NUTR 251 - final
Terms in this set (77)
What are 3 main sources of water for humans?
food, beverages, catabolic reactions (metabolic reactions)
What is the recommendation water intake for college students? (not in sports)
1 - 1.5 liters per every 1,000 calories
Approximately what percentage of water comes from foods eaten each day?
33% water comes from food (2/3 from beverages)
For a typical adult who consumed no food or water for the day, what is the estimated obligatory water loss?
500 ml (2 cups) per day
List the components of water lost by a typical adult who is eating and drinking
GI tract (feces)
What is extracellular water and intracellular water
Extracellular - fluid outside the cell (blood vessels and interstitial fluid) 1/3 of the boy's water, full of sodium and chloride
Intracellular - fluid within the cells, 2/3 of the water body's water, potassium, magnesium, phosphate and sulfate
Where is interstitial fluid?
between the cells
Describe the basic principal of osmosis which explains why fluids are maintained in these compartments
movement of water across a membrane toward more concentrated solutes - water flows to where there is more solutes
Filtration - blood flowing the capillaries is filtered by the glomerulus, Electrolytes, water and urea are filtered into the tubules of the nephron
Reabsorption - as needed, water and electrolytes are reabsorbed into the blood by the actions of osmosis and membrane pumps
Excretion - excess water, urea and electrolytes travel through the nephron tubules to the bladder and are excreted via urine
How much is reabsorbed? How much is excreted as urine?
water output exceeds input due to not enough water coming in and too much getting lost - more electrolytes outside of the cell so water flows to it, = concentration but dries out the cell
- hypothalamus signals pituitary to release this in response to dehydration. - tells kidney to reabsorb more water - elevates BP
enzyme released by kidney, responds to low BP, kidney reabsorbes sodium, water follows sodium, increases volume and blood pressure, hydrolyzes angiotensis
hydrolyzed by renin - angiotensin 1 to 2 - vasoconstrictor and stimulates aldosterone
stimulated by angiotensin, released by the adrenal glands, tells kidney to excrete potassium and reabsorb sodium
maintaining acid base balance, nerve impulse transmission and muscle contractions
sodium AI, UL, DV, tsp -> mg --> g
AI = 1500 mg
UL = 2300 mg
DV = 2400 mg
1 tsp = 2300 mg = 6 g
some people are less efficient at removing excess sodium and therefore experience HTN (25% of people with normal BP and 50% with high BP)
What other minerals may affect blood pressure regulation?
potassium, magnesium, calcium
dietary approach to stop hypertension
- high in fruits, vegetables, whole grains, lean meats, low fait dairy, nuts and seeds
- lower sodium, and increase potassium and magnesium intake
- reduces risk for kidney stones
Major function of potassium in the body
electrolyte balance, nerve transmission, muscle contraction, maintaining blood pressure by causing kidneys to excrete sodium
If blood clacium is rising...
calcitonin inhibits activation of vit D, reabsoption in kidney, intestines, and osteoclasts from breaking down bone
- lowered blood calcium levels
If blood calcium is falling...
PTH stimulates activation of vitamin D, PTH and D stimulate reabsorption in the kidneys, D enhances in the intestines, PTH/ D stimulate osteoclasts to break down bone.
Higher blood calcium levels
What percent of adults over 75 years of age have osteoporosis and about what percent are women?
1:3, 80% are women
- men have greater bone density, menopause = 20% loss, peak bone mass = 20s and declines in mid 30s
Osteoporosis and nutrition/ physical activity
- a low calcium diet during growing years limits the body's ability to reach their optimal bone density
- People who don;t drink a lot of milk - lower bone density and greater risk for fractures
- Being underweight increases risk because they have a smaller body frame size - decrease peak bone mass
Calcium AI, UL and 300 mg rule
AI = 1,000 mg per day
UL = 2,5000 mg per day
300 mg rule = 1 serving dairy which is close to the RDAs if you have 3 meals
factors that enhance calcium absorption
- hydrochloric acid, vitamin D, lactose (infants only), growth hormone ( adults = 30%, pregnancy/ children = 50- 60 %)
Trabecular bone vs. cortical bone
trabecular - stores Ca - gives it up when needed
cortical - 70- 80% of the bone, lose this after age 40
- iron embedded in a heme structure is found only in foods of animal origin and has high bioavailability (more absorbed) - meat, fish, poultry
- 25% absorbed
from plants or animals
- accounts for 90% of iron intake but not well absorbed
- broccoli, spinach, beans
- 17% absorbed
What are the roles of vitamin C and MFP factor in the absorption of nonheme iron? What does MFP stand for?
- Enhance absorption
- meat, fish, poultry - peptide
lower bioavailability (% absorption)
- legumes, grain, rice
Roles of ferritin, ferroportin, blood tranferrin, hepcidin
Ferritin - the iron storage protein
Ferroportin - the transmembrane protein that transports iron from the inside of the cell to the outside (door watch)
Blood tranferrin - the iron transport protein (chaperone that brings it around)
Hepcidin - a hormone produced by the liver that regulated iron balance (very reactive dont want it going around all willy nilly)
- Hereditary iron overload is the most common genetic disorder in the US
- Genetic failure to prevent unneeded iron from being absorbed - iron overload and tissue damage
- Risk of diabetes, liver cancer, heart disease, arthritis, infections (bacteria love iron rich blood)
- may cause hemosiderosis- Fe accumalates in liver, heart, joints
- caused by a mutation in a gene that controls the amount of iron your body absorbs from the food you eat
RDA for iron
men - 8 mg/ day
women - 18 mg/day (19-50) and 8 mg (>50)
Which groups of individuals are MOST at risk for iron deficiency anemia
- women, pregnant women especially young, growing children, low economic groups
- pica - pregnant women have strange cravings - consequence is enemia since foods have low iron
Iron deficiency anemia
- depleted iron stores, depleted iron transport and reduced RBC production.
- low hemoglobin, ad small pale red blood cells
- anemia that impair hemoglobin are microcytic
Iron deficiency anemia - symptoms
- blue sclera, decreased immunity, energy, wound healing , resistance to cold (pica - not edible)
- pale skin, nail beds, eye membranes, concave nails
- fatigue, weakness, apathy, behavior changes
- regulate immune function, thyroid, motor/ cognitive, insulin, vitamin A metabolism, taste, wound healing
What are the symptoms of zinc deficiency? Why are children in developing countries particularly susceptible to zinc deficiency?
- severe zinc deficiency is characterized by growth retardation and delayed sexual maturity in children and adolescents
- zinc is found in protein rich food which may be lacking in developing countries
Describe the similarities and differences of the regulation of iron and zinc absorption in the small intestine.
similarity - phytates influence absorption, limiting its bio-availability
differences - zinc goes through the small intestines, out to the body then comes back to the small intestines
What is the role of metallothionein?
storing and distributing zinc throughout the body
List 4 good sources of zinc in the US food supply.
1. red meats - steak
2. shell fish - oysters
3. milk, cheese
4. whole grains
5. fortified cereals
What is the role of iodine in the body?
- part of the structure of thyroid hormone, thyroxine
- BMR, body temp, groth, reproduction, muscle function, energy metabolism
Iodine deficiency during pregnancy
- severe mental and physical retardation of the developing fetus - cretinism
What is the effect of iodine deficiency on the thyroid gland?
thyroxine production declines, body responds by secreting more TSH to accelerate iodine uptake by the thyroid gland - gland enlarges to catch as much iodine as it can and this leads to development of a goiter
Where and when in the US were goiters prevalent and how was it resolved?
- Rocky Mountain Region - soil not rich in iodine
- Iodized salt
what is the role of fluoride in reducing tooth decay?
Fluoride replaces the hydroxyl group in hydroxyapatite and forms an even stronger compound, fluorapatite, which makes the teeth stronger and more resistant to tooth decay
What are the functions of chromium with the body?
- chromium is essential mineral that plays a role in carbohydrate and lipid metabolism. it helps maintain glucose homeostasis by enhancing insulin activity
- powerful antioxidant
- relative of beta- carotine
- yellow pigment
- berries, citrus, oregano, purple grapes, black and green tee
- protects arteries from high fat diets
- red wine
- may inhibit enzymes that activate carcinogens
Describe the role of the placenta in providing nutrients to the fetus and in the regulation of fecal growth
- the placenta is a metabolically active organ producing hormones that regulate fetal growth and maternal support tissue
- The maternal blood transfers oxygen and nutrients to the fetus blood and picks up fetal waste products.
- intense development and rapid cell division; critical -cellular activities can occur only at those times
- first trimester
Why do formulations of vitamin/mineral supplements omit preformed vitamin A (retinol)?
too much vitamin A can cause toxicity, generally use beta carotene instead
- birth defects??
What public health measure is now in place to try to reduce the incidence of neural tube defect? Has it been successful? When is the critical period in terms of risk for neural tube defect? why aren't all women at risk?
- critical period for neural tube defect is 17- 30 days
- grains have been fortified with folate - has improved status
- spina bifida is when vertebrae of the spine do not close and causes central nervous system disorders
- not all women are at risk because they have enough folate
pregnant women - caffeine, alcohol use and fish consumption
- caffeine - 1 cup of coffee or 2 cups of of coke
- alcohol should be avoided because it causes fetal alcohol poisoning
- Fish have high levels of mercury which can be harmful to the brain and nervous system
- For fish avoid eating shark, swordfish, king mackerel, and tilefish, golden snapper, and golden bass. limit to 12 ounces
Health professionals recommend an extra 330 kcals per day for a lactating woman. However, 500 kcal per day are actually needed. Why this difference?
the fat stores from being pregnant make up the difference
Advantages of breastfeeding for the infant
-Providing the appropriate composition and balance of nutrients with high bio availability.
-Provides hormones that promote physiological development
-Improves cognitive development
-Protects against a variety of infections and illnesses, including diarrhea, ear infections, and pneumonia
-May protect against some chronic diseases- such as diabetes (both types), obesity, atherosclerosis, asthma, and hypertension later in life.
- colostrum - first few days after delivery, antibiotics and WBC
- bifidus factors - growth of good bacteria in GI
- Lactoferrin - binds iron in breast milk and prevents growth of harmful bacteria
- growth factors - healthy GI development
- lipase enzymes - protects from infection
Advantages of breastfeeding for mothers
-Delays the return of regular ovulation, thus lengthening birth intervals - iron conserved
-may protect against breast and ovarian cancer and reduce the risk of diabetes
-Increase energy expenditure, which may contribute to weight loss
What nutrients would need to be supplemented during the first 6 months in an exclusively breast-fed infant?
- single dose of vit K at birth
- vit D at birth - 400 IU/day
- iron and fluoride supplementation
If a woman wanted to get pregnant in the next year, what nutrients should the woman pay close attention to before pregnancy and continue to get adequate amounts throughout pregnancy? Why?
- iron - enlarge maternal blood volume and blood loss during birth
- calcium and vit D - important for teeth and bone development
- vit D activates enzyme for folate (neural tube defect)
- zinc - DNA and RNA synthesis
What nutrients show a dramatic increase in absorption during pregnancy?
calcium and iron
What are the changes in energy needs for each trimester of pregnancy?
increase from an additional 350 calories per day to an additional 450 calories per day
in the first few days after delivery in the breast milk, high in antibodies and WBC
What is the "let down" reflex? What causes "let down" to happen?
oxytocin - reflux occurs when infant starts nursing, nerves in the breast send signals that brings milk to front of the breast
prolactin - hormone - milk production
What is nursing bottle tooth decay? How would you prevent this?
extensive tooth decay due to prolonged tooth contact with formula, mik, fruit juice, or other carbohydrate-rich liquid offered to an infant through in a bottle
What should be the first solids introduced to the infant? When and why?
- Offer iron fortified rice cereal first, then pureed strained vegetables, fruits or meats.
- Introduce solids gradually to aid in identifying food allergies. (one new food per week)
- 4 - 6 months
What advice would you give a woman regarding caloric intake and weight gain?
women would healthy BMI should gain 20 -30 pounds during pregnancy
- underweight - 28-40
- overweight 15- 25
Why shouldn't infants and children under age 2 years be fed honey or corn syrup?
Because they may develop botulism
What strategies are useful to try if a child is reluctant to taste a new food?
- encourage by having family eat the same foods, be patient, mix it with other foods, form a routine, get child involved in food purchasing and preparation, minimize distractions, avoid short- order cooking
What is the WIC program? Who does it serve?
A high quality, cost effective health care and nutrition services program for women, infants and children in the US
What does it mean if an infant over the course of 6 months is tracking at the 25th percentile for weight and 50th percentile for height? Why do health professionals track growth by the CDC charts?
- plotting the pattern of growth is the first way to assess nutritional status in infants 0 - 1 years old and children. CDC supplies national growth charts for health professionals and parents
- 25th percentile means 25% are lower and 75% higher
- important to note when infant rapidly changes - healthy infant doubles birth weight during first 5 months and triples by 1 year
Why should an infant in the first 6 months of life not be fed cow's milk?
- contains casein and may cause intestinal bleeding and anemia
- after 12 months
- after 2 years - reduced fat
Why is infant cereal or pureed meat important as second foods (first food is breast milk or formula) for 6 month old infants?
human milk is low in iron
What could be the consequences of a young child drinking too much milk or too much juice? How much is too much?
- These situations can interfere with children eating iron rich foods at critical time for brain growth and development
- milk anemia - increase milk, displaces Fe rich foods (2-3 cups per day)
- Avoid juice till they can use a cup - diarrhea or intestinal upset (sugar alcohols like apple juice) (less than 4 -6 ounces = 1/2 cup)