Tofu is low in calories, high in protein, and has a decent amount of other nutrients like iron and calcium.
It seems like the perfect food for vegans who want to get more protein, since most vegan diets are carbohydrate-heavy.
Tofu is also relatively cheap in most places.
So, the natural question to ask is whether or not there’s anything stopping you from eating a ton of tofu on a regular basis?
Are there any potential negative health effects?
I’ve seen a few terribly written articles on this topic, so I decided to dig into the research and create one that’s properly sourced with credible research.
I’ll go through the main concerns that some people have raised about eating a lot of tofu, but you can skip to the summary at the end if you just want the takeaway.
Claim #1 – Tofu Can Raise Uric Acid Levels to Dangerous Levels
Tofu, like many foods (both from plants and animals), contains purines.
Your body breaks purine down into uric acid, which is then excreted through urine or feces.
It’s possible for your body to produce too much uric acid, or not clear it fast enough. If levels get high enough, uric acid can form crystals and cause you to get gout (a type of arthritis).
Tofu is relatively high in purines compared to foods like vegetables, which is why it’s sometimes restricted for those with gout or at risk of developing it.
What does the research say?
- Studies so far show that purines from plant foods (including soy) may increase the risk for uric acid accumulation. However, most high purine foods are animal meats, fish, and animal organs. [Source] (Translation – If tofu is the only high purine food you eat, you have less to worry about than someone who regularly eats animal proteins).
- A study of the typical Taiwanese vegetarian diet found that it was associated with a lower risk of gout. [Source]
- There’s a positive association between seafood consumption and hyperuricemia (high uric acid levels), while there’s an inverse association between soy consumption and hyperuricemia. [Source]
- A cohort of 63,257 Chinese adults found that a higher intake of protein from poultry and fish was associated with an increased risk of gout, but intake of legumes (soy and other) was associated with a reduced risk of gout. [Source]
- In a large prospective study, men who had the highest quintile of vegetable-protein had a 27% lower risk of gout than those in the lowest quintile. [Source]
Put all that together, and it looks like people who eat a plant-based diet have nothing to worry about when it comes to gout.
One other interesting note is that a study based on EPIC-OXFORD data showed that vegans do have the highest uric acid serum levels of any diet group [Source]. Now, that study wasn’t an observational study, so it doesn’t prove causality, but it does bring up an interesting point.
There may be other aspects of plant-based proteins besides purines, that actually have a protective effect against conditions like gout, even if they do increase uric acid serum levels (again, not proven with causality, but a possibility).
Claim #2 – Tofu May Alter Hormone Levels
This is one of those myths that has lived on despite almost every study showing otherwise.
Long story short: Soy intake (in reasonable amounts) has no proven effect on testosterone levels. Soy intake either has minimal or no effect on estrogen levels.
Here are a few studies that back up that assertion:
- A randomized intervention study found that the consumption of 400 mL per day of soymilk had no statistically significant effect on total and free-testosterone, estradiol (the main type of estrogen), or sex hormone-binding globulin (correlates with estrogen levels). [Source]
- A study comparing whey protein to soy protein found that neither protein type affected biomarkers related to muscle androgenic (i.e. testosterone) or estrogenic signalling. [Source]
There are many other studies that come to similar conclusions. If you’d like a summary of them you can read my more detailed look at if tofu or soy raises estrogen levels.
One important note: There are limitations on these studies. Most of these look at daily soy intake for a few months. While there’s no reason to think a longer term would make a difference, it’s possible.
Secondly, most of these studies cap out at about 70 mg per day of isoflavones (the phytoestrogens in soy). That’s equivalent to about a block of tofu.
So if you stick to a block of tofu a day, it’s very unlikely to have any effect on testosterone or estrogen. If you eat more than that, it may or may not, we don’t have the data either way to back it up.
Claim #3 – Protein Inhibitors in Tofu Can Impair Protein Digestion
There are a few protein inhibitors in soybeans (and other foods of course), trypsin the main one. A trypsin inhibitor interferes with the trypsin in your body, which is needed to break down many proteins.
In theory, if you consume too many of these protein inhibitors, they could affect muscle repair and growth.
Once again, this concern is blown way out of proportion by people who seem to hate tofu for whatever reason.
Here’s what you need to know:
- Trypsin inhibitor is relatively high in whole soybeans. Heating and processing them deactivates most of the inhibitors. Tofu contains just 2.5-7.9% of the original amount found in soybeans. For reference, soymilk is about 13%, natto (a fermented product) is 0.7%, and soy sauce is 0.8%. [Source]
- Another study found similar results, with commercial soy milk containing about 10% active trypsin inhibitors. [Source]
There’s nothing to worry about here, and if you’re really worried about this, get sprouted tofu (soaking and sprouting also reduces the amounts of protein inhibitors).
Claim #4 – Tofu Contains Phytates Which Could Cause Mineral Deficiencies
This is very similar to the case with protein inhibitors.
Phytates are an “antinutrient” which bind to minerals and prevents absorption. Legumes are relatively high in phytates, including soybeans.
However, phytates are destroyed through soaking and heating.
When tofu is processed and cooked, a large portion of phytates will be destroyed.
Additionally, you can buy sprouted tofu if you’re worried about this.
Considering that the biggest consumers of tofu are vegans, which typically get way more nutrients than necessary, a little bit of phytates aren’t going to hurt you.
Summary: How Much Tofu is Too Much?
Based on all that, there are no obvious issues caused by eating tofu on a regular basis.
Unfortunately we can’t quite answer the original question completely.
What we can say is that eating a block of tofu per day should have no negative effects, that’s the amount that most studies look at.
So that’s a good “safe” limit to start with.
Eating more than that could be perfectly safe as well, we just don’t have research backing up whether or not it is.
It’s up to you how “safe” you’d like to be with your tofu and soy intake. Hopefully more research will come out soon looking at higher intakes of soy so that we can answer this question better.