Legumes are a type of plant that belongs to the Fabaceae family, which is also known as the pea family. They are known for producing seeds that are encased in pods and are an important source of protein and nutrients for people around the world. Some of their common examples are beans, lentils, peas, peanuts, and chickpeas.
These plants are used for food, feed, and other products such as oil and fuel. They are also known for their ability to fix nitrogen from the air and enrich the soil in which they are grown. This makes them an important component of sustainable agriculture and an attractive choice for farmers looking to improve soil fertility.
The word “legume” comes from the Latin word “legumen,” which means “pod” or “seed vessel.” The term “legume” is also used to refer to the edible seeds of these plants, which are often used as a source of protein and nutrition. The term “pulse” refers to the dried seed of certain legume crops.
Scientific classification of legumes
The Fabaceae family is a large and diverse group of plants that includes a wide variety of trees, shrubs, and herbaceous plants. Within the Fabaceae family, they are classified as members of the subfamily Faboideae.
The scientific classification of legumes is as follows:
History of legumes
They have been an important food source for humans for thousands of years and have a long and rich history. They are believed to have originated in the tropics and subtropics of Africa and Asia, and they were likely first cultivated by ancient civilizations in these regions.
Some of the earliest evidence of its cultivation comes from the ancient Near East, where they, such as peas and lentils, were grown as early as the Neolithic period (8000-4500 BC). They were also an important part of the diet of ancient Egyptian and Greek civilizations, and they were widely cultivated in the Mediterranean region.
During the Age of Exploration in the 15th and 16th centuries, they were introduced to new parts of the world, including the Caribbean and the Philippines. In the Caribbean, they, such as beans and pigeon peas, became an important part of the diet, and in the Philippines, they, such as mung beans and lentils, were widely cultivated.
In ancient China, they, such as soybeans and mung beans, were an important part of the diet and were used to make fermented foods like tofu and tempeh. They were also an important food source in ancient India, where they were used to make dishes like dal and chana masala.
In the Americas, they, such as beans and peanuts, were an important part of the diet of indigenous peoples and were widely cultivated in the Andean region of South America. In North America, they, such as beans and peas, were also an important food source for Native American cultures.
During the Middle Ages, they became an important food source in Europe, where they were grown as a cheap and nutritious source of protein. They were also widely cultivated in the Americas, where they were introduced by European colonists and became an important part of the diet of indigenous peoples.
In the 19th and 20th centuries, they became an important food source in many parts of Africa, where they were used to help combat malnutrition. They were also an important food source in Europe and North America, where they were often used as a cheap and nutritious source of protein.
Global statistics about legumes
According to the United Nations Food and Agriculture Organization (FAO), they are the third most important food crop in the world, after cereals (such as rice, wheat, and corn) and roots and tubers (such as potatoes and cassava). In 2019, their global production was estimated to be over 400 million metric tons, with the largest producers being China, India, and Brazil.
According to the United Nations Food and Agriculture Organization (FAO), the top five legume producing countries in the world are China, India, Indonesia, Brazil, and the United States. These countries account for over 60% of their global production.
The most widely produced legume in the world is soybeans, followed by dry beans, lentils, peas, and chickpeas. And these five account for over 90% of their global production.
They are also an important source of income for smallholder farmers in many parts of the world. In 2019, their global trade was estimated to be worth over $45 billion.
Classification of legumes
They are a diverse group of plants that can be classified in a number of different ways. One way to classify them is by the type of seed they produce. Phaseolus vulgaris, also known as the common bean, is a type of legume that belongs to the Fabaceae family and is widely cultivated for its edible seeds. Depending on the variety, Phaseolus vulgaris may be called “common bean,” “kidney bean,” “haricot bean,” “pinto bean,” or “navy bean,” among other names.
In addition to being classified by the type of seed they produce, they can also be classified in other ways. Some other ways to classify them include:
By growth habit
They can be classified based on their growth habit, such as annual, biennial, or perennial. Annual legumes are planted every year and only live for one growing season which includes beans, peas, lentils, and chickpeas., while biennial live for two growing seasons which include faba beans and vetch and perennial legumes live for more than two growing seasons which includes alfalfa, clovers, and acacia.
By plant height
They can be classified based on the height of the plant, such as short (less than 1 meter), medium (1-2 meters), or tall (more than 2 meters). Examples of short legumes include lentils and peas, while examples of tall ones include soybeans and beans.
By plant shape
They can be classified based on the shape of the plant, such as vining, bush, or tree-like. Examples of vining legumes include runner beans and peas, while examples of bush include lentils and chickpeas. Examples of tree-like legumes include acacia and mesquite.
By seed type
They can be classified based on the type of seed they produce, such as whole seeds, split seeds, or ground seeds. Examples of whole-seed legumes include beans and peas, while examples of split-seed include lentils and mung beans. Examples of ground seeds include chickpeas and peanuts.
By seed coat color
They can also be classified based on the color of the seed coat, such as white, yellow, brown, black, or mottled. Examples of white seed coat legumes include navy beans and lentils, while examples of brown seed coat include pinto beans and chickpeas. Examples of black seed coat legumes include black beans and black-eyed peas.
By seed size
They can be classified based on the size of the seed, such as small, medium, or large. Examples of small-seed legumes include lentils and peas, while examples of medium-seed include beans and chickpeas. While examples of large-seed legumes include soybeans and peanuts.
The Food and Agriculture Organization (FAO) of the United Nations recognizes 11 primary pulses, which are defined as “grain legumes, harvested primarily for dry grain.” These primary pulses include:
- Beans (Phaseolus vulgaris)
- Chickpeas (Cicer arietinum)
- Dry peas (Pisum sativum)
- Faba beans (Vicia faba)
- Lentils (Lens culinaris)
- Dry beans (Phaseolus spp.)
- Cowpeas (Vigna unguiculata)
- Pigeon peas (Cajanus cajan)
- Bambara beans (Vigna subterranea)
- Lentil (Lens culinaris)
- Lupins (Lupinus spp.)
In addition to these primary pulses, there are many other types that are grown for their edible seeds, such as peanuts, soybeans, and mung beans. They are an important food source around the world and are widely cultivated in many different countries. They are a staple food in many cultures and are used in a variety of dishes, including soups, stews, and side dishes.
International Year of Pulses
The International Year of Pulses (IYP) was a global campaign organized by the United Nations (UN) in 2016 to raise awareness about the nutritional and environmental benefits of pulses and to encourage the production and consumption of pulses around the world. The IYP was endorsed by the UN General Assembly and was supported by a number of international organizations, including the Food and Agriculture Organization (FAO), the International Fund for Agricultural Development (IFAD), and the International Council for the Improvement of Maize and Wheat (CIMMYT).
During the IYP, a number of events and initiatives were organized around the world to promote the benefits of pulses and to encourage their production and consumption. These events included conferences, workshops, exhibitions, and other educational activities. The IYP also aimed to highlight the important role that pulses play in food security, sustainable agriculture, and environmental conservation.
The IYP was successful in raising awareness about the nutritional and environmental benefits of pulses, and it helped to increase the production and consumption of pulses around the world. It also helped to highlight the important role that pulses play in addressing global challenges, such as food security, climate change, and environmental degradation.
Advantages of legumes
They are nutritious and versatile food that offer a number of advantages. Some of the benefits of legumes include:
Nutritious: They are a good source of protein, fiber, and other essential nutrients, such as iron, zinc, and B vitamins. They are also low in fat and are a good source of complex carbohydrates.
Versatile: They can be used in a variety of dishes, including soups, stews, salads, and baked goods, and can be eaten on their own as a snack.
Sustainable: They are a more sustainable and environmentally friendly source of protein compared to animal-based protein sources, as they require fewer resources to produce and have a lower carbon footprint.
Affordable: They are often cheaper than other sources of protein, making them an affordable option for people on a budget.
Long shelf life: They have a long shelf life and can be stored for long periods of time, making them convenient food to have on hand.
Good for the soil: They are an important source of nitrogen for the soil, as they have the ability to fix nitrogen from the air through a symbiotic relationship with nitrogen-fixing bacteria. This ability makes them a valuable crop for farmers and gardeners, as they can improve the fertility of the soil and help support the growth of other plants.
Forage: Forage legumes are a type that is grown specifically for livestock feed. They are an important source of protein and other nutrients for livestock, and they are often used to improve the quality of pasture land. Some common types of them include alfalfa, clovers, and beans.
Good for weight management: They are low in fat and high in fiber, which can help with weight management and weight loss.
Good for digestion: They are high in fiber, which can help with digestion and can prevent constipation.
Cancer prevention: Some studies have suggested that consuming them regularly may help to reduce the risk of certain types of cancer, such as colon cancer and breast cancer. This may be due to their high fiber content, which can help to remove toxins from the body and reduce the risk of cancer.
Good for pregnancy: They are a good source of folic acid, which is important for pregnant women. Folic acid can help to prevent birth defects and may also help to reduce the risk of preterm labor.
Here are a few examples of scientific literature that provides evidence for the health benefits of legumes:
- A review of studies published in the American Journal of Clinical Nutrition found that its consumption was associated with a reduced risk of heart disease, type 2 diabetes, and certain types of cancer, including colorectal, breast, and prostate cancer. The review also found that they were effective at improving blood sugar control and reducing cholesterol levels.
- A systematic review published in the Journal of the American College of Nutrition found that legume consumption was associated with a lower risk of cardiovascular disease and a lower body mass index (BMI). The review also found that they had a positive effect on blood pressure and cholesterol levels.
- A study published in the British Journal of Nutrition found that its consumption was associated with a lower risk of type 2 diabetes. The study also found that they had a positive effect on blood sugar control and insulin sensitivity.
- A systematic review published in the journal Nutrition Reviews found that its consumption was associated with a reduced risk of colorectal cancer. The review also found that they had a positive effect on blood pressure and cholesterol levels.
- A review published in the journal Advances in Nutrition found that its consumption was associated with a reduced risk of breast cancer. The review also found that they had a positive effect on blood pressure, cholesterol levels, and blood sugar control.
- A study published in the journal Appetite found that legume consumption was associated with a lower risk of obesity and weight gain. The study also found that they had a positive effect on satiety (feeling of fullness) and food intake.
Nitrogen fixation is the process by which legumes, such as beans, lentils, and peas, convert nitrogen from the air into a form that can be used by plants. Nitrogen is an essential element for plant growth, but it is not readily available in the soil. They have a symbiotic relationship with nitrogen-fixing bacteria called rhizobia, which live inside the roots of the legume plant.
The process of nitrogen fixation begins when the legume plant produces chemicals called flavonoids, which attract rhizobia to the root system. The rhizobia then form nodules on the roots of the legume plant, which are specialized structures that house the bacteria.
Inside the nodules, the rhizobia convert atmospheric nitrogen gas (N2) into a form of nitrogen that can be used by the legume plant. This process involves the enzyme nitrogenase, which catalyzes the conversion of N2 into ammonium (NH4+). The ammonium is then converted into other forms of nitrogen, such as nitrite (NO2-) and nitrate (NO3-), which can be used by the legume plant for growth.
Nitrogen fixation is an important process for legume plants, as it allows them to grow in soil that is poor in nitrogen. It also helps to enrich the soil, as the legume plant adds nitrogen back into the soil when it dies and decomposes. This can be beneficial for other plants growing in the same soil, as they can use the nitrogen that was fixed by the legume plant.
Disadvantages of legumes
Like any food, they have both advantages and disadvantages. Here are some potential disadvantages of legumes:
Allergies: Some people may be allergic to them, which can cause symptoms such as itching, swelling, and difficulty breathing. Legume allergies are more common in children, but they can occur at any age.
Flatulence: They are high in fiber and can be difficult to digest, which can cause bloating and flatulence in some people. This can be a particular concern for people who are not used to eating high-fiber foods.
High in phytates: They are high in phytates, which are compounds that can interfere with the absorption of certain minerals, such as iron and zinc. This can be a concern for people who have low levels of these minerals in their diet. Soaking and cooking them can help to reduce the levels of phytates, which can improve the bioavailability of minerals.
Soaking and cooking time: They often require soaking and cooking time, which can be inconvenient for some people. Soaking them can help to reduce the cooking time, but it does require advance planning.
Limited availability: They may not be widely available in some areas, or they may be more expensive than other types of food. This can make it difficult for some people to include them in their diet on a regular basis.
Digestive discomfort: Some people may experience digestive discomfort when they first start consuming them, due to their high fiber content. This can include symptoms such as bloating, gas, and diarrhea. Gradually increasing the intake of them can help to reduce these symptoms.
Interactions with medications: They contain compounds called lectins, which can interfere with the absorption of certain medications. It is important to speak with a healthcare professional if you are taking medications and are considering adding them to your diet.
In addition to the potential disadvantages to human health and nutrition, they can also have negative impacts on the environment and other species. Here are some potential disadvantages of legumes to the environment and others:
Land degradation: Their production can contribute to land degradation if soil management practices are not implemented. This can include soil erosion, nutrient depletion, and salinization. Proper soil management, including the use of cover crops and the application of organic matter, can help to prevent land degradation in legume production.
Monoculture: They are often grown as monoculture crops, meaning that a single crop is planted over a large area. Monoculture can lead to a loss of biodiversity and can make crops more vulnerable to pests and diseases.
Pesticide use: They are vulnerable to a range of pests, and farmers may use pesticides to control these pests. The use of pesticides can have negative impacts on non-target species, including pollinators and beneficial insects, and can contribute to the contamination of water and soil. It is important to use pesticides judiciously and to consider alternative pest control methods, such as biological control.
Pests, diseases, and weeds of legumes
They can be affected by a variety of pests, diseases, and weeds, which can reduce their yield and quality. Some common pests that can affect legumes include aphids, bean beetles, thrips, and caterpillars. Diseases that can affect them include bacterial blight, powdery mildew, and root rot. Weeds that can compete with them for water, nutrients, and light include grasses, broadleaves, and sedges.
To control pests and diseases, farmers can use a variety of methods, such as cultural practices (such as crop rotation and proper fertilization), physical control methods (such as handpicking or trapping), and chemical control methods (such as the use of pesticides). The choice of control method will depend on the specific pest or disease, as well as the type being grown.
To control weeds, farmers can use a variety of methods, such as mechanical control (such as tilling or hand-weeding), chemical control (such as the use of herbicides), and cultural control (such as crop rotation). The choice of control method will depend on the specific weeds present and the type of legume being grown.
Nutritional properties of legumes
Their nutritional content varies depending on the type of legume and the form in which it is consumed. Here is a general overview of the nutritional properties of legumes:
- Protein: They are a good source of protein, with most types providing around 15-20% of their calories from protein. They are considered a “complete” protein, meaning that they contain all nine essential amino acids that the body cannot produce on its own. They are an important source of plant-based protein and are low in fat and cholesterol-free and can be used to add protein to vegetarian and vegan diets.
- Fiber: They are a good source of fiber, with most types providing around 5-10 grams of fiber per 100 grams. Fiber is important for digestion and can help to prevent constipation and other digestive disorders.
- Carbohydrates: They are a good source of complex carbohydrates, which are slowly digested and can help to provide sustained energy. Most of them contain around 50-70% of their calories from carbohydrates.
- Fat: They are generally low in fat, with most types containing less than 1 gram of fat per 100 grams.
- Vitamins and minerals: They are a good source of a range of vitamins and minerals, including B vitamins, iron, magnesium, potassium, and zinc. They are also a good source of antioxidants, which can help to protect cells from damage caused by free radicals.
- Folate: They are a particularly good source of folate, which is important for cell division and the synthesis of DNA. Folate is especially important for women who are pregnant or trying to become pregnant, as it can help to prevent birth defects.
- Phytochemicals: They are also a good source of phytochemicals, which are compounds that are found in plants and may have a range of health benefits. Phytochemicals found in them include flavonoids, which have antioxidant properties, and phytoestrogens, which may have a protective effect against certain types of cancer.
They are nutritious and healthful food that can be included as part of a balanced diet. They can be enjoyed in a variety of dishes, such as soups, stews, salads, and dips, or can be used as a protein-rich alternative to meat in dishes such as chili and tacos.
Legumes are a diverse group of plants that are known for their nutritious seeds. They are an important food crop that is grown around the world. In addition to their nutritional value, they also have environmental benefits, as they are able to fix nitrogen in the soil, which can improve soil fertility and reduce the need for synthetic fertilizers.