One of the most common questions I get asked is on the topic of gas and bloating, especially from people who’ve changed their diet overnight, from eating more processed and animal-based foods, to eating more high-fibre vegetables and legumes. So my first questions would be: What’s changed in your diet recently? Are you eating foods that you didn’t eat before? I have some tips that might help—you can skip ahead to those, or you can read on if you’d like to learn more about why your gut produces gas.
Here’s the thing: passing gas (flatulence) is totally normal: the average person passes gas between 12-25 times a day1
Why the gas?
If you’re experiencing bloating after eating certain foods, this is a result of a build-up of gas in the gut. This can come from swallowed air—I was surprised too—and from the fermentation of certain kinds of carbohydrates that end up undigested in the gut, such as lactose (from dairy), oligosaccharides (from legumes), raffinose (from legumes and cruciferous vegetables), and noncaloric sweeteners (e.g. xylitol) 2https://www.ncbi.nlm.nih.gov/pubmed/3068547. But, this isn’t a reason to not eat these foods! As you’ll learn, legumes and cruciferous vegetables are a really important part of a balanced diet. (Dairy, on the other hand, you can go ahead and skip. There are all kinds of reasons to choose plant-based options instead.)
Our gut microbiome
Each person’s gut microbiome (or gut flora) consists of hundreds of different types of bacteria, both good and bad. In total, our gut is home to trillions of bacteria and other microorganisms (mainly in the large intestine), doing their bit to help us digest foods, synthesise vitamins and destroy harmful bacteria. The overall balance between healthy and harmful gut bacteria is regulated by what we eat: highly-processed and animal-based foods tend to promote the growth of harmful gut bacteria, while high-fibre plant-based foods tend to promote the growth of beneficial bacteria. An overpopulation of harmful bacteria can produce toxins that result in reduced immune function, chronic inflammation, damage to the lining of the gut, and weakened metabolism (leading to weight gain).
Probiotics vs Prebiotics
There’s a lot of talk about probiotics, which are live beneficial bacteria and yeasts that can be consumed through foods like yoghurt, sauerkraut, tempeh and kombucha, or in supplement form (although there’s controversy around the effectiveness of probiotic supplements3https://www.ncbi.nlm.nih.gov/pubmed/23086285). These live cultures are thought to improve our gut flora.
However, there’s another way that’s considered more effective at promoting a healthy gut: consuming prebiotics! Prebiotics are basically high-fibre plant foods (such as legumes, oats, onions, garlic, tomatoes, soybeans, bananas, artichokes, barley, sweet potatoes, chicory and many more) that promote the growth of healthy bacteria in the large intestine.
If you want the nitty-gritty, I’ve taken some notes from Dr Greger’s excellent video Prebiotics: Tending our Inner Garden:
- Fibre from whole plant foods feeds the good bacteria in our gut.
- This good bacteria, in turn, synthesises a short-chain fatty acid called butyrate.
- Butyrate fuels the single-cell lining of our gut, which is the protective barrier between the gut and the rest of the body
- Butyrate also signals the immune system that there’s a healthy balance of bacteria in our gut, effectively calming it down.
- If there are low levels of butyrate in the gut, the immune system basically becomes hyper-responsive, mistaking low-butyrate levels for an overload of pathogenic bacteria.
- As a result, low fibre intake can lead to the immune system attacking the healthy bacterial population, too, resulting in inflammatory bowel diseases.
So, in short, if you want healthy gut flora, feed those good bacteria with a varied whole food plant-based diet, and limit the refined foods. And learn to be okay with your flatulence: it’s normal and natural.
Some tips to mitigate the gas
All that said, there are some things you can do to mitigate excessive gas production. Firstly, try not to swallow too much air. I’m not kidding, it’s a very real source of intestinal gas. Here are some things you could try:
- Eat slowly, with your mouth closed.
- Chew well before swallowing.
- Avoid carbonated drinks (e.g. soda, beer etc.).
- Avoid chewing gum, sucking on hard candy, and smoking (yet another reason!)
Secondly, you can reduce the amount of undigested carbohydrates (the ones that get fermented by the good gut bacteria, with gas as an end-product):
- Rinse canned beans well with fresh water before eating.
- Try lower-fibre and fermented legume products such as tofu, tempeh and miso.
- Smaller beans tend to be easier to digest than larger ones, so choose split peas, red lentils and mung beans over black beans and kidney beans.
- When cooking beans from dry, soak them for 12 hours and discard the soaking water, before cooking in fresh water. You can also repeat this process for a double soak, to further reduce the oligosaccharide content.
- While the beans are cooking, skim off the white foam on the surface.
- Make sure the beans are well cooked before eating them.
- Sprout legumes before eating or cooking, thereby converting oligosaccharides into sugars. You can eat sprouted lentils, mung beans and chickpeas raw; and the others should be cooked first.
Some extra tips:
- Take your time. Gradually introduce legumes into your diet, and increase the portions over a few weeks. This will allow your gut microbiome to adjust, to eventually digest oligosaccharides fully.
- Avoid overeating, by chewing more and taking more time to finish your meal.
- Uses spices such as cloves, cinnamon, garlic, turmeric, black pepper, asafoetida and ginger: these help to counteract the intestinal gas production.
- Drink enough water (or other unsweetened beverages) to aid the digestion of fibre.
- Exercise! This will help keep your bowel (and its contents) moving and functioning well.
And if I haven’t said it already: eat your beans!
That wraps up what I have to say about beans, gas and bloating. It’s a fascinating topic and I’ve learnt a lot in researching this—and there’s a lot more to learn. After all, the medical field is just scratching the surface of the connection between gut health and brain health.