A Nut is a fruit composed of a hard shell and a seed, which is generally edible. However, a wide variety of dried seeds are called Nuts, but in a botanical context there is an additional requirement that the shell does not open to release the seed.
Most seeds come from fruits that naturally free themselves from the shell, unlike Nuts such as Hazelnuts, Chestnuts and Acorns, which have hard shell walls. Many Nuts such as Almonds, Pecans, Pistachios, Walnuts and Brazil Nuts, are not Nuts in a botanical sense. Common usage of the term often refers to any hard-walled, edible kernel as a Nut and large, oily kernels found within a shell and used in food are commonly called Nuts.
Nuts are the source of energy and nutrients for the new plant and they contain a relatively large quantity of calories, essential unsaturated and mono-unsaturated fats, vitamins, and essential amino acids. Many Nuts are good sources of vitamin E, vitamin B2, folate, fibre and the essential minerals magnesium, phosphorus, potassium, copper and selenium and are an important source of nutrients for both humans and wildlife.
Nuts are most healthy in their raw unroasted form, because up to 15% of the fats are destroyed during the roasting process. Because Nuts generally have a high oil content, they are a highly prized food and energy source. A large number of Nuts are used in cooking, eaten raw, sprouted, or roasted as a snack food, or pressed for oil that is used in cookery and cosmetics. Nuts are also a significant source of nutrition for wildlife. This is particularly true in temperate climates where jays and squirrels store acorns and other Nuts during the autumn to keep from starving during the late autumn, winter and early spring.
Nuts used for food, whether a true Nut or not, are among the most common food allergens, but people who consume Nuts regularly are less likely to develop coronary heart disease. Eating Nuts is also associated with lower mortality from schemic heart disease and cardiovascular disease. Dietitians frequently recommend that Nuts be included in diets for patients with insulin resistance.
Over the next few months we will be looking at different varieties of Nuts.