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Nut is a general term for the large, dry, oily seeds or fruit of some plants. While a wide variety of dried seeds and fruits are called nuts, only a certain number of them are considered by biologists to be true nuts. Nuts are an important source of nutrients for both humans and wildlife.
A nut is a type of seed. Nuts are both the seed and the fruit, and cannot be separated. Seeds come from fruit, and can be removed from the fruit, like almonds, cashews, walnuts, and pistachios, which were once inside fruit.
Botanical definition
A nut in botany is a simple dry fruit with one seed (rarely two) in which the ovary wall becomes very hard (stony or woody) at maturity, and where the seed remains unattached or unfused with the ovary wall. Most nuts come from the pistils with inferior ovaries (see flower) and all are indehiscent (not opening at maturity). True nuts are produced, for example, by some plant families of the order Fagales.
- Order Fagales
- Family Fagaceae
- Family Betulaceae
Culinary definition and uses
A nut in cuisine is a much less restrictive category than a nut in botany, as the term is applied to many seeds that are not botanically true nuts. Any large, oily kernel found within a shell and used in food may be regarded as a nut. Because nuts generally have a high oil content, they are a highly prized food and energy source. A large number of seeds are edible by humans and used in cooking, eaten raw, sprouted, or roasted as a snack food, or pressed for oil that is used in cookery and cosmetics. Nuts (or seeds generally) are also a significant source of nutrition for wildlife. This is particularly true in temperate climates where animals such as jays and squirrels store acorns and other nuts during the autumn to keep them from starving during the late autumn, all of winter, and early spring.
Nuts, including both tree nuts and peanuts, are among the most common food allergens.
Some fruits and seeds that are nuts in the culinary sense:
- Almonds and Walnuts are the edible seeds of drupe fruits — the leathery "flesh" is removed at harvest.
- Brazil nut is the seed from a capsule.
- Candlenut (used for oil) is a seed.
- Cashew nut is a seed.
- Coconut is a dry, fibrous drupe.
- Gevuinanut
- Horse-chestnut is an inedible capsule.
- Macadamia nut is a creamy white kernel (Macadamia integrifolia).
- Malabar chestnut
- Mongongo
- Peanut is a legume and a seed.
- Pine nut is the seed of several species of pine (coniferous trees).
- Pistachio nut is the seed of a thin-shelled drupe.
- Lychee is a member of the soapberry family, in which its berrylike fruits can be eaten fresh or sun dried as nuts.
See also: List of edible seeds
Nutritional benefits
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Several epidemiological studies have revealed that people who consume nuts regularly are less likely to suffer from coronary heart disease. Recent clinical trials have found that consumption of various nuts such as almonds and walnuts can lower serum LDL cholesterol concentrations. Although nuts contain various substances thought to possess cardioprotective effects, scientists believe that their Omega 3 fatty acid profile is at least in part responsible for the hypolipidemic response observed in clinical trials.
In addition to possessing cardioprotective effects, nuts generally have a very low glycemic index (GI). Consequently, dietitians frequently recommend nuts be included in diets prescribed for patients with insulin resistance problems such as diabetes mellitus type 2.
One study found that people who eat nuts live two to three years longer than those who do not. However, this may be because people who eat nuts tend to eat less junk food.
Other uses
The nut of the horse-chestnut tree (Aesculus species, especially Aesculus hippocastanum), is called a conker in the British Isles. Conkers are inedible because they contain toxic glucoside aesculin. They are used in a popular children's game, known as conkers, where the nuts are threaded onto a strong cord and then each contestant attempts to break his opponent's conker by hitting it with his own. Horse chestnuts are also popular slingshot ammunition.
A related species, Aesculus californica, was eaten by the Native Americans of California during famines after the toxic constituents were leached out.
See also
References
- "Common Food Allergens". Food Allergy & Anaphylaxis Network. Retrieved 2007-06-24.
- David Mendosa (2002). "Revised International Table of Glycemic Index (GI) and Glycemic Load (GL) Values". Retrieved 2007-11-23.
{{cite web}}: Cite has empty unknown parameter:|1=(help) - "ABC News: The Places Where People Live Longest". URL accessed January 18, 2007.
Kellogg, John H. "Nuts May Save the Race." The Itinerary of Breakfast. New York: Funk & Wagnalls Company, 1920. 165–203.
External links
- Photos of nuts
- Nutra-Smart.net Health Benefits of Nuts
- Linus Pauling Micronutrient Information Centre Nuts
- American Journal of Clinical Nutrition Nuts and their bioactive constituents: effects on serum lipids and other factors that affect disease risk