Vegan Diet And Bloating: What's The Deal?

Bloating is a common side effect of switching to a vegan diet, and it can last anywhere from two weeks to two months. This is due to the high fibre content of plant-based diets, which the human body cannot fully digest. Instead, fibre is broken down by bacteria in the gut, and the sudden increase in fibre that comes with a vegan diet can overwhelm the gut, leading to bloating. However, this is only a temporary issue, and there are several strategies to reduce bloating, including increasing water intake, eating smaller meals, and taking probiotic supplements.

High fibre intake

A vegan diet is typically high in fibre, which is great for gut health but can cause bloating. Fibre is a type of carbohydrate that remains undigested as it passes through our digestive tract. Instead, it is fermented by our gut bacteria in the large intestine, producing a lot of gas, which can cause bloating.

The good news is that this type of bloating is often not permanent. While your gut adjusts to the high-fibre diet, there are several things you can do to reduce bloating:

• Increase fibre intake slowly: Gradually increase your consumption of plant-based foods to allow your gut bacteria to get used to the higher fibre load.
• Peel and/or cook fruits and vegetables: Cooking foods helps break them down, making them easier to digest.
• Incorporate lower-fibre plant-based proteins: Opt for tofu, soy milk, protein powder, and mock meats instead of legumes at every meal.
• Choose refined varieties of grains: Swap out some whole grains for more refined varieties such as white rice or white bread.
• Drink enough water: Fibre requires a significant amount of water to do its job properly. Aim to drink enough water to urinate pale urine every couple of hours.
• Chew thoroughly: Plant cell walls take a lot of grinding to break down properly. Chewing thoroughly increases the surface area for acids and enzymes to attach to, optimising the digestion process.
• Spread fibre consumption throughout the day: Instead of consuming a lot of high-fibre foods in one meal, try to eat smaller fibre doses at each meal.

High FODMAP foods

FODMAP stands for fermentable oligo-, di-, mono-saccharides, and polyols. These are the scientific names for carbs that may cause digestive issues. FODMAPs are a group of short-chain carbohydrates that share similar properties.

FODMAPs are small in molecular size and are often associated with digestive symptoms like gas, bloating, diarrhoea, and constipation because they are difficult to break down and tend to be poorly absorbed in the small intestine.

FODMAPs are poorly absorbed and sit in the small bowel and intestine, where they are fermented and produce excess gas, leading to bloating and stomach pains. FODMAP compounds draw water into the small intestine, and that excess water in the digestive tract can cause feelings of pressure and fullness around the abdomen.

Wheat

Wheat is one of the biggest contributors of FODMAPs in the Western diet. Wheat is consumed in large quantities, not because it is a concentrated source of FODMAPs. Wheat contains one of the lowest amounts of FODMAPs by weight.

The most common sources of wheat include bread, pasta, breakfast cereals, biscuits, and pastries.

Garlic

Garlic is one of the most concentrated sources of FODMAPs. Restricting garlic in your diet is difficult because it is added to many sauces, gravies, and flavourings. In processed food, garlic may be listed as flavouring or natural flavour.

Fructans are the main type of FODMAP in garlic. The quantity of fructans depends on whether the garlic is fresh or dried, with dried garlic containing about three times as many fructans as fresh garlic.

Onions

Onions are another concentrated source of fructans. Onions are commonly used to flavour a wide range of dishes, making them difficult to restrict. Shallots are one of the highest sources of fructans, while Spanish onions are one of the lowest sources.

While different varieties of onions contain different amounts of FODMAPs, all onions are considered high in FODMAPs.

Fruits

All fruits contain the FODMAP fructose. However, not all fruits are considered high in FODMAPs, as some contain less fructose than others. Some fruits contain high amounts of glucose, a non-FODMAP sugar that helps the body absorb fructose.

Fruits that are high in both fructose and glucose do not typically cause gut symptoms. Only fruits with more fructose than glucose are considered high in FODMAPs.

Even low FODMAP fruits can cause gut symptoms if consumed in large quantities. Sensitive people are encouraged to eat only one portion of fruit per sitting, or approximately 3 ounces (80 grams).

High FODMAP fruits include:

Blackberries, blueberries, and raspberries, depending on quantity

Low FODMAP fruits include:

• Bananas
• Oranges
• Pineapple
• Kiwi
• Cantaloupe

Vegetables

Vegetables contain the most diverse range of FODMAPs, including fructans, GOS, fructose, mannitol, and sorbitol. Several vegetables contain more than one type of FODMAP. For example, asparagus contains fructans and fructose.

High FODMAP vegetables include:

• Globe and Jerusalem artichokes
• Mushrooms
• Cauliflower
• Snow peas

Low FODMAP vegetables include:

• Tomato (cooked or canned)
• Aubergine/eggplant
• Beans (green)
• Bok Choy
• Green capsicum (bell pepper)

Legumes and Pulses

Legumes and pulses are notorious for causing excess gas and bloating, partly attributed to their high FODMAP content. The key FODMAP in legumes and pulses is called GOS.

The GOS content of legumes and pulses is affected by how they are prepared. For instance, canned lentils contain half the GOS of boiled lentils because GOS is water-soluble, meaning some of it leaches out of the lentils and into the liquid.

High FODMAP legumes and pulses include:

• Red kidney beans
• Split peas
• Falafels
• Baked beans

Low FODMAP, vegetarian sources of protein include:

• Tofu
• Eggs
• Meat
• Poultry
• Fish

Sweeteners

Sweeteners can be a hidden source of FODMAPs, as adding sweeteners to a low FODMAP food can increase its overall FODMAP content.

High FODMAP sweeteners include:

• High fructose corn syrup
• Added polyols in sugar-free mints and chewing gums (check the labels for sorbitol, mannitol, xylitol, or isomalt)

Low FODMAP sweeteners include:

• Most artificial sweeteners like aspartame, saccharin, and stevia
• Brown sugar (in small amounts)
• Table sugar (sucrose)

Grains

Wheat is not the only grain high in FODMAPs. Other grains like rye contain nearly twice the amount of FODMAPs as wheat.

Some types of rye bread, such as sourdough rye bread, can be low in FODMAPs because the fermentation step breaks down some of its FODMAPs into digestible sugars.

High FODMAP grains include:

• Rye
• Wheat

Low FODMAP grains include:

• Oats
• Quinoa flakes
• Quinoa/rice/corn pasta
• Rice cakes (plain)
• Sourdough spelt bread
• Wheat/rye/barley-free breads

Larger meal portions

Plant-based foods tend to be lower in calories, so vegans often need to eat larger volumes of food to meet their calorie needs. This can lead to an increased feeling of fullness or physical distension associated with bloating.

To help alleviate this feeling, there are a few strategies you can try:

• Split your food intake into smaller meals eaten more frequently throughout the day. This gives your body a smaller load of food to deal with at once.
• Opt for cooked vegetables over raw ones to reduce the volume of food consumed.
• Avoid drinking too much fluid with meals, as this will only increase the volume in your stomach.
• Incorporate more calorie-dense foods such as nuts, seeds, avocado, olives, coconut, and olive oil into your diet.

It's also important to note that a larger volume of food may mean a higher fibre load, which can contribute to bloating. Increasing your fibre intake slowly and gradually can help your gut bacteria adjust to the higher fibre content of a vegan diet.

Incorrect preparation of legumes

Soak and Sprout Legumes Before Cooking

Soaking legumes helps break down compounds like phytic acid and oligosaccharides, which are difficult to digest. Sprouting legumes also increases the bioavailability of vitamins and iron.

Cook Legumes with Digestive Aids

Using certain spices like cumin, coriander, fennel seeds, or ginger can aid in breaking down complex carbohydrates in legumes.

Incorporate Legumes Gradually into Your Diet

Introducing legumes gradually gives your digestive system time to adjust. Start with small portions and slowly increase the amount as your body gets used to them.

Choose the Right Legumes

Some legumes are easier to digest than others. For instance, lentils and split peas are generally more digestible than beans or whole chickpeas.

Use a Pressure Cooker

A pressure cooker can reduce cooking time and make legumes more gut-friendly. The high pressure and heat effectively break down complex carbohydrates, making legumes easier to digest.

Add Vinegar or Lemon Juice

Adding a small amount of vinegar or lemon juice to legumes helps reduce bloating and improve flavour. The acidic properties of these ingredients break down complex carbohydrates, making legumes more digestible.

Lifestyle factors

Eating Habits

When adopting a vegan diet, it is important to be mindful of how much fibre you are consuming. A vegan diet is typically high in fibre, which is great for gut health, but too much fibre can cause bloating. It is recommended to increase your fibre intake slowly and track how much fibre you are consuming each day. It is also important to spread fibre consumption throughout the day, rather than consuming a lot of high-fibre foods in one meal.

It is also beneficial to be mindful of how you are consuming your food. Chew your food thoroughly and slowly, as this will help to break down the food properly and minimise the amount of air you are swallowing. It is also best to avoid drinking through a straw, as this can cause you to swallow excess air, which can lead to bloating.

Stress

Stress, anxiety, and poor mental health can also contribute to bloating. Engaging in stress-relieving activities and practising diaphragmatic breathing techniques may help to reduce bloating.

Exercise

Exercising can also help to relieve bloating, as it gets things moving in your gut and improves gas clearance from the bowel.

Frequently asked questions