Fat-Soluble and Water-Soluble Vitamins: Functions, Sources, and Health Effects

What are fat-soluble vitamins?

Vitamins A, D, E, and K that are absorbed along with dietary fats.

What is the absorption rate of fat-soluble vitamins?

40-90% absorbed depending on dietary fat.

How do fat-soluble vitamins differ from water-soluble vitamins in absorption?

Fat-soluble vitamins are absorbed with dietary fats; water-soluble vitamins are absorbed independently.

What is the role of bile in fat-soluble vitamin absorption?

Bile is necessary for the absorption of fat-soluble vitamins.

What is a vitamin?

An essential, organic substance needed in small amounts in the diet.

What are retinoids?

Biologically active forms of vitamin A.

What does teratogenic mean?

Causing birth defects.

What is a prohormone?

A precursor of an active hormone.

What is a provitamin?

A substance that can be converted to a vitamin.

What is a free radical?

Very unstable compounds that have one or more unpaired electrons.

What is an International Unit (IU)?

A measure of the amount of vitamin A and other nutrients.

What has replaced IU for measuring vitamins?

Milligrams and micrograms due to being more sensitive.

What are common dietary sources of Vitamin A?

Foods of animal origin.

What is the physiological function of Vitamin A?

Growth and development, vision, immune function, dermatology.

What is the RDA for adult men for Vitamin A?

900 RAE.

What is the RDA for adult women for Vitamin A?

700 RAE.

What are common sources of Vitamin D?

Oily, fatty fish and fortified milk.

What is the physiological function of Vitamin D?

Regulation of calcium and phosphorus.

What is the RDA for Vitamin D for adults?

15 µg/day.

What is the RDA for adults over 70 for Vitamin D?

20 µg/day.

What are common sources of Vitamin E?

Plant oils, wheat germ, avocado, peanuts.

What is the RDA for Vitamin E?

15 mg/day.

What are common sources of Vitamin K?

Green leafy vegetables and vegetable oil.

What is the RDA for Vitamin K for adult men?

120 µg/day.

What is the RDA for Vitamin K for adult women?

90 µg/day.

How do retinoids differ from carotenoids?

Retinoids are active forms of vitamin A found in animal foods; carotenoids are plant pigments acting as provitamins.

What does Retinol Activity Equivalents (RAE) measure?

Overall vitamin A activity.

What does Retinol Equivalent (RE) measure?

An older system of measurement for vitamin A values.

Which organ stores most of the vitamin A in the body?

The liver.

How does the liver release vitamin A?

It takes up chylomicron remnants, stores them, and repackages them with new proteins.

What are the physiological functions of Vitamin A?

Vision, cell differentiation, growth and development, immune function.

What are the physiological functions of carotenoids?

Provitamin A activity, antioxidant protection, eye health protection, cardiovascular and cognitive health.

What are the effects of Vitamin A dysregulation?

Xerophthalmia, follicular hyperkeratosis, impaired growth, and increased infection risk.

What is the relationship between dietary Vitamin D and endogenous Vitamin D?

Both enter circulation and are activated in the liver and kidneys.

How is Vitamin D3 formed in the skin?

From 7 dehydrocholesterol when exposed to sunlight.

How do Vitamin D needs vary by age?

Infants need supplements; adults 1-70 need 15 µg/day; adults over 70 need 20 µg/day.

What is the recommended daily allowance (RDA) of Vitamin D for adults over 70?

20 µg/day (800 IU/day)

Why does the RDA of Vitamin D increase for adults over 70?

Skin production capacity decreases by about 70% by age 70.

What factors affect Vitamin D synthesis from sunlight?

Geographic location, season, skin color, and sunscreen use.

Why might individuals in northern climates need Vitamin D supplements during winter?

They cannot produce skin Vitamin D from November through February.

Who requires Vitamin D supplements?

Breastfed infants, older adults with limited mobility, and individuals with fat malabsorption diseases.

What is the physiological function of calcitriol (active Vitamin D)?

It controls the body's concentration of calcium and phosphorus.

How does Vitamin D affect intestinal mineral absorption?

It promotes the absorption of calcium and phosphorus from foods when blood calcium levels are low.

What role does Vitamin D play in bone mineralization?

It helps deposit calcium and phosphorus into bone matrix for skeletal health.

What are the effects of Vitamin D deficiency in children?

Rickets, causing weakened bones and deformities.

What condition does Vitamin D deficiency cause in adults?

Osteomalacia, leading to soft bones and frequent fractures.

What is hypercalcemia?

Excessive calcium levels in the blood due to high Vitamin D supplementation.

What are the symptoms of Vitamin D toxicity?

Anorexia, nausea, vomiting, bone demineralization, joint pain, and severe kidney dysfunction.

How is Vitamin E absorbed in the body?

By passive diffusion, requiring incorporation into micelles in the small intestine.

What is the primary storage site for Vitamin E?

Adipose tissue.

What are the effects of Vitamin E deficiency?

Serious structural breakdowns (hemolysis) and impaired immune function.

How does Vitamin K function in the body?

As a coenzyme for blood clotting and in bone metabolism.

What role do gut microbiota play in Vitamin K levels?

They synthesize menaquinones (Vitamin K2) in the colon.

What happens if there is a Vitamin K deficiency?

Defective blood clotting and prolonged bleeding times.

How is Vitamin K absorbed in the body?

Approximately 80% is taken up in the small intestine and integrated into chylomicrons.

What are the limitations of using supplements for nutrient intake?

They cannot fully correct a poor diet and may lead to toxicity.

What are dietary supplements?

Products intended to supplement the diet containing vitamins, minerals, amino acids, or herbs.

How are dietary supplements regulated?

They are not regulated like drugs and food additives by the FDA.

What is a co-factor?

An organic or inorganic substance that binds to a specific region on an enzyme and is necessary for enzyme activity.

What is a co-enzyme?

A compound that combines with an inactive protein (apoenzyme) to form a catalytically active enzyme (holoenzyme).

What is epigenetics?

The study of heritable changes to gene expression that are not due to changes in the underlying DNA sequence.

How does the absorption of water-soluble vitamins differ from fat-soluble vitamins?

Only small amounts are stored in the body.

Why has a tolerable upper intake level only been set for some water-soluble vitamins?

Only set for 4 vitamins; most are readily removed by the kidneys and excreted in the urine.

What are coenzymes?

Small, organic molecules that are a type of cofactor formed by all B vitamins.

Why are whole grains favored over milled grains?

Milled grains lose minerals, vitamins, and fiber due to the removal of the germ, bran, and husk.

What are common sources of Thiamin?

Pork products, sunflower seeds, legumes, bread, rolls, cereal, pasta, and milk.

What is the physiological function of Thiamin?

Required for metabolism of carbohydrates and branched-chain amino acids; coenzyme for transketolase.

What is the RDA for Thiamin in adult men?

1.2 mg/day.

What is the RDA for Thiamin in adult women?

1.1 mg/day.

What are common sources of Riboflavin (B-2)?

Milk products, coffee, tea, breads, and eggs.

What is the physiological function of Riboflavin?

Component of 2 coenzymes that play key roles in energy metabolism (FMN & FAD).

What is the RDA for Riboflavin in adult men?

1.3 mg/day.

What is the RDA for Riboflavin in adult women?

1.1 mg/day.

What is the effect of dysregulated thiamin intake on health?

Deficiency can cause beriberi, characterized by weakness, pain, heart enlargement, and edema.

What is the effect of dysregulated B-2 intake on health?

Deficiency (ariboflavinosis) affects mouth, skin, and RBC; can cause poor growth, anemia, and fatigue.

What is the effect of dysregulated intake of niacin on health?

Deficiency (pellagra) can cause dermatitis, diarrhea, dementia, and death if untreated.

How can niacin be used as a pharmaceutical?

High doses are prescribed to lower LDL and triglyceride levels, but not considered effective for general cardiovascular protection.

What is the effect of dysregulated intake of pantothenic acid on health?

Deficiency is rare; symptoms include headache, fatigue, and GI disturbance. No toxicity observed.

What is the effect of dysregulated intake of biotin on health?

Deficiency is rare but can cause skin rashes, hair loss, and convulsions; no established UL for toxicity.

What is the effect of dysregulated intake of B-6 on health?

Deficiency can cause seborrheic dermatitis, anemia, convulsions, and confusion; toxicity can cause neurological damage.

How can B-6 be used as a pharmaceutical?

Supplemental vitamin B-6 has been used for carpal tunnel syndrome, PMS, and nausea during pregnancy.

What is the effect of dysregulated intake of folate on health?

Deficiency can lead to inefficient RBCs, GI issues, immune suppression, and increased cancer risk.

How does dysregulated intake of B-12 affect health?

Deficiency can cause neurological damage, secondary folate deficiency, and no established UL for toxicity.

What are the differences between macrocytic, microcytic, and pernicious anemia?

Macrocytic anemia involves large RBCs due to impaired DNA synthesis; microcytic anemia involves decreased hemoglobin synthesis; pernicious anemia results from inadequate intrinsic factor for B12 absorption.

How does vitamin C intake vary with lifestyle choices?

Smoking increases RDA by 35 mg/day; burn/trauma patients have increased needs; obesity and birth control may also require more vitamin C.

What is the effect of dysregulated intake of vitamin C on health?

Deficiency can lead to scurvy, causing weak collagen fibers; toxicity can cause abdominal bloating and kidney stones.