8a. Vitamins - Fat Soluble Flashcards
Who coined the phrase ‘vitamines’?
Casimir Funk
What is a vitamer?
Different chemical forms of each vitamin
How many vitamins are there?
13
What are the key functions of vitamins?
Supporting immune system Regulating gene expression Supporting neurological activity Facilitating ATP production Producing blood cells Regulating hormones Facilitating physiological functions
What are vitamins?
Carbon containing compounds that are essential to the body in small amounts for normal growth and function
In general, can the body produce vitamins?
No (except vit D)
Do supplements offer the same therapeutic advantages as consuming them in food?
No, as the vitamins need to work as part of a team
They can’t work in isolation
What are vitamins co-factors for?
Vitamin-dependent enzymes
Which are the fat-soluble vitamins?
A
D
E
K
How are fat-soluble vitamins absorbed?
With fat in the small intestine
Travel into the lymphatic capillaries
Then into the blood
Which are the water-soluble vitamins?
Bs
C
How are water-soluble vitamins absorbed?
In the small intestine directly into the blood
Which type of vitamins are more easily excreted?
Water-soluble
What’s the easiest way to maintain levels of water-soluble vitamins?
Little and often throughout the day
What is vitamin insufficiency?
Sub-clinical deficiency
Vague symptoms
What is vitamin deficiency?
Clinical signs and symptoms
How does vitamin insufficiency progress to vitamin deficiency?
- Preliminary reduction of stores
- Reduction in enzyme activity
- Physiological impairment (early signs and symptoms)
- Classical deficiency syndromes
- Terminal tissue pathology
Which vitamins are people more likely to be deficient in?
Vit B12
Vit D
What are the vitamers/active forms of vit A?
Retinol
Retinal
Retinoic Acid
What does retinol support?
Retina health
Vision
What does retinal support?
Rod and cone cells in retina
What does retinoic acid support?
Growth and differentiation of epithelial cells
Skin health
What is pro-vitamin A?
Precursor to the active form of vit A (retinol)
Found in non-animal foods
Where is pro-vitamin A converted into retinol?
SI
Liver
What is carotene?
An example of pro-vitamin A
What is pre-formed vit A?
Active form of vit A (retinol) that is ready to use by the body
Found in animal foods
Examples of vit A food sources
Mango Squash Sweet potato Carrots Spinach Egg yolks Fish oils Liver
Why are dietary carotenes not considered toxic?
They’re only converted to vit A as and when needed
What percentage of carotenes are absorbed in the small intestine?
Between 5-60%
What is needed in a meal to optimise the absorption of carotenes?
Healthy fats
Lightly steamed
Which gene is needed to convert carotenes to retinol in the SI/liver?
BCO1
What can reduce carotene conversion in the SI/liver?
Liver disorders
Hyperlipidaemia
Diabetes
Hypothyroidism
What can excessive intake of carotenes lead to?
Yellowing of skin
What percentage of pre-formed vit A is absorbed by the SI/liver?
70-90%
Functions of vit A
Reproduction Eye health Differentiation of cells Immunity Systemic immunity
What are the reproductive functions of vit A?
Sperm synthesis
Egg development and implantation
What are the eye health functions of vit A?
Required for the light-sensitive protein (rhodopsin) that converts light into an electrical signal that goes into the brain (creating an image)
What are the cell differentiation functions of vit A?
Regulating gene expression
Synthesis of glycoproteins that support bone, teeth and skin development
What are the immunity functions of vit A?
Supports first line of defence
(skin and mucous membrane barrier)
T-cell proliferation
IL-2 secretion
What are the systemic immunity functions of vit A?
AO properties
What are the therapeutic uses of vit A in reproduction?
Infertility
What are the therapeutics uses of vit A in eye health?
Photosensitivity
Visual loss
Night blindness
Senile cataracts
What are the therapeutic uses of vit A in cell differentiation?
Acne Anaemia Hair loss (women) Fracture repair OA GIT ulceration Periodontal disease
What are the therapeutic uses of vit A in immunity?
Recurrent infections
What are the therapeutic uses of vit A in systemic immunity?
Cancer prevention
What are the signs/symptoms of a vit A deficiency?
Vision impairment at night Hyperkeratosis of skin Acne Eczema Poor wound healing Poor bone growth Poor sense of taste/smell Lowered immunity
What states/conditions can affect the absorption of vit A?
Alcoholism
Poor gut health
Conditions that affect fat absorption
Zinc deficiency
Why is it important to optimise the intake of zinc-rich foods?
Required to make retinol binding protein
Without that, vit A is trapped in the liver and can’t be used
What is the function of retinol binding protein?
Moves vit A out of storage in the liver to the tissues for utilisation
What conditions can vit A toxicity lead to?
Birth defects
Dry, red scaling skin
Increased osteoclast activity/bone fractures
Damage to liver cells, causing liver disease
Hyperlipidaemia
Amenorrhoea
When taking which drug should you avoid vit A supplementation?
Warfarin
decreases vit K absorption, increasing bleeding risk
What are the two types of vit D?
Ergocalciferol D2 - plants
Cholecalciferol D3 - animals
Examples of vit D food sources
Mushrooms
Oily fish
Egg yolks