Flashcards in Vitamins Deck (28):
How are water soluble vitamins absorbed?
The water soluble vitamins are partially digested by hydrolyses and then absorbed into the mucosal cell in the small intestine then travel via the hepatic portal vein to the liver where some are stored.
How are fat soluble vitamins absorbed?
The fat soluble vitamins are taken up by a similar means to triglycerides and cholesterol. They form micelles which then enter the mucosal cell to form chylomicrons which then travel first through the lymph and then into the plasma to end up being stored in lipid deposits in the body.
How does the recommended daily intake and estimated average intake differ?
The RDI is a recommendation based on the population as a whole whereas the EAR (estimated average requirement) is more of an individual recommendation as it takes into account the individual requirements of a person (eg age, sex, activity levels, underlying health issues).
How often are water soluble vitamins needed compared to fat soluble vitamins?
Because water soluble vitamins are readily excreted in the urine they are required frequently (every 1 to 3 days).
In contrast the fat soluble vitamins are less readily excreted and tend to remain in fat storage sites and so we only require these in periodic doses eg every few weeks to months)
What are some examples of fat soluble vitamins?
Vit A, D, E, K
What are some examples of water soluble vitamins?
Vit B and C
Why is folate needed in the body?
It is a conenzyme involved in the transfer of one carbon units and is therefore very important for DNA synthesis and healthy brain function
Folate naturally occurs as a polyglutamate in foods but what happens to it in the intestine in order for it be absorbed?
Digestion breaks off the glutamates and adds a methyl group so it can be absorbed into the cells.
What does a deficiency in folate cause in adults? What impact can this deficiency have on an unborn foetus?
Megoblastic anaemia - if a preganant women has this deficiency it can result in neural tube defects as the spinal cord fails to form properly without it.
What is spina bifida?
A condition where the spinal cord is formed outside of the body wall (a type of neural tube defect often a result of folate deficiency)
Why is thiamine important in the body?
It is used as a coenzyme that helps to convert carbohydrates to energy that can be used by the body
What is the most common cause of thiamine deficiency in NZ?
Alcoholism - alcohol limits the conversion of thiamine in the liver as well as the factor of alcholics generally having worser diets.
Why is thiamine deficiency common in asian countries?
The staple food in asia is white rice and white rice only contains about 10% of the thiamine in brown rice.
What two main conditions does thiamine deficiency result in? and what are the differences between them?
Dry beriberi and wet beriberi.
Wet affects the cardiovascular system and causes swelling/edema and indentations in the skin when pressed on.
Dry beriberi affects the nervous system and results in muscle wasting of the extremities as well as peripheral neuropathy (pain and tingling in the hands and feet).
What is the main source of thiamine in the diet?
Wholegrains cereals and fortified grains (deficiency is mainly caused by people eating refined grains as the thiamine is found in the outer coating called the bran)
What is korsakoff syndrome?
A memory disorder resulting from severe deficiency of thiamine often resulting from alcoholism where people are forgetful (amnesia) and have an inability to concentrate/learn.
What is wernicke-encephalopathy syndrome?
A neurological issue/brain damage resulting from deficiency in thiamine/alcoholism where the patient has difficulties with language and walking.
What is the relationship between beta carotene and vitamin A/retinol?
Beta carotene is the precursor for vitamin A which has the potential to be converted to vitamin A once in the body.
Why can eating fatty food like olive oil help with absorption of vitamin A?
It is a fat soluble vitamin and so requires fat to be transported in through the body.
What are the sources of vitamin A (retinol) and beta carotene?
Vitamin A/retinol is only found naturally in animal products as the digestive system is able to efficiently convert it the beta carotene from the plants they eat into retinol.
Beta carotene is found in plant products and it is responsible for giving things its orange pigment.
What is the main role of Vitamin A?
Involved in maintaining healthy vision.
What role does Vitamin A have in maintaining a healthy cornea of the eye?
Vit A maintains healthy mucus cells in order to keep the cornea moist. A deficiency would cause the cornea to dry up and become white/opaque in colour.
What role does vitamin A have in terms of when light hits the back of the eye?
The back of the eye where the light hits is called the retina. This is made of rods and cones which are made of rhodopsin. Rhodopsin is derived from retinol. Hence retinol (vit A) is important for sight.
What does a deficiency in Vit A result in?
Night blindness and chicken skin (keritinization of the skin resulting in dry and scaled appearance)
What is the result of consuming too many carrots?
Overconsumption of beta carotene can result in orange skin as the body has consumed toxic amounts of beta carotene of which it can absorb/process.
What is another common name for Vitamin D?
In NZ what is the main source of our Vit D and how do our levels change over the years?
Main source is the sun - our levels decrease over winter months and increase over summer.