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Mirella Giuberti
Nutritionist
Teacher By State Hotel Institute "Orio Vergani in
Ferrara"
Source
Zafferano Magazine Vol1 No.2
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Vegetables
derive from different part of many plants. In some cases, we
eat the leaves (lettuce, spinach and chicory), roots (carrots,
turnips and radishes) and fruit (peppers, cucumbers, tomatoes
and aubergines), while in others, we eat the stems (celery),
flowers (broccoli, cauliflower and artichokes) and bulbs
(onions and garlic). In certain cases, we even eat the seed
(peas and beans) and tubers, as in the case of the potato
plant.Despite
their diverse botanical origins, all vegetables share a number
of common nutritional attributes. With the sole exception of
seeds and tubers, they all have a water content of as much as
90%, and contain few proteins, sugars and fats. |
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In terms of
energy, their contribution to our daily diet is therefore
extremely limited, although they can be very filling. They are
a good source of vitamins and minerals and their high fibre
content aids digestion.
An
examination now follows of the main nutritional
characteristics of vegetables and their importance in our
diet.
Calorie
content
Apart from pulses which are not dealt with in this article and
which have a significant protein and starch content, most
vegetables provide a low source of energy, varying from 10 to
40 kcal per 100 grams of edible matter. The exception to this
rule is the potato, which has a ratio of about 80 kcal per 100
grams. But not even the potato is really "fattening"
as is so often misconstrued. In reality, the fats with which
potatoes and other vegetables are prepared are actually what
makes them fattening.
Vitamin
content
Vegetables contain large amounts of certain vitamins.
Carotenoids, precursors of vitamin A, are abundant in carrots,
spinach, peppers, green chicory and yellow pumpkin, while
vitamin C can be found in peppers, tomatoes, brassicas
(cabbage, cauliflower, broccoli etc.) and potatoes.
Particularly in the case of vitamin C, it is essential to cook
vegetables properly in order to presence their vitamin con
tent. Ideally, they should be placed in a little boiling water
without bicarbonate of soda. Care should be taken not to
overcook them as this causes them to break up, thereby
destroying the vitamins they contain.
Carotenoids
are converted by the human organism into vitamin A, an
essential vitamin for the promotion of good vision, a healthy
skin and strong bones.
Vitamin
C is instead used in variety of metabolic processes that help
produce collagen in connective tissues, haemoglobin and red
corpuscles. It also aids the absorption of iron in the
intestines and promotes he action of defensive cellular
mechanisms against oxidising agents.
In
scientific circles, carotenoids and vitamin C are currently a
major topic of interest following a number of research
projects that have targeted their effects as protective agents
against ageing and tumours. These results could hence explain
the findings of epidemiological studies carried out some time
ago on Mediterranean populations which identified a low
incidence of cardiovascular disease and tumours, combined with
a high rate of longevity.
Mineral
content
Green chicory and spinach are excellent sources of iron while
endives, brassicas and spinach contain large quantities of
calcium. It should be noted however, that compared to animal
food products, vegetable iron and calcium are less easily
absorbed by the human digestive system, due to their
association with other compounds.
Other
salts, such as sodium, potassium, magnesium and phosphorus are
also present in significant quantities. For this reason,,
vegetables should be seen as alkalising agents, capable of
restoring the blood's acid balance.
Fibre
content
Vegetables contain a variety of fibrous elements (cellulose,
hemicellulose etc.) which the human digestive system cannot
absorb, but which nonetheless exercise important direct and
indirect effects. Their capacity to absorb large quantities of
water helps regulate digestion, an action that not only has
obvious benefits for sufferers of constipation and/or
diverticulosis, but one that also reduces the absorption of
cholesterol and sugars, thereby preventing cardio-vascular
damage and diabetes. The need to chew fibrous matter for
longer also promotes a feeling of fullness, thereby making a
high-fibre diet essential for any slimming program.
Minor
elements
Some vegetables contain special aromas: sulphur compounds are
responsible for the characteristic aroma of garlic, onions,
leaks, cabbage and broccoli etc. Vanillin and methyl mercaptan
give asparagus its distinctive smell, while apiole is the
substance that gives celery its unique aroma. The piquant
taste of turnips and radishes is instead attributed to allyl
isothiocyanate.
Dietetic
attributes
A diet high in vegetables is the key to balanced nutrition.
Vegetables in fact perform a unique function insofar that
their daily consumption provides many of the hydro-soluble
vitamins and mineral salts that the body needs.
Since
vegetables differ enormously in nutritional terms, it is also
important to eat a varied selection in order to guarantee the
necessary daily intake of vitamins A and C, iron, calcium,
potassium, magnesium and dietary fibre.
Due
to the adverse effects of technological treatments and cooking
methods, it is also important to balance one's diet with equal
quantities of cooked or preserved vegetables and raw
vegetables.
The
summer months in particular make for a more varied died due to
the increased availability of fresh vegetables and a greater
propensity of cold dishes. Neither should we forget the
importance in combating dehydration and salt deficiencies due
to increased perspiration. The use of saline integrators, a
practice now widespread even here, can only be justified when
the level of dehydration exceeds the maximum limit of 2-2.5
litres a day.
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