Just about all beans cause gas to some degree, mainly because they contain significant amounts of oligosaccharides.
Since tofu is made from soybeans, it’s not surprising that tofu often causes gas for people who eat large amounts of it.
I’m going to explain why tofu causes gas and bloating in the simplest terms possible, and go over a few possible solutions.
Table of Contents
Why Do Beans Cause Gas? (Including Soybeans)
The vast majority of gas comes from carbohydrates, not fat or protein (although protein with sulfur can affect the smell).
While some carbohydrates are easy to digest (e.g. glucose), others are not – fiber and FODMAPs.
Fiber and FODMAPs don’t break down much (or at all) in the stomach or small intestine, so they get fermented in the large intestine, which produces gas as a byproduct. If this gas builds up rapidly, it causes bloating until it is released (mainly through flatulence).
We won’t go into detail on all that, but in the context of soybeans, you’ll need to know that the “O” in FODMAPs stands for oligosaccharides, which are known to cause stomach problems even in relatively small amounts.
A Note on Silken vs Firm Tofu and Gas
Firm tofu has lower FODMAP content, which is due to how silken and firm tofu are made (source).
The pressing process that removes moisture from firm tofu also removes certain FODMAPs that dissolve in the water.
Fiber in Tofu
Let’s take a quick look at the macronutrient profile of tofu.
The data below is for 100 grams of firm tofu. Note that a block of firm tofu is usually about 300-400 grams total.
| Tofu | |
|---|---|
| Energy (kcal) | 144 |
| Protein (g) | 17.3 |
| Total Lipid (g) | 8.72 |
| Carbohydrate (g) | 2.78 |
| Fiber (g) | 2.3 |
Tofu is very low in carbohydrates, but almost all of that is in fact fiber.
Still, there’s not a ton of fiber in tofu. Even if you eat a full block, that’s about 10 grams of fiber. This is a significant amount of tofu, but a single serving of certain vegetables can get you that amount.
In other words, the raw fiber content of tofu might contribute a bit to gas, but shouldn’t cause huge issues.
FODMAPs in Tofu
The more common reason that beans and bean-products typically cause gas is because of the oligosaccharides in them.
Specifically, the oligosaccharides raffinose and stachyose.
It’s hard to find data on this, especially for tofu, but I was able to find oligosaccharide data for soybeans (source):
Obviously we’ll look at “soaked” and cooked” data, since tofu is already cooked when you buy it. I’ve reproduced that data below:
| Soybeans (100 g) | |
|---|---|
| Sucrose | 1.71 g |
| Raffinose | 0.23 g |
| Stachyose | 0.11 g |
Sucrose can cause some stomach trouble in large amounts, but the bigger concerns here are the raffinose and stachyose, even though they’re present in smaller amounts.
Still, soybeans (and logically tofu) have lower amounts of FODMAPs compared to most other beans (see data on chickpeas and gas here).
How Can You Reduce Gas From Tofu?
Unless someone has a soy intolerance, we’ve seen that tofu can cause some gas, but it shouldn’t be a ridiculous amount.
Still, if tofu or other bean-products give you excessive gas and bloating, there are a few things you can do.
First, you can buy sprouted tofu. While not every grocery store carries it, I assure you it does exist. Sprouting (i.e. fermentation) is one of the most effective ways to reduce oligosaccharide content in beans (source).
In addition, you can take a bean enzyme product like Beano alongside your tofu. These products contain the enzymes needed to digest oligosaccharides before they reach the large intestine.
