求一篇英语作文140字左右，下边的例文无用

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2025-03-11 11:06:28

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回答（1）：

What is iron and why do we need it?
Iron is a mineral needed by
our bodies. Iron is a part of all cells and does many things in our
bodies. For example, iron (as part of the protein hemoglobin) carries
oxygen from our lungs throughout our bodies. Having too little
hemoglobin is called anemia. Iron also helps our muscles store and use
oxygen.
Iron is a part of many enzymes and is used in many cell
functions. Enzymes help our bodies digest foods and also help with many
other important reactions that occur within our bodies. When our bodies
don't have enough iron, many parts of our bodies are affected.
What is iron deficiency and why is it a concern?
Iron
deficiency is a condition resulting from too little iron in the body.
Iron deficiency is the most common nutritional deficiency and the
leading cause of anemia in the United States.1
The terms anemia, iron
deficiency, and iron deficiency anemia often are used interchangeably
but equivalent. Iron deficiency ranges from depleted iron stores without
functional or health impairment to iron deficiency with anemia, which
affects the functioning of several organ systems.2
Iron deficiency is a concern because it can:
Iron
deficiency can delay normal infant motor function (normal activity and
movement) or mental function (normal thinking and processing skills).3-6
Iron
deficiency anemia during pregnancy can increase risk for small or early
(preterm) babies.7-8 Small or early babies are more likely to have
health problems or die in the first year of life than infants who are
born full term and are not small.
Iron deficiency can cause fatigue
that impairs the ability to do physical work in adults.9-10Iron
deficiency may also affect memory or other mental function in teens.11
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What causes iron deficiency?
Iron deficiency has many causes. (See table below for a summary). These causes fall into two main categories:
1. Increased iron needs
Many common conditions can cause people to need additional iron:
Because
of their rapid growth, infants and toddlers need more iron than older
children. Sometimes it can be hard for them to get enough iron from
their normal diet.
Women who are pregnant have higher iron needs. To
get enough, most women must take an iron supplement as recommended by
their healthcare provider.
When people lose blood, they also lose
iron. They need extra iron to replace what they have lost. Increased
blood loss can occur with heavy menstrual periods, frequent blood
donation, as well as with some stomach and intestinal conditions (food
sensitivity, hookworms.)
2. Decreased iron intake or absorption (not enough iron taken into the body)
The amount of iron absorbed from the diet depends on many factors:
Iron
from meat, poultry, and fish (i.e., heme iron) is absorbed two to three
times more efficiently than iron from plants (i.e., non-heme iron).
The amount of iron absorbed from plant foods (non-heme iron) depends on the other types of foods eaten at the same meal.
Foods
containing heme iron (meat, poultry, and fish) enhance iron absorption
from foods that contain non-heme iron (e.g., fortified cereals, some
beans, and spinach).
Foods containing vitamin C (see Dietary Sources of vitamin C) also enhance non-heme iron absorption when eaten at the same meal.
Substances
(such as polyphenols, phytates, or calcium) that are part of some foods
or drinks such as tea, coffee, whole grains, legumes and milk or dairy
products can decrease the amount of non-heme iron absorbed at a meal.
Calcium can also decrease the amount heme-iron absorbed at a meal.
However, for healthy individuals who consume a varied diet that conforms
to the Dietary Guidelines for Americans, the amount of iron inhibition
from these substances is usually not of concern.
Vegetarian diets are low in heme iron, but careful meal planning can help increase the amount of iron absorbed.
Some
other factors (such as taking antacids beyond the recommended dose or
medicine used to treat peptic ulcer disease and acid reflux) can reduce
the amount of acid in the stomach and the iron absorbed and cause iron
deficiency.

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