鐵質: 攝入量,因素,缺鐵和建議等

What is iron?

Iron is an important mineral involved in various body functions. This is essential to provide energy for daily life. About one-third of the world’s population is iron deficient. Iron is lost through sweat, intestinal cell shedding and blood loss.

The role of iron in the body

Iron helps maintain many important functions in the body, including general energy and concentration, gastrointestinal processes, the immune system, and temperature regulation. The benefits of iron are often overlooked until a person doesn't get enough. Iron deficiency anemia can cause fatigue, heart palpitations, pale skin and difficulty breathing. A lack of iron in the blood can lead to a range of serious health problems, including iron deficiency anemia.

Oxygen transport

Red blood cells contain hemoglobin, a complex protein that carries oxygen from the lungs to the rest of the body. Hemoglobin is partly made of iron and accounts for about two-thirds of the body's iron.

Myoglobin

A special protein that helps store oxygen in muscle cells. Myoglobin contains iron and is responsible for the red color of muscles.

Enzymes

Iron is found in many enzymes throughout the body, including those involved in energy production. Enzymes are catalysts that drive many cellular functions.

Immune system

Proper functioning of the immune system depends in part on adequate iron. The immune system helps us fight infections.

    Recommended dietary iron intake

    The recommended daily allowance (RDA) for iron depends on a person's age and gender.

    Baby

    0 to 6 months: 0.27 milligrams (mg)
    7 to 12 months: 11 mg

    Children

    1 to 3 years old: 7 mg
    4 to 8 years old: 10 mg

    Male

    9 to 13 years old: 8 mg
    14 to 18 years old: 11 mg
    19 years and over: 8 mg

    Female

    9 to 13 years old: 8 mg
    14 to 18 years old: 15 mg
    19 to 50 years old: 18 mg
    51 years and older: 8 mg

    During pregnancy

    27 mg
    14 to 18 years breastfeeding: 10 mg
    19+ years breastfeeding: 9 mg

    Iron supplements may be helpful when people find it difficult to get enough iron through dietary measures alone. It's best to get enough iron through your diet. Vegetarians also have different iron requirements. That's because many iron-rich foods also contain a range of other beneficial nutrients that work together to support overall health.

    Iron has low bioavailability

    Iron has low bioavailability, which means the small intestine cannot easily absorb large amounts of iron. This reduces the usability of its use and increases the likelihood of defects.

    Absorption efficiency depends on a range of factors, including:

    • Source of Iron
    • Other components of the diet
    • Gastrointestinal Health
    • Using medications or supplements
    • A person’s overall iron status
    • Trusted sources of iron boosters, such as vitamin C, exist

    Types of iron in our diet

    The two types of iron found in our diet are:

    haem iron

    Animal foods, including meat and seafood, contain heme iron. Visceral products such as liver and kidneys are particularly rich in heme iron. Heme iron is more easily absorbed by the body. The bioavailability of heme iron from animal sources is up to 40%.

    Non-haem iron

    Non-heme iron is iron found in plants and requires the body to take multiple steps to absorb it. The bioavailability of non-heme iron from plant sources is 2 to 20 percent.

    Good vegetarian sources of non-heme iron include

    • Iron-fortified bread and breakfast cereals
    • Nuts and seeds
    • Dried fruits
    • Whole wheat pasta and bread
    • Pulses - such as mixed beans, baked beans, lentils and chickpeas
    • Dark leafy green vegetables – such as spinach, silverbeet and broccoli
    • Tofu

    The best source of iron

    • Canned clams: 3 ounces (oz) provides 26 milligrams (mg) of iron.

    • Fortified Original Dry Grain Oats: 100 g provides 24.72 mg.

    • White beans: One cup offers 21.09.

    • Dark chocolate (45% to 69% cocoa): One chocolate bar provides 12.99 mg.

    • Cooked Pacific Oysters: 3 ounces provides 7.82 mg.

    • Cooked spinach: One cup provides 6.43 mg.

    • Beef liver: 3 ounces provides 4.17 mg.

    • Boiled and drained lentils: One-half cup provides 3.3 mg.

    • Firm tofu: One-half cup provides 2.03 mg.

    • Cooked and drained chickpeas: One-half cup provides 2.37 mg.

    • Canned, stewed tomatoes: One-half cup provides 1.7 mg.

    • Lean ground beef: 3 ounces provides 2.07 mg.

    • Medium-roasted potatoes: Provides 1.87 mg.

    • Roasted cashews: 3 ounces provides 2 mg.

    Vegetarian

    If you are a vegetarian and do not include animal tissue in your diet, you may need twice the daily amount of dietary iron as a non-vegetarian.

    When following a vegetarian diet, it is also important to consider "foods and drugs that block or reduce iron absorption" ingredients, such as:

    • Proton pump inhibitors and omeprazole, used to reduce the acidity of gastric contents
    • Polyphenols in grains and legumes and spinach
    • Tannins in coffee, tea, some wines, and some berries
    • Phosphates in carbonated drinks (such as soda)
    • Phytates in legumes and cereals

    How much iron is absorbed from the diet?

    Different dietary cultures can also affect iron absorption. About 18% of available iron is absorbed from a typical Western diet and about 10% from a vegetarian diet.

    Even if your diet includes iron-rich foods, your absorption may be far less than this. How much iron you absorb from your diet depends on how much iron your body stores. The most significant effect on iron absorption is the amount of iron already stored in the body. The body stores iron in different places, including the liver. If your iron levels are high, your body absorbs less iron from the foods you eat. Conversely, low iron stores increase your ability to absorb iron.

    Dietary factors affecting iron absorption

    Foods that promote iron absorption

    Foods rich in vitamin C, vitamin A and beta-carotene

    Eating foods rich in vitamin C, vitamin A, or beta-carotene can enhance your body's absorption of dietary iron. Examples of vitamin C foods: citrus fruits, dark green leafy vegetables, bell peppers, melons and strawberries. and vitamin A and beta-caroteneFoods: Carrots, sweet potatoes, spinach, kale, squash, red peppers, cantaloupe, apricots, oranges and peaches.

    Meat

    Meat, fish, and poultry not only provide well-absorbed heme iron but also stimulate absorption of non-heme forms. Eating a diet containing heme iron and non-heme iron can help increase the amount of non-heme iron your body absorbs.

      Diets that reduce iron absorption

      Foods containing phytic acid

      Phytic acid is found in whole grains, cereals, soybeans, nuts and legumes. Soaking eliminates the phytic acid in beans and lentils. Phytic acid reduces iron absorption, but this can be counteracted by consuming vitamin C or meat.

      Calcium-rich foods

      Calcium is essential for bone health, but it can hinder iron absorption. A 2021 study found that while calcium has a small negative effect on iron absorption, the effect is small. For maximum absorption, avoid eating calcium-rich foods with iron-rich foods. When taking supplements, try to take calcium and iron at different times throughout the day.

      Foods containing polyphenols

      Polyphenols are found in plant-based foods and beverages such as vegetables, fruits, grains, legumes, tea, coffee and wine. Coffee and tea are rich in polyphenols, which block the absorption of non-heme iron. While the 2019 review found no interference, further research was recommended due to limitations. To lessen this effect, wait a few hours after an iron-rich meal before drinking coffee or tea.

      Groups at high risk of iron deficiency

      On average, one in eight people ages 2 and older does not get enough iron to meet their needs. If you don't have enough iron in your body, it's called an "iron deficiency." This can make you feel tired and lower your immunity. Including iron-rich foods in your diet can help.

      People at increased risk of iron deficiency include:

      • For infants, use cow's milk or other milk instead of breast milk or infant formula
      • Young children, especially if they drink too much milk
      • Teenage girl
      • Menstruating women, especially women with heavy menstruation
      • Women who use IUDs (because their periods are usually heavier)
      • Pregnant women
      • Breastfeeding women
      • People who eat poorly, such as alcoholics, people following "fad diets," or people with eating disorders
      • People on a vegetarian or vegan diet
      • Australian Aboriginals
      • People with intestinal worms
      • People with conditions that bleed easily, such as gum disease or stomach ulcers, polyps, or bowel cancer
      • People with chronic illnesses such as cancer, autoimmune disease, heart failure, or kidney disease
      • People who take aspirin as a regular medication
      • People who have less than normal ability to absorb or use iron, such as those with celiac disease

      Stages and symptoms of iron deficiency

      If you don't get enough iron in your diet, your body's iron stores will decrease over time. This may result in:

      • Iron depletion – When hemoglobin levels are normal, but your body stores only a small amount of iron, it quickly runs out. There are usually no obvious symptoms at this stage.
      • Iron deficiency – When the amount of iron in your stores and blood is low and your hemoglobin levels are lower than normal. You may experience some symptoms, including tiredness.
      • Iron deficiency anemia – When your hemoglobin levels are so low that your blood cannot provide enough oxygen to your cells. Symptoms include paleness, difficulty breathing, dizziness and fatigue. People with iron deficiency anemia may also have reduced immune function and therefore be more susceptible to infections. In children, iron deficiency anemia can affect growth and brain development.

      Symptoms of iron deficiency anemia in children

      Signs and symptoms of iron deficiency anemia in children may include:

      • Behavioral Problems
      • Reinfection
      • Loss of appetite
      • Lethargy
      • Out of breath
      • Increased sweating
      • Strange "food" cravings, such as eating dirt
      • Failed to grow at the expected rate.

      Causes of iron deficiency in adults

      In adults, some common causes of iron deficiency include:

      • Not getting enough iron in your diet There are many reasons why a person's dietary iron intake may be too low, such as due to an unbalanced vegetarian diet, chronic fad dieting, or a lack of access to a variety of fresh foods.
      • Blood Loss Iron deficiency can easily occur in cases of chronic blood loss. Common causes include menorrhagia, regular blood donation, frequent nosebleeds, other chronic conditions involving bleeding, and certain medications, especially aspirin.
      • Increased demand for iron If you are pregnant or breastfeeding, your body needs more iron. If this increased need is not met, iron deficiency can quickly develop.
      • Exercise Athletes are prone to iron deficiency because regular exercise increases the body's need for iron in a variety of ways. For example, hard training increases the production of red blood cells, and iron is lost through sweating.
      • Inability to Absorb Iron Healthy adults absorb about 10 to 15 percent of dietary iron, but some people's bodies are unable to absorb or utilize iron from food.

      Causes of iron deficiency in children

      Main risk factors for iron deficiency in children include:

      • Preterm birth and low birth weight
      • Exclusive breastfeeding (no introduction of solids) beyond 6 months
      • Children under 2 years old consume large amounts of milk
      • Low or no meat intake
      • Vegetarians and Vegetarians
      • Poor diet in the second year of life
      • Possible gastrointestinal disease
      • Lead poisoning

      Infants, children, and adolescents experience rapid growth spurts that increase their iron needs. The main causes of iron deficiency in children of all ages include:

      • Babies younger than 6 months old – A newborn’s iron is stored in the uterus, which means the mother’s diet during pregnancy is very important. Babies with low birth weight or who were born prematurely are at increased risk of iron deficiency and require iron supplementation only under medical supervision. Please consult your doctor for further advice.
      • Infants 6 months to 1 year old—Infants’ iron stores are depleted during the second half of the first year. Iron deficiency can result if their diet does not include enough iron-rich solid foods. At about 6 months of age, you can start taking 2 servings per day of pure iron-fortified infant cereal mixed with breast milk or infant formula. Once your baby is used to cereals, pureed meats can soon be offered along with other solids. Late introduction of solids into an infant's diet is a common cause of iron deficiency in this age group.
      • Children 1 to 5 years old—Breast milk contains small amounts of iron, but prolonged breastfeeding can lead to iron deficiency, especially when breast milk replaces solid foods in the diet. Low-iron milks such as cow's milk, goat's milk and soy milk should be consumed before 12 months of age. Children who drink milk instead of eating solid foods are at risk for iron deficiency.
      • Adolescents - Adolescent girls are at risk due to a variety of factors, including the growth spurt during puberty, iron loss during menstruation, and the risk of nutritional deficiencies due to restrictive fad dieting.

      Advice for parents – babies

      Some recommendations for preventing iron deficiency in infants younger than 12 months include:

      • Eat an iron-rich diet during pregnancy. Red meat is the best source of iron.
      • Tests to check for anemia should be done during pregnancy. If your doctor prescribes iron supplements, take them only as directed.
      • Breastfeed your baby or choose an iron-fortified infant formula.
      • Do not give your baby milk or other liquids that may replace iron-rich solid foods before 12 months of age.
      • Do not delay the introduction of solid foods. Start feeding your baby pureed foods when they are about 6 months old. Fortified infant cereals made from iron-fortified infant formula or breast milk are usually the first food offered. This is because of its iron content, but also because its texture changes easily. Introduce soft lump foods or mashed foods at about 7 months.

      Advice for parents – young children

      To prevent iron deficiency in toddlers and preschoolers:

      • Include lean red meat into their diet 3 to 4 times a week. Offer meat alternatives such as dried beans, lentils, chickpeas, canned beans, poultry, fish, eggs and small amounts of nuts and nut butters. These are great sources of iron in your child's daily diet. If your family follows a vegan or vegetarian diet, you may want to seek advice from a nutritionist to ensure you are meeting all of your child's dietary needs.
      • Include vitamin C in their diet as this helps the body absorb more iron. Make sure your child eats plenty of foods rich in vitamin C, such as oranges, lemons, tangerines, berries, kiwis, tomatoes, cabbage, peppers and broccoli.
      • Encourage solid foods at mealtimes and be careful not to allow young children to "fill" drinks between meals.
      • Remember that chronic diarrhea can deplete your child's iron stores, and intestinal parasites such as worms can cause iron deficiency. See your doctor for prompt diagnosis and treatment.
      • Picky eaters may be at risk due to insufficient intake or a lack of variety in the foods they eat. Ask your nutritionist, local doctor or child care nurse for advice on how to manage a picky eater.

      Advice for Parents – Teenagers

      Preventing iron deficiency in adolescents:

      • Talk to your children about the importance of iron. Help them gain enough information to make their own responsible food choices.
      • Encourage iron-rich foods and meals, such as iron-fortified breakfast cereals and breads, and offer meat, poultry, or fish at dinner.
      • If your child wants to avoid red meat or become a vegetarian, provide good sources of non-heme iron such as dry beans, lentils, peas, broccoli, spinach, legumes, fortified cereals, breads, and whole foods. cereals. Eating foods rich in vitamin C, such as fruits or vegetables with meals, should also be encouraged.
      • Only moderate amounts of tea and coffee are encouraged as they can interfere with iron absorption.

      Diagnosis of iron deficiency

      If you think you may be iron deficient, make an appointment with your doctor. The diagnosis is designed to rule out other conditions that may have similar symptoms, such as celiac disease.

      Diagnostic methods include:

      • Physical examination
      • Medical history
      • Blood test
      • Treat iron deficiency

      Treatment of iron deficiency depends on your iron status and underlying cause:

      If you are iron deficient

      Your doctor can give you information about adding iron-rich foods to your diet. You will have another blood test in about 6 months to check if your iron levels have improved. Your doctor will give you dietary advice and closely monitor your diet, and may prescribe supplements.

      If you have iron deficiency anemia

      Your doctor may prescribe iron supplements. It may take your body 6 months to a year to replenish its iron stores. Your iron levels will be checked regularly with blood tests.

      If you have an underlying problem that causes iron deficiency

      Then it is very important to investigate the cause. If it is a medical cause, it is important to get appropriate treatment.

      Do not self-diagnose iron deficiency

      Since iron supplements are available without a prescription, it may be easy to self-diagnose, but this is not recommended because:

      • Having too much iron in the body can be toxic and even fatal.
      • Fatigue, pallor, dizziness, and difficulty breathing are symptoms of many other health conditions, not just iron deficiency anemia. Incorrect self-diagnosis and self-treatment can be dangerous and waste valuable time getting the treatment you need. Getting the right treatment in the early stages of the disease can provide a greater chance of recovery. Therefore, it is important to see your doctor if you think you may be iron deficient.
      • If iron deficiency anemia is not a problem, iron supplements will not help relieve symptoms.
      • Taking iron supplements when not needed can interfere with the body's absorption of other minerals.
      • Hemochromatosis is a genetic disorder that causes the body to absorb more iron than usual. Excess iron can damage the body. People with hemochromatosis need to limit the amount of iron they eat.

      Do not self-diagnose or give your child over-the-counter iron supplements because too much iron can cause death.

      Health risks of excess iron

      Iron toxicity in food is rare because the body has its own balancing system. However, excessive intake of iron supplements can lead to fatal overdose and adverse health effects. Hemochromatosis, caused by genes that enhance absorption, can also cause high iron levels. Other causes include blood transfusions, overeating and rare metabolic disorders. Over time, excess iron can cause large deposits to form in the liver and other tissues.

      Iron supplements

      If you are advised to take an iron supplement, remember:

      • The most common side effect of iron supplements is dark or black stools, so don’t be alarmed by this change in bowel habits.
      • Other common side effects include nausea, vomiting, constipation and diarrhea. Check with your doctor, but generally, treatment involves lowering the recommended dose for a short period of time to give the body time to adjust.
      • If possible, iron supplements should be taken on an empty stomach.
      • Supplements should be taken exactly as recommended by your doctor. The human body is not good at excreting iron, and you may become toxic if you take more than the recommended dose.

      The secret to getting enough iron

      It can generally help you increase your iron intake in your diet

      • Eat lean red meat several times a week and a variety of meats and fish.

      • Eating foods rich in vitamin C with meals can help increase the absorption of non-heme iron. For example, drizzling lemon juice over leafy greens can increase the amount of iron absorbed.

      • Avoid drinking coffee, tea or milk with iron-rich foods: drink coffee or tea between meals instead.
      • Choose foods rich in non-heme iron: If you avoid meat and fish, include plenty of iron-rich plant foods in your diet.

      Iron-rich recipes

      • Steak with goulash sauce and sweet potato fries

      • Rosemary Balsamic Lamb with Vegetable Puree

      • Oysters with chilli and ginger sauce

      • Mutton and Chickpea Soup

      • Beef and Red Pepper Burger

      • Mutton Curry

      • Steak, Roasted Pepper and Barley Salad

      Review

      All comments are moderated before being published