Vitamins, minerals and trace elements Flashcards
How are vitamins absorbed?
Fat soluble vitamins (K, A, D and E) are solubilised into micelles and absorbed in small intestine
Water soluble vitamins are absorbed by diffusion or mediated transport, mainly in the jejunum
Vitamin B12 and intrinsic factor complex absorbed in terminal ileum
MUST - Malnutrition Universal Screening Tool. 5 steps.
1 - Measure height and weight to get a BMI score
2 - Note percentage unplanned weight loss
3 - Establish acute disease effect and score.
4 -Add scores from steps 1, 2 and 3 together to obtain overall risk of malnutrition.
5 - Use management guidelines and/or local policy to develop care plan.
BMI
BMI is a person’s weight in kilograms (kg) divided by his or her height in meters squared. The National Institutes of Health (NIH) now defines normal weight, overweight, and obesity according to BMI.
Digestion and absorption of lipids
- Lipase breaks bonds forming a monoglyceride and 2 fatty acids (colipase from pancreas binds lipase to cell surface)
- Large droplets are broken down by mechanical disruption of GI tract and emulsified by bile salts
- They form micelles (which act as holding stations, this maintains the diffusion gradient)
- Uptake into epithelial cell of intestine, smooth endoplasmic reticulum contains enzymes for triglyceride synthesis
- Vesicles containing fat molecule pinch off cell membrane
forming chylomicrons which are taken up by lymphatics and blood system - Lipoprotein lipase is activated in the capillary and converts triglycerides to fatty acids and glycerol
- fatty acid are taken into cell and either reesterfied for storage or oxidised for use as fuel
Digestion and absorption of proteins
Pepsin in the stomach
Pancreatic endopeptidases and exopeptidases in the small intestine
Free amino acids are absorbed in the small intestine by active transport coupled to sodium
Digestion and absorption of carbohydrates
- Digestion starts in the mouth with amylase
- Gastric acid in stomach, deactivates amylase
- Pancreatic enzymes in the small intestine (95% amylase- converts into disaacharides, maltose and mix of short branched changes of glucose molecules)
- BB enzymes break down into monosaccharides
- Absorbed into enterocyte through villi (Na+/glucose, galactose cotransporter) (fructose via GLUT5 carrier)
- Absorbed into blood stream via GLUT2 protein (fructose, glucose and galactose)
Complex polysaccharides are partially digested in the large intestine by bacteria
What is the vitamin B complex
Vitamin B is composed of 8 substances
- essential for the working of certain enzymes in the body
- not chemically related
- generally found together in the same foods.
- They include thiamine ( vitamin B1 ), riboflavin ( vitamin B2 ), pyridoxine ( vitamin B6 ), and cyanocobalamin ( vitamin B12 ).
What can vitamins be classed into? give some examples
- Water-soluble (form coenzymes, NAD, FAD, coenzymeA)
- fat soluble (K, A, D, E, ) -poorly excreted
What does Vit A do?
- forms light-sensitive pigment in eye
- can lead to night time blindness
What is malabsorption?
-When foods are not absorbed properly
eg, if there is interference with bile salt production or action in small intestine fat soluble vitamins and fats will not be absorbed properly
eg 2. celiac’s disease/gluten-senstive enteropathy/non-tropical sprue = autoimmune mediated loss of intestinal SA due to sensitivity to gluten. Loss of BB = decreased absorption of many nutrients = vitamin D = decreased calcium ion absorption in GI tract
How are most water-soluble vitamins absorbed?
Via diffusion or mediated transport
How is B12 absorbed?
-Large charged molecule
-Terminal ileum
-binds to intrinsic factor in stomach (secreted by parietal cells in stomach/)
-bound B12 then binds to specific sites on epithelial cells in terminal ileum
-absorbed via endocytosis
B12= erythrocyte production so deficiencies = pernicious anemia (can be due to stomach removal or when intrinsic factor is not secreted properly, or terminal ileum removal)
treatment = B12 injections
What is hemochromatosis?
Large ingestion of iron, increased iron deposition in tissues, changes in skin pigmentation, diabetes mellitus, liver and heart failure, decreased testicular function
- can be genetic when ingestion is normal
- frequent blood transfusions
What is vit C needed for, name some sources
Ascorbic acid (vitamin C)
Antioxidant; part of an enzyme needed for protein metabolism; important for immune system health; aids in iron absorption
Found only in fruits and vegetables, especially citrus fruits, vegetables in the cabbage family, cantaloupe, strawberries, peppers, tomatoes, potatoes, lettuce, papayas, mangoes, kiwifrui
What is vit B12 needed for, name some sources
Cobalamin (vitamin B12)
Part of an enzyme needed for making new cells; important to nerve function
Meat, poultry, fish, seafood, eggs, milk and milk products; not found in plant foods
What is folic acid needed for, name some sources
Folic acid
Part of an enzyme needed for making DNA and new cells, especially red blood cells
Leafy green vegetables and legumes, seeds, orange juice, and liver; now added to most refined grains
What is vit A needed for, name some sources
Vitamin A (and its precursor*, beta-carotene)
- FAT SOLUBLE
- A precursor is converted by the body to the vitamin.
Needed for vision, healthy skin and mucous membranes, bone and tooth growth, immune system health
Vitamin A from animal sources (retinol): fortified milk, cheese, cream, butter, fortified margarine, eggs, liver
Beta-carotene (from plant sources): Leafy, dark green vegetables; dark orange fruits (apricots, cantaloupe) and vegetables (carrots, winter squash, sweet potatoes, pumpkin)
What is vit D needed for, name some sources
Vitamin D
-FAT SOUBLE
Needed for proper absorption of calcium; stored in bones
Egg yolks, liver, fatty fish, fortified milk, fortified margarine. When exposed to sunlight, the skin can make vitamin D.
What is vit E needed for, name some sources
Vitamin E
-FAT SOLUBLE
Antioxidant; protects cell walls
Polyunsaturated plant oils (soybean, corn, cottonseed, safflower); leafy green vegetables; wheat germ; whole-grain products; liver; egg yolks; nuts and seeds
What is vit K needed for, name some sources
Vitamin K
-FAT SOLUBLE
Needed for proper blood clotting
Leafy green vegetables and vegetables in the cabbage family; milk; also produced in intestinal tract by bacteria
What is sodium needed for, name some sources
Sodium
Needed for proper fluid balance, nerve transmission, and muscle contraction
Table salt, soy sauce; large amounts in processed foods; small amounts in milk, breads, vegetables, and unprocessed meats
What is chloride needed for, name some sources
Chloride
Needed for proper fluid balance, stomach acid
Table salt, soy sauce; large amounts in processed foods; small amounts in milk, meats, breads, and vegetables
What is potassium needed for, name some sources
Potassium
Needed for proper fluid balance, nerve transmission, and muscle contraction
Meats, milk, fresh fruits and vegetables, whole grains, legumes
What is calcium needed for, name some sources
Calcium
Important for healthy bones and teeth; helps muscles relax and contract; important in nerve functioning, blood clotting, blood pressure regulation, immune system health
Milk and milk products; canned fish with bones (salmon, sardines); fortified tofu and fortified soy milk; greens (broccoli, mustard greens); legumes
What is phosphorus needed for, name some sources
Phosphorus
Important for healthy bones and teeth; found in every cell; part of the system that maintains acid-base balance
Meat, fish, poultry, eggs, milk, processed foods (including soda pop)
What is magnesium needed for, name some sources
Magnesium
Found in bones; needed for making protein, muscle contraction, nerve transmission, immune system health
Nuts and seeds; legumes; leafy, green vegetables; seafood; chocolate; artichokes; “hard” drinking water
What is sulfur needed for, name some sources
Sulfur
Found in protein molecules
Occurs in foods as part of protein: meats, poultry, fish, eggs, milk, legumes, nuts
What is iron needed for, name some sources
Iron
Part of a molecule (hemoglobin) found in red blood cells that carries oxygen in the body; needed for energy metabolism
Organ meats; red meats; fish; poultry; shellfish (especially clams); egg yolks; legumes; dried fruits; dark, leafy greens; iron-enriched breads and cereals; and fortified cereals
What is zinc needed for, name some sources
Zinc
Part of many enzymes; needed for making protein and genetic material; has a function in taste perception, wound healing, normal fetal development, production of sperm, normal growth and sexual maturation, immune system health
Meats, fish, poultry, leavened whole grains, vegetables
What is iodine needed for, name some sources
Iodine
Found in thyroid hormone, which helps regulate growth, development, and metabolism
Seafood, foods grown in iodine-rich soil, iodized salt, bread, dairy products
What is selenium needed for, name some sources
Selenium
Antioxidant
Meats, seafood, grains
What is fluoride needed for, name some sources
Fluoride
Involved in formation of bones and teeth; helps prevent tooth decay
Drinking water (either fluoridated or naturally containing fluoride), fish, and most teas
What is chromium needed for, name some sources
Chromium
Works closely with insulin to regulate blood sugar (glucose) levels
Unrefined foods, especially liver, brewer’s yeast, whole grains, nuts, cheeses
What is copper needed for, name some sources
Copper
Part of many enzymes; needed for iron metabolism
Legumes, nuts and seeds, whole grains, organ meats, drinking water
What is manganese needed for, name some sources
Manganese
Part of many enzymes
Widespread in foods, especially plant foods
What is molybdenum needed for, name some sources
Molybdenum
Part of some enzymes
Legumes; breads and grains; leafy greens; leafy, green vegetables; milk; liver
How is fat stored within the body?
As triglcerides in adipose tissue (15kg)
How are carbohydrates stored within the body?
As glycogen in the liver and muscles (200g in the liver, 150g in the muscles)
How is protein stored within the body?
As protein in the muscles (6kg)
Energy values from carbohydrates
4kcal/g
Energy values from protein
4kcal/g
Energy values from lipids
9kcal/g
Energy values from alcohol (ethanol)
7kcal/g
SYMPTOMS OF MAL ABSORPTION
FATS = extremely foul-smelling stools, CA = BONE PAIN FOLATE = FATIGUE AND WEAKNESS BLEEDING/BRUSING = K AND C ANEMIA = B12, FOLATE
