Ch.10

Vitamins Overview

  • How do vitamins differ from energy-yielding nutrients?
    Vitamins do not provide energy (calories) like carbohydrates, fats, and proteins do. Instead, they act as regulators in the body, helping various biochemical processes function efficiently, such as energy production, immune system support, and tissue repair.

  • What is bioavailability?
    Bioavailability refers to the degree to which a nutrient from food or supplements can be absorbed and utilized by the body. Factors like the nutrient's form, the presence of other nutrients, and an individual’s health status influence bioavailability.

  • What are the factors influencing bioavailability?
    Factors that influence bioavailability include the efficiency of digestion, food preparation methods, the presence of other nutrients or compounds (e.g., fat-soluble vitamins need fat for absorption), and an individual’s health conditions (e.g., gut health).

  • What is a precursor/pro-vitamin?
    A precursor or pro-vitamin is a compound that can be converted into an active vitamin form in the body. For example, beta-carotene is a precursor to vitamin A.

  • Which are the water-soluble vitamins? Which are fat-soluble?

    • Water-soluble vitamins: B vitamins (e.g., B1, B2, B3, B6, B12, folate, biotin, pantothenic acid) and vitamin C.

    • Fat-soluble vitamins: Vitamins A, D, E, and K.

  • What are the characteristics of water-soluble vitamins vs. fat-soluble vitamins?

    • Water-soluble vitamins: They are absorbed directly into the bloodstream, and excess amounts are excreted in urine (rarely stored in the body). They need to be consumed regularly as they are not stored for long-term use.

    • Fat-soluble vitamins: They are absorbed into the lymphatic system and stored in the liver and fat tissues. They can be stored for longer periods, so deficiencies in these vitamins are less common unless intake is consistently low.

  • What is meant by EAR?
    EAR (Estimated Average Requirement) is the daily intake level estimated to meet the needs of 50% of healthy individuals in a specific life stage and gender group.

  • What is meant by UL?
    UL (Tolerable Upper Intake Level) is the highest level of daily nutrient intake that is unlikely to pose a risk of adverse health effects for most people.

  • What is meant by AI?
    AI (Adequate Intake) is the recommended average daily intake level based on observed or experimentally determined approximations of nutrient intake by healthy people when there is insufficient data to establish an RDA.

  • What is meant by RDA?
    RDA (Recommended Dietary Allowance) is the average daily intake level that meets the nutrient needs of nearly all (97–98%) healthy individuals in a specific life stage and gender group.

B Vitamins

  • What is the main function of B vitamins?
    B vitamins primarily function as coenzymes in energy metabolism. They help the body convert food into energy (ATP) and play a role in cell growth, development, and repair.

  • Know the name of the B vitamins and the major disease associated with each one:

    1. B1 (Thiamine): Beriberi

    2. B2 (Riboflavin): Ariboflavinosis

    3. B3 (Niacin): Pellagra

    4. B6 (Pyridoxine): Pyridoxine deficiency (affects nerve function and hemoglobin production)

    5. B12 (Cobalamin): Pernicious anemia, neurological damage

    6. Folate (B9): Neural tube defects (in pregnancy), megaloblastic anemia

    7. Biotin: Rare, but can cause hair loss, skin rash

    8. Pantothenic acid: Rare, but causes fatigue, irritability (known as "burning feet syndrome")

  • Know generally which food groups provide the various B vitamins:

    • B1 (Thiamine): Whole grains, pork, legumes, seeds, and nuts.

    • B2 (Riboflavin): Dairy products, meat, eggs, leafy greens.

    • B3 (Niacin): Meat, poultry, fish, whole grains, fortified cereals.

    • B6 (Pyridoxine): Poultry, fish, potatoes, bananas, fortified cereals.

    • B12 (Cobalamin): Animal products like meat, fish, poultry, dairy.

    • Folate (B9): Leafy green vegetables, legumes, fortified grains.

    • Biotin: Eggs, almonds, spinach, sweet potatoes.

    • Pantothenic acid: Chicken, beef, potatoes, oats, tomatoes.

  • Know the specific absorption paths for certain vitamins if they’re included in the slides (e.g., Folate and B12):

    • Folate (B9): Absorbed in the small intestine. It requires a process of enzymatic conversion into its active form (tetrahydrofolate) for use by the body.

    • B12 (Cobalamin): Absorbed in the ileum of the small intestine with the help of intrinsic factor (produced in the stomach). Deficiency in intrinsic factor can lead to pernicious anemia.

  • What are the B vitamin Interactions?
    B vitamins often work together in various biochemical pathways, especially in energy metabolism. For example, vitamin B6, B12, and folate are interconnected in the metabolism of homocysteine, which is a risk factor for cardiovascular disease.

Choline

  • What is choline?
    Choline is a water-soluble essential nutrient that is needed for liver function, brain development, muscle movement, and nerve function.

  • What is choline used to make in the body?
    Choline is used to make acetylcholine (a neurotransmitter important for memory and muscle control), phosphatidylcholine (a major component of cell membranes), and sphingomyelin (important for cell signaling).

  • How does choline impact fetal development?
    Choline is essential during fetal development for brain and spinal cord development, particularly in the formation of the neural tube. Adequate choline intake is crucial for preventing neural tube defects.

Vitamin C

  • What is the main function of Vitamin C?
    Vitamin C is a powerful antioxidant and is essential for collagen synthesis, wound healing, and the maintenance of skin, blood vessels, and bones. It also supports immune function.

  • How does vitamin C affect iron absorption?
    Vitamin C enhances non-heme iron absorption (the type of iron found in plant-based foods) by reducing it to a more absorbable form in the digestive tract.

  • What is the main disease associated with vitamin C deficiency?
    Scurvy, a disease characterized by weakness, gum disease, skin rashes, and poor wound healing, is associated with vitamin C deficiency.

  • Under what conditions are our vitamin C needs increased?
    Vitamin C needs are increased during periods of illness, infection, pregnancy, and lactation. Smokers also have higher vitamin C needs due to oxidative stress.

  • What are the food sources of vitamin C?
    Rich sources of vitamin C include citrus fruits, strawberries, bell peppers, broccoli, and tomatoes.

  • What is the max absorption of vitamin C?
    The body can absorb approximately 200-250 mg of vitamin C per dose. Any excess is excreted in the urine.

  • What are the potential implications of high doses of vitamin C supplements?
    High doses of vitamin C (above 2,000 mg per day) can lead to gastrointestinal discomfort, diarrhea, and kidney stones in some individuals.