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.
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When hurricanes and other extreme storms unleash downpours like Tropical Storm Beta has been doing in the South, the floodwater doesn't always stay within the government's flood risk zones.
New research suggests that nearly twice as many properties are at risk from a 100-year flood today than the Federal Emergency Management Agency's flood maps indicate.
Flooding Outside the Zones<p>About <a href="https://furmancenter.org/files/Floodplain_PopulationBrief_12DEC2017.pdf" target="_blank">15 million</a> Americans live in FEMA's current 100-year flood zones. The designation warns them that their properties face a 1% risk of flooding in any given year. They must obtain flood insurance if they want a federally ensured loan – insurance that helps them recover from flooding.</p><p>In Greater Houston, however, <a href="https://doi.org/10.1111/j.1539-6924.2012.01840.x" target="_blank">47% of claims</a> made to FEMA across three decades before Hurricane Harvey were outside of the 100-year flood zones. Harris County, recognizing that FEMA flood maps don't capture the full risk, now <a href="https://www.hcfcd.org/floodinsurance" target="_blank" rel="noopener noreferrer">recommends that every household</a> in Houston and the rest of the county have flood insurance.</p><p>New risk models point to a similar conclusion: Flood risk in these areas outstrips expectations in the current FEMA flood maps.</p><p>One of those models, from the <a href="https://firststreet.org/flood-lab/research/2020-national-flood-risk-assessment-highlights/" target="_blank">First Street Foundation</a>, estimates that the number of properties at risk in a 100-year storm is 1.7 times higher than the FEMA maps suggest. Other <a href="https://doi.org/10.1088/1748-9326/aaac65" target="_blank" rel="noopener noreferrer">researchers</a> find an even higher margin, with 2.6 to 3.1 times more people exposed to serious flooding in a 100-year storm than FEMA estimates.</p>
What FEMA’s Flood Maps Miss<p>Understanding why areas outside the 100-year flood zones are flooding more often than the FEMA maps suggest involves larger social and environmental issues. Three reasons stand out.</p><p>First, some places rely on relatively old FEMA maps that don't account for recent urbanization.</p><p>Urbanization matters because impervious surfaces – think pavement and buildings – are not effective sponges like natural landscapes can be. Moreover, the process for updating floodplain maps is locally variable and can take years to complete. Famously, New York City was updating its maps when Hurricane Sandy hit in 2012 but hadn't finished, meaning flood maps in effect <a href="https://projects.propublica.org/nyc-flood/" target="_blank">were from 1983</a>. FEMA is required to assess whether updates are needed every five years, but the <a href="https://www.fema.gov/cis/nation.html" target="_blank" rel="noopener noreferrer">majority of maps</a> <a href="https://www.oig.dhs.gov/sites/default/files/assets/2017/OIG-17-110-Sep17.pdf" target="_blank" rel="noopener noreferrer">are older</a>.</p><p>Second, binary thinking can lead people to an underaccounting of risk, and that can mean communities fail to take steps that could protect a neighborhood from flooding. The logic goes: if I'm not in the 100-year floodplain, then I'm not at risk. Risk perception <a href="https://doi.org/10.1088/1748-9326/ab195a" target="_blank" rel="noopener noreferrer">research</a> backs this up. FEMA-delineated flood zones are the major factor shaping flood mitigation behaviors.</p><p>Third, the era of climate change scuttles conventional assumptions.</p><p>As the planet warms, extreme storms are becoming <a href="https://nca2018.globalchange.gov/" target="_blank">more common and severe</a>. If greenhouse gas emissions continue to increase at a high rate, computer models suggest that the chances of a severe storm dropping 20 inches of rain on Texas in any given year will increase from about 1% at the end of the last century to 18% at the end of this one, a chance of <a href="https://doi.org/10.1073/pnas.1716222114" target="_blank" rel="noopener noreferrer">once every 5.5 years</a>. So far, <a href="https://www.rstreet.org/wp-content/uploads/2020/02/195.pdf" target="_blank" rel="noopener noreferrer">FEMA hasn't taken into account the impact climate change is having</a> on extreme weather and sea level rise.</p>
Racial Disparities in Flooding Outside the Zones<p>So, who is at risk?</p><p>Years of research and evidence from storms have highlighted social inequalities in areas with a high risk of flooding. But most local governments have less understanding of the social and demographic composition of communities that experience flood impacts outside of flood zones.</p><p>In analyzing the damage from Hurricane Harvey in the Houston area, I found that <a href="https://doi.org/10.1088/1748-9326/aba0fe" target="_blank">Black and Hispanic residents disproportionately experienced flooding</a> in areas beyond FEMA's 100-year flood zones.</p><p>With the majority of flooding from Hurricane Harvey occurring outside of 100-year flood zones, this meant that the overall impact of Harvey was racially unequal too.</p><p>Research into where flooding occurs in Baltimore, Chicago and Phoenix points to some of the potential causes. <a href="https://www.nap.edu/read/25381/chapter/4#16" target="_blank" rel="noopener noreferrer">In Baltimore and Chicago</a>, for example, aging storm and sewer infrastructure, poor construction and insufficient efforts to mitigate flooding are part of the flooding problem in some predominantly Black neighborhoods.</p>
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