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Questions and Answers
What is the main difference between water-soluble and lipid-soluble vitamins in terms of their storage in the body?
What is the main difference between water-soluble and lipid-soluble vitamins in terms of their storage in the body?
- Water-soluble vitamins are stored in the liver, while lipid-soluble vitamins are stored in fatty tissues.
- Lipid-soluble vitamins are excreted through urine, while water-soluble vitamins are stored in the liver.
- Water-soluble vitamins are stored in fatty tissues, while lipid-soluble vitamins are excreted through urine.
- Water-soluble vitamins are not stored in the body, while lipid-soluble vitamins are stored in fatty tissues and the liver. (correct)
What is the main reason for vitamin deficiency in humans?
What is the main reason for vitamin deficiency in humans?
- Inadequate dietary intake
- Impaired absorption of vitamins from food
- Humans are unable to synthesize vitamins
- All of the above (correct)
Which of the following vitamins is NOT a water-soluble vitamin?
Which of the following vitamins is NOT a water-soluble vitamin?
- Vitamin B12
- Vitamin B6
- Vitamin A (correct)
- Vitamin C
What is the potential risk of excessive consumption of lipid-soluble vitamins?
What is the potential risk of excessive consumption of lipid-soluble vitamins?
Which of the following groups may be at higher risk of vitamin deficiency?
Which of the following groups may be at higher risk of vitamin deficiency?
What is the main purpose of prescribing vitamins in general?
What is the main purpose of prescribing vitamins in general?
What is the name of the form of Vitamin A?
What is the name of the form of Vitamin A?
What is the reason for conducting large prospective placebo-controlled intervention trials?
What is the reason for conducting large prospective placebo-controlled intervention trials?
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Study Notes
Vitamins and Minerals
- Vitamins are classified into two categories: water-soluble and fat-soluble.
- Water-soluble vitamins include:
- Vitamin C
- Vitamin B1 (Thiamine)
- Vitamin B2 (Riboflavin)
- Vitamin B3 (Niacin)
- Vitamin B6 (Pyridoxine)
- Vitamin B9 (Folic Acid)
- Vitamin B12
- Fat-soluble vitamins include:
- Vitamin A
- Vitamin D
- Vitamin E
- Vitamin K (not listed but important)
- Minerals include:
- Iron
- Zinc
- Copper
- Iodine
- Selenium
Importance of Classification
- Water-soluble vitamins are not stored in the body and are excreted through urine when consumed in excess.
- Fat-soluble vitamins are stored in fatty tissues and the liver and are not excreted as readily, potentially leading to toxicity if consumed excessively.
General Physiology of Vitamins
- Humans are unable to synthesize adequate amounts of vitamins.
- Vitamin deficiency can result from:
- Inadequate dietary intake
- Increased demand (e.g. pregnancy or growth)
- Impaired absorption (e.g. coeliac disease, cystic fibrosis, pancreatic insufficiency or certain drugs)
- Vitamin deficiencies are rarely diagnosed in the UK, but their true incidence may be under-recognized, particularly in:
- Elderly
- Alcoholics
- Poor people
- Certain ethnic groups
Vitamin A (Retinoic Acid) and Its Derivatives
- Vitamin A exists in several forms that are interconverted.
- Retinol (vitamin A1) is a primary alcohol and is present in the tissues of animals and marine fishes.
- 3-dehydroretinol (vitamin A2) is present in freshwater fish.
- Retinoic acid has some but not all of the actions of retinol.
- Carotene is provitamin A and is readily converted into retinol in the body.
- Vitamin A has many physiological functions, including:
- Promoting growth and development
- Preventing night blindness
- Preventing keratomalacia and dry eyes
- Preventing keratinization of the skin
- Dietary sources of vitamin A include:
- Eggs
- Fish liver oil
- Liver
- Milk
- Vegetables
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