said, they may still trigger symptoms in some individuals with IBS, but that typically occurs only with higher intakes of resistant starch. So if you're consuming a varied diet of wholesome plant foods, unripe bananas and other sources of resistant starch may be well tolerated. In fact, resistant starch may even offer some health benefits:

• It helps maintain and normalize gut motility.
• It increases "friendly" (good) gut bacteria and protects against the growth of bad bacteria and pathogens.
• It supports the production of biotin, folate, and vitamin K.
• It aids the breakdown and elimination of toxins.
• It stabilizes blood glucose levels and increases insulin sensitivity.
• It improves cholesterol and triglyceride levels.
• It decreases appetite and increases satiety, which can aid weight loss and weight management,

There are four different types of resistant starch, although several different types can coexist in the same food:

• Type 1 is found in whole or partially milled grains, seeds, and legumes and resists digestion because the starch is bound within the fibrous cell walls.
• Type 2 is found in some starchy foods, such as raw potatoes, unripe (green) bananas, and some legumes.
• Type 3 is formed when certain starchy foods -- such as potatoes, rice, and pasta -- are cooked and then cooled. The cooling turns some of the digestible starches into resistant starches through a process called retrogradation.
• Type 4 is a chemically modified starch found in a wide range of manufactured products.

If you’re not used to consuming resistant starch, wait to try foods that are high in it until your IBS symptoms are in remission or have stabilized (preferably after the elimination phase of the low-FODMAP diet). Then, add it gradually to your diet and in small amounts. See how it agrees with you before you introduce larger quantities. If it exacerbates your digestive issues, discontinue it.

If you'd like to try adding more foods with resistant start to your diet, the following are some good options to start with:

---

Here are a few easy ways to incorporate resistant starch into your daily diet:

• Add canned lentils to rice, pasta, or salads (1/2 cup lentils per serving).
• Add 1 to 2 tablespoons of raw rolled oats to a smoothie before processing it.
• Make a rice or pasta salad with cooked then cooled rice or pasta. Add low-FODMAP veggies and your favorite low-FODMAP salad dressing.
• Add canned chickpeas to soups or salads (1/4 cup chickpeas per serving).
• Dice a cooked and cooled yam and add it to soup or salad (1/2 cup yam per serving).
• Enjoy the Classic Lentil Loaf, Creamy Lentil and Coconut Soup, or Hummus recipes from Low-FODMAP and Vegan.
• Add half an unripe banana to a smoothie or bowl of cooked oatmeal, or use it in a PB and banana sandwich on low-FODMAP sourdough bread.

*****
QUESTIONS FOR DISCUSSION:
How well do you tolerate ripe or unripe bananas? Which foods high in resistant starch do you include regularly in your diet? Which foods have been most problematic for you? Let's get a dialogue going!

I love hearing from you! Please post your thoughts and responses in the comment section below.