Vitamins and Minerals · 2018. 9. 6. · Vitamin D •Chronic excess ingestion of vitamin D may be...
Transcript of Vitamins and Minerals · 2018. 9. 6. · Vitamin D •Chronic excess ingestion of vitamin D may be...
Vitamins and Minerals
Vitamins
• Vitamins are substances made by plants and animals (organic molecules with carbon backbone) that are required in relatively small amounts.
• Vitamins function as co-enzymes – needed for enzymes to work
• Any vitamin that is missing from the diet will cause a specific deficiency.
Vitamins• Fat soluble:
– A,D,E,K
– Carried in the blood by protein carriers, can be stored in the liver and other fatty tissues and may build up to toxic concentrations
• Water soluble:– B vitamins – thiamin (B1), riboflavin (B2), niacin
(B3), folate, vitamin B12, vitamin B6, biotin, pantothenic acid, Vitamin C
– Absorbed directly into the blood stream, not stored in any tissues, excesses are excreted in urine
Vitamin A
• Retinol and other forms, or carotenoids from plants
• Involved in immune function, and critical for vision as a part of the light perception of the retina
• Preformed vitamin A is found in foods from animal sources such as dairy, fish, meat (especially liver)
• Provitamin A – beta-carotene is converted by the body into the active form – is found in orange fruits and vegetables such as sweet potato, carrots and leafy green vegetables
Vitamin A deficiency
• Deficiency is rare in Canada, but common in many developing countries, because residents have limited access to animal products, and foods containing beta-carotene due to poverty.
• The most common symptom of vitamin A deficiency is blindness which starts out as night blindness.
• Deficiency also causes increased risk of infections due to weak immune response.
Health Risks
• Excess intake of preformed vitamin A can be toxic.
• Arctic explorers who ate polar bear liver experienced a range of symptoms including death.
Vitamin D
• Unique – the body can synthesize all it needs with the help of sunlight
• Maintains calcium and phosphorus levels for strong bones
• Deficiency is the disease rickets – softening of the bones.
Vitamin D
• Chronic excess ingestion of vitamin D may be toxic to the body – anorexia, and calcium deposits in soft tissue
• When UV light from the sun shines on a cholesterol compound in human skin the compound is transformed into vitamin D precursor
• Dark skinned people require longer exposure to direct sun than light skinned for vitamin D production
• Vitamin D is also found in fortified milk
Vitamin E - Tocopherol
• An antioxidant – defends the body against oxidative damage
• No Vitamin E deficiency in humans since the vitamin is found in many foods
• Also the body stores vitamin E
• Found in raw oils – but destroyed by cooking
Vitamin K
• Help make proteins that help clot blood
• Also necessary for bone formation
• Can be obtained from non-food source:
– Intestinal bacteria synthesize vitamin K
• Also available in green leafy vegetables such as spinach and cabbage.
Water soluble vitamins
• The B vitamins and vitamin C are easily absorbed from food, but any excess is also easily excreted in urine.
• B vitamins are coenzymes – a molecule that combines with an enzyme for it to function properly
• The active forms of thiamin, riboflavin, niacin, pantothenic acid and biotin participate in the release of energy from carbohydrate, fat and protein
• Vitamin B6 helps the body use amino acids to make proteins
• Folate and vitamin B12 help cells to multiply, important for cells that reproduce frequently
Thiamin and Riboflavin
• Thiamin deficiency is beriberi – edema (fluid accumulation) or muscle wasting
• Riboflavin deficiency occurs with thiamin deficiency but symptoms are not as severe.
• A diet that contains sufficient thiamin will also have enough riboflavin.
• Found in milk, black beans, enriched cereal, and yogurt
Niacin
• Niacin participates in energy metabolism.
• Niacin can be formed from eating the amino acid tryptophan
• Deficiency is pellagra which was prevalent in diets relying on corn for protein source.
• Niacin or tryptophan is found in meat, and enriched cereal.
Folate
• Women of childbearing age should consume a folate supplement as prevention, since the defects occur in the first days or weeks of pregnancy.
• Folate is added to cereals, but also found in asparagus, and beef liver.
• Helps to make DNA, necessary for new cells
• Folate deficiency is associated with a group of birth defects called neural tube defects.
Vitamins B12 and B6
• Vitamin B12 works closely with folate. Involved in proper nerve function
• Deficiency symptoms begin with anemia, but more severe symptoms such as paralysis and malfunctioning of nerves occur if deficiency continues.
• B12 is only available through animal sources, such as cheese, and meat, so vegans, vegetarians, may become deficient.
• Vitamin B6 helps to convert amino acid into another essential nutrient.
Biotin and Pantothenic Acid
• Important in energy metabolism, as coenzymes for metabolism of carbohydrate, fat and proteins
• Healthy people eating ordinary diets are not at risk for deficiences.
Vitamin C
• Two hundred years ago sailors on long voyages often died of scurvy. Doctors attempting to treat the disease found that citrus fruits cured the disease, and later scientists discovered vitamin C or ascorbic acid in citrus.
• Involved in the formation of collagen – connective tissue.
• Acts as an antioxidant protecting the body, and in immune system function
• Is found in citrus fruit but also broccoli and red pepper.
Water
• Importance of water:
• Clears tissues and blood of wastes
• Serves as a solvent for minerals, vitamins, amino acids, glucose, and other small molecules
• Actively participates in many chemical reactions
• Serves as a shock absorber in eyes, spinal cords, joints
• Aids in maintaining the body’s temperature
How much water do you need to drink?
• Water needs vary greatly depending on the food a person eats, the environmental temperature and humidity, and the person’s activity level.
• Under normal conditions adults need between 1 and 1.5 milliliters of water from all sources for each calorie spent in the day.
• A person who expends about 2000 calories needs between 2 and 3 litres of water.
Signs of dehydration
• Mild (a loss of less than 5% of your body weight)
– Thirst
– Sudden weight loss
– Rough dry skin, dry mouth, throat, body linings
– Rapid pulse
– Low blood pressure
Signs of dehydration
• Severe (a loss of more than 5% of your body weight)– Pale skin
– Bluish lips, fingertips
– Confusion, disorientation
– Rapid, shallow breathing
– Thickening of blood
– Shock, seizures
– Coma, death
Calcium
• Most abundant mineral in the body, 99% stored in bones and teeth
• Both calcium and phosphorus are needed for bone formation
• Calcium is present in blood at a constant level
• Calcium in body fluids is important for:– Nerve transmission, blood pressure, blood
clotting, muscle contraction and activating enzymes.
Calcium
• Recommended intakes are highest for adolescents since bone growth is active.
• Adults after 40 begin to lose bone density, and need to get sufficient calcium.
• Calcium is present in dairy products, and also broccoli and turnip greens
Phosphorus
• Phosphorus is a part of the DNA and RNA of every cell, and is essential for growth and renewal of tissues
• Phosphorus deficiencies are unknown since phosphorus is abundant in cells
• Foods that contain phosphorus include dairy products, meats, and legumes
Magnesium
• Critical to many cell functions as a part of the enzyme machinery
• Magnesium is also important for proper functioning of the heart
• Magnesium deficiency may be related to cardiovascular disease, heart attack, and high blood pressure
• Most people receive only 75% of recommended magnesium
• Magnesium can be found in spinach, avocado, yogurt and black beans
Sodium
• Chemically sodium is the positive ion in the compound sodium chloride (table salt) and a gram of salt contains 400 milligrams of sodium
• The amount of sodium most diets contain is more than 2300 mg.
• Sodium is present in high levels in many processed foods.
• Sodium is a major part of the body’s fluid and electrolyte balance and acid-base balance
• High intake of sodium causes temporary higher blood pressure as more water is needed to offset the amount of salt in the body
• Excess sodium is filtered by the kidneys while they also remove excess water with the salt.
Potassium
• Plays a major role in maintaining fluid and electrolyte balance, and it is critical for maintaining the heartbeat
• Potassium deficiency is unlikely
• All living cells contain potassium, so fresh foods are the best source, such as: bananas, melons, and baked potato
Iodine
• Iodine is needed in very small amounts.
• It is a part of thyroxine a hormone made by the thyroid gland.
• This hormone regulates basal metabolic rate
• In iodine deficiency the cells of the thyroid enlarge and can become a visible lump, in pregnant women the deficiency results in serious mental retardation of the child.
• All table salt is iodized in Canada
Iron• Most of the iron in the body is found in
hemoglobin in red blood cells, or myoglobin in muscle cells
• Iron helps these proteins to hold and carry oxygen
• The body recycles the iron that is in blood cells, so bleeding can cause significant iron loss
• Iron deficiency can lead to anemia where red blood cells don’t contain enough hemoglobin.
• A person with anemia will have a diminished supply of oxygen, resulting in tiredness, apathy and a tendency to feel cold.
• Women require 1.5 times more iron in their diet.
• Iron is present in spinach, swiss chard, enriched cereal and red meat