Vitamins and Nutrition in Medicine

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Questions and Answers

What did F.Gowland Hopkins discover in 1912?

The cause of scurvy

The role of thiamin in metabolic pathways

The correlation between polished rice and beri-beri

The factors in milk needed for rat growth (correct)

What was the origin of the term 'vitamine'?

From the Greek words 'vita' and 'amine'

Coined by McCallum and Davis

Introduced by Casimir Funk in 1912 (correct)

Derived from the phrase 'vital amine'

What is the main characteristic of fat-soluble vitamins?

They are not stored extensively

They are only found in plant-based foods

They are stored and may be toxic in excess (correct)

They are not needed regularly

What was the main factor in the diet of patients that Eijkman worked with in Java?

Polished rice Signup and view all the answers

What is the main role of B vitamins in the body?

They act as co-enzymes in metabolic pathways Signup and view all the answers

What was the year that thiamin was isolated as the anti beri-beri factor?

1926 Signup and view all the answers

Why was the concept of 'Deficiency Disease' difficult to accept at the time?

Because diseases were thought to be caused by a toxic factor, not the absence of a factor Signup and view all the answers

What is a common characteristic of water-soluble vitamins?

They are not toxic in excess (within reason) Signup and view all the answers

What is the primary reason for thiamin deficiency in alcoholics?

Inhibition of the enzyme that converts thiamin into TPP Signup and view all the answers

Which of the following vitamins is most sensitive to UV light?

Riboflavin Signup and view all the answers

What is the primary function of riboflavin in the body?

As a cofactor in redox reactions Signup and view all the answers

Which of the following conditions is associated with a deficiency of niacin?

Pellagra Signup and view all the answers

What is the active form of pyridoxine?

Pyridoxal phosphate Signup and view all the answers

What is the primary cause of secondary pyridoxine deficiency?

Presence of antagonists such as isoniazid Signup and view all the answers

Which of the following groups is at risk of riboflavin deficiency?

All of the above Signup and view all the answers

What is the term for the different structural forms of a vitamin?

Vitamers Signup and view all the answers

What is the function of vitamin B12 in mammalian metabolism?

A carrier of methyl groups Signup and view all the answers

What is the primary source of vitamin B12 in the diet?

Animal tissues Signup and view all the answers

What is the consequence of a lack of intrinsic factor in the gut?

Impaired absorption of vitamin B12 Signup and view all the answers

What is the function of dihydrofolate reductase?

To convert dihydrofolate to tetrahydrofolate Signup and view all the answers

What is the consequence of self-medicating with high doses of folate for premenstrual tension syndrome?

Peripheral neuropathy Signup and view all the answers

What is the role of folate in purine and pyrimidine synthesis?

To donate 1-C units Signup and view all the answers

What is the recommended daily intake of vitamin B12?

1 μg/day Signup and view all the answers

What is the consequence of a lack of folate in the diet?

Megaloblastic anemia Signup and view all the answers

What is the role of B12 in the conversion of homocysteine to methionine?

As a cofactor in the methionine synthetase reaction Signup and view all the answers

What is the consequence of B12 deficiency on the folate pool?

Trapping of THF in the MeTHF form Signup and view all the answers

What is the primary mechanism of methotrexate's action?

Inhibition of DHF reductase Signup and view all the answers

What is the characteristic feature of megaloblastosis in B12 deficiency?

Giant germ cells Signup and view all the answers

What is the primary neurological symptom of B12 deficiency?

Numbness and tingling in the hands and feet Signup and view all the answers

What is the role of folate in DNA synthesis?

As a precursor to the synthesis of thymidylate Signup and view all the answers

What is the primary hematological consequence of B12 deficiency?

Haemopoietic cells die in bone marrow without completing cell cycle Signup and view all the answers

What is the role of methionine synthetase in the metabolism of homocysteine?

Conversion of homocysteine to methionine Signup and view all the answers

Which of the following conditions is most commonly associated with a deficiency in vitamin B12?

Crohn's disease Signup and view all the answers

What is the primary reason for folate supplementation in pregnant women in the UK?

To prevent neural tube defects Signup and view all the answers

What is the result of high dose supplements of B vitamins on cardiovascular mortality?

The results are inconsistent and unclear Signup and view all the answers

What is the result of high dose supplements of B vitamins on brain shrinkage in elderly people with mild memory problems?

A significant decrease in brain shrinkage Signup and view all the answers

What is the primary site of vitamin B12 absorption?

Terminal ileum Signup and view all the answers

What is the condition associated with a high homocysteine concentration in the blood?

Hyperhomocysteinaemia Signup and view all the answers

Which of the following is a cause of folate deficiency?

All of the above Signup and view all the answers

What is the percentage reduction in the incidence of neural tube defects in women who take folic acid supplements?

72% Signup and view all the answers

Study Notes

History of Vitamins

500 BC: Hippocrates discovered that liver consumption could cure night-blindness
1757: Lind discovered that fresh fruit and vegetables could cure scurvy in the British Navy
1893: Eijkman described and cured beri-beri in patients who consumed polished rice
1912: F.G. Gowland Hopkins found that milk contains factors necessary for rat growth
1912: Hopkins and Funk introduced the "vitamine theory" of disease, proposing that specific diseases are caused by a lack of specific nutritional factors

The Vitamine Theory of Disease

The theory proposed that diseases such as beri-beri, scurvy, and rickets are caused by a lack of specific nutritional factors
This was a difficult concept to accept at the time, as diseases were thought to be caused by toxic factors rather than the absence of a factor

Origin of Vitamin Names

McCallum and Davis (US) discovered fat-soluble factor A in butter and egg yolk
Heat-labile factor B was found in wheat germ and was necessary for rat growth
McCallum and Davis later found that these factors were mixtures of vitamins

Definition of Vitamins

Vitamins are complex organic substances required in the diet in small amounts
Vitamins are essential for normal growth and development, and their absence leads to a deficiency disease
Vitamins can be classified as either water-soluble (B and C) or fat-soluble (A, D, E, and K)

Water-Soluble Vitamins

B group and C vitamins are not stored extensively in the body
Water-soluble vitamins are needed regularly and are not toxic in excess (within reason)

Fat-Soluble Vitamins

A, D, E, and K vitamins are stored in the body
Fat-soluble vitamins are not absorbed easily and are not excreted easily
Fat-soluble vitamins can be toxic in excess (A and D)

B Group Vitamins

All B vitamins act as co-enzymes in metabolic pathways
Thiamin (B1) was isolated in 1926 as the anti-beri-beri factor
Thiamin deficiency can lead to Wernicke-Korsakoff syndrome, which is often seen in alcoholics
Riboflavin (B2) is UV-sensitive and mainly found in milk
Riboflavin is protein-bound and is not toxic in excess
Niacin (B3) is found in cereals, but its bioavailability is low
Niacin deficiency can lead to pellagra, which is characterized by dermatitis, diarrhea, and dementia
Pyridoxine (B6) is essential for amino acid metabolism and haem synthesis
Pyridoxine deficiency can lead to seizures, Down's syndrome, and autism
Folate and vitamin B12 are essential for the synthesis of 1-carbon units

Folate and Vitamin B12

Folate and vitamin B12 are essential for the synthesis of 1-carbon units
Folate is a carrier of 1-C fragments, and its active form is tetrahydrofolate
Vitamin B12 is a carrier of methyl groups and is essential for the synthesis of methionine
Folate and vitamin B12 are essential for the synthesis of purines and pyrimidines
Deficiency in folate and vitamin B12 can lead to megaloblastosis, which is characterized by giant germ cells and a lack of DNA synthesis

Methotrexate

Methotrexate is a drug used in chemotherapy, as an immunosuppressant, and to treat ectopic pregnancies
Methotrexate works by inhibiting the enzyme dihydrofolate reductase, which is necessary for the synthesis of tetrahydrofolate

Folate and Neural Tube Defects

Folate supplementation around conception time can prevent neural tube defects (anencephaly, spina bifida, encephalocele) in women who have had a previous pregnancy affected by these defects
In the UK, all pregnant women attending ante-natal clinics are prescribed folate supplements

Folate, B6, and B12 and Cardiovascular Mortality

Some studies have shown a link between high homocysteine concentrations and cardiovascular disease, but it is unclear whether this is a cause or effect
Some studies have shown that high-dose supplements of B vitamins can reduce the risk of cardiovascular disease, but others have not found this association

Folate, B6, and B12 and Alzheimer's Disease

Some studies have shown that high-dose supplements of B vitamins can reduce the rate of brain shrinkage in elderly people with mild memory problems.

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Description

This quiz covers the basics of vitamins and nutrition, including their history, importance, and how to determine nutrient intake. It's suitable for MBBS stage 1 students studying Nutrition and Metabolism.