BEANS, LENTILS and other LEGUMES:
The Ideal Carbohydrates*
Beans lentils and other legumes are protein-packed energy capsules, with a nutritional food value that can improve your health in many ways. They are an ideal food.
A legume is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. Well known legumes include alfalfa, clover, peas, beans, lentils, carob, soybeans, and peanuts.
A legume fruit is a simple dry fruit that develops from a simple carpel, and usually dihisces (opens along a seam) on two sides. A common name for this type of fruit is a pod, although the term pod is also applied to a few other fruit types, such as vanilla and radish.
Legumes are among the most versatile and nutritious foods available.
The legumes listed above contain symbiotic bacteria called Rhizobia within root nodules of their root system. These bacteria have the special ability of fixing nitrogen from the atmosphere, molecular nitrogen (N2), into ammonia (NH3). This means that the root nodules are sources of nitrogen for legumes, making them relatively rich in plant proteins. All proteins contain nitrogenous amino acids. Nitrogen is therefore a necessary ingredient in the production of proteins. Hence, legumes are among the best sources of plant protein.
When a legume plant dies in the field, all of its remaining nitrogen (incorporated into amino acids inside the remaining plant parts) is released back into the soil. In the soil, the amino acids are converted to nitrate (NO3), making the nitrogen available to other plants, thereby serving as fertiliser for future crops.
Farmed legumes belong to many agricultural classes including forage and grain.
Forage legumes, like alfalfa and clover are sown in pasture and grazed by livestock.
Grain legumes are cultivated for their seeds, and are also called pulses. The seeds are used for human and animal consumption, or for the production of oils for industrial uses. Grain legumes include beans, lentils, peas and peanuts.
Bean is the common name for large plant seeds used for human food or animal feed of several genera of the family Fabaceae (or Leguminosae).
The term bean originally referred to the seed of the broad bean or fava bean, but was later expanded to all the members of the family Fabaceae. The tern bean usually excludes crops used mainly for oil extraction (such as soybeans and peanuts), as well as those used exclusively for sowing purposes (such as clover and alfalfa).
Leguminous crops harvested green for food, such as snap peas (with rounded pods) and snow peas (with flat pods) are not considered beans, and are classified as vegetable crops.
In English usage, the word bean is also sometimes used to refer to the seeds or pods of plants that are not in the family of Fabaceae or Leguminosae, but which bear a superficial resemblance to true beans. For example, coffee beans, cocoa beans, castor beans and vanilla beans, which superficially resemble bean pods.
Legumes are among the best protein sources in the plant kingdom. They are also typically high in fibre (including soluble fibre), low in fat, contain no cholesterol, and are high in folate, potassium, iron and magnesium.
Although legumes contain relatively low quantities of the essential amino acid methionine as compared, for example, to eggs and meat, this can be compensated for by simply eating more of them.
There is a wide variation in the nutritional content of different types of legumes. The following table sets out the nutritional values of lentils and kidney beans by way of example:
|Calories||Total||116 (486kJ)||127 (532kJ)|
|From Carbohydrate||81.5 (341kJ)||92.7 (388kJ)|
|From Fat||3.2 (13.4kJ)||4.2 (17.6kJ)|
|From Protein||31.3 (131kJ)||30.1 (126kJ)|
|E, K, B vitamins||trace||Trace|
|Magnesium||36.0 mg||42.0 mg|
|Potassium||369 mg||405 mg|
|Zinc||1.3 mg||1.0 mg|
The above table comes from www.nutritiondata.self.com, where the lentils and kidney beans (all types) analysed were "mature seeds, cooked, boiled without added salt".
Types of Legumes
A wide variety of legumes are commercially available, both dry and canned. The following are the more common ones:
- Adzuki beans. Also known as field peas or red oriental beans.
- Anasazi beans. Also known as Jacob's cattle beans.
- Black beans. Also known as turtle beans.
- Black-eyed peas. Also known as cowpeas.
- Chickpeas. Also known as garbanzo beans.
- Endamame. Also known as green soybeans.
- Fava beans. Also known as broad or horse beans.
- Lima beans. Also known as butter beans.
- Red kidney beans.
- Soy nuts. Also known as soybeans or soya beans.
Health Benefits of Beans and other Legumes
Beans and other legumes are an excellent source of protein. They are a healthy substitute for meat.
Beans and other legumes have uniquely high levels of fibre (especially soluble fibre) and resistant starch.
Soluble fibre attracts water and forms a gel which slows down digestion. It delays the emptying of the stomach, giving a sense of fullness, as well as being beneficial to blood sugar (glucose) control. Soluble fibre also helps lower blood cholesterol by interfering with the absorption of dietary cholesterol. It also binds bile salts (for the digestion of fats), preventing them from being reabsorbed back to the liver (enterohepatic circulation), causing the liver to produce more of them, which it does from cholesterol. Soluble fibre is found in legumes, as well as in oats, certain fruits and vegetables and psyllium.
Insoluble fibre does not dissolve in water and so it passes through the gastrointestinal tract relatively intact and speeds up the passage of food and waste through the gut. It has a laxative effect. It is found mainly in whole grains and vegetables.
Resistant starch is starch and starch degradation products that escape from digestion in the small intestine of healthy individuals. Resistant starch is considered the third type of dietary fibre, as it can deliver some of the benefits of both insoluble fibre and soluble fibre. Some carbohydrates, such as sugars and most starches, are rapidly digested and absorbed as glucose into the body through the small intestine and subsequently used for short-term energy needs or stored. Resistant starch, on the other hand, resists digestion and passes through to the large intestine where it acts like dietary fibre.
Thus beans and other legumes have uniquely high levels of soluble fibre and resistant starch, which results in a number of valuable health benefits:
- Because the soluble fibre and resistant starch are indigestible, they reduce the total number of calories that can be absorbed from the beans or legumes. Beans and other legumes, being high-nutrient, high-fibre and low-calorie, can be eaten in large quantities without the danger of weight gain. They give the feeling of fullness and satiety, thus reducing food cravings.
- The soluble fibre and resistant starch limit the glycemic (blood sugar raising) effects of beans and other legumes. By keeping the glycemic load low, the fibre and resistant starch in beans and other legumes make them great foods for preventing or reversing diabetes.
- When resistant starch and some fibres reach the colon, they act as food for the healthy gut bacteria, which then ferment them into anti-cancer compounds in the colon. Colon cancer is a very common cancer, and diet has been shown to be a key contributor to colon cancer risk. Numerous studies have found decreased risk of colorectal adenomas and cancers in those who consume beans and other legumes regularly.
Preparing Beans and other Legumes
Dried beans and other legumes (with the exception of lentils, split peas and black-eyed peas) require soaking in room temperature water, a step that re-hydrates them for more even cooking.
After soaking, rinse them and add to a stockpot. Cover with three times their volume of water. Add herbs or spices as desired. Bring to the boil. Then reduce the heat and simmer gently, uncovered, stirring occasionally, until tender.
Lentils, split peas and black-eyed peas do not need to be soaked.
Canned legumes do not require long simmering, but should be well rinsed to remove some of the sodium (salt) added during processing.
The Gas Factor
Beans and other legumes can lead to the formation of intestinal gas. They contain oligosaccharides (particularly raffinose and stachyose), a type of sugar molecule also found in cabbage. An anti-oligosaccharide enzyme is necessary to digest these sugar molecules properly in the small intestine. As a normal human digestive tract does not contain any anti-oligosaccharide enzymes, consumed oligosaccharides are typically digested by bacteria in the large intestine. This digestion produces flatulence, causing gases as a by-product.
To reduce the flatulence-inducing quality of legumes:
- Change the water several times during soaking. Do not use the soaking water to cook the beans/legumes. The water will have absorbed some of the oligosaccharides, the gas-producing indigestible sugars.
- Simmer the beans/legumes slowly until they are tender. This makes them easier to digest.
- Canned beans may help, since the canning process eliminates some of the oligosaccharides.
The regular, daily intake of beans, lentils or other legumes is highly recommended. There is a wide variety to choose from. They are a cost-effective alternative to meats, without the significant drawback of meat which is acid-forming (see my September 2005 newsletter Acid / Alkaline Balance - The Ideal Diet) and has a complete absence of fibre.
*Copyright 2014: The Huntly Centre.
Disclaimer: All material in this newsletter is provided for informational or educational purposes only. Consult a health professional regarding the applicability of any opinions or recommendations expressed herein, with respect to your symptoms or medical condition.
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