Tofu is one of those foods that sparks debate. Some can't rave enough about its versatility and health benefits. Others think it is a genetically-modified poison to be avoided at all costs. This may leave you wondering whether tofu should be a part of your diet or not.
This article takes a detailed look at tofu and its health effects, both good and bad.
What is Tofu?
Tofu is a food made of condensed soy milk that is pressed into solid white blocks. It originated in China and the process is quite similar to how cheese is made.
Rumor has it that a Chinese cook discovered tofu more than 2,000 years ago by accidentally mixing a batch of fresh soy milk with nigari.
Nigari is what remains when salt is extracted from seawater. It is a mineral-rich coagulant used to help tofu solidify and keep its form.
This is what fresh tofu looks like:
Most of the world's soybeans are currently grown in the U.S. and a very large proportion is genetically modified.
However, if you're worried about it, simply opt for non-GMO, organic tofu brands.
Bottom Line: Tofu is made from condensed soy milk, in a process similar to how cheese is made. Whether made from GMO soybeans or not, tofu is generally considered safe for human consumption.
Tofu Contains Many Nutrients
One 3.5-oz (100-gram) serving of tofu contains:
- Protein: 8 grams.
- Carbs: 2 grams.
- Fiber: 1 gram.
- Fat: 4 grams.
- Manganese: 31 percent of the RDI.
- Calcium: 20 percent of the RDI.
- Selenium: 14 percent of the RDI.
- Phosphorus: 12 percent of the RDI.
- Copper: 11 percent of the RDI.
- Magnesium: 9 percent of the RDI.
- Iron: 9 percent of the RDI.
- Zinc: 6 percent of the RDI.
However, the micronutrient content of tofu can vary, depending on the coagulant used to make it. Nigari adds more magnesium, while precipitated calcium increases the calcium content.
Bottom Line: Tofu is low in calories, but high in protein and fat. It also contains many important vitamins and minerals.
Tofu Also Contains Antinutrients
Like most plant foods, tofu contains several antinutrients.
- Phytates: Phytates can reduce the absorption of minerals such as calcium, zinc and iron.
- Lectins: Lectins are proteins that can cause nausea and bloating when uncooked, improperly cooked or eaten in excess.
However, soaking or cooking soybeans can inactivate or eliminate some of these antinutrients.
Sprouting soybeans before making tofu reduces phytates by up to 56 percent and trypsin inhibitors by up to 81 percent, while also increasing protein content by up to 13 percent (2).
Fermentation can also reduce anti-nutrients. For this reason, make sure to add fermented probiotic soy foods to your diet, such as miso, tempeh, tamari or natto.
Bottom Line: Tofu contains antinutrients like trypsin inhibitors, phytates and lectins. It is possible to degrade these antinutrients, which increases the nutritional value of tofu.
Tofu Contains Beneficial Isoflavones
Soybeans contain natural plant compounds called isoflavones.
These isoflavones function as phytoestrogens, meaning that they can attach to and activate estrogen receptors in the body.
This produces effects similar to the hormone estrogen, although they are weaker.
Many of the health benefits of tofu are attributed to the high isoflavone content.
Bottom Line: All soy-based products contain isoflavones, which are believed to have various health benefits.
Tofu May Reduce the Risk of Heart Disease
Only a few studies specifically look at tofu's effects on heart health.
We also know that soy isoflavones can reduce blood vessel inflammation and improve their elasticity (5).
One study found that supplementing with 80 mg of isoflavones per day for 12 weeks improved blood flow by 68 percent in patients who were at risk of stroke (6).
Taking 50 grams of soy protein per day is also associated with improved blood fats and an estimated 10 percent lower risk of heart disease (7).
What's more, in post-menopausal women, high soy isoflavone intake was linked to several heart protective factors. These included improvements to body mass index, waist circumference, fasting insulin and HDL cholesterol (8).
Animal studies have shown that saponins improve blood cholesterol and increase the disposal of bile acids, both of which can help lower heart disease risk (10).
Bottom Line: Whole soy foods like tofu can improve several markers of heart health. This may lead to a reduced risk of heart disease.
Tofu is Linked to Reduced Risk of Some Cancers
Studies have looked into the effects of tofu on breast, prostate and digestive system cancers.
Tofu and Breast Cancer
It seems that exposure to soy during childhood and adolescence may be most protective, but that's not to say that intake later in life is not beneficial (15).
In fact, research shows that women who ate soy products at least once a week throughout adolescence and adulthood had a 24 percent lower risk of developing breast cancer, compared to those who ate soy during adolescence alone (16).
One often-heard criticism of tofu and other soy products is that they may increase breast cancer risk. However, a two-year study in which post-menopausal women consumed two servings of soy per day failed to find an increased risk (17).
Tofu and Cancers of the Digestive System
One study observed that higher intakes of tofu were linked to a 61 percent lower risk of stomach cancer in men (21).
Interestingly, a second study reported a 59 percent lower risk in women (22).
What's more, a recent review of 633,476 participants linked higher soy intake to a 7 percent lower risk of cancer of the digestive system (23).
Tofu and Prostate Cancer
A third review agrees with this, but adds that the beneficial effects of isoflavones may depend on the amount consumed and type of gut bacteria present (26).
Bottom Line: Research indicates that soy has a protective effect against breast, digestive and prostate cancers.
Tofu May Reduce the Risk of Diabetes
In one study of healthy post-menopausal women, 100 mg of soy isoflavones per day reduced blood sugar levels by 15 percent and insulin levels by 23 percent (29).
For diabetic post-menopausal women, supplementing with 30 grams of isolated soy protein lowered fasting insulin levels by 8.1 percent, insulin resistance by 6.5 percent, LDL cholesterol by 7.1 percent and total cholesterol by 4.1 percent (30).
In another study, taking isoflavones each day for a year improved insulin sensitivity and blood fats, while reducing the risk of heart disease (31).
However, these findings are not universal. A recent review of 24 human studies found that intact soy protein—as opposed to isoflavone supplements or protein extracts—was more likely to lower blood sugar (32, 33).
Bottom Line: Tofu may have positive effects on blood sugar control, but more studies are needed to confirm this link.
Other Potential Health Benefits of Tofu
Due to its high isoflavone content, tofu may also have benefits for:
- Bone health: Scientific data suggests that 80 mg of soy isoflavones per day may reduce bone loss, especially in early menopause (34, 35).
- Brain function: Soy isoflavones may have a positive influence on memory and brain function, especially for women over 65 (36).
- Menopause symptoms: Soy isoflavones may help reduce hot flashes. However, not all studies agree (37, 38, 39, 40, 41).
- Skin elasticity: Taking 40 mg of soy isoflavones per day significantly reduced wrinkles and improved skin elasticity after 8–12 weeks (42).
- Weight loss: In one study, taking soy isoflavones for 8–52 weeks resulted in an average weight loss of 10 lbs (4.5 kg) more than a control group (43).
Bottom Line: Due to its high isoflavone content, tofu may have benefits for a variety of health conditions. However, more research is needed.
Tofu May Cause Problems for Some People
Eating tofu and other soy foods every day is generally considered to be safe. That being said, you may want to moderate your intake if you have:
- Kidney or gallbladder stones: Tofu contains a good amount of oxalates, which may worsen oxalate-containing kidney or gallbladder stones.
- Breast tumors: Due to tofu's weak hormonal effects, some doctors tell women with estrogen-sensitive breast tumors to limit their soy intake.
- Thyroid issues: Some professionals also advise individuals with poor thyroid function to avoid tofu due to its goitrogen content.
However, not all researchers agree. Some even say that consuming soy foods like tofu can benefit people with kidney stones (44).
Bottom Line: Eating tofu is safe for most people. If you're worried about negative health effects, then double-check with your healthcare provider.
How to Select Tofu or Make Your Own
Tofu can be purchased in bulk or individual packages, refrigerated or not.
You can also find it dehydrated, freeze-dried, jarred or canned.
Generally, not a lot of processing is necessary to make tofu, so choose varieties that have short nutrition labels.
You can expect to see ingredients like soybeans, water, coagulants (such as calcium sulfate, magnesium chloride or delta gluconolactone) and maybe some seasoning.
Once opened, tofu blocks need to be rinsed prior to being used.
Leftovers can be stored in the refrigerator, covered with water. Stored this way, tofu can be kept for up to one week—just make sure you change the water often.
Tofu can also be frozen, in its original package, for up to five months.
Finally, making your own tofu is also a possibility. All you need are soybeans, lemon and water. If you'd like to give it a try, check out this simple video:
Bottom Line: Tofu can be found in a variety of shapes and forms. Homemade tofu is also surprisingly easy to make.
Tofu is a Healthy Food
Tofu is high in protein and many healthy nutrients.
Eating tofu may protect against a variety of health conditions, such as heart disease, diabetes and even certain cancers.
This article was reposted from our media associate Authority Nutrition.
YOU MIGHT ALSO LIKE
EcoWatch Daily Newsletter
By Jake Johnson
In a move that environmentalists warned could further imperil hundreds of endangered species and a protected habitat for the sake of profit, President Donald Trump on Friday signed a proclamation rolling back an Obama-era order and opening nearly 5,000 square miles off the coast of New England to commercial fishing.
Why You Should Wash Fresh Produce<p>Global pandemic or not, properly washing fresh fruits and vegetables is a good habit to practice to minimize the ingestion of potentially harmful residues and germs.</p><p>Fresh produce is handled by numerous people before you purchase it from the grocery store or the farmers market. It's best to assume that not every hand that has touched fresh produce has been clean.</p><p>With all of the people constantly bustling through these environments, it's also safe to assume that much of the <a href="https://www.healthline.com/nutrition/fresh-vs-frozen-fruit-and-vegetables" target="_blank">fresh produce</a> you purchase has been coughed on, sneezed on, and breathed on as well.</p><p>Adequately washing fresh fruits and vegetables before you eat them can significantly reduce residues that may be left on them during their journey to your kitchen.</p><p><strong>Summary</strong></p><p><strong></strong>Washing fresh fruits and vegetables is a proven way to remove germs and unwanted residues from their surfaces before eating them.</p>
Best Produce Cleaning Methods<p>While rinsing fresh produce with water has long been the traditional method of preparing fruits and veggies before consumption, the current pandemic has many people wondering whether that's enough to really clean them.</p><p>Some people have advocated the use of soap, <a href="https://www.healthline.com/nutrition/white-vinegar" target="_blank">vinegar</a>, lemon juice, or even commercial cleaners like bleach as an added measure.</p><p>However, health and food safety experts, including the Food and Drug Administration (FDA) and Centers for Disease Control (CDC), strongly urge consumers not to take this advice and stick with plain water.</p><p>Using such substances may pose further health dangers, and they're unnecessary to remove the most harmful residues from produce. <a href="https://www.healthline.com/health/chlorine-poisoning" target="_blank">Ingesting commercial cleaning chemicals</a> like bleach can be lethal and should never be used to clean food.</p><p>Furthermore, substances like lemon juice, vinegar, and produce washes have not been shown to be any more effective at cleaning produce than plain water — and may even leave additional deposits on food.</p><p>While some research has suggested that using neutral electrolyzed water or a baking soda bath can be even more effective at removing certain substances, the consensus continues to be that cool tap water is sufficient in most cases.</p><p><strong>Summary</strong></p><p><strong></strong>The best way to wash fresh produce before eating it is with cool water. Using other substances is largely unnecessary. Plus they're often not as effective as water and gentle friction. Commercial cleaners should never be used on food.</p>
How to Wash Fruits and Vegetables With Water<p>Washing fresh fruits and vegetables in cool water before eating them is a good practice when it comes to health hygiene and food safety.</p><p>Note that fresh produce should not be washed until right before you're ready to eat it. Washing fruits and vegetables before storing them may create an environment in which bacterial growth is more likely.</p><p>Before you begin washing fresh produce, <a href="https://www.healthline.com/health/how-long-should-you-wash-your-hands" target="_blank">wash your hands well</a> with soap and water. Be sure that any utensils, sinks, and surfaces you're using to prepare your produce are also thoroughly cleaned first.</p><p>Begin by cutting away any bruised or visibly rotten areas of fresh produce. If you're handling a fruit or vegetable that'll be peeled, such as an orange, wash it before peeling it to prevent any surface bacteria from entering the flesh.</p><p>The general methods to wash produce are as follows:</p><ul><li><strong>Firm produce.</strong> Fruits with firmer skins like apples, lemons, and pears, as well as <a href="https://www.healthline.com/nutrition/root-vegetables" target="_blank">root vegetables</a> like potatoes, carrots, and turnips, can benefit from being brushed with a clean, soft bristle to better remove residues from their pores.</li><li><strong>Leafy greens.</strong> Spinach, lettuce, Swiss chard, leeks, and cruciferous vegetables like Brussels sprouts and bok choy should have their outermost layer removed, then be submerged in a bowl of cool water, swished, drained, and rinsed with fresh water.</li><li><strong>Delicate produce.</strong> Berries, mushrooms, and other types of produce that are more likely to fall apart can be cleaned with a steady stream of water and gentle friction using your fingers to remove grit.</li></ul><p>Once you have thoroughly rinsed your produce, dry it using a clean paper or cloth towel. More fragile produce can be laid out on the towel and gently patted or rolled around to dry them without damaging them.</p><p>Before consuming your fruits and veggies, follow the simple steps above to minimize the amount of germs and substances that may be on them.</p><p><strong>Summary</strong></p><p><strong></strong>Most fresh fruits and veggies can gently be scrubbed under cold running water (using a clean soft brush for those with firmer skins) and then dried. It can help to soak, drain, and rinse produce that has more dirt-trapping layers.</p>
The Bottom Line<p>Practicing good food hygiene is an important health habit. Washing fresh produce helps minimize surface germs and residues that could make you sick.</p><p>Recent fears during the <a href="https://www.healthline.com/coronavirus" target="_blank">COVID-19 pandemic</a> have caused many people to wonder whether more aggressive washing methods, such as using soap or commercial cleaners on fresh produce, are better.</p><p>Health professionals agree that this isn't recommended or necessary — and could even be dangerous. Most fruits and vegetables can be sufficiently cleaned with cool water and light friction right before eating them.</p><p>Produce that has more layers and surface area can be more thoroughly washed by swishing it in a bowl of cool water to remove dirt particles.</p><p>Fresh fruits and vegetables offer a number of healthy nutrients and should continue to be eaten, as long as safe cleaning methods are practiced.</p>
- 30 Awesome Ways to Use Apple Cider Vinegar Everyday - EcoWatch ›
- Here's How to Clean Your Groceries During the COVID-19 Outbreak ... ›
- 5 Facts You Should Know About Pesticides on Fruits and Vegetables ›
By Danielle Nierenberg
Following the murder of George Floyd by police in Minneapolis, people around the United States are protesting racism, police brutality, inequality, and violence in their own communities. No matter your political affiliation, the violence by multiple police departments in this country is unacceptable.
Mangroves play a vital role in capturing carbon from the atmosphere. Mangrove forests are tremendous assets in the fight to stem the climate crisis. They store more carbon than a rainforest of the same size.
- Protecting Mangroves Can Prevent Billions of Dollars in Global ... ›
- Could the 'Mangrove Effect' Save Coasts From Sea Level Rise ... ›
Monday is World Oceans Day, but how can you celebrate our blue planet while social distancing?
- 5 Things to Know About Earth's Warming Oceans - EcoWatch ›
- Bioluminescent Waves Mesmerize California Beachgoers, Surfers ... ›
- NOAA: 2020 Could Be Warmest Year on Record - EcoWatch ›
- On June 8, We Celebrate Our Oceans, Our Future - EcoWatch ›
- 5 Things to Know About the State of Our Oceans for World Oceans Day ›
By Jacob L. Steenwyk and Antonis Rokas
From the mythical minotaur to the mule, creatures created from merging two or more distinct organisms – hybrids – have played defining roles in human history and culture. However, not all hybrids are as fantastic as the minotaur or as dependable as the mule; in fact, some of them cause human diseases.
When Looking Through a Microscope Isn’t Close Enough.<p>For the last few years, <a href="http://www.rokaslab.org/" target="_blank">our team at Vanderbilt University</a>, <a href="https://www.researchgate.net/lab/Gustavo-Goldman-Lab" target="_blank">Gustavo Goldman's team at São Paulo University in Brazil</a> and many other collaborators around the world have been collecting samples of fungi from patients infected with different species of <em>Aspergillus</em> molds. One of the species we are particularly interested in is <a href="https://doi.org/10.1006/rwgn.2001.0082" target="_blank"><em>Aspergillus nidulans</em>, a relatively common and generally harmless fungus</a>. Clinical laboratories typically identify the species of <em>Aspergillus</em> causing the infection by examining cultures of the fungi under the microscope. The problem with this approach is that very closely related species of <em>Aspergillus</em> tend to look very similar in their broad morphology or physical appearance when viewing them through a microscope.</p><p>Interested in examining the varying abilities of different <em>A. nidulans</em> strains to cause disease, we decided to analyze their total genetic content, or genomes. What we saw came as a total surprise. We had not collected <em>A. nidulans</em> but <em>Aspergillus latus</em>, a close relative of <em>A. nidulans</em> and, as we were to soon find out, <a href="https://doi.org/10.1016/j.cub.2020.04.071" target="_blank">a hybrid species that evolved through the fusion of the genomes</a> of two other <em>Aspergillus</em> species: <em>Aspergillus spinulosporus</em> and an unknown close relative of <em>Aspergillus quadrilineatus</em>. Thus, we realized not only that these patients harbored infections from an entirely different species than we thought they were, but also that this species was the first ever <em>Aspergillus</em> hybrid known to cause human infections.</p>
Several Different Fungal Hybrids Cause Human Disease.<p>Hybrid fungi that can cause infections in humans are well known to occur in several different lineages of single-celled fungi known as yeasts. Notable examples include multiple different species of <a href="https://doi.org/10.1002/yea.3242" target="_blank">yeast hybrids</a> that cause the human diseases <a href="https://rarediseases.info.nih.gov/diseases/6218/cryptococcosis" target="_blank">cryptococcosis</a> and <a href="https://www.cdc.gov/fungal/diseases/candidiasis/index.html" target="_blank">candidiasis</a>. Although pathogenic yeast hybrids are well known, our discovery that the <em>A. latus</em> pathogen is a hybrid is a first for molds that cause disease in humans.</p>
(Left) Candida yeasts live on parts of the human body. Imbalance of microbes on the body can allow these yeasts, some of which are hybrids, to grow and cause infection. (Right) Cryptococcus yeasts, including ones that are hybrids, can cause life-threatening infections in primarily immunocompromised people. Centers for Disease Control and Prevention<p><a href="https://doi.org/10.1371/journal.ppat.1008315" target="_blank">Why certain <em>Aspergillus</em> species are so deadly</a> while others are harmless remains unknown. This may in part be because <a href="https://doi.org/10.1016/j.fbr.2007.02.007" target="_blank">combinations of traits, rather than individual traits</a>, underlie organisms' ability to cause disease. So why then are hybrids frequently associated with human disease? Hybrids inherit genetic material from both parents, which may result in new combinations of traits. This may make them more similar to one parent in some of their characteristics, reflect both parents in others or may differ from both in the rest. It is precisely this mix and match of traits that hybrids have inherited from their parental species that <a href="https://www.nytimes.com/2010/09/14/science/14creatures.html" target="_blank">facilitates their evolutionary success</a>, including their ability to cause disease.</p>
The Evolutionary Origin of an Aspergillus Hybrid.<p>Multiple evolutionary paths can lead to the emergence of hybrids. One path is through mating, just as the horse and donkey mate to create a mule. Another path is through the merging or fusion of genetic material from cells of different species.</p><p>It is this second path that appears to have been taken by our fungus. <em>A. latus</em> appears to have two of almost everything compared to its parental species: twice the genome size, twice the total number of genes and so on. But unlike other hybrids, which are often sterile like the mule, we found that <em>A. latus</em> is capable of reproducing both asexually and sexually.</p><p>But how distinct were the parents of <em>A. latus</em>? By comparing the parts contributed by each parent in the <em>A. latus</em> genome, we estimate that its parents are approximately 93% genetically similar, which is about as related as we humans are with lemurs. In other words, <em>A. latus</em>, an agent of infectious disease, is the fungal equivalent of a human-lemur hybrid.</p>
How A. Latus Differs From its Parents.<p>Elucidating the identity of closely related fungal pathogens and how they differ from each other in infection-relevant characteristics is a key step toward reducing the burden of fungal disease. For example, we found that <em>A. latus</em> was three times more resistant than <em>A. nidulans</em>, the species it was originally identified as using microscopy-based methods, to one of the most common antifungal drugs, <a href="https://www.drugbank.ca/drugs/DB00520" target="_blank">caspofungin</a>. This result provides a clear example of the potential importance of accurate identification of the <em>Aspergillus</em> pathogen causing an infection.</p><p>We also examined how <em>A. latus</em> and <em>A. nidulans</em> interact with cells from our immune system. We found that immune cells were less efficient at combating <em>A. latus</em> compared to <em>A. nidulans</em>, suggesting the hybrid fungus may be trickier for our immune systems to identify and destroy.</p><p>In the midst of the COVID-19 pandemic, our quest to understand <em>Aspergillus</em> pathogens is becoming more urgent. Growing evidence suggests that <a href="https://doi.org/10.1111/myc.13096" target="_blank">a fraction of COVID-19 patients are also infected with <em>Aspergillus</em>.</a> More worrying is that these <a href="https://doi.org/10.3201/eid2607.201603" target="_blank">secondary <em>Aspergillus</em> infections</a> can worsen the clinical outcomes for those infected with the novel coronavirus. That being said, we stress that little is known about <em>Aspergillus</em> infections in COVID-19 patients due to a lack of systematic testing, and none of the infections identified so far appear to have been caused by hybrids.</p><p>So, when it comes to hybrids, some are fantastic (the minotaur), some are helpful (the mule) and some are dangerous (<em>Aspergillus latus</em>). Understanding more about the biology of <em>Aspergillus latus</em> may help in our understanding of how microbial pathogens arise and how to best prevent and combat their infections.</p>
This Saturday, June 6, marks National Trails Day, an annual celebration of the remarkable recreational, scenic and hiking trails that crisscross parks nationwide. The event, which started in 1993, honors the National Trail System and calls for volunteers to help with trail maintenance in parks across the country.
- As Protests Rage, Climate Activists Embrace Racial Justice ... ›
- First-Ever Black Birders Week Tackles Racism Outdoors - EcoWatch ›
- 15 EcoWatch Stories on Environmental and Racial Injustice ... ›
- Take a Hike Day Is Around the Bend. What's Your Dream Hike ... ›