Vitamin A Roles: Gene Regulation and Cell Differentiation

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Questions and Answers

What is the recommended daily intake of Vitamin A for women?

1,000 micrograms

700 micrograms (correct)

3,000 micrograms

900 micrograms

Which of the following foods is rich in Vitamin A?

Salads with cheese and carrots

Fast food

Liver (correct)

Milk and milk products

What is the Tolerable Upper Intake Level of Vitamin A?

4,000 micrograms

1,000 micrograms

3,000 micrograms (correct)

2,000 micrograms

What is the benefit of eating carrots and other rich sources of beta-carotene?

It promotes good vision Signup and view all the answers

Which of the following foods lacks Vitamin A?

Fast food Signup and view all the answers

How much Vitamin A does an ounce of ordinary beef or pork liver deliver?

3x the DRI recommendation Signup and view all the answers

What is the benefit of eating fortified foods?

It improves nutritional quality Signup and view all the answers

Which of the following vegetables is a rich source of beta-carotene?

All of the above Signup and view all the answers

What is a characteristic of water-soluble vitamins in food?

They are easily dissolved and drained away with cooking water Signup and view all the answers

What is a role of vitamin C in the body?

To assist enzymes involved in collagen formation Signup and view all the answers

What is a benefit of vitamin C's antioxidant properties?

It reduces inflammation in the body Signup and view all the answers

Where do cells of the immune system store high levels of vitamin C?

To protect themselves from free radicals Signup and view all the answers

What is the effect of vitamin C on iron absorption in the intestines?

It increases the absorption of iron Signup and view all the answers

Can vitamin C supplements cure the common cold?

No, they have no effect on the common cold Signup and view all the answers

What is the primary function of retinoic acid in the body?

Cell differentiation and gene regulation Signup and view all the answers

What is the consequence of vitamin A deficiency in epithelial tissues?

Displacement of mucus-producing cells with keratin Signup and view all the answers

What is the role of vitamin A in reproductive health?

Supporting fetal development during pregnancy Signup and view all the answers

What is the estimated number of children worldwide suffering from severe vitamin A deficiency?

5 million Signup and view all the answers

What is the consequence of excessive vitamin A intake during pregnancy?

Increased risk of birth defects Signup and view all the answers

What is the primary cause of respiratory infections in vitamin A-deficient individuals?

Displacement of mucus-producing cells with keratin Signup and view all the answers

What is the role of vitamin A in growth and development?

Indispensable for growth Signup and view all the answers

What is the consequence of vitamin A deficiency on immune function?

Weakened immune function Signup and view all the answers

What is the estimated number of children worldwide with impaired immunity due to vitamin A deficiency?

190 million Signup and view all the answers

What is the risk of excessive vitamin A intake in children?

Increased risk of toxicity Signup and view all the answers

What is the main function of vitamin K?

To help activate proteins that help clot the blood Signup and view all the answers

Why do newborns need to be given vitamin K at birth?

Because they are born with a sterile intestinal tract Signup and view all the answers

What is the result of vitamin K toxicity in infants and pregnant women?

Breakage of RBC and release of bilirubin Signup and view all the answers

What is the recommended daily intake of vitamin E for adults?

15 milligrams per day Signup and view all the answers

Why do people taking warfarin need to be cautious when taking vitamin K supplements?

It can cause dangerous clotting of their blood Signup and view all the answers

What is the significance of vitamin K-producing bacteria in the intestinal tract?

They can produce vitamin K, reducing the risk of deficiency Signup and view all the answers

What was the primary reason for the high mortality rate among crew members in seagoing ships over 200 years ago?

Scurvy Signup and view all the answers

What is the primary function of collagen in the human body?

Supporting the structure of skin and bones Signup and view all the answers

What is the most common characteristic of individuals at risk of Vitamin C deficiency?

They are addicted to drugs or alcohol Signup and view all the answers

What is the primary symptom of Vitamin C deficiency that affects the skin?

Red spots Signup and view all the answers

What is the effect of Vitamin C deficiency on the growth of infants?

It causes growth cessation Signup and view all the answers

What is the primary cause of anemia in individuals with Vitamin C deficiency?

Internal bleeding Signup and view all the answers

Study Notes

Roles of Vitamin A

Hundreds of genes are regulated by the retinoic acid form of vitamin A
Genes direct the synthesis of proteins that perform the metabolic work of tissues
Vitamin A affects the metabolic activities of tissues and, in turn, the health of the body

Cell Differentiation

Vitamin A is needed by all epithelial tissue (external skin and internal linings) such as protective linings of the lungs, intestines, vagina, urinary tract, and bladder
Cell differentiation is when each type of cell develops to perform a specific function
Example: When goblet cells mature, they specialize in synthesizing and releasing mucus to protect delicate tissues from toxins or other harmful elements

Roles of Vitamin A - Cell Differentiation

If vitamin A is deficient, cells fail to make mucus and eventually die off, are displaced with Keratin
As dead cells accumulate on the surface, the tissue becomes vulnerable to infection
Examples:
- Cornea → xerophthalmia
- In the lungs, the displacement of mucus-producing cells makes respiratory infections likely
- In the urinary tract → urinary tract infections

Immune Function

Vitamin A has an "anti-infective" reputation
With no sufficient Vitamin A, the body's defenses are weakened, and illness can become severe

Reproduction and Growth

In men: Vitamin A participates in sperm development
In women: Vitamin A supports normal fetal development during pregnancy
In the developing embryo: Vitamin A is critical for the formation of the spinal cord, heart, and other organs
Vitamin A is indispensable for growth; failure to grow is one of the first signs of poor vitamin A status in a child

Vitamin A Deficiency around the world

An estimated 5 million children suffer from severe vitamin A deficiency
190 million more children have impaired immunity, leaving them open to infections

Vitamin A Toxicity

Can occur when excess vitamin A is taken as supplements or fortified foods
Pregnant women: especially, should be wary—excessive vitamin A can injure the spinal cord and other tissues of the developing fetus, causing birth defects
Children: can be easily hurt by vitamin A excesses when they mistake chewable vitamin pills and vitamin-laced gum for treats
Adolescents: at risk when they take high doses of vitamin A in misguided attempts to cure acne

Vitamin A Recommendations

DRI for men is 900 micrograms
DRI for women is 700 micrograms
Tolerable Upper Intake Level is 3,000 micrograms

Food Sources of Vitamin A

Active vitamin A is present in foods of animal origin
Richest sources: liver and fish oil
Good sources: milk and milk products, and other vitamin A–fortified foods such as enriched cereals
Beta-carotene is naturally present in many vegetables and fruit varieties

Vitamin K

The main function of vitamin K is to help activate proteins that help clot the blood
Also necessary for the synthesis of key bone proteins
Deficiency: few people have vitamin K deficiency, can be produced by intestinal bacteria
Newborns need to be given Vitamin K at birth since they are born with a sterile intestinal tract

Vitamin K Toxicity

Very rare
No UL set for vitamin K
However, in infants & pregnant women, vitamin K toxicity can result when supplements of a synthetic version of vitamin K are given → breakage of RBC and their release of their pigments → release of bilirubin by the liver into the blood → Jaundice

The Water-Soluble Vitamins

Vitamins B & C
Dissolve in water
In food, easily dissolve and drain away with cooking water
Some are destroyed on exposure to light, heat, or oxygen during processing
In the body, easily absorbed and just as easily excreted in the urine
A few can remain in the lean tissues for a month or more – but no real storage tissues exist

Roles of Vitamin C

Assists enzymes involved in the formation and maintenance of collagen
Participates in the production of carnitine
Creation of certain hormones
Antioxidant: protects substances found in foods and in the body from oxidation by being oxidized itself
Example: Cells of the immune system maintain high levels of vitamin C to protect themselves from free radicals

Vitamin C Supplements

Can Vitamin C Supplements cure a cold? Research most often fails to support those long-lived beliefs

Vitamin C Deficiency

Scurvy symptoms are due to collagen breakdown
Loss of appetite, growth cessation, tenderness to touch, bleeding gums, swollen ankles and wrists, anemia, red spots on skin, and weakness
Persons at risk of deficiency are: smokers, people addicted to alcohol/drugs, infants fed cow’s milk only and receive no fruit juice and no vitamin C in formulas, and elderly

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Description

Explore the essential roles of Vitamin A in regulating genes and facilitating cell differentiation, impacting tissue health and overall bodily functions.