Q: When eating a plant-based diet, will the body’s digestive system reach a point where the foods will no longer cause digestive issues, like gas and bloating?
A: In my experience, most people adopting a higher-fiber plant-based diet seem to have improved bowel habits quite quickly with brief and mild, if any, digestive problems. Having improved bowel movements is probably quite a good reflection of improved health.
But certainly not all people have such a smooth transition. The average American consumes about 15-20 grams of fiber a day. In rural China around 1980, there were some counties where people were eating an average of over 70 grams of fiber a day! This is the amount of fiber you might eat on a bulky, 95%+ whole-food, plant-based diet. So moving quickly from the strikingly low fiber intake of a Western diet of animal and processed foods to a diet made almost entirely of beans, whole grains, fruits and vegetables can be of a shock to your digestion. There’s suddenly a LOT more fiber.
Fiber is food for bacteria in your gut, particularly your large intestine. In a very simplistic way, when you first change your diet, you may not have the optimal bacterial community adapted to your new diet. And the bacteria you do have to ferment fiber may be producing gas in amounts that is new to your gastrointestinal system and may cause bloating, discomfort, and gassiness. This does usually get better as your bacterial community changes. In my experience, this may take a few weeks, though this is highly variable. We certainly have much to learn about this process.
Though I’m not aware of any published research on this exact scenario, I have sometimes found it to be helpful for patients with complaints of bloating due to a quick and dramatic change to a whole-foods, plant-based diet to temporarily take probiotic supplements for a month or so. Perhaps this helps speed up the process of bacterial adaptation? I’m not entirely certain, but some patients have had good results. Alternatively, there are common over the counter digestive enzyme medications available to help reduce gas.
Some people do have ongoing intolerance of certain plant foods, namely beans and, sometimes, raw vegetables. This might manifest as problematic bloating and gassiness that does not improve with time. Although this occurs less frequently than many people assume, if this is the case, you may want to avoid problematic foods as best you can. However, I would encourage you to continue to try to integrate these foods cautiously into your diet every now and then as you get more used to a high-fiber, plant-based diet.
In the case of beans, here are some cooking techniques to try to reduce the gassiness factor:
Perhaps with a bit of time you can start to eat these foods. Of course, non-whole plant foods may be problematic, particularly dairy. Rich, oily foods may also be problematic. Avoid those foods.
Please be aware that there are numerous other causes for bloating and abdominal discomfort that are worth discussing with your doctor if symptoms persist. Many medications have gastrointestinal side effects, which may change significantly in both severity and character as you change your diet. Some serious medical conditions manifest as bloating and abdominal discomfort. Irritable bowel syndrome, inflammatory bowel disease (Crohn’s and Ulcerative Colitis), colorectal cancer, and even ovarian cancer in women can appear as symptoms of bloating and/or discomfort. People with a history of bowel surgery or any history of a related, serious medical condition should get individualized dietary advice from a professional. People with persistent abdominal discomfort, pain, constipation, bloating, etc. should see a doctor.
There are also more benign but real causes of bloating and discomfort. To address these, consider:
This is not intended as personal medical advice. Please consult with a health professional prior to changing medications or supplements or to discuss and ongoing medical complaints and symptoms.
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