Vitamins Flashcards
1
Q
What are vitamins?
A
- Micronutrient: substance required in small quantities for normal health and development of an organism (mg or μg)
- Function as co-factor of enzymes, may include minerals (elements)
- Provide various functions in the organism and a deficiency of a particular vitamin can result in illness or death
2
Q
How are vitamins classified?
A
- Fat soluble: long, non-polar (hydrophobic) hydrocarbon chains/rings. e.g. vitamin A, D, E, F, K. They accumulate in fatty tissues of body
- Fat insoluble: water soluble, polar (hydrophilic), contain hydrogen attached directly to oxygen or nitrogen atoms, form hydrogen bonds
- Fat insoluble do not accumulate in body, regular intake required, refrigerated slows down oxidation process
3
Q
What is hypervitaminosis?
A
- ‘Overdose’, some vitamins can be excreted through urine, others build up
- Over-consumption of vitamin A results in liver damage
4
Q
Explain the role of vitamin A.
A
- Retinol
- Fat soluble (does however contain 1 -OH)
- Long non-polar hydrocarbon chain
- Conjugated chain consists of 9 carbons with an -OH group on the end, which means chain alternates between single and double carbon bonds
- Cannot be broken down readily by cooking
- Helps in night vision, skin health, grows and develops rods and cones
- Excess CANNOT be excreted in urine (no soluble in water), stored in fat tissues (liver)
5
Q
Explain the role of vitamin C.
A
- Ascorbic acid
- Lots of polar -OH groups, fat insoluble
- Can be excreted through urine
- Deficiency leads to scurvy, swollen legs, rotten gums, bloody lesions, depression
- Ring structure, short hydrocarbon chain, two hydroxyl groups
- Dietary necessity, found in plants. Acts as an antioxidant, allows body to repair itself from free radicals
6
Q
What is the role of vitamin D?
A
- Calciferol
- A large hydrocarbon chain with one -OH group, fat soluble, very low solubility in water
- Consits of steroid base with hydroxyl group
- Carried to liver by transport proteins for storage after synthesised in skin
- Synthesised from cholesterol, catalysed by light from sun
- Deficiency leads to bone softening and malformation, rickets
- Used to absorb certain microminerals into intestine e.g. calcium, zinc, iron
7
Q
What is the role of vitamin B?
A
- Includes 8 different compounds, vary greatly but all are water-soluble
- Vitamin B used to catalyse metabolic processes by acting as a coenzyme (compound needed for an enzyme to function)
- Plant sources of vitamin D: legumes, whole grains, bananas, turkey, tuna
8
Q
What is the role of vitamin E?
A
- Compounds known as tocopherols
- Structure of fused rings, long hydrocarbon chains (hydrophobic and non-polar), fat-soluble
- Works as antioxidant, found in plant oils
9
Q
What is the role of vitamin K?
A
- Fat-soluble, used in blood clotting
- Found in dark green leafy vegetables
- Bacteria in large intestine also synthesises some vitamin K, absorbed
10
Q
What is a vitamin deficiency?
A
- When the body does jot receive essential macro and micronutrients to undergo metabolic processes
- Lead to temporary or long-term health effects
11
Q
How can be vitamins obtained?
A
- Most synthesised by the body, others must be consumed
1. Balanced diet with fruits and vegetables, rich sources of vitamins
2. Supplements or tablets, contain mixture of vitamins and minerals
3. Genetically modified food (GMOs)
4. Adding nutrients that are missing in commonly consumed foods
12
Q
What can lead to vitamin deficiency?
A
- Vitamins are heat sensitive, allow vitamins to undergo oxidation reactions at a greater rate, lowers vitamin concentration
- Food storage or processing methods, exposure to O2 greater oxidation
- Exposure to light can also result in oxidation
13
Q
What effect does vitamin A deficiency have?
A
- Aids in vision development, a lack can lead to blindness
- Essential vitamin, deficiencies common in developing countries (meat, carrot, sweet potato consumption low)
- Deficiency can also occur from liver damaged (excess alcohol consumption)
- To change this, fortify food with vitamin A
- Genetically modified crops ‘golden rice’
14
Q
What effect does vitamin D deficiency have?
A
- Necessary for absorption of several micronutrients for bone development in children
- Most vitamin D produced from cholesterol in skin and catalysed by sunlight, hence high levels of sunlight exposure increases vitamin D levels
- Vitamin D absorbs calcium, lack thereof can lead to rickets, bones are soft and flexible, bend
- In adults, can lead to osteoporosis, decreased bone strength, depression
- Supplements used, oily fish, sunlight
15
Q
What effect does vitamin C deficiency have?
A
- Lack can lead to scurvy, disease of malnutrition
- Usually sailors had it, no fresh fruits for long time
- Type of antioxidant, important in providing electrons to free radicals that cause oxidative damage to cells. Vitamin C prevents damage
- Symptoms: fatigue, pain in gums, bone pain, poor wound healing, depression
- Supplementation, foods (citrus, red peppers)
