Screenshot 2021-10-27 at 11.11.18
Screenshot 2021-10-27 at 11.11.18

What is the low-FODMAP diet?

Struggling with gut issues? You are not alone… it is suggested that 2 in 10 people in the UK suffer with IBS issues at one point in their life!

And if you have been to the doctor or worked with a dietician or nutritionist, then you have probably heard about, if not followed, a low fodmap diet.

The low fodmap diet has been touted as a magic diet to fix your bloating issues, IBS symptoms and irregular inconsistent bowel movements. And as fantastic as the low FODMAP diet is in controlling your symptoms, it isn’t for everyone, and unfortunately doesn’t always get to the root cause of why you have symptoms in the first place.

Read on to learn all things FODMAPS and how the diet may or may not work for you.


FODMAPS are fermentable, poorly absorbed, short-chain carbohydrates found in everything from bread to avocados, and even coconut water.

For some sensitive individuals, eating fodmap containing foods may trigger gut symptoms such as bloating, gas, stomach pain, diarrhoea and constipation.

The prebiotic compounds from FODMAPS are poorly absorbed in our small intestines, therefore they are passed through undigested into the colon, where they are rapidly fermented by colonic bacteria.

The process is totally natural, however, if you are prone to IBS type symptoms, the gas produced when burning through the FODMAPs you’re consuming could result in gut issues from bowel sensitivity or stretching. (1)



  • Fermentable: The process where our gut bacteria ferment undigested carbohydrates to produce gases

  • Oligosaccharides- Fructans and GOS- Found in: wheat, rye, pulses, legumes, cashews and various vegetables such as garlic and onion

  • Disaccharides- Lactose- Found in: dairy products such as ice cream, yogurt, milk, custard and soft cheese

  • Monosaccharides- Fructose- Found in: Honey, fruit juice and fruits such as figs and mangoes

  • Polyols- Sorbitol and Mannitol- Found in some artificial sweeteners, and certain vegetables and fruits including blackberries and lychees

Many foods contain FODMAPs, but they can’t all be avoided. Many of these FODMAP containing foods don’t usually become troublesome until a larger quantity of the food is consumed. Therefore, they can be consumed in smaller portion sizes without causing any issues.



For the majority of individuals, FODMAP foods do not cause symptoms. However, if you’re prone to IBS symptoms, they may cause additional stomach troubles due to, as mentioned previously, an individual having a bowel that is more sensitive to being stretched.

We all are different in our ability to digest FODMAPs, with portion size, motility, enzyme production and dysbiosis/state of the gut all playing a role in how we react. (2)

It’s important to note that it isn’t the FODMAPs themselves that are triggering a reaction, it is the effect they are having on the gut. These FODMAPs are moved into the bowel, where they are fermented by bacteria- this stage produces gas and can result in water moving into the bowel. This stretches the bowel wall, stimulating the gut, often resulting in urgent bowel movements and a sudden need to dash to the toilet! (3)



There is currently no diagnostic test for FODMAP sensitivity, so undertaking a low FODMAP diet involves an elimination diet, followed by a gradual reintroduction of various high FODMAP foods to try to determine a person’s individual triggers and tolerance threshold.

Most nutritionists recommend an elimination phase of 4-6 weeks, before a reintroduction phase. This phase is key! Each food should be reintroduced gradually in portion sizes, so that each within each food group you can note your own personal tolerance. I.e on one week you will introduce a food group in a ¼ serving, ½ serving and full serving, and note if and when symptoms developed. By the end of this phase, you will have an understanding of which foods in which portion sizes you can tolerate.

It is important to remember that the low FODMAP diet is not a forever diet. The reintroduction is absolutely key to ensuring an individual has a well-rounded balanced diet at the end of the process. And if not followed correctly, alongside a nutritionist, the low FODMAP diet can be pointless or even detrimental to one’s gut health.



The low FODMAP diet limits fibre intake for a short period of time, with research showing that the low FODMAP diet can alter gut microbiota by reducing the diversity and amount of healthy bacteria in the gut, which is another reason not to follow the diet for more than 6 weeks. (4)

To maintain an adequate fibre intake on a low FODMAP diet, ensure that the sources of fibre you are consuming are carefully selected and eaten in smaller quantities. My top tips include:

  • Snack on low FODMAP fruits with their skin on such as kiwis or 10 raspberries

  • Add in seeds everywhere – chia seeds (2 tbsp or less) or flax seeds (1 tbsp)

  • Add canned chickpeas and lentils to salads and meals- stick to ¼ cup to keep it low fodmap and ensure to rinse well being consuming

  • Add oat bran to your breakfast- 2 tbsp is a low FODMAP serving size

The foods you can and can’t eat on a low FODMAP diet are incredibly complicated, so adequate research must be done before starting the diet. Check out the FODMAP diet app or click the link here to book in a free discovery call to find out if I think the low FODMAP diet is right for you.



Research has found that a low FODMAP diet may help to relieve symptoms in 75% of sufferers. (5)

Many studies and clinical trials have concluded enough evidence that a low FODMAP diet is now strong enough to be rolled out as first-line therapy for IBS patients in many practices.

If the low FODMAP diet is something you are considering due to your uncomfortable and long-lasting gut symptoms, it is important to always work with a Nutritionist alongside to help monitor your progress. They will also take into consideration your health history, symptoms and lifestyle measures as everyone is individual when it comes to their gut health.

Send my team an email if you would like to learn more about working with me and how I can help, at


References: (1) (2) (3) (4) (5)

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Hi there

London Nutritionist Clarissa Lenherr

I’m Clarissa, a registered nutritionist (mBANT) and workplace wellness expert. In my practice, I have helped hundreds of clients reach optimal health through creating sustainable, effective habits and dietary adjustments. My aim is to empower people with the skills, tools and knowledge to take their health into their own hands and feel the happiest, healthiest versions of themselves. Featured in The Daily Mail, Women’s Health, The Telegraph, and more.




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