Nutrition exam 3 VITAMINS

What type of nutrient is Vitamin D?

Vitamin D is not an essential nutrient because the body can produce it when the skin is exposed to UVB sunlight, given the precursor is present.

How is Vitamin D produced in the body?

UVB rays from sunlight act on a cholesterol compound in the skin, converting it into Vitamin D.

What unit is Vitamin D measured in?

Vitamin D is measured in International Units (IU).

Conversion: 1 microgram (mcg) = 40 IU

What are major food sources of Vitamin D?

• Fatty fish (mackerel, sardines, tuna)

• Fortified milk

• Egg yolks

• Sun-exposed mushrooms

What is the main function of Vitamin D?

Promotes bone mineralization by regulating calcium and phosphorus.

How does Vitamin D affect calcium in the body?

• Increases calcium absorption into the blood

• Helps maintain blood calcium levels

• Supports strong bones

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What additional role does Vitamin D have beyond bone health?

Assists in immune function

What factors decrease Vitamin D synthesis from sunlight?

• Air pollution

• City living

• Cloudy skies

• Clothing covering skin

• Sunscreen use

• Limited sun exposure (homebound)

How does age affect Vitamin D production?

As people age, the skin becomes less efficient at synthesizing Vitamin D

How does skin pigmentation affect Vitamin D synthesis?

Darker skin produces less Vitamin D compared to lighter skin under the same sunlight conditions.

What time of day provides the most effective Vitamin D synthesis?

Midday, when sunlight is most direct.

What is a major deficiency disease of Vitamin D in children?

Rickets – causes bowed legs and improper bone development.

 What is a major deficiency disease of Vitamin D in adults?

Osteomalacia – bones become soft, weak, and flexible.

What are symptoms of Vitamin D deficiency?

• Weak, soft bones

• Increased fracture risk

• Bone deformities

Why is Vitamin D considered potentially toxic?

It is one of the most potentially toxic vitamins, especially when intake exceeds about 5× the RDA.

What happens in Vitamin D toxicity?

• Excess calcium in blood (hypercalcemia)

• Calcium pulled from bones

• Can lead to kidney damage + soft tissue damage and may be deadly

Can sunlight cause Vitamin D toxicity?

No, toxicity does NOT occur from sun exposure—only from excessive intake (supplements).

How does obesity affect Vitamin D levels?

Vitamin D gets stored in fat tissue, leaving less available in the bloodstream.

What happens to calcium regulation when Vitamin D is too high?

• Excess calcium is released from bones

• Kidneys are stimulated to reabsorb more calcium

• Leads to dangerously high blood calcium levels

What are the two main forms of Vitamin A?

• Preformed Vitamin A (retinol) – from animal foods

• Provitamin A (beta-carotene) – from plant foods

What kind of vitamin is Vitamin A?

Fat-soluble

What foods are high in Vitamin A?

• Liver, dairy, eggs (retinol)

• Carrots, sweet potatoes, spinach (beta-carotene)

What is the main function of Vitamin A in vision?

Helps form rhodopsin, needed for night vision

What are other functions of Vitamin A?

• Maintains epithelial tissues (skin, lungs)

• Supports immune function

• Aids cell growth

What is an early symptom of Vitamin A deficiency?

Night blindness

What severe eye condition can result from vitamin A deficiency?

Xerophthalmia (dry eyes → blindness)

Why is Vitamin A toxicity dangerous?

Stored in liver → can build up and cause:

• Liver damage

• Birth defects

• Headaches, nausea

What type of vitamin is Vitamin E?

Fat-soluble antioxidant

 What is the main role of Vitamin E?

Protects cells from oxidative damage (free radicals)

What cells are especially protected by Vitamin E?

Red blood cells and cell membranes

What foods contain Vitamin E?

• Nuts and seeds

• Vegetable oils

• Green leafy vegetables

Risk factors in Vitamin E deficiency?

RARE: GI, cystic fibrosis, FAT MALABSORPTION

• Hemolysis (RBC destruction)

• Nerve damage (rare)

What is a risk of too much Vitamin E?

Can interfere with blood clotting

What type of vitamin is Vitamin K?

Fat-soluble

What is the main function of Vitamin K?

Essential for blood clotting

What else does Vitamin K help with?

Bone metabolism

Where do we get Vitamin K?

• Green leafy vegetables

• Intestinal bacteria production

What happens with Vitamin K deficiency?

-excessive bleeding

-infants given vitamin K injection bc their intestinal tract is not full of bacteria yet

What type of vitamin is Vitamin C?

Water-soluble

What is Vitamin C’s main role?

Collagen synthesis

What are other functions of Vitamin C?

• Antioxidant

• Enhances iron absorption

• Immune support

What foods are high in Vitamin C?

• Citrus fruits

• Strawberries

• Peppers

• Broccoli

 What disease is caused by Vitamin C deficiency?

Scurvy

Symptoms of scurvy?

10mg a day needed to prevent scurvy- pinpoint bruises + bleeding gums

What is the main function of Thiamin?

Energy metabolism & nerve function

Deficiency disease of thiamin?

Beriberi

Symptoms of beriberi (4)

• skin retains thumb imprint (can be wed or dry)

• loss of sensation

• muscular weakness

• abnormal heart action

Function of riboflavin

Energy production

Deficiency symptoms of riboflavin

Cracks at mouth corners, sore throat

Function of Niacin

Energy metabolism

Niacin deficiency disease

Pellagra (rough skin)

4 d’s of pallegra

Diarrhea, dermatitis, dementia, death

Function of vitamin B6

1. amino acid synthesis (converting tryptophan to niacin)

2. Hemoglobin synthesis

3. Regulation of blood glucose (assists in releasing stored glucose from glycogen)

Vitamin B6 deficiency

Generalized symptoms (weakness irritability, insomnia, weakened immune response, depression confusion, )

Which B vitamin is stored

Vitamin B6

Food sources of thiamin, riboflavin, and niacin

Whole grain brads and cereals + enriched breads + cereals

overall function of thiamin, riboflavin, and niacin

energy metabolism, all cells use them

Vitamin B6 food sources

1. MFP

2. potatoes

3. bananas

4. leafy greens(as well as many other B vitamins)

Which vitamin toxicity causes neuropathies in hands and mouth that CAN be restored

Vitamin B6

Folate function

DNA synthesis and metabolism

Folate sources

1. Green, leafy vegetables

2. Breads and cereals now fortified with folic acid (we absorb it better that folate)

What enables folate to get into cells?

B12

what 2 drugs interfere with bodys use of folate

antiacids + aspirin

3 deficiencies of folate

1. Anemia

2. impaired cell division

3. neural tube defect--spina bifida

Folate toxicity

can mast B12 deficiency causing the nerve damage of B12 deficiency to continue

B12 functions (2)

1. Enables folate to get into cells (so it can perform its function of DNA SYNTHESIS)

2. Helps maintain sheaths around nerves

B12 sources

1. Animal products (meat, fish, dairy)

2. Fortified cereals and supplements (recommended for vegans)

B12 deficiency results from….

poor absorption NOT poor intake

B12 deficiency

-Pernicious anemia——a type of anemia caused by the inability to absorb vitamin B12, often due to a lack of intrinsic factor.

-Paralysis of nerves and muscles

(folate can mask this)

Function of biotin and pantothenic acid (together and individually)

together: energy metabolism

Biotin- Coenzyme in CHO, fat + protein digestion

Pantothenic acid- stimulates growth

Biotin toxicity and deficiency

no symptoms reported for either, an adequate diet will provide both in sufficient amounts