Starting the low FODMAP diet can be both restrictive and challenging. If not done correctly the diet may be nutritionally deficient. Vegetarians and particularly individuals following a vegan diet are further at risk of nutritional deficiencies. In addition to foods high in FODMAPs, IBS sufferers may also be avoiding other foods to reduce symptoms; such as vegetables with a high content of insoluble fibre (Heizer, Southern & McGovern, 2009). Those on vegetarian and vegan diets further restrict their intake, increasing the risk of developing nutritional deficiencies (Hayes et al, 2013). The low FODMAP diet should be undertaken under the care of a FODMAP trained dietitian to ensure nutritional adequacy (Gibson Barrett & Muir, 2013; NICE CG61; 2015). Unfortunately many patients do not seek help or are not referred on to a dietitian and follow the diet on their own. However with sufficient information on suitable food alternatives it is possible to have a nutritionally adequate diet whilst following a low FODMAP diet (Barrett & Gibson, 2007).
The avoidance of meat, animal products, beans and lentils can lead to an inadequate intake of protein, iron and vitamin B12.
Adequate protein is essential for proper functioning. Protein is required for growth and repair, digestion, energy production, blood coagulation, and to make antibodies and hormones. Suitable low FODMAP and vegetarian and vegan protein sources are listed below. Although soya beans contain galacto-oligosaccharides; a FODMAP, some products made from soya beans are low FODMAP due to the development process. These products include tofu and tempeh. Tempeh undergoes a fermentation process which makes it low FODMAP whereas during the production of tofu the FODMAPs are separated out. A few pulses are also low FODMAP in small amounts and can be included in the diet.
- Pulses include canned chickpeas (up to 44g), canned lentils (up to 46g), canned butter beans (up to 35g), green boiled lentils (up to 23g), red boiled lentils (up to 23g), boiled lima beans (up to 39g). These are low FODMAP as the galacto-oligosaccharides leach out in the water, lowering the FODMAP content. The water in the cans and water used to boil the beans and lentils should be discarded and pulses rinsed. Adding pulses to meals is a great way to increase protein intake.
- Nuts: almonds (up to 12g), walnuts (up to 30g), peanuts (up to 28g), hazelnuts (up to 15g), macadamia (up to 40g), pecan (up to 22g), pine nuts (up to 14g). Nut butters made from low FODMAP nuts. Nuts make an excellent snack.
- Seeds: chia (up to 24g), Pumpkin (up to 23g), sesame (up to 11g), sunflower (up to 6g).
- Grains: oats (up to 23g), quinoa, and buckwheat (up to 27g).
- Vegetarians may also get protein from eggs and dairy products such as lactose free yoghurt, lactose free milk and hard cheeses.
A varied intake of plant foods is important as these do not contain all the essential amino acids. Essential amino acids cannot be made by the body therefore they must be acquired from food. The consumption of a mixture of plant foods ensures the intake of all the essential amino acids. E.g. combining grains with dairy, nuts/seeds with dairy, dairy with legumes, legumes with nuts, legumes with grains and legumes with seeds. Example bread with cheese and rice with beans. However, soya, buckwheat and quinoa contain all the essential amino acids.
Adequate iron intake is important, as iron forms part of oxygen-carrying proteins around the body. Inadequate iron intake can lead to iron deficiency which causes lack of energy, dizziness, headache and difficulty concentrating. Dietary iron is found in two forms; haem and non-haem. Haem iron is found in animal products whereas non-haem iron is found in animal and plant foods. Non-haem iron is less efficiently absorbed as plant foods contain inhibitors such as phytates and oxalates. Other meal components can also inhibit iron absorption such as soy protein, polyphenols and calcium (SACN, 2010). However the absorption of non-haem iron can be enhanced if it is combined with the intake of Vitamin C with the meal e.g. a glass of orange juice. The best sources of non-haem iron are (BDA, 2014a):
- Pulses: beans, lentils, chickpeas, Tofu. Check the pulses listed in the protein section.
- Nuts: check the nuts listed in the protein section.
- Dried fruit: up to 1 tbsp of low fodmap dried fruit e.g. raisins, cranberries
- Fortified breakfast cereals (check the food labels)
- Dark green leafy vegetables: kale, watercress, spinach, cabbage and broccoli
- If you eat them: eggs
- Wholegrains: oats, brown rice, wholemeal bread
Males require 8.7mg/day and females require 14.8mg/day (SACN, 2010).
Vitamin B12 plays an important role in metabolism, formation of red blood cells and maintenance of the nervous system. Vegetarians and vegans may struggle to obtain vitamin B12 as plant foods contain no vitamin B12. However vitamin B12 can be obtained from the following (Gandy, 2014, BDA, 2014a):
- Fortified breakfast cereals
- Nutritional yeast
- If you eat them: eggs, lactose free milk, lactose free yoghurt, hard cheeses
These are essential fats as the body cannot make them and must get them from food. Omega-3 fats reduce inflammation in the body and may reduce the risk of heart disease. They also play a role in cognitive function and are part of cell membranes. The best source is oily fish however omega-3 fats can also be obtained from plant foods (Gandy, 2014; BDA, 2014a):
- Nuts: Walnuts, pecan
- Oils: Rapeseed oil, Hempseed oil, walnut oil, flaxseed oil
- Omega-3 enriched foods such as eggs, milk, margarine (Check food labels for content)
- DHA rich micro algae
This is a mineral which is needed for healthy bones and teeth. It is also important for muscles and nerves to work well and is also involved in blood clotting and digestion (The Dairy Council, 2015). Sources of calcium include (Gandy, 2014; BDA, 2014b):
- Calcium fortified plant based milk
- Calcium fortified orange juice
- Nuts and seeds: almonds, hazelnuts and sesame seeds
- Okra (up to 60g)
- Green leafy vegetables e.g. Kale and pak choi
- If you consume these: lactose free milk and yoghurt, hard cheeses
Nuts and seeds however are not good sources as they contain oxalates and phytates which inhibit the absorption of calcium (BDA, 2014b, Gandy, 2014). To absorb calcium well we need vitamin D. The main source of vitamin D is exposure to the sun, therefore exposure to the sun from April to September without sunscreen in the UK is required to produce adequate amounts of vitamin D (BDA, 2014b). Sufficient skin exposure is required to achieve adequate levels of vitamin D in the UK (SACN, 2007). Exposure for 5-15 minutes between 10.00 and 15.00 is recommended for light skinned individuals (SACN, 2007). Vegetarian dietary sources for vitamin D include fortified breakfast cereal and margarine. Margarine in the UK is fortified with vitamin D. If you consume eggs these also are sources of vitamin D. Food alone however does not provide adequate quantities of vitamin D.
Zinc is important for growth and development, reproduction, night vision, proper function of the immune system and appetite (Gandy, 2014; Vegetarian Nutrition, 2015). Plant sources of zinc include:
- Nuts e.g. walnuts, almonds
- Seeds e.g. pumpkin seeds, sunflower seeds
- Fortified breakfast cereals
- Nutritional yeast
- Wholegrains such as oats
As mentioned before plant foods contain phytates which inhibit nutrient absorption. Phytates also prevent the absorption of zinc. Soaking beans, grains and seeds reduces phytates (Vegetarian Nutrition, 2015; Gandy, 2014.). If you consume dairy products these provide zinc which is more readily absorbed.
For adequate nutrition include foods high in these nutrients daily.
*All portion sizes indicated were based on the Monash University Low FODMAP diet app recommendations and were correct at time of publishing (August 2015).
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- British Dietetic Association (BDA), 2014a. Vegetarian diets [online]. Available at: https://www.bda.uk.com/foodfacts/vegetarianfoodfacts.pdf Accessed on 12/09/2015.
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