
Nutrients in plants are not always easily digested.
This is because plants may contain antinutrients.
These are plant compounds that reduce the absorption of nutrients from the digestive system.
They are of a particular concern in societies that base their diets largely on grains and legumes.
This article reviews several simple ways to reduce the amount of antinutrients in foods.
In some cases, they can be eliminated almost completely.
Beans and other legumes are often soaked in water overnight to improve their nutritional value. Photo credit: Shutterstock
What are Antinutrients?
Antinutrients are plant compounds that reduce the body's ability to absorb essential nutrients.
They are not a major concern for most people, but may become a problem during periods of malnutrition, or among people who base their diets almost solely on grains and legumes.
However, antinutrients aren't always “bad." Under some circumstances, antinutrients like phytate and tannins may have some beneficial health effects as well (1, 2, 3).
The most widely studied antinutrients include:
- Phytate (phytic acid): Mainly found in seeds, grains and legumes, phytate reduces the absorption of minerals from a meal. These include iron, zinc, magnesium and calcium (4).
- Tannins: A class of antioxidant polyphenols that may impair the digestion of various nutrients (5).
- Lectins: Found in all food plants, especially in seeds, legumes and grains. Some lectins may be harmful in high amounts and interfere with the absorption of nutrients (6, 7).
- Protease inhibitors: Widely distributed among plants, especially in seeds, grains and legumes. They interfere with protein digestion by inhibiting digestive enzymes.
- Calcium oxalate: The primary form of calcium in many vegetables, such as spinach. The calcium bound to oxalate is poorly absorbed (8, 9).
Bottom Line: The most important antinutrients are phytate, tannins, protease inhibitors, calcium oxalate and lectins.
Soaking
Beans and other legumes are often soaked in water overnight to improve their nutritional value (10).
Most of the antinutrients in these foods are found in the skin. Since many antinutrients are water-soluble, they simply dissolve when foods are soaked.
In legumes, soaking has been found to decrease phytate, protease inhibitors, lectins, tannins and calcium oxalate.
For example, a 12-hour soak reduced the phytate content of peas by up to 9 percent (11).
Another study found that soaking pigeon peas for 6-18 hours decreased lectins by 38-50 percent, tannins by 13-25 percent and protease inhibitors by 28-30 percent (12).
However, the reduction of antinutrients may depend on the type of legume. In kidney beans, soybeans and faba beans, soaking reduces protease inhibitors only very slightly (13, 14, 15).
Not only is soaking useful for legumes, leafy vegetables can also be soaked to reduce some of their calcium oxalate (16).
Soaking is typically used in combination with other methods, such as sprouting, fermenting and cooking.
Bottom Line: Soaking legumes in water overnight may reduce phytate, protease inhibitors, lectins and tannins. However, the effect depends on the type of legume. Soaking may also decrease oxalates in leafy vegetables.
Sprouting
Sprouting is a period in the life cycle of plants when they start emerging from the seed. This natural process is also known as germination.
This process increases the availability of nutrients in seeds, grains and legumes (17).
Sprouting takes a few days and may be initiated by a few simple steps:
- Begin by rinsing the seeds to remove all debris, dirt and soil.
- Soak the seeds for 2-12 hours in cool water. The soaking time depends on the type of seed.
- Rinse them thoroughly in water.
- Drain as much water as possible and place the seeds in a sprouting vessel, also called a sprouter. Make sure to place it out of direct sunlight.
- Repeat rinsing and draining 2-4 times. This should be done regularly, or once every 8-12 hours.
During sprouting, changes take place within the seed that lead to the degradation of antinutrients such as phytate and protease inhibitors.
Sprouting has been shown to reduce phytate by 37-81 percent in various types of grains and legumes (18, 19, 20).
There also seems to be a slight decrease in lectins and protease inhibitors during sprouting (21).
You can find detailed instructions on other websites. For example, Sprout People has excellent information on how to sprout various types of beans, grains and other plant foods.
If you need to buy a sprouting vessel or a sprouter, then there is a wide selection on Amazon.
Bottom Line: Sprouting reduces phytate in grains and legumes and may slightly degrade lectins and protease inhibitors.
Fermentation
Fermentation is an ancient method originally used to preserve food.
It is a natural process that occurs when microorganisms, such as bacteria or yeasts, start digesting carbs in food.
Although food that becomes fermented by accident is most often considered spoiled, controlled fermentation is widely used in food production.
Food products that are processed by fermentation include yogurt, cheese, wine, beer, coffee, cocoa and soy sauce.
Another good example of fermented food is sourdough bread.
Making of sourdough effectively degrades antinutrients in the grains, leading to increased availability of nutrients (17, 22, 23).
In fact, sourdough fermentation is more effective at reducing antinutrients in grains than yeast fermentation in typical bread (24, 25).
In various grains and legumes, fermentation effectively degrades phytate and lectins (26, 27, 28, 29).
For example, fermenting pre-soaked brown beans for 48 hours caused an 88 percent reduction in phytate (30).
Bottom Line: Fermentation of grains and legumes leads to a significant reduction in phytate and lectins.
Boiling
High heat, especially when boiling, can degrade antinutrients like lectins, tannins and protease inhibitors (14, 31, 32, 33).
One study showed that boiling pigeon peas for 80 minutes reduced protease inhibitors by 70 percent, lectin by 79 percent and tannin by 69 percent (12).
Additionally, calcium oxalate is reduced by 19-87 percent in boiled green leafy vegetables. Steaming and baking are not as effective (34, 35).
In contrast, phytate is heat-resistant and not as easily degraded with boiling (4, 12).
The cooking time required depends on the type of antinutrient, food plant and the cooking method. Generally, a longer cooking time results in greater reductions of antinutrients.
Bottom Line: Boiling is effective at reducing various antinutrients, including lectins, tannins, protease inhibitors and calcium oxalate.
Combination of Methods
Combining many methods can reduce antinutrients substantially, sometimes even completely.
As an example, soaking, sprouting and lactic acid fermentation decreased the phytate in quinoa by 98 percent (36).
Similarly, sprouting and lactic acid fermentation of corn and sorghum degraded phytate almost completely (37).
In addition, soaking and boiling pigeon peas led to a 98-100 percent reduction in lectins, tannins and protease inhibitors (12).
Bottom Line: The most effective way to reduce antinutrients in plant foods is to combine several different elimination strategies. Combining methods may even degrade some of the antinutrients completely.
Overview
Below is an overview of the main antinutrients and effective ways to eliminate them.
- Phytate (phytic acid): Soaking, sprouting, fermentation.
- Lectins: Soaking, boiling, heating, fermentation.
- Tannins: Soaking, boiling.
- Protease inhibitors: Soaking, sprouting, boiling.
- Calcium oxalate: Soaking, boiling.
Take Home Message
Antinutrients can significantly reduce the nutritional value of many plant foods.
Luckily, they can be degraded with a few simple methods such as heating, boiling, soaking, sprouting and fermenting.
By combining different methods, many antinutrients can be degraded almost completely.
This article was reposted from our media associate Authority Nutrition.
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A Healthy Microbiome Builds a Strong Immune System That Could Help Defeat COVID-19
By Ana Maldonado-Contreras
Takeaways
- Your gut is home to trillions of bacteria that are vital for keeping you healthy.
- Some of these microbes help to regulate the immune system.
- New research, which has not yet been peer-reviewed, shows the presence of certain bacteria in the gut may reveal which people are more vulnerable to a more severe case of COVID-19.
You may not know it, but you have an army of microbes living inside of you that are essential for fighting off threats, including the virus that causes COVID-19.
How Do Resident Bacteria Keep You Healthy?
<p>Our immune defense is part of a complex biological response against harmful pathogens, such as viruses or bacteria. However, because our bodies are inhabited by trillions of mostly beneficial bacteria, virus and fungi, activation of our immune response is tightly regulated to distinguish between harmful and helpful microbes.</p><p>Our bacteria are spectacular companions diligently helping prime our immune system defenses to combat infections. A seminal study found that mice treated with antibiotics that eliminate bacteria in the gut exhibited an impaired immune response. These animals had low counts of virus-fighting white blood cells, weak antibody responses and poor production of a protein that is vital for <a href="https://doi.org/10.1073/pnas.1019378108" target="_blank">combating viral infection and modulating the immune response</a>.</p><p><a href="https://doi.org/10.1371/journal.pone.0184976" target="_blank" rel="noopener noreferrer">In another study</a>, mice were fed <em>Lactobacillus</em> bacteria, commonly used as probiotic in fermented food. These microbes reduced the severity of influenza infection. The <em>Lactobacillus</em>-treated mice did not lose weight and had only mild lung damage compared with untreated mice. Similarly, others have found that treatment of mice with <em>Lactobacillus</em> protects against different <a href="https://doi.org/10.1038/srep04638" target="_blank" rel="noopener noreferrer">subtypes of</a> <a href="https://doi.org/10.1038/s41598-017-17487-8" target="_blank" rel="noopener noreferrer">influenza</a> <a href="https://doi.org/10.1371/journal.ppat.1008072" target="_blank" rel="noopener noreferrer">virus</a> and human respiratory syncytial virus – the <a href="https://doi.org/10.1038/s41598-019-39602-7" target="_blank" rel="noopener noreferrer">major cause of viral bronchiolitis and pneumonia in children</a>.</p>Chronic Disease and Microbes
<p>Patients with chronic illnesses including Type 2 diabetes, obesity and cardiovascular disease exhibit a hyperactive immune system that fails to recognize a harmless stimulus and is linked to an altered gut microbiome.</p><p>In these chronic diseases, the gut microbiome lacks bacteria that activate <a href="https://doi.org/10.1126/science.1198469" target="_blank" rel="noopener noreferrer">immune cells</a> that block the response against harmless bacteria in our guts. Such alteration of the gut microbiome is also observed in <a href="https://doi.org/10.1073/pnas.1002601107" target="_blank" rel="noopener noreferrer">babies delivered by cesarean section</a>, individuals consuming a poor <a href="https://doi.org/10.1038/nature12820" target="_blank" rel="noopener noreferrer">diet</a> and the <a href="https://doi.org/10.1038/nature11053" target="_blank" rel="noopener noreferrer">elderly</a>.</p><p>In the U.S., 117 million individuals – about half the adult population – <a href="https://health.gov/our-work/food-nutrition/2015-2020-dietary-guidelines/guidelines/" target="_blank" rel="noopener noreferrer">suffer from Type 2 diabetes, obesity, cardiovascular disease or a combination of them</a>. That suggests that half of American adults carry a faulty microbiome army.</p><p>Research in my laboratory focuses on identifying gut bacteria that are critical for creating a balanced immune system, which fights life-threatening bacterial and viral infections, while tolerating the beneficial bacteria in and on us.</p><p>Given that diet affects the diversity of bacteria in the gut, <a href="https://www.umassmed.edu/nutrition/melody-trial-info/" target="_blank" rel="noopener noreferrer">my lab studies show how diet can be used</a> as a therapy for chronic diseases. Using different foods, people can shift their gut microbiome to one that boosts a healthy immune response.</p><p>A fraction of patients infected with SARS-CoV-2, the virus that causes COVID-19 disease, develop severe complications that require hospitalization in intensive care units. What do many of those patients have in common? <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm6912e2.htm" target="_blank" rel="noopener noreferrer">Old age</a> and chronic diet-related diseases like obesity, Type 2 diabetes and cardiovascular disease.</p><p><a href="http://doi.org/10.1016/j.jada.2008.12.019" target="_blank" rel="noopener noreferrer">Black and Latinx people are disproportionately affected by obesity, Type 2 diabetes and cardiovascular disease</a>, all of which are linked to poor nutrition. Thus, it is not a coincidence that <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm6933e1.htm" target="_blank" rel="noopener noreferrer">these groups have suffered more deaths from COVID-19</a> compared with whites. This is the case not only in the U.S. but also <a href="https://www.washingtonpost.com/world/europe/blacks-in-britain-are-four-times-as-likely-to-die-of-coronavirus-as-whites-data-show/2020/05/07/2dc76710-9067-11ea-9322-a29e75effc93_story.html" target="_blank" rel="noopener noreferrer">in Britain</a>.</p>Discovering Microbes That Predict COVID-19 Severity
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Thus, researchers like me need to take repeated patient stool, saliva and blood samples over a longer time frame to learn how the altered microbiome observed in COVID-19 patients can modulate COVID-19 disease severity, perhaps by altering the development of the T-regulatory cells.</p><p>As a Latina scientist investigating interactions between diet, microbiome and immunity, I must stress the importance of better policies to improve access to healthy foods, which lead to a healthier microbiome. It is also important to design culturally sensitive dietary interventions for Black and Latinx communities. 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