Vitamines

• Vitamins are measured in milligrams (one-thousandth of 1g) or micrograms (one-millionth of 1g)
• Vitamins are usually obtained from foods, except for Vitamin D which can be obtained from sunlight
• Megadose of a vitamin is 10 times the R.D.A. and can have toxic effects, for example, Vitamin D
• Vitamins are classified into fat-soluble (D, E, K, A) and water-soluble (B group vitamins, C)
• Fat-soluble vitamins can be stored in the body (D, E, K, A), while water-soluble vitamins need to be consumed daily (B group vitamns, C)
• Vitamin A is essential for normal vision, iron metabolism, and the immune system
• Vitamin A can be obtained as retinol from animal sources or as beta carotene from plant sources
• Vitamin D is crucial for the absorption of calcium and phosphorus, maintaining bone health, muscle function, and the immune system
• Vitamin D is mainly synthesized in the skin following sunlight exposure, found in oily fish, meat, eggs, and fortified foods
• Deficiency of Vitamin D can lead to conditions like rickets (leg bones become weakened/bent) in children and osteoporosis in adults (similar to rickets)
• Sources of B vitamins include whole grains, nuts, meat, milk, eggs, and fortified breakfast cereals
• Vitamin C helps with iron absorption, prevents infection, strengthens blood vessels, aids wound healing, and prevents scurvy
• Sources of Vitamin C include blackcurrants, citrus fruits, green vegetables, and parsley
• Severe deficiency of Vitamin C leads to scurvy, characterized by fatigue, weakness, and poor wound healing
• To reduce Vitamin C loss, avoid cutting vegetables long before cooking, minimize water usage, avoid overcooking, and use fruits and vegetables quickly after purchase
• Green vegetables are beneficial in our diet due to their sources of folate, Vitamin C, and other essential nutrients
• Folic acid deficiency can lead to neural tube defects in newborns, such as Spina Bifida, and anaemia
• Spina Bifida is a condition affecting about one in every 1000 children born per year in Ireland, with one of the highest incidences in the world
• Vitamin C is lost by chopping, shredding, and reheating vegetables due to the release of enzymes that destroy it
• Fat-soluble:

  • can be stored in the body (D,E, K, A)
  • not required daily as the body can build up stores in the liver and fatty tissues for future use
  • mainly found in fatty foods and animal products
• Vitamin A: 2 forms

  • retinol - ready made from animal source
  • beta carotene - from plant sources, from which retinol can be made in the body
• The concentration of vitamin A is usually expressed as retinol equivalents (RE)
• Vitamin A is found (as retinol) in liver and whole milk.
• Beta-carotene provided by dark green leafy vegetables, carrots, and orange coloured fruit can also be converted to retinol to provide vitamin A
• In the UK margarine must be fortified with vitamin A and D by law.
• Vit A is necessary for normal vision and prevents night blindness
• Excess retinol during pregnancy can lead to birth defects

  pregnant women should not consume liver and liver pâté as high levels of retinol may be present.
• Sources of vitamin A: (animal)

  • oily fish
  • liver
  • dairy products
  • egg yolk
• Sources of carotene: (Vit A)

  • carrots, tomatoes, apricots (red/orange coloured)
  • green veg.
• Vitamin D is needed for:

  • the absorption and use of calcium and phosphorus
  • normal blood calcium levels
  • the maintenance of normal bones and teeth
  • the maintenance of normal muscle function
  • the normal function of the immune system
• Sources of vitamin D: (no plant source!)

  • sunlight
  • oily fish (salmon, mackerel, tuna)
  • meat, eggs
  • margarine spreads
  • fortified cereals
• Deficiency of vitamin D:

  • commonly with people who have darker skin, wear concealing clothes, or are housebound
• Links have also been made between poor vitamin D status and an increase in falls in elderly people, which is thought to be linked to an adverse effect on muscles
• Vitamin B:

  • number of B vitamins, each with a specific function in the body
  • regular intake is required as the body is unable to store water-soluble vitamins
• The different types of B vitamins are:

  • vitamin B1 (Thiamin)
  • vitamin B2 (Riboflavin)
  • vitamin B3 (Niacin)
  • vitamin B6
  • vitamin B12
  • folate
• B group vitamin functions:

  • release energy from CHO foods
  • correct functioning of nerves
• Thiamin funciton: (Vit B1)

  • release of energy from carbohydrates
  • normal function of the nervous system and heart
• Sources of Thiamin: (Vit B1)

  • Wholegrains, nuts, meat, milk, fruit, vegetables and fortified breakfast cereals
  • White and brown flour in the UK are fortified with thiamin
• Thiamin deficiency (Vit B1) causes the nervous system disease beri-beri
• Riboflavin functions: (B2)

  • release energy from protein, carbohydrate and fat
  • transport and metabolism of iron in the body
  • normal structure and function of mucous membranes and the skin